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Flanders WH, Moïse NS, Otani NF. Use of machine learning and Poincaré density grid in the diagnosis of sinus node dysfunction caused by sinoatrial conduction block in dogs. J Vet Intern Med 2024; 38:1305-1324. [PMID: 38682817 PMCID: PMC11099791 DOI: 10.1111/jvim.17071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 03/27/2024] [Indexed: 05/01/2024] Open
Abstract
BACKGROUND Sinus node dysfunction because of abnormal impulse generation or sinoatrial conduction block causes bradycardia that can be difficult to differentiate from high parasympathetic/low sympathetic modulation (HP/LSM). HYPOTHESIS Beat-to-beat relationships of sinus node dysfunction are quantifiably distinguishable by Poincaré plots, machine learning, and 3-dimensional density grid analysis. Moreover, computer modeling establishes sinoatrial conduction block as a mechanism. ANIMALS Three groups of dogs were studied with a diagnosis of: (1) balanced autonomic modulation (n = 26), (2) HP/LSM (n = 26), and (3) sinus node dysfunction (n = 21). METHODS Heart rate parameters and Poincaré plot data were determined [median (25%-75%)]. Recordings were randomly assigned to training or testing. Supervised machine learning of the training data was evaluated with the testing data. The computer model included impulse rate, exit block probability, and HP/LSM. RESULTS Confusion matrices illustrated the effectiveness in diagnosing by both machine learning and Poincaré density grid. Sinus pauses >2 s differentiated (P < .0001) HP/LSM (2340; 583-3947 s) from sinus node dysfunction (8503; 7078-10 050 s), but average heart rate did not. The shortest linear intervals were longer with sinus node dysfunction (315; 278-323 ms) vs HP/LSM (260; 251-292 ms; P = .008), but the longest linear intervals were shorter with sinus node dysfunction (620; 565-698 ms) vs HP/LSM (843; 799-888 ms; P < .0001). CONCLUSIONS Number and duration of pauses, not heart rate, differentiated sinus node dysfunction from HP/LSM. Machine learning and Poincaré density grid can accurately identify sinus node dysfunction. Computer modeling supports sinoatrial conduction block as a mechanism of sinus node dysfunction.
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Affiliation(s)
- Wyatt Hutson Flanders
- Department of Clinical Sciences, College of Veterinary MedicineCornell UniversityIthacaNew YorkUSA
| | - N. Sydney Moïse
- Section of Cardiology, Department of Clinical Sciences, College of Veterinary MedicineCornell UniversityIthacaNew YorkUSA
| | - Niels F. Otani
- School of Mathematical SciencesRochester Institute of TechnologyRochesterNew YorkUSA
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2
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Bartolucci C, Ni H. Calcium-directed feedback control of the sinoatrial node robustness. Biophys J 2023; 122:1571-1573. [PMID: 37040769 PMCID: PMC10183369 DOI: 10.1016/j.bpj.2023.03.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 03/22/2023] [Accepted: 03/27/2023] [Indexed: 04/13/2023] Open
Affiliation(s)
- Chiara Bartolucci
- Department of Electrical, Electronic and Information Engineering "Guglielmo Marconi", University of Bologna - Cesena Campus, Cesena, Italy
| | - Haibo Ni
- Department of Pharmacology, University of California, Davis, Davis, California.
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3
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Kappadan V, Sohi A, Parlitz U, Luther S, Uzelac I, Fenton F, Peters NS, Christoph J, Ng FS. Optical mapping of contracting hearts. J Physiol 2023; 601:1353-1370. [PMID: 36866700 PMCID: PMC10952556 DOI: 10.1113/jp283683] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 02/27/2023] [Indexed: 03/04/2023] Open
Abstract
Optical mapping is a widely used tool to record and visualize the electrophysiological properties in a variety of myocardial preparations such as Langendorff-perfused isolated hearts, coronary-perfused wedge preparations, and cell culture monolayers. Motion artifact originating from the mechanical contraction of the myocardium creates a significant challenge to performing optical mapping of contracting hearts. Hence, to minimize the motion artifact, cardiac optical mapping studies are mostly performed on non-contracting hearts, where the mechanical contraction is removed using pharmacological excitation-contraction uncouplers. However, such experimental preparations eliminate the possibility of electromechanical interaction, and effects such as mechano-electric feedback cannot be studied. Recent developments in computer vision algorithms and ratiometric techniques have opened the possibility of performing optical mapping studies on isolated contracting hearts. In this review, we discuss the existing techniques and challenges of optical mapping of contracting hearts.
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Affiliation(s)
- Vineesh Kappadan
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Anies Sohi
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Ulrich Parlitz
- Biomedical Physcis GroupMax Planck Institute for Dynamics and Self‐OrganizationGöttingenGermany
| | - Stefan Luther
- Biomedical Physcis GroupMax Planck Institute for Dynamics and Self‐OrganizationGöttingenGermany
| | - Ilija Uzelac
- School of PhysicsGeorgia Institute of TechnologyAtlantaGAUSA
| | - Flavio Fenton
- School of PhysicsGeorgia Institute of TechnologyAtlantaGAUSA
| | - Nicholas S Peters
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
| | - Jan Christoph
- Cardiovascular Research InstituteUniversity of CaliforniaSan FranciscoCAUSA
| | - Fu Siong Ng
- National Heart and Lung Institute (NHLI)Imperial College LondonLondonUK
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4
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Kalyanasundaram A, Li N, Augostini RS, Weiss R, Hummel JD, Fedorov VV. Three-dimensional functional anatomy of the human sinoatrial node for epicardial and endocardial mapping and ablation. Heart Rhythm 2023; 20:122-133. [PMID: 36113768 PMCID: PMC9897959 DOI: 10.1016/j.hrthm.2022.08.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 08/25/2022] [Accepted: 08/30/2022] [Indexed: 02/05/2023]
Abstract
The sinoatrial node (SAN) is the primary pacemaker of the human heart. It is a single, elongated, 3-dimensional (3D) intramural fibrotic structure located at the junction of the superior vena cava intercaval region bordering the crista terminalis (CT). SAN activation originates in the intranodal pacemakers and is conducted to the atria through 1 or more discrete sinoatrial conduction pathways. The complexity of the 3D SAN pacemaker structure and intramural conduction are underappreciated during clinical multielectrode mapping and ablation procedures of SAN and atrial arrhythmias. In fact, defining and targeting SAN is extremely challenging because, even during sinus rhythm, surface-only multielectrode mapping may not define the leading pacemaker sites in intramural SAN but instead misinterpret them as epicardial or endocardial exit sites through sinoatrial conduction pathways. These SAN exit sites may be distributed up to 50 mm along the CT beyond the ∼20-mm-long anatomic SAN structure. Moreover, because SAN reentrant tachycardia beats may exit through the same sinoatrial conduction pathway as during sinus rhythm, many SAN arrhythmias are underdiagnosed. Misinterpretation of arrhythmia sources and/or mechanisms (eg, enhanced automaticity, intranodal vs CT reentry) limits diagnosis and success of catheter ablation treatments for poorly understood SAN arrhythmias. The aim of this review is to provide a state-of-the-art overview of the 3D structure and function of the human SAN complex, mechanisms of SAN arrhythmias and available approaches for electrophysiological mapping, 3D structural imaging, pharmacologic interventions, and ablation to improve diagnosis and mechanistic treatment of SAN and atrial arrhythmias.
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Affiliation(s)
- Anuradha Kalyanasundaram
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, Ohio; Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Ning Li
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, Ohio; Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Ralph S Augostini
- Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, Ohio; Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Raul Weiss
- Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, Ohio; Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - John D Hummel
- Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, Ohio; Division of Cardiovascular Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Vadim V Fedorov
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, Ohio; Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, Ohio.
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5
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Siles-Paredes JG, Crowley CJ, Fenton FH, Bhatia N, Iravanian S, Sandoval I, Pollnow S, Dössel O, Salinet J, Uzelac I. Circle Method for Robust Estimation of Local Conduction Velocity High-Density Maps From Optical Mapping Data: Characterization of Radiofrequency Ablation Sites. Front Physiol 2022; 13:794761. [PMID: 36035466 PMCID: PMC9417315 DOI: 10.3389/fphys.2022.794761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 06/15/2022] [Indexed: 01/10/2023] Open
Abstract
Conduction velocity (CV) slowing is associated with atrial fibrillation (AF) and reentrant ventricular tachycardia (VT). Clinical electroanatomical mapping systems used to localize AF or VT sources as ablation targets remain limited by the number of measuring electrodes and signal processing methods to generate high-density local activation time (LAT) and CV maps of heterogeneous atrial or trabeculated ventricular endocardium. The morphology and amplitude of bipolar electrograms depend on the direction of propagating electrical wavefront, making identification of low-amplitude signal sources commonly associated with fibrotic area difficulty. In comparison, unipolar electrograms are not sensitive to wavefront direction, but measurements are susceptible to distal activity. This study proposes a method for local CV calculation from optical mapping measurements, termed the circle method (CM). The local CV is obtained as a weighted sum of CV values calculated along different chords spanning a circle of predefined radius centered at a CV measurement location. As a distinct maximum in LAT differences is along the chord normal to the propagating wavefront, the method is adaptive to the propagating wavefront direction changes, suitable for electrical conductivity characterization of heterogeneous myocardium. In numerical simulations, CM was validated characterizing modeled ablated areas as zones of distinct CV slowing. Experimentally, CM was used to characterize lesions created by radiofrequency ablation (RFA) on isolated hearts of rats, guinea pig, and explanted human hearts. To infer the depth of RFA-created lesions, excitation light bands of different penetration depths were used, and a beat-to-beat CV difference analysis was performed to identify CV alternans. Despite being limited to laboratory research, studies based on CM with optical mapping may lead to new translational insights into better-guided ablation therapies.
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Affiliation(s)
- Jimena G. Siles-Paredes
- Graduate Program in Biotechnoscience, Federal University of ABC, São Paulo, Brazil
- HEartLab, Federal University of ABC, São Paulo, Brazil
- *Correspondence: Jimena G. Siles-Paredes,
| | | | - Flavio H. Fenton
- Georgia Institute of Technology, School of Physics, Atlanta, GA, United States
| | - Neal Bhatia
- Division of Cardiology, Section of Electrophysiology, Emory University Hospital, Atlanta, GA, United States
| | - Shahriar Iravanian
- Division of Cardiology, Section of Electrophysiology, Emory University Hospital, Atlanta, GA, United States
| | | | - Stefan Pollnow
- Karlsruhe Institute of Technology (KIT)/Institute of Biomedical Engineering, Karlsruhe, Germany
| | - Olaf Dössel
- Karlsruhe Institute of Technology (KIT)/Institute of Biomedical Engineering, Karlsruhe, Germany
| | - João Salinet
- Graduate Program in Biotechnoscience, Federal University of ABC, São Paulo, Brazil
- HEartLab, Federal University of ABC, São Paulo, Brazil
| | - Ilija Uzelac
- Georgia Institute of Technology, School of Physics, Atlanta, GA, United States
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Sekihara T, Aoyama D, Eguchi T, Uzui H, Tada H. Pseudo superior vena cava entrance block during sinus rhythm uncovered by continuous atrial pacing. J Arrhythm 2022; 38:653-655. [PMID: 35936030 PMCID: PMC9347197 DOI: 10.1002/joa3.12740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/16/2022] [Accepted: 05/15/2022] [Indexed: 11/07/2022] Open
Abstract
Usually, superior vena cava (SVC) entrance block is confirmed when SVC potentials disappear during sinus rhythm. We present a case of pseudo SVC entrance block during sinus rhythm, which was uncovered by continuous atrial pacing.
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Affiliation(s)
- Takayuki Sekihara
- Department of Cardiovascular Medicine, Faculty of Medical SciencesUniversity of FukuiFukuiJapan
| | - Daisetsu Aoyama
- Department of Cardiovascular Medicine, Faculty of Medical SciencesUniversity of FukuiFukuiJapan
| | - Tomoya Eguchi
- Department of Cardiovascular Medicine, Faculty of Medical SciencesUniversity of FukuiFukuiJapan
| | - Hiroyasu Uzui
- Department of Cardiovascular Medicine, Faculty of Medical SciencesUniversity of FukuiFukuiJapan
| | - Hiroshi Tada
- Department of Cardiovascular Medicine, Faculty of Medical SciencesUniversity of FukuiFukuiJapan
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7
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Darche FF, Ullrich ND, Huang Z, Koenen M, Rivinius R, Frey N, Schweizer PA. Improved Generation of Human Induced Pluripotent Stem Cell-Derived Cardiac Pacemaker Cells Using Novel Differentiation Protocols. Int J Mol Sci 2022; 23:ijms23137318. [PMID: 35806319 PMCID: PMC9266442 DOI: 10.3390/ijms23137318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 02/01/2023] Open
Abstract
Current protocols for the differentiation of human-induced pluripotent stem cells (hiPSC) into cardiomyocytes only generate a small amount of cardiac pacemaker cells. In previous work, we reported the generation of high amounts of cardiac pacemaker cells by co-culturing hiPSC with mouse visceral endoderm-like (END2) cells. However, potential medical applications of cardiac pacemaker cells generated according to this protocol, comprise an incalculable xenogeneic risk. We thus aimed to establish novel protocols maintaining the differentiation efficiency of the END2 cell-based protocol, yet eliminating the use of END2 cells. Three protocols were based on the activation and inhibition of the Wingless/Integrated (Wnt) signaling pathway, supplemented either with retinoic acid and the Wnt activator CHIR99021 (protocol B) or with the NODAL inhibitor SB431542 (protocol C) or with a combination of all three components (protocol D). An additional fourth protocol (protocol E) was used, which was originally developed by the manufacturer STEMCELL Technologies for the differentiation of hiPSC or hESC into atrial cardiomyocytes. All protocols (B, C, D, E) were compared to the END2 cell-based protocol A, serving as reference, in terms of their ability to differentiate hiPSC into cardiac pacemaker cells. Our analysis revealed that protocol E induced upregulation of 12 out of 15 cardiac pacemaker-specific genes. For comparison, reference protocol A upregulated 11, while protocols B, C and D upregulated 9, 10 and 8 cardiac pacemaker-specific genes, respectively. Cells differentiated according to protocol E displayed intense fluorescence signals of cardiac pacemaker-specific markers and showed excellent rate responsiveness to adrenergic and cholinergic stimulation. In conclusion, we characterized four novel and END2 cell-independent protocols for the differentiation of hiPSC into cardiac pacemaker cells, of which protocol E was the most efficient.
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Affiliation(s)
- Fabrice F. Darche
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (M.K.); (R.R.); (N.F.); (P.A.S.)
- German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany;
- Correspondence: ; Tel.: +49-6221-56-8676; Fax: +49-6221-56-5515
| | - Nina D. Ullrich
- German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany;
- Institute of Physiology and Pathophysiology, Heidelberg University, 69120 Heidelberg, Germany
| | - Ziqiang Huang
- EMBL Imaging Centre, European Molecular Biology Laboratory (EMBL), Meyerhofstraße 1, 69117 Heidelberg, Germany;
| | - Michael Koenen
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (M.K.); (R.R.); (N.F.); (P.A.S.)
- Department of Molecular Neurobiology, Max-Planck-Institute for Medical Research, Jahnstraße 29, 69120 Heidelberg, Germany
| | - Rasmus Rivinius
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (M.K.); (R.R.); (N.F.); (P.A.S.)
- German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany;
| | - Norbert Frey
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (M.K.); (R.R.); (N.F.); (P.A.S.)
- German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany;
| | - Patrick A. Schweizer
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (M.K.); (R.R.); (N.F.); (P.A.S.)
- German Center for Cardiovascular Research (DZHK), Partner Site Heidelberg/Mannheim, 69120 Heidelberg, Germany;
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Van Steenkiste G, Delhaas T, Hermans B, Vera L, Decloedt A, van Loon G. An Exploratory Study on Vectorcardiographic Identification of the Site of Origin of Focally Induced Premature Depolarizations in Horses, Part I: The Atria. Animals (Basel) 2022; 12:549. [PMID: 35268117 PMCID: PMC8908827 DOI: 10.3390/ani12050549] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 02/05/2023] Open
Abstract
In human cardiology, the anatomical origin of atrial premature depolarizations (APDs) is derived from P wave characteristics on a 12-lead electrocardiogram (ECG) and from vectorcardiography (VCG). The objective of this study is to differentiate between anatomical locations of APDs and to differentiate APDs from sinus rhythm (SR) based upon VCG characteristics in seven horses without cardiovascular disease. A 12-lead ECG was recorded under general anaesthesia while endomyocardial atrial pacing was performed (800−1000 ms cycle length) at the left atrial free wall and septum, right atrial free wall, intervenous tubercle, as well as at the junction with the cranial and caudal vena cava. Catheter positioning was guided by 3D electro-anatomical mapping and transthoracic ultrasound. The VCG was calculated from the 12-lead ECG using custom-made algorithms and was used to determine the mean electrical axis of the first and second half of the P wave. An ANOVA for spherical data was used to test if the maximal directions between each paced location and the maximal directions between every paced location and SR were significantly (p < 0.05) different. Atrial pacing data were not available from the LA septum in three horses, the intervenous tubercle in two horses, and from the LA free wall in one horse. The directions of the maximal electrical axes showed significant differences between all paced locations and between the paced locations and SR. The current results suggest that VCG is useful for identifying the anatomical origin of an atrial ectopy.
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Affiliation(s)
- Glenn Van Steenkiste
- Equine Cardioteam, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium; (L.V.); (A.D.); (G.v.L.)
| | - Tammo Delhaas
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, 6200 MD Maastricht, The Netherlands; (T.D.); (B.H.)
| | - Ben Hermans
- Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, 6200 MD Maastricht, The Netherlands; (T.D.); (B.H.)
| | - Lisse Vera
- Equine Cardioteam, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium; (L.V.); (A.D.); (G.v.L.)
| | - Annelies Decloedt
- Equine Cardioteam, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium; (L.V.); (A.D.); (G.v.L.)
| | - Gunther van Loon
- Equine Cardioteam, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium; (L.V.); (A.D.); (G.v.L.)
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Mesquita T, Zhang R, Cho JH, Zhang R, Lin YN, Sanchez L, Goldhaber J, Yu JK, Liang JA, Liu W, Trayanova NA, Cingolani E. Mechanisms of Sinoatrial Node Dysfunction in Heart Failure With Preserved Ejection Fraction. Circulation 2022; 145:45-60. [PMID: 34905696 PMCID: PMC9083886 DOI: 10.1161/circulationaha.121.054976] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND The ability to increase heart rate during exercise and other stressors is a key homeostatic feature of the sinoatrial node (SAN). When the physiological heart rate response is blunted, chronotropic incompetence limits exercise capacity, a common problem in patients with heart failure with preserved ejection fraction (HFpEF). Despite its clinical relevance, the mechanisms of chronotropic incompetence remain unknown. METHODS Dahl salt-sensitive rats fed a high-salt diet and C57Bl6 mice fed a high-fat diet and an inhibitor of constitutive nitric oxide synthase (Nω-nitro-L-arginine methyl ester [L-NAME]; 2-hit) were used as models of HFpEF. Myocardial infarction was created to induce HF with reduced ejection fraction. Rats and mice fed with a normal diet or those that had a sham surgery served as respective controls. A comprehensive characterization of SAN function and chronotropic response was conducted by in vivo, ex vivo, and single-cell electrophysiologic studies. RNA sequencing of SAN was performed to identify transcriptomic changes. Computational modeling of biophysically-detailed human HFpEF SAN was created. RESULTS Rats with phenotypically-verified HFpEF exhibited limited chronotropic response associated with intrinsic SAN dysfunction, including impaired β-adrenergic responsiveness and an alternating leading pacemaker within the SAN. Prolonged SAN recovery time and reduced SAN sensitivity to isoproterenol were confirmed in the 2-hit mouse model. Adenosine challenge unmasked conduction blocks within the SAN, which were associated with structural remodeling. Chronotropic incompetence and SAN dysfunction were also found in rats with HF with reduced ejection fraction. Single-cell studies and transcriptomic profiling revealed HFpEF-related alterations in both the "membrane clock" (ion channels) and the "Ca2+ clock" (spontaneous Ca2+ release events). The physiologic impairments were reproduced in silico by empirically-constrained quantitative modeling of human SAN function. CONCLUSIONS Chronotropic incompetence and SAN dysfunction were seen in both models of HF. We identified that intrinsic abnormalities of SAN structure and function underlie the chronotropic response in HFpEF.
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Affiliation(s)
- Thassio Mesquita
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Rui Zhang
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Jae Hyung Cho
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Rui Zhang
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Yen-Nien Lin
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Lizbeth Sanchez
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Joshua Goldhaber
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Joseph K. Yu
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Jialiu A. Liang
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Weixin Liu
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Natalia A. Trayanova
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
- Alliance for Cardiovascular and Diagnostic and treatment Innovation (ADVANCE), Johns Hopkins University, Baltimore, Maryland
| | - Eugenio Cingolani
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
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10
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Turner D, Kang C, Mesirca P, Hong J, Mangoni ME, Glukhov AV, Sah R. Electrophysiological and Molecular Mechanisms of Sinoatrial Node Mechanosensitivity. Front Cardiovasc Med 2021; 8:662410. [PMID: 34434970 PMCID: PMC8382116 DOI: 10.3389/fcvm.2021.662410] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 06/24/2021] [Indexed: 01/01/2023] Open
Abstract
The understanding of the electrophysiological mechanisms that underlie mechanosensitivity of the sinoatrial node (SAN), the primary pacemaker of the heart, has been evolving over the past century. The heart is constantly exposed to a dynamic mechanical environment; as such, the SAN has numerous canonical and emerging mechanosensitive ion channels and signaling pathways that govern its ability to respond to both fast (within second or on beat-to-beat manner) and slow (minutes) timescales. This review summarizes the effects of mechanical loading on the SAN activity and reviews putative candidates, including fast mechanoactivated channels (Piezo, TREK, and BK) and slow mechanoresponsive ion channels [including volume-regulated chloride channels and transient receptor potential (TRP)], as well as the components of mechanochemical signal transduction, which may contribute to SAN mechanosensitivity. Furthermore, we examine the structural foundation for both mechano-electrical and mechanochemical signal transduction and discuss the role of specialized membrane nanodomains, namely, caveolae, in mechanical regulation of both membrane and calcium clock components of the so-called coupled-clock pacemaker system responsible for SAN automaticity. Finally, we emphasize how these mechanically activated changes contribute to the pathophysiology of SAN dysfunction and discuss controversial areas necessitating future investigations. Though the exact mechanisms of SAN mechanosensitivity are currently unknown, identification of such components, their impact into SAN pacemaking, and pathological remodeling may provide new therapeutic targets for the treatment of SAN dysfunction and associated rhythm abnormalities.
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Affiliation(s)
- Daniel Turner
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, United States
| | - Chen Kang
- Cardiovascular Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Juan Hong
- Cardiovascular Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Alexey V Glukhov
- Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI, United States
| | - Rajan Sah
- Cardiovascular Division, Department of Internal Medicine, Washington University School of Medicine, St. Louis, MO, United States
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11
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Heida A, van der Does WFB, van Staveren LN, Taverne YJHJ, Roos-Serote MC, Bogers AJJC, de Groot NMS. Conduction Heterogeneity: Impact of Underlying Heart Disease and Atrial Fibrillation. JACC Clin Electrophysiol 2021; 6:1844-1854. [PMID: 33357582 DOI: 10.1016/j.jacep.2020.09.030] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 08/25/2020] [Accepted: 09/22/2020] [Indexed: 11/25/2022]
Abstract
OBJECTIVES The goal of this study is to investigate the impact of various underlying heart diseases (UHDs) and prior atrial fibrillation (AF) episodes on conduction heterogeneity. BACKGROUND It is unknown whether intra-atrial conduction during sinus rhythm differs between various UHD or is influenced by AF episodes. METHODS Epicardial sinus rhythm mapping of the right atrium, Bachmann's bundle (BB), left atrium and pulmonary vein area was performed in 447 participants (median age: 67 [interquartile range (IQR): 59 to 73] years) with or without AF undergoing cardiac surgery for ischemic heart disease, (ischemic and) valvular heart disease, or congenital heart disease. Conduction times (CTs) were defined as Δ local activation time between 2 adjacent electrodes and used to assess frequency (CTs ≥ 4 ms) and magnitude of conduction disorders (in increments of 10 ms). RESULTS When comparing the 3 types of UHD, there were no differences in frequencies and magnitude of CTs at all locations (p ≥ 0.017 and p ≥ 0.005, respectively). Prior AF episodes were associated with conduction slowing throughout both atria (14.9% [IQR: 11.8 to 17.0] vs. 12.8% [IQR: 10.9 to 14.6]; p < 0.001). At BB, CTs with magnitudes ≥30 ms were more common in patients with AF (n = 56.2% vs. n = 36.0%; p < 0.004). CONCLUSIONS UHD has no impact on the frequency and severity of conduction disorders. AF episodes are associated with more conduction disorders throughout both atria and with more severe conduction disorders at BB. The next step will be to determine the relevance of these conduction disorders for AF development and maintenance.
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Affiliation(s)
- Annejet Heida
- Department of Cardiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | | | | | - Yannick J H J Taverne
- Department of Cardiothoracic Surgery, Erasmus Medical Center, Rotterdam, the Netherlands
| | | | - Ad J J C Bogers
- Department of Cardiothoracic Surgery, Erasmus Medical Center, Rotterdam, the Netherlands
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12
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Mantri S, Wu SM, Goodyer WR. Molecular Profiling of the Cardiac Conduction System: the Dawn of a New Era. Curr Cardiol Rep 2021; 23:103. [PMID: 34196831 DOI: 10.1007/s11886-021-01536-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/17/2021] [Indexed: 11/28/2022]
Abstract
PURPOSE OF REVIEW Recent technological advances have led to an increased ability to define the gene expression profile of the cardiac conduction system (CCS). Here, we review the most salient studies to emerge in recent years and discuss existing gaps in our knowledge as well as future areas of investigation. RECENT FINDINGS Molecular profiling of the CCS spans several decades. However, the advent of high-throughput sequencing strategies has allowed for the discovery of unique transcriptional programs of the many diverse CCS cell types. The CCS, a diverse structure with significant inter- and intra-component cellular heterogeneity, is essential to the normal function of the heart. Progress in transcriptomic profiling has improved the resolution and depth of characterization of these unique and clinically relevant CCS cell types. Future studies leveraging this big data will play a crucial role in improving our understanding of CCS development and function as well as translating these findings into tangible translational tools for the improved detection, prevention, and treatment of cardiac arrhythmias.
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Affiliation(s)
- Sruthi Mantri
- Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Sean M Wu
- Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, 94305, USA.,Division of Pediatric Cardiology, Department of Pediatrics, Stanford University, Stanford, CA, 94305, USA.,Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - William R Goodyer
- Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, 94305, USA. .,Division of Pediatric Cardiology, Department of Pediatrics, Stanford University, Stanford, CA, 94305, USA. .,Division of Pediatric Cardiology, Electrophysiology, Department of Pediatrics, Lucile Packard Children's Hospital, Stanford University School of Medicine, Room G1105 Lokey Stem Cell Research Building, 265 Campus Drive, Stanford, CA, 94305, USA.
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13
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Assembly of the Cardiac Pacemaking Complex: Electrogenic Principles of Sinoatrial Node Morphogenesis. J Cardiovasc Dev Dis 2021; 8:jcdd8040040. [PMID: 33917972 PMCID: PMC8068396 DOI: 10.3390/jcdd8040040] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 03/31/2021] [Accepted: 04/05/2021] [Indexed: 11/24/2022] Open
Abstract
Cardiac pacemaker cells located in the sinoatrial node initiate the electrical impulses that drive rhythmic contraction of the heart. The sinoatrial node accounts for only a small proportion of the total mass of the heart yet must produce a stimulus of sufficient strength to stimulate the entire volume of downstream cardiac tissue. This requires balancing a delicate set of electrical interactions both within the sinoatrial node and with the downstream working myocardium. Understanding the fundamental features of these interactions is critical for defining vulnerabilities that arise in human arrhythmic disease and may provide insight towards the design and implementation of the next generation of potential cellular-based cardiac therapeutics. Here, we discuss physiological conditions that influence electrical impulse generation and propagation in the sinoatrial node and describe developmental events that construct the tissue-level architecture that appears necessary for sinoatrial node function.
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14
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Moïse NS, Brewer FC, Flanders WH, Kornreich BG, Otani NF. Insights into sinus arrhythmia of the dog: Acetylcholine perfusion of canine right atrium results in beat-to-beat patterns that mimic sinus arrhythmia supporting exit block in the sinoatrial conduction pathways. Vet J 2021; 272:105651. [PMID: 33745806 DOI: 10.1016/j.tvjl.2021.105651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 02/28/2021] [Accepted: 03/01/2021] [Indexed: 12/19/2022]
Abstract
Sinus arrhythmia of the dog is unique because of the pronounced alternating beat-to-beat intervals. The clustering of these short (faster rates) and long (slower rates) intervals is not just influenced by autonomic input from breathing; sinus arrhythmia can persist in the panting or apneic dog. The multiplicity of central and peripheral influences on the sinus node complicates the unraveling of the mechanisms of sinus arrhythmia. Studies of the sinus node suggest that acetylcholine can slow cellular depolarization and block sinoatrial conduction. Electrocardiographic monitoring of the dog supports this notion in that abrupt bifurcation into short and long intervals develop at lower heart rates. We sought to determine whether this phenomenon could be recapitulated in canine atrial preparations perfused with acetylcholine and whether selective pharmacologic blockade of the voltage and calcium clocks could provide insight into its mechanism. Spontaneous beat to beat (A-A) intervals were obtained from monophasic action potential recordings of perfused canine right atrial preparations before and during perfusion with acetylcholine (2-5 μM). The calcium clock was blocked with ryanodine (2-3 μM). The membrane clock was blocked with diltiazem hydrochloride (ICa,L blocker; 0.25 μM) and ZD7288 (If blocker; 3 μM). Hyperpolarization was hindered by blockade of IK,Ado/IK,Ach with tertiapin Q (100 nM) before and during acetylcholine perfusion. Acetylcholine resulted in beat clusters similar to those seen in sinus arrhythmia of the dog. Beat clusters were consistent with intermittent 2:1 and 3:1 sinoatrial conduction block. Tertiapin Q abolished this patterning suggesting a role of IK,Ado/IK,ACh in the mechanism of these acetylcholine-induced beat-to-beat patterns.
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Affiliation(s)
- N S Moïse
- Section of Cardiology, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
| | - F C Brewer
- California Pet Cardiology, Long Beach, CA 90808, USA
| | - W H Flanders
- Department of Physics, University of Washington, Seattle, WA 98195, USA
| | - B G Kornreich
- Section of Cardiology, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - N F Otani
- School of Mathematical Sciences, College of Science, Rochester Institute of Technology, Rochester, NY 14623, USA
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15
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Moïse NS, Flanders NH, Gunzel ER. Instantaneous and averaged heart rate profiles: Developing strategies for programming pacing rates in dogs. Vet J 2021; 270:105624. [PMID: 33641808 DOI: 10.1016/j.tvjl.2021.105624] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 01/21/2021] [Accepted: 01/21/2021] [Indexed: 12/14/2022]
Abstract
Pacemakers use heart rate histograms (% beats) and sensor indicated rate histograms (% time) to illustrate rate distributions. When programmed to the rate adaptive modes, these data are used to determine the appropriateness of rate response to activity. These histograms are generated from instantaneous heart rate calculations. In humans, such data are compared to known histographic rate profiles. Such rate profiles during 24 h in the dog are not available. Moreover, data representation differ between Holter monitoring and pacemakers making comparisons challenging. The rate distribution in dogs >7-years of age was determined over 24 h using instantaneous and rolling average heart rate. Such data could serve as a guide to programming pacing rates for dogs. Sinus arrhythmia resulted in dissimilar heart rate profiles depending on the method of determining rate. The long intervals of sinus arrhythmia resulted in median values for the percent of time with an instantaneous heart rate of <50 beats/min (bpm) of 15%, whereas a rolling average heart rate of <50 bpm was 0.2%. Based on the cumulative time of the rolling average rate, dogs spent 26.3% of the day between 70-90 bpm with rates <65 bpm and >90 bpm approximating 30% for each. Rates >160 bpm were uncommon (<1%). However, high variability existed between dogs. This study demonstrated the shortcomings of both instantaneous and averaging methods to evaluate heart rate profiles in the dog and that both methods should be incorporated when making pacing rate decisions during programming.
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Affiliation(s)
- N S Moïse
- Section of Cardiology, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
| | | | - E R Gunzel
- Section of Cardiology, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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16
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Mavroidis M, Athanasiadis NC, Rigas P, Kostavasili I, Kloukina I, Te Rijdt WP, Kavantzas N, Chaniotis D, van Tintelen JP, Skaliora I, Davos CH. Desmin is essential for the structure and function of the sinoatrial node: implications for increased arrhythmogenesis. Am J Physiol Heart Circ Physiol 2020; 319:H557-H570. [PMID: 32678709 DOI: 10.1152/ajpheart.00594.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Our objective was to investigate the effect of desmin depletion on the structure and function of the sinoatrial pacemaker complex (SANcl) and its implication in arrhythmogenesis. Analysis of mice and humans (SANcl) indicated that the sinoatrial node exhibits high amounts of desmin, desmoplakin, N-cadherin, and β-catenin in structures we call "lateral intercalated disks" connecting myocytes side by side. Examination of the SANcl from an arrhythmogenic cardiomyopathy model, desmin-deficient (Des-/-) mouse, by immunofluorescence, ultrastructural, and Western blot analysis showed that the number of these lateral intercalated disks was diminished. Also, electrophysiological recordings of the isolated compact sinoatrial node revealed increased pacemaker systolic potential and higher diastolic depolarization rate compared with wild-type mice. Prolonged interatrial conduction expressed as a longer P wave duration was also observed in Des-/- mice. Upregulation of mRNA levels of both T-type Ca2+ current channels, Cav3.1 and Cav3.2, in the Des-/- myocardium (1.8- and 2.3-fold, respectively) and a 1.9-fold reduction of funny hyperpolarization-activated cyclic nucleotide-gated K+ channel 1 could underlie these functional differences. To investigate arrhythmogenicity, electrocardiographic analysis of Des-deficient mice revealed a major increase in supraventricular and ventricular ectopic beats compared with wild-type mice. Heart rate variability analysis indicated a sympathetic predominance in Des-/- mice, which may further contribute to arrhythmogenicity. In conclusion, our results indicate that desmin elimination leads to structural and functional abnormalities of the SANcl. These alterations may be enhanced by the sympathetic component of the cardiac autonomic nervous system, which is predominant in the desmin-deficient heart, thus leading to increased arrhythmogenesis.NEW & NOTEWORTHY The sinoatrial node exhibits high amounts of desmin and desmoplakin in structures we call "lateral intercalated disks," connecting side-by-side adjacent cardiomyocytes. These structures are diminished in desmin-deficient mouse models. Misregulation of T-type Ca2+ current and hyperpolarization-activated cyclic nucleotide-gated K+ channel 1 was proved along with prolonged interatrial conduction and cardiac autonomic nervous system dysfunction.
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Affiliation(s)
- Manolis Mavroidis
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Nikolaos C Athanasiadis
- Center of Clinical Research and Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Pavlos Rigas
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Ioanna Kostavasili
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Ismini Kloukina
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Wouter P Te Rijdt
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Department of Experimental Cardiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Nikolaos Kavantzas
- First Department of Pathology, National and Kapodistrian University of Athens, Athens, Greece
| | - Dimitris Chaniotis
- Center of Clinical Research and Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - J Peter van Tintelen
- Department of Genetics, University Medical Center Utrecht, University of Utrecht, Utrecht, The Netherlands
| | - Irini Skaliora
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Constantinos H Davos
- Center of Clinical Research and Experimental Surgery, Biomedical Research Foundation, Academy of Athens, Athens, Greece
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17
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Scholman KT, Meijborg VMF, Gálvez-Montón C, Lodder EM, Boukens BJ. From Genome-Wide Association Studies to Cardiac Electrophysiology: Through the Maze of Biological Complexity. Front Physiol 2020; 11:557. [PMID: 32536879 PMCID: PMC7267057 DOI: 10.3389/fphys.2020.00557] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 05/04/2020] [Indexed: 12/19/2022] Open
Abstract
Genome Wide Association Studies (GWAS) have provided an enormous amount of data on genomic loci associated with cardiac electrophysiology and arrhythmias. Clinical relevance, however, remains unclear since GWAS do not provide a mechanistic explanation for this association. Determining the electrophysiological relevance of variants for arrhythmias would aid development of risk stratification models for patients with arrhythmias. In this review, we give an overview of genetic variants related to ECG intervals and arrhythmogenic pathologies and discuss how these variants may influence cardiac electrophysiology and the occurrence of arrhythmias.
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Affiliation(s)
- Koen T Scholman
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Veronique M F Meijborg
- Department of Experimental Cardiology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands.,Netherlands Heart Institute, Utrecht, Netherlands
| | - Carolina Gálvez-Montón
- ICREC Research Program, Germans Trias i Pujol Health Science Research Institute, Badalona, Spain.,CIBERCV, Instituto de Salud Carlos III, Madrid, Spain
| | - Elisabeth M Lodder
- Department of Experimental Cardiology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
| | - Bastiaan J Boukens
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands.,Department of Experimental Cardiology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands
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18
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Gradual differentiation and confinement of the cardiac conduction system as indicated by marker gene expression. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118509. [DOI: 10.1016/j.bbamcr.2019.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 07/05/2019] [Accepted: 07/09/2019] [Indexed: 11/23/2022]
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19
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Moïse NS, Flanders WH, Pariaut R. Beat-to-Beat Patterning of Sinus Rhythm Reveals Non-linear Rhythm in the Dog Compared to the Human. Front Physiol 2020; 10:1548. [PMID: 32038271 PMCID: PMC6990411 DOI: 10.3389/fphys.2019.01548] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 12/09/2019] [Indexed: 02/06/2023] Open
Abstract
The human and dog have sinus arrhythmia; however, the beat-to-beat interval changes were hypothesized to be different. Geometric analyses (R–R interval tachograms, dynamic Poincaré plots) to examine rate changes on a beat-to-beat basis were analyzed along with time and frequency domain heart rate variability from 40 human and 130 canine 24-h electrocardiographic recordings. Humans had bell-shaped beat-interval distributions, narrow interval bands across time with continuous interval change and linear changes in rate. In contrast, dogs had skewed non-singular beat distributions, wide interval bands {despite faster average heart rate of dogs [mean (range); 81 (64–119)] bpm compared to humans [74.5 (59–103) p = 0.005]} with regions displaying a paucity of intervals (zone of avoidance) and linear plus non-linear rate changes. In the dog, dynamic Poincaré plots showed linear rate changes as intervals prolonged until a point of divergence from the line of identity at a mean interval of 598.5 (95% CI: 583.5–613.5) ms (bifurcation interval). The dog had bimodal beat distribution during sleep with slower rates and greater variability than during active hours that showed singular interval distributions, higher rates and less variability. During sleep, Poincaré plots of the dog had clustered or branched patterns of intervals. A slower rate supported greater parasympathetic modulation with a branched compared to the clustered distribution. Treatment with atropine eliminated the non-linear patterns, while hydromorphone shifted the bifurcated branching and beat clustering to longer intervals. These results demonstrate the unique non-linear nature of beat-to-beat variability in the dog compared to humans with increases in interval duration (decrease heart rate). These results provoke the possibility that changes are linear with a dominant sympathetic modulation and non-linear with a dominant parasympathetic modulation. The abrupt bifurcation, zone of avoidance and beat-to-beat patterning are concordant with other studies demonstrating the development of exit block from the sinus node with parasympathetic modulation influencing not only the oscillation of the pacing cells, but conduction to the atria. Studies are required to associate the in vivo sinus node beat patterns identified in this study to the mapping of sinus impulse origin and exit from the sinus node.
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Affiliation(s)
- N Sydney Moïse
- College of Veterinary Medicine, Department of Clinical Sciences, Cornell University, Ithaca, NY, United States
| | - Wyatt H Flanders
- Department of Physics, University of Washington, Seattle, WA, United States
| | - Romain Pariaut
- College of Veterinary Medicine, Department of Clinical Sciences, Cornell University, Ithaca, NY, United States
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20
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Bressan M, Henley T, Louie JD, Liu G, Christodoulou D, Bai X, Taylor J, Seidman CE, Seidman JG, Mikawa T. Dynamic Cellular Integration Drives Functional Assembly of the Heart's Pacemaker Complex. Cell Rep 2019; 23:2283-2291. [PMID: 29791840 PMCID: PMC6007983 DOI: 10.1016/j.celrep.2018.04.075] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 02/27/2018] [Accepted: 04/17/2018] [Indexed: 11/23/2022] Open
Abstract
Impulses generated by a multicellular, bioelectric signaling center termed the sinoatrial node (SAN) stimulate the rhythmic contraction of the heart. The SAN consists of a network of electrochemically oscillating pacemaker cells encased in a heterogeneous connective tissue microenvironment. Although the cellular composition of the SAN has been a point of interest for more than a century, the biological processes that drive the tissue-level assembly of the cells within the SAN are unknown. Here, we demonstrate that the SAN’s structural features result from a developmental process during which mesenchymal cells derived from a multipotent progenitor structure, the proepicardium, integrate with and surround pacemaker myocardium. This process actively remodels the forming SAN and is necessary for sustained electrogenic signal generation and propagation. Collectively, these findings provide experimental evidence for how the microenvironmental architecture of the SAN is patterned and demonstrate that proper cellular arrangement is critical for cardiac pacemaker biorhythmicity.
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Affiliation(s)
- Michael Bressan
- Department of Cell Biology and Physiology, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Trevor Henley
- Department of Cell Biology and Physiology, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jonathan D Louie
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Gary Liu
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | | | - Xue Bai
- Department of Pathology, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Joan Taylor
- Department of Pathology, McAllister Heart Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | | | - J G Seidman
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Takashi Mikawa
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
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21
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van der Does LJME, Lanters EAH, Teuwen CP, Mouws EMJP, Yaksh A, Knops P, Kik C, Bogers AJJC, de Groot NMS. The Effects of Valvular Heart Disease on Atrial Conduction During Sinus Rhythm. J Cardiovasc Transl Res 2019; 13:632-639. [PMID: 31773460 PMCID: PMC7423861 DOI: 10.1007/s12265-019-09936-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2019] [Accepted: 11/13/2019] [Indexed: 11/16/2022]
Abstract
Different arrhythmogenic substrates for atrial fibrillation (AF) may underlie aortic valve (AV) and mitral valve (MV) disease. We located conduction disorders during sinus rhythm by high-resolution epicardial mapping in patients undergoing AV (n = 85) or MV (n = 54) surgery. Extent and distribution of conduction delay (CD) and block (CD) across the entire right and left atrial surface was determined from circa 1880 unipolar electrogram recordings per patient. CD and CB were most pronounced at the superior intercaval area (2.5% of surface, maximal degree 6.6%/cm2). MV patients had a higher maximal degree of CD at the lateral left atrium than AV patients (4.2 vs 2.3%/cm2, p = 0.001). A history of AF was most strongly correlated to CD/CB at Bachmann’s bundle and age. Although MV patients have more conduction disorders at the lateral left atrium, disturbed conduction at Bachmann’s bundle during sinus rhythm indicates the presence of atrial remodeling which is related to AF episodes.
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Affiliation(s)
- Lisette J M E van der Does
- Department of Cardiology, Erasmus Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands
| | - Eva A H Lanters
- Department of Cardiology, Erasmus Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands
| | - Christophe P Teuwen
- Department of Cardiology, Erasmus Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands
| | - Elisabeth M J P Mouws
- Department of Cardiology, Erasmus Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands.,Department of Cardiothoracic Surgery, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Ameeta Yaksh
- Department of Cardiology, Erasmus Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands
| | - Paul Knops
- Department of Cardiology, Erasmus Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands
| | - Charles Kik
- Department of Cardiothoracic Surgery, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Ad J J C Bogers
- Department of Cardiothoracic Surgery, Erasmus Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Natasja M S de Groot
- Department of Cardiology, Erasmus Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands.
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22
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Swift LM, Jaimes R, McCullough D, Burke M, Reilly M, Maeda T, Zhang H, Ishibashi N, Rogers JM, Posnack NG. Optocardiography and Electrophysiology Studies of Ex Vivo Langendorff-perfused Hearts. J Vis Exp 2019. [PMID: 31762469 DOI: 10.3791/60472] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Small animal models are most commonly used in cardiovascular research due to the availability of genetically modified species and lower cost compared to larger animals. Yet, larger mammals are better suited for translational research questions related to normal cardiac physiology, pathophysiology, and preclinical testing of therapeutic agents. To overcome the technical barriers associated with employing a larger animal model in cardiac research, we describe an approach to measure physiological parameters in an isolated, Langendorff-perfused piglet heart. This approach combines two powerful experimental tools to evaluate the state of the heart: electrophysiology (EP) study and simultaneous optical mapping of transmembrane voltage and intracellular calcium using parameter sensitive dyes (RH237, Rhod2-AM). The described methodologies are well suited for translational studies investigating the cardiac conduction system, alterations in action potential morphology, calcium handling, excitation-contraction coupling and the incidence of cardiac alternans or arrhythmias.
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Affiliation(s)
- Luther M Swift
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital
| | - Rafael Jaimes
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital
| | - Damon McCullough
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital
| | - Morgan Burke
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital
| | - Marissa Reilly
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital
| | - Takuya Maeda
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital; Center for Neuroscience Research, Children's National Hospital
| | - Hanyu Zhang
- Department of Biomedical Engineering, School of Engineering, University of Alabama at Birmingham
| | - Nobuyuki Ishibashi
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital; Center for Neuroscience Research, Children's National Hospital
| | - Jack M Rogers
- Department of Biomedical Engineering, School of Engineering, University of Alabama at Birmingham
| | - Nikki Gillum Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Hospital; Children's National Heart Institute, Children's National Hospital; Department of Pediatrics, Department of Pharmacology & Physiology, School of Medicine and Health Sciences, George Washington University;
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23
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Grijalva SI, Gu J, Li J, Fernandez N, Fan J, Sung JH, Lee SY, Herndon C, Buckley EM, Park S, Fenton FH, Cho HC. Engineered Cardiac Pacemaker Nodes Created by TBX18 Gene Transfer Overcome Source-Sink Mismatch. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2019; 6:1901099. [PMID: 31763140 PMCID: PMC6864514 DOI: 10.1002/advs.201901099] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 08/23/2019] [Indexed: 06/10/2023]
Abstract
Every heartbeat originates from a tiny tissue in the heart called the sinoatrial node (SAN). The SAN harbors only ≈10 000 cardiac pacemaker cells, initiating an electrical impulse that captures the entire heart, consisting of billions of cardiomyocytes for each cardiac contraction. How these rare cardiac pacemaker cells (the electrical source) can overcome the electrically hyperpolarizing and quiescent myocardium (the electrical sink) is incompletely understood. Due to the scarcity of native pacemaker cells, this concept of source-sink mismatch cannot be tested directly with live cardiac tissue constructs. By exploiting TBX18 induced pacemaker cells by somatic gene transfer, 3D cardiac pacemaker spheroids can be tissue-engineered. The TBX18 induced pacemakers (sphTBX18) pace autonomously and drive the contraction of neighboring myocardium in vitro. TBX18 spheroids demonstrate the need for reduced electrical coupling and physical separation from the neighboring ventricular myocytes, successfully recapitulating a key design principle of the native SAN. β-Adrenergic stimulation as well as electrical uncoupling significantly increase sphTBX18s' ability to pace-and-drive the neighboring myocardium. This model represents the first platform to test design principles of the SAN for mechanistic understanding and to better engineer biological pacemakers for therapeutic translation.
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Affiliation(s)
- Sandra I. Grijalva
- Department of Biomedical EngineeringGeorgia Institute of Technology and Emory UniversityAtlantaGA30332USA
| | - Jin‐mo Gu
- Department of PediatricsEmory UniversityAtlantaGA30322USA
| | - Jun Li
- Department of PediatricsEmory UniversityAtlantaGA30322USA
| | | | - Jinqi Fan
- Department of PediatricsEmory UniversityAtlantaGA30322USA
| | - Jung Hoon Sung
- Department of PediatricsEmory UniversityAtlantaGA30322USA
- Department of Internal MedicineCHA Bundang Medical CenterSeoul13557South Korea
| | - Seung Yup Lee
- Department of Biomedical EngineeringGeorgia Institute of Technology and Emory UniversityAtlantaGA30332USA
| | - Conner Herndon
- Department of PhysicsGeorgia Institute of TechnologyAtlantaGA30332USA
| | - Erin M. Buckley
- Department of Biomedical EngineeringGeorgia Institute of Technology and Emory UniversityAtlantaGA30332USA
| | - Sung‐Jin Park
- Department of Biomedical EngineeringGeorgia Institute of Technology and Emory UniversityAtlantaGA30332USA
| | - Flavio H. Fenton
- Department of PhysicsGeorgia Institute of TechnologyAtlantaGA30332USA
| | - Hee Cheol Cho
- Department of Biomedical EngineeringGeorgia Institute of Technology and Emory UniversityAtlantaGA30332USA
- Department of PediatricsEmory UniversityAtlantaGA30322USA
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Goodyer WR, Beyersdorf BM, Paik DT, Tian L, Li G, Buikema JW, Chirikian O, Choi S, Venkatraman S, Adams EL, Tessier-Lavigne M, Wu JC, Wu SM. Transcriptomic Profiling of the Developing Cardiac Conduction System at Single-Cell Resolution. Circ Res 2019; 125:379-397. [PMID: 31284824 DOI: 10.1161/circresaha.118.314578] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
RATIONALE The cardiac conduction system (CCS) consists of distinct components including the sinoatrial node, atrioventricular node, His bundle, bundle branches, and Purkinje fibers. Despite an essential role for the CCS in heart development and function, the CCS has remained challenging to interrogate because of inherent obstacles including small cell numbers, large cell-type heterogeneity, complex anatomy, and difficulty in isolation. Single-cell RNA-sequencing allows for genome-wide analysis of gene expression at single-cell resolution. OBJECTIVE Assess the transcriptional landscape of the entire CCS at single-cell resolution by single-cell RNA-sequencing within the developing mouse heart. METHODS AND RESULTS Wild-type, embryonic day 16.5 mouse hearts (n=6 per zone) were harvested and 3 zones of microdissection were isolated, including: Zone I-sinoatrial node region; Zone II-atrioventricular node/His region; and Zone III-bundle branch/Purkinje fiber region. Tissue was digested into single-cell suspensions, cells isolated, mRNA reverse transcribed, and barcoded before high-throughput sequencing and bioinformatics analyses. Single-cell RNA-sequencing was performed on over 22 000 cells, and all major cell types of the murine heart were successfully captured including bona fide clusters of cells consistent with each major component of the CCS. Unsupervised weighted gene coexpression network analysis led to the discovery of a host of novel CCS genes, a subset of which were validated using fluorescent in situ hybridization as well as whole-mount immunolabeling with volume imaging (iDISCO+) in 3 dimensions on intact mouse hearts. Further, subcluster analysis unveiled isolation of distinct CCS cell subtypes, including the clinically relevant but poorly characterized transitional cells that bridge the CCS and surrounding myocardium. CONCLUSIONS Our study represents the first comprehensive assessment of the transcriptional profiles from the entire CCS at single-cell resolution and provides a characterization in the context of development and disease.
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Affiliation(s)
- William R Goodyer
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA.,Department of Pediatrics (W.R.G., S.M.W.), Stanford University, CA
| | - Benjamin M Beyersdorf
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA.,Department of Cardiovascular Surgery, Institute Insure (Institute for Translational Cardiac Surgery), German Heart Center Munich at the Technical University of Munich, Germany (B.M.B.)
| | - David T Paik
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA
| | - Lei Tian
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA
| | - Guang Li
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA.,Department of Developmental Biology, University of Pittsburgh School of Medicine, PA (G.L.)
| | - Jan W Buikema
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA.,Department of Cardiology, Utrecht Regenerative Medicine Center, University Medical Center Utrecht, Utrecht University, The Netherlands (J.W.B.)
| | - Orlando Chirikian
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA.,Department of Molecular, Cellular, and Developmental Biology, UC Santa Barbara, CA (O.C.)
| | - Shannon Choi
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA
| | - Sneha Venkatraman
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA
| | - Eliza L Adams
- Department of Biology (E.L.A., M.T.-L.), Stanford University, CA
| | | | - Joseph C Wu
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA.,Department of Medicine, Cardiovascular Medicine (J.C.W., S.M.W.), Stanford University School of Medicine, CA
| | - Sean M Wu
- From the Cardiovascular Institute (W.R.G., B.M.B., D.T.P., L.T., G.L., J.W.B., O.C., S.C., S.V., J.C.W., S.M.W.), Stanford University School of Medicine, CA.,Department of Medicine, Cardiovascular Medicine (J.C.W., S.M.W.), Stanford University School of Medicine, CA.,Department of Pediatrics (W.R.G., S.M.W.), Stanford University, CA
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25
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Sayegh MN, Fernandez N, Cho HC. Strength-duration relationship as a tool to prioritize cardiac tissue properties that govern electrical excitability. Am J Physiol Heart Circ Physiol 2019; 317:H13-H25. [PMID: 30925072 PMCID: PMC7199233 DOI: 10.1152/ajpheart.00161.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Engineered cardiac tissue and cardiomyocyte cell cultures offer wide opportunities for improved therapeutic intervention and laboratory heart models. Electrical field excitation is a common intervention in the production of engineered tissue and the investigation of the electrical properties of in vitro cell cultures. In this work, we use strength-duration relationships to investigate systematically factors influencing electrical excitability of two- (2D) and three-dimensional (3D) neonatal rat ventricular myocyte cultures. We find that the strength of the voltage pulse is negatively correlated with the threshold duration, as predicted by the Lapicque-Hill equation, and show that higher pacing frequencies require higher thresholds to capture paced cultures. We also study the impact of properties intrinsic to the 2D and 3D cultures on strength-duration relationships. We show that a smaller culture dimension, perpendicular anisotropic culture orientation with respect to electrical field, higher proportion of added fibroblasts, and TBX18-induced pacemaker reprogramming independently result in higher stimulation thresholds. These properties reflect the characteristics of the well-insulated endogenous pacemaking tissue in the heart (sinoatrial node) and should guide the engineering of biological pacemakers for improved outcomes. NEW & NOTEWORTHY Gaps exist in the availability of in vitro functional assessment tools that can emulate the integration of regenerative cells and tissues to the host myocardium. We use strength-duration relationships of electrically stimulated two- and three-dimensional myocardial constructs to study the effects of pacing frequency, culture dimensions, anisotropic cell alignment, fibroblast content, and pacemaker phenotype on electrical excitability. Our study delivers electrical strength-duration as a quantifiable parameter to evaluate design parameters of engineered cardiac tissue constructs.
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Affiliation(s)
- Michael N. Sayegh
- 1Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia,2Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
| | - Natasha Fernandez
- 1Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia
| | - Hee Cheol Cho
- 1Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia,2Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia
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26
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Schulze ML, Lemoine MD, Fischer AW, Scherschel K, David R, Riecken K, Hansen A, Eschenhagen T, Ulmer BM. Dissecting hiPSC-CM pacemaker function in a cardiac organoid model. Biomaterials 2019; 206:133-145. [DOI: 10.1016/j.biomaterials.2019.03.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 03/15/2019] [Accepted: 03/17/2019] [Indexed: 12/21/2022]
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27
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Ashton JL, Trew ML, LeGrice IJ, Paterson DJ, Paton JF, Gillis AM, Smaill BH. Shift of leading pacemaker site during reflex vagal stimulation and altered electrical source-to-sink balance. J Physiol 2019; 597:3297-3313. [PMID: 31087820 DOI: 10.1113/jp276876] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 04/30/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Vagal reflexes slow heart rate and can change where the heartbeat originates within the sinoatrial node (SAN). The mechanisms responsible for this process - termed leading pacemaker (LP) shift - have not been investigated fully. We used optical mapping to measure the effects of baroreflex, chemoreflex and carbachol on pacemaker entrainment and electrical conduction across the SAN. All methods of stimulation triggered shifts in LP site from the central SAN to one or two caudal pacemaker regions. These shifts were associated with reduced current generation capacity centrally and increased electrical load caudally. Previous studies suggest LP shift is a rate-dependent phenomenon whereby acetylcholine slows central pacemaker rate disproportionately, enabling caudal cells that are less acetylcholine sensitive to assume control. However, our findings indicate the LP region is defined by both pacemaker rate and capacity to drive activation. Shifts in LP site provide an important homeostatic mechanism for rapid switches in heart rate. ABSTRACT Reflex vagal activity causes abrupt heart rate slowing with concomitant caudal shifts of the leading pacemaker (LP) site within the sinoatrial node (SAN). However, neither the mechanisms responsible nor their dynamics have been investigated fully. Therefore, the objective of this study was to elucidate the mechanisms driving cholinergic LP shift. Optical maps of right atrial activation were acquired in a rat working heart-brainstem preparation during baroreflex and chemoreflex stimulation or with carbachol. All methods of stimulation triggered shifts in LP site from the central SAN to caudal pacemaker regions, which were positive for HCN4 and received uniform cholinergic innervation. During baroreflex onset, the capacity of the central region to drive activation declined with a decrease in amplitude and gradient of optical action potentials (OAPs) in the surrounding myocardium. Accompanying this decline, there was altered entrainment in the caudal SAN as shown by decreased conduction velocity, OAP amplitude, gradient and activation time. Atropine abolished these responses. Chemoreflex stimulation produced similar effects but central capacity to drive activation was preserved before the LP shift. In contrast, carbachol produced a prolonged period of reduced capacity to drive and altered entrainment. Previous studies suggest LP shift is a rate-dependent phenomenon whereby acetylcholine slows central pacemaker rate disproportionately, enabling caudal cells that are less acetylcholine sensitive to assume control. Our findings indicate that cholinergic LP shifts are also determined by altered electrical source-to-sink balance in the SAN. We conclude that the LP region is defined by both rate and capacity to drive atrial activation.
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Affiliation(s)
| | - Mark L Trew
- University of Auckland, Auckland, New Zealand
| | | | | | | | - Anne M Gillis
- University of Calgary - Libin Cardiovascular Institute of Alberta, Calgary, AB, Canada
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Khiabani AJ, Greenberg JW, Hansalia VH, Schuessler RB, Melby SJ, Damiano RJ. Late Outcomes of Surgical Ablation for Inappropriate Sinus Tachycardia. Ann Thorac Surg 2019; 108:1162-1168. [PMID: 31077661 DOI: 10.1016/j.athoracsur.2019.03.103] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Revised: 02/09/2019] [Accepted: 03/25/2019] [Indexed: 11/26/2022]
Abstract
BACKGROUND Inappropriate sinus tachycardia (IST) is a rare clinical disorder characterized by an elevated resting heart rate and an exaggerated rate response to exercise or autonomic stress. Pharmacologic therapy and catheter ablation are considered first-line treatments for IST but can yield suboptimal relief of symptoms. The results of surgical ablation at our center were reviewed for patients with refractory IST. METHODS Between 1987 and 2018, 18 patients underwent surgical sinoatrial (SA) node isolation for treatment-refractory IST. All 18 patients had previously failed pharmacologic therapy, and 15 patients had failed catheter ablation of the SA node. RESULTS Ten patients underwent a median sternotomy, and 8 patients underwent a minimally invasive right thoracotomy. The SA node was isolated with the use of surgical incisions, cryoablation, or bipolar radiofrequency ablations. Sinus tachycardia was eliminated in 100% of patients in the immediate postoperative period. Long-term follow-up data were available for 17 patients, with a mean follow-up of 11.4 ± 7.9 years. At last follow-up, 100% of patients were free from recurrent symptomatic IST. More than 80% of patients were completely asymptomatic, whereas 3 patients reported occasional palpitations. Four patients were on β-blockers, and 5 patients required subsequent pacemaker implantation. All 8 patients who underwent minimally invasive isolation were in normal sinus rhythm at last follow-up, and only 1 patient complained of palpitations. CONCLUSIONS Surgical isolation of the SA node is a feasible treatment for IST refractory to pharmacologic therapy and catheter ablation. A minimally invasive surgical approach offers a less morbid alternative to traditional median sternotomy.
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Affiliation(s)
- Ali J Khiabani
- Division of Cardiothoracic Surgery, Department of Surgery, Washinton University School of Medicine in St Louis, St Louis, Missouri
| | - Jason W Greenberg
- Division of Cardiothoracic Surgery, Department of Surgery, Washinton University School of Medicine in St Louis, St Louis, Missouri
| | - Vivek H Hansalia
- Division of Cardiothoracic Surgery, Department of Surgery, Washinton University School of Medicine in St Louis, St Louis, Missouri
| | - Richard B Schuessler
- Division of Cardiothoracic Surgery, Department of Surgery, Washinton University School of Medicine in St Louis, St Louis, Missouri
| | - Spencer J Melby
- Division of Cardiothoracic Surgery, Department of Surgery, Washinton University School of Medicine in St Louis, St Louis, Missouri
| | - Ralph J Damiano
- Division of Cardiothoracic Surgery, Department of Surgery, Washinton University School of Medicine in St Louis, St Louis, Missouri.
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Canine and human sinoatrial node: differences and similarities in the structure, function, molecular profiles, and arrhythmia. J Vet Cardiol 2018; 22:2-19. [PMID: 30559056 DOI: 10.1016/j.jvc.2018.10.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 10/02/2018] [Accepted: 10/02/2018] [Indexed: 12/17/2022]
Abstract
The sinoatrial node (SAN) is the primary pacemaker in canine and human hearts. The SAN in both species has a unique three-dimensional heterogeneous structure characterized by small pacemaker myocytes enmeshed within fibrotic strands, which partially insulate the cells from aberrant atrial activation. The SAN pacemaker tissue expresses a unique signature of proteins and receptors that mediate SAN automaticity, ion channel currents, and cell-to-cell communication, which are predominantly similar in both species. Recent intramural optical mapping, integrated with structural and molecular studies, has revealed the existence of up to five specialized SAN conduction pathways that preferentially conduct electrical activation to atrial tissues. The intrinsic heart rate, intranodal leading pacemaker shifts, and changes in conduction in response to physiological and pathophysiological stimuli are similar. Structural and/or functional impairments due to cardiac diseases including heart failure cause SAN dysfunctions (SNDs) in both species. These dysfunctions are usually manifested as severe bradycardia, tachy-brady arrhythmias, and conduction abnormalities including exit block and SAN reentry, which could lead to atrial tachycardia and fibrillation, cardiac arrest, and heart failure. Pharmaceutical drugs and implantable pacemakers are only partially successful in managing SNDs, emphasizing a critical need to develop targeted mechanism-based therapies to treat SNDs. Because several structural and functional characteristics are similar between the canine and human SAN, research in these species may be mutually beneficial for developing novel treatment approaches. This review describes structural, functional, and molecular similarities and differences between the canine and human SAN, with special emphasis on arrhythmias and unique causal mechanisms of SND in diseased hearts.
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Natriuretic Peptide Receptor-C Protects Against Angiotensin II-Mediated Sinoatrial Node Disease in Mice. JACC Basic Transl Sci 2018; 3:824-843. [PMID: 30623142 PMCID: PMC6314975 DOI: 10.1016/j.jacbts.2018.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 08/15/2018] [Accepted: 08/16/2018] [Indexed: 12/19/2022]
Abstract
SAN disease is prevalent in hypertension and heart failure and can be induced by chronic Ang II treatment in mice. Ang II caused SAN disease in mice in association with impaired electrical conduction, reduction in the hyperpolarization-activated current (If) in SAN myocytes, and increased SAN fibrosis. Ang II-induced SAN disease was worsened in mice lacking NPR-C in association with enhanced SAN fibrosis. Mice co-treated with Ang II and an NPR-C agonist (cANF) were protected from SAN disease. NPR-C may represent a new target to protect against Ang II-induced SAN disease.
Sinoatrial node (SAN) disease mechanisms are poorly understood, and therapeutic options are limited. Natriuretic peptide(s) (NP) are cardioprotective hormones whose effects can be mediated partly by the NP receptor C (NPR-C). We investigated the role of NPR-C in angiotensin II (Ang II)-mediated SAN disease in mice. Ang II caused SAN disease due to impaired electrical activity in SAN myocytes and increased SAN fibrosis. Strikingly, Ang II treatment in NPR-C−/− mice worsened SAN disease, whereas co-treatment of wild-type mice with Ang II and a selective NPR-C agonist (cANF) prevented SAN dysfunction. NPR-C may represent a new target to protect against the development of Ang II-induced SAN disease.
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Key Words
- AP, action potential
- Ang II, angiotensin II
- CV, conduction velocity
- DD, diastolic depolarization
- Gmax, maximum conductance
- HR, heart rate
- ICa,L, L-type calcium current
- ICa,T, T-type calcium current
- INCX, sodium–calcium exchanger current
- IV, current voltage relationship
- If, hyperpolarization-activated current
- NP, natriuretic peptide
- NPR, natriuretic peptide receptor
- NPR-C, natriuretic peptide receptor C
- SAN, sinoatrial node
- SBP, systolic blood pressure
- V1/2(act), voltage for 50% channel activation
- cSNRT, corrected sinoatrial node recovery time
- fibrosis
- hypertension
- ion currents
- natriuretic peptide
- sinoatrial node
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Ly C, Weinberg SH. Analysis of heterogeneous cardiac pacemaker tissue models and traveling wave dynamics. J Theor Biol 2018; 459:18-35. [PMID: 30248329 DOI: 10.1016/j.jtbi.2018.09.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 09/12/2018] [Accepted: 09/20/2018] [Indexed: 01/06/2023]
Abstract
The sinoatrial-node (SAN) is a complex heterogeneous tissue that generates a stable rhythm in healthy hearts, yet a general mechanistic explanation for when and how this tissue remains stable is lacking. Although computational and theoretical analyses could elucidate these phenomena, such methods have rarely been used in realistic (large-dimensional) gap-junction coupled heterogeneous pacemaker tissue models. In this study, we adapt a recent model of pacemaker cells (Severi et al., 2012), incorporating biophysical representations of ion channel and intracellular calcium dynamics, to capture physiological features of a heterogeneous population of pacemaker cells, in particular "center" and "peripheral" cells with distinct intrinsic frequencies and action potential morphology. Large-scale simulations of the SAN tissue, represented by a heterogeneous tissue structure of pacemaker cells, exhibit a rich repertoire of behaviors, including complete synchrony, traveling waves of activity originating from periphery to center, and transient traveling waves originating from the center. We use phase reduction methods that do not require fully simulating the large-scale model to capture these observations. Moreover, the phase reduced models accurately predict key properties of the tissue electrical dynamics, including wave frequencies when synchronization occurs, and wave propagation direction in a variety of tissue models. With the reduced phase models, we analyze the relationship between cell distributions and coupling strengths and the resulting transient dynamics. Further, the reduced phase model predicts parameter regimes of irregular electrical dynamics. Thus, we demonstrate that phase reduced oscillator models applied to realistic pacemaker tissue is a useful tool for investigating the spatial-temporal dynamics of cardiac pacemaker activity.
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Affiliation(s)
- Cheng Ly
- Department of Statistical Sciences & Operations Research, Virginia Commonwealth University, USA.
| | - Seth H Weinberg
- Department of Biomedical Engineering, Virginia Commonwealth University USA. http://www.shweinberglab.com
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Guirado R, Carceller H, Castillo-Gómez E, Castrén E, Nacher J. Automated analysis of images for molecular quantification in immunohistochemistry. Heliyon 2018; 4:e00669. [PMID: 30003163 PMCID: PMC6039854 DOI: 10.1016/j.heliyon.2018.e00669] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/18/2018] [Accepted: 06/25/2018] [Indexed: 11/19/2022] Open
Abstract
The quantification of the expression of different molecules is a key question in both basic and applied sciences. While protein quantification through molecular techniques leads to the loss of spatial information and resolution, immunohistochemistry is usually associated with time-consuming image analysis and human bias. In addition, the scarce automatic software analysis is often proprietary and expensive and relies on a fixed threshold binarization. Here we describe and share a set of macros ready for automated fluorescence analysis of large batches of fixed tissue samples using FIJI/ImageJ. The quantification of the molecules of interest are based on an automatic threshold analysis of immunofluorescence images to automatically identify the top brightest structures of each image. These macros measure several parameters commonly quantified in basic neuroscience research, such as neuropil density and fluorescence intensity of synaptic puncta, perisomatic innervation and col-localization of different molecules and analysis of the neurochemical phenotype of neuronal subpopulations. In addition, these same macro functions can be easily modified to improve similar analysis of fluorescent probes in human biopsies for diagnostic purposes based on the expression patterns of several molecules.
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Affiliation(s)
- Ramon Guirado
- Neurobiology Unit, Department of Cell Biology, Interdisciplinary Research Structure for Biotechnology and Biomedicine (BIOTECMED), Universitat de Valencia, Spain
- Corresponding author.
| | - Héctor Carceller
- Neurobiology Unit, Department of Cell Biology, Interdisciplinary Research Structure for Biotechnology and Biomedicine (BIOTECMED), Universitat de Valencia, Spain
| | | | - Eero Castrén
- Neuroscience Center, University of Helsinki, Finland
| | - Juan Nacher
- Neurobiology Unit, Department of Cell Biology, Interdisciplinary Research Structure for Biotechnology and Biomedicine (BIOTECMED), Universitat de Valencia, Spain
- CIBERSAM: Spanish National Network for Research in Mental Health, Spain
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Csepe TA, Zhao J, Sul LV, Wang Y, Hansen BJ, Li N, Ignozzi AJ, Bratasz A, Powell KA, Kilic A, Mohler PJ, Janssen PML, Hummel JD, Simonetti OP, Fedorov VV. Novel application of 3D contrast-enhanced CMR to define fibrotic structure of the human sinoatrial node in vivo. Eur Heart J Cardiovasc Imaging 2018; 18:862-869. [PMID: 28087602 DOI: 10.1093/ehjci/jew304] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 11/16/2016] [Indexed: 11/13/2022] Open
Abstract
Aims The adult human sinoatrial node (SAN) has a specialized fibrotic intramural structure (35-55% fibrotic tissue) that provides mechanical and electrical protection from the surrounding atria. We hypothesize that late gadolinium-enhanced cardiovascular magnetic resonance (LGE-CMR) can be applied to define the fibrotic human SAN structure in vivo. Methods and results LGE-CMR atrial scans of healthy volunteers (n olu, 23-52 y.o.) using a 3 Tesla magnetic resonance imaging system with a spatial resolution of 1.0 mm3 or 0.625 × 0.625 × 1.25 mm3 were obtained and analysed. Percent fibrosis of total connective and cardiomyocyte tissue area in segmented atrial regions were measured based on signal intensity differences of fibrotic vs. non-fibrotic cardiomyocyte tissue. A distinct ellipsoidal fibrotic region (length: 23.6 ± 1.9 mm; width: 7.2 ± 0.9 mm; depth: 2.9 ± 0.4 mm) in all hearts was observed along the posterior junction of the crista terminalis and superior vena cava extending towards the interatrial septum, corresponding to the anatomical location of the human SAN. The SAN fibrotic region consisted of 41.9 ± 5.4% of LGE voxels above an average threshold of 2.7 SD (range 2-3 SD) from the non-fibrotic right atrial free wall tissue. Fibrosis quantification and SAN identification by in vivo LGE-CMR were validated in optically mapped explanted donor hearts ex vivo (n ivo, 19-65 y.o.) by contrast-enhanced CMR (9.4 Tesla; up to 90 µm3 resolution) correlated with serial histological sections of the SAN. Conclusion This is the first study to visualize the 3D human SAN fibrotic structure in vivo using LGE-CMR. Identification of the 3D SAN location and its high fibrotic content by LGE-CMR may provide a new tool to avoid or target SAN structure during ablation.
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Affiliation(s)
- Thomas A Csepe
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA
| | - Jichao Zhao
- Auckland Bioengineering Institute, The University of Auckland, 70 Symonds Street, Auckland 1142, New Zealand
| | - Lidiya V Sul
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA
| | - Yufeng Wang
- Auckland Bioengineering Institute, The University of Auckland, 70 Symonds Street, Auckland 1142, New Zealand
| | - Brian J Hansen
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA
| | - Ning Li
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA
| | - Anthony J Ignozzi
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA
| | - Anna Bratasz
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W 12th Avenue, Columbus, OH 43210, USA
| | - Kimerly A Powell
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W 12th Avenue, Columbus, OH 43210, USA
| | - Ahmet Kilic
- Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W 12th Avenue, Columbus, OH 43210, USA.,Department of Surgery, The Ohio State University Wexner Medical Center, 410 W 10th Avenue, Columbus, OH 43210, USA
| | - Peter J Mohler
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W 12th Avenue, Columbus, OH 43210, USA.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, 395 W 12th Avenue, Columbus, OH 43210, USA
| | - Paul M L Janssen
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W 12th Avenue, Columbus, OH 43210, USA.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, 395 W 12th Avenue, Columbus, OH 43210, USA
| | - John D Hummel
- Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W 12th Avenue, Columbus, OH 43210, USA.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, 395 W 12th Avenue, Columbus, OH 43210, USA
| | - Orlando P Simonetti
- Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W 12th Avenue, Columbus, OH 43210, USA.,Department of Biomedical Informatics, The Ohio State University Wexner Medical Center, 250 Lincoln Tower, 1800 Cannon Drive, Columbus, OH 43210, USA
| | - Vadim V Fedorov
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, 304 Hamilton Hall, 1645 Neil Avenue, Columbus, OH 43210, USA.,Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, 473 W 12th Avenue, Columbus, OH 43210, USA
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Schweizer PA, Darche FF, Ullrich ND, Geschwill P, Greber B, Rivinius R, Seyler C, Müller-Decker K, Draguhn A, Utikal J, Koenen M, Katus HA, Thomas D. Subtype-specific differentiation of cardiac pacemaker cell clusters from human induced pluripotent stem cells. Stem Cell Res Ther 2017; 8:229. [PMID: 29037217 PMCID: PMC5644063 DOI: 10.1186/s13287-017-0681-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Revised: 09/07/2017] [Accepted: 09/25/2017] [Indexed: 12/11/2022] Open
Abstract
Background Human induced pluripotent stem cells (hiPSC) harbor the potential to differentiate into diverse cardiac cell types. Previous experimental efforts were primarily directed at the generation of hiPSC-derived cells with ventricular cardiomyocyte characteristics. Aiming at a straightforward approach for pacemaker cell modeling and replacement, we sought to selectively differentiate cells with nodal-type properties. Methods hiPSC were differentiated into spontaneously beating clusters by co-culturing with visceral endoderm-like cells in a serum-free medium. Subsequent culturing in a specified fetal bovine serum (FBS)-enriched cell medium produced a pacemaker-type phenotype that was studied in detail using quantitative real-time polymerase chain reaction (qRT-PCR), immunocytochemistry, and patch-clamp electrophysiology. Further investigations comprised pharmacological stimulations and co-culturing with neonatal cardiomyocytes. Results hiPSC co-cultured in a serum-free medium with the visceral endoderm-like cell line END-2 produced spontaneously beating clusters after 10–12 days of culture. The pacemaker-specific genes HCN4, TBX3, and TBX18 were abundantly expressed at this early developmental stage, while levels of sarcomeric gene products remained low. We observed that working-type cardiomyogenic differentiation can be suppressed by transfer of early clusters into a FBS-enriched cell medium immediately after beating onset. After 6 weeks under these conditions, sinoatrial node (SAN) hallmark genes remained at high levels, while working-type myocardial transcripts (NKX2.5, TBX5) were low. Clusters were characterized by regular activity and robust beating rates (70–90 beats/min) and were triggered by spontaneous Ca2+ transients recapitulating calcium clock properties of genuine pacemaker cells. They were responsive to adrenergic/cholinergic stimulation and able to pace neonatal rat ventricular myocytes in co-culture experiments. Action potential (AP) measurements of cells individualized from clusters exhibited nodal-type (63.4%) and atrial-type (36.6%) AP morphologies, while ventricular AP configurations were not observed. Conclusion We provide a novel culture media-based, transgene-free approach for targeted generation of hiPSC-derived pacemaker-type cells that grow in clusters and offer the potential for disease modeling, drug testing, and individualized cell-based replacement therapy of the SAN. Electronic supplementary material The online version of this article (doi:10.1186/s13287-017-0681-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Patrick A Schweizer
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany. .,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany.
| | - Fabrice F Darche
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany
| | - Nina D Ullrich
- DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany.,Institute of Physiology and Pathophysiology, Division of Cardiovascular Physiology, Heidelberg University, INF 326, D-69120, Heidelberg, Germany
| | - Pascal Geschwill
- Institute of Physiology and Pathophysiology, Division of Neuro- and Sensory Physiology, Heidelberg University, INF 326, D-69120, Heidelberg, Germany
| | - Boris Greber
- Department of Cell and Developmental Biology, Max-Planck-Institute for Molecular Biomedicine, Röntgenstrasse, 20, D-48149, Münster, Germany
| | - Rasmus Rivinius
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany
| | - Claudia Seyler
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany
| | - Karin Müller-Decker
- Unit Tumor Models, German Cancer Research Center (DKFZ), Heidelberg, INF 280, D-69120, Heidelberg, Germany
| | - Andreas Draguhn
- Institute of Physiology and Pathophysiology, Division of Neuro- and Sensory Physiology, Heidelberg University, INF 326, D-69120, Heidelberg, Germany
| | - Jochen Utikal
- DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany.,Dermato-Oncology (G300), German Cancer Research Center (DKFZ), Heidelberg, INF 280, D-69120, Heidelberg, Germany.,Department of Dermatology, Venereology and Allergology, University Medical Center Mannheim, Ruprecht-Karl University of Heidelberg, Theodor-Kutzer-Ufer 1-3, D-68167, Mannheim, Germany
| | - Michael Koenen
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany.,Department of Molecular Neurobiology, Max-Planck-Institute for Medical Research, Jahnstrasse 29, D-69120, Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany
| | - Dierk Thomas
- Department of Cardiology, Medical University Hospital Heidelberg, INF 410, D-69120, Heidelberg, Germany.,DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, University of Heidelberg, INF 410, D-69120, Heidelberg, Germany
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Kharche SR, Vigmond E, Efimov IR, Dobrzynski H. Computational assessment of the functional role of sinoatrial node exit pathways in the human heart. PLoS One 2017; 12:e0183727. [PMID: 28873427 PMCID: PMC5584965 DOI: 10.1371/journal.pone.0183727] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 08/09/2017] [Indexed: 11/19/2022] Open
Abstract
AIM The human right atrium and sinoatrial node (SAN) anatomy is complex. Optical mapping experiments suggest that the SAN is functionally insulated from atrial tissue except at discrete SAN-atrial electrical junctions called SAN exit pathways, SEPs. Additionally, histological imaging suggests the presence of a secondary pacemaker close to the SAN. We hypothesise that a) an insulating border-SEP anatomical configuration is related to SAN arrhythmia; and b) a secondary pacemaker, the paranodal area, is an alternate pacemaker but accentuates tachycardia. A 3D electro-anatomical computational model was used to test these hypotheses. METHODS A detailed 3D human SAN electro-anatomical mathematical model was developed based on our previous anatomical reconstruction. Electrical activity was simulated using tissue specific variants of the Fenton-Karma action potential equations. Simulation experiments were designed to deploy this complex electro-anatomical system to assess the roles of border-SEPs and paranodal area by mimicking experimentally observed SAN arrhythmia. Robust and accurate numerical algorithms were implemented for solving the mono domain reaction-diffusion equation implicitly, calculating 3D filament traces, and computing dominant frequency among other quantitative measurements. RESULTS A centre to periphery gradient of increasing diffusion was sufficient to permit initiation of pacemaking at the centre of the 3D SAN. Re-entry within the SAN, micro re-entry, was possible by imposing significant SAN fibrosis in the presence of the insulating border. SEPs promoted the micro re-entry to generate more complex SAN-atrial tachycardia. Simulation of macro re-entry, i.e. re-entry around the SAN, was possible by inclusion of atrial fibrosis in the presence of the insulating border. The border shielded the SAN from atrial tachycardia. However, SAN micro-structure intercellular gap junctional coupling and the paranodal area contributed to prolonged atrial fibrillation. Finally, the micro-structure was found to be sufficient to explain shifts of leading pacemaker site location. CONCLUSIONS The simulations establish a relationship between anatomy and SAN electrical function. Microstructure, in the form of intercellular gap junction coupling, was found to regulate SAN function and arrhythmia.
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Affiliation(s)
- Sanjay R. Kharche
- Institute of Cardiovascular Sciences, School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Edward Vigmond
- University of Bordeaux, IMB, UMR 5251, Talence, France
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac- Bordeaux, France
| | - Igor R. Efimov
- Department of Biomedical Engineering, The George Washington University, Washington, DC, United States of America
| | - Halina Dobrzynski
- Institute of Cardiovascular Sciences, School of Medical Sciences, University of Manchester, Manchester, United Kingdom
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Stephenson RS, Atkinson A, Kottas P, Perde F, Jafarzadeh F, Bateman M, Iaizzo PA, Zhao J, Zhang H, Anderson RH, Jarvis JC, Dobrzynski H. High resolution 3-Dimensional imaging of the human cardiac conduction system from microanatomy to mathematical modeling. Sci Rep 2017; 7:7188. [PMID: 28775383 PMCID: PMC5543124 DOI: 10.1038/s41598-017-07694-8] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 07/03/2017] [Indexed: 12/23/2022] Open
Abstract
Cardiac arrhythmias and conduction disturbances are accompanied by structural remodelling of the specialised cardiomyocytes known collectively as the cardiac conduction system. Here, using contrast enhanced micro-computed tomography, we present, in attitudinally appropriate fashion, the first 3-dimensional representations of the cardiac conduction system within the intact human heart. We show that cardiomyocyte orientation can be extracted from these datasets at spatial resolutions approaching the single cell. These data show that commonly accepted anatomical representations are oversimplified. We have incorporated the high-resolution anatomical data into mathematical simulations of cardiac electrical depolarisation. The data presented should have multidisciplinary impact. Since the rate of depolarisation is dictated by cardiac microstructure, and the precise orientation of the cardiomyocytes, our data should improve the fidelity of mathematical models. By showing the precise 3-dimensional relationships between the cardiac conduction system and surrounding structures, we provide new insights relevant to valvar replacement surgery and ablation therapies. We also offer a practical method for investigation of remodelling in disease, and thus, virtual pathology and archiving. Such data presented as 3D images or 3D printed models, will inform discussions between medical teams and their patients, and aid the education of medical and surgical trainees.
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Affiliation(s)
- Robert S Stephenson
- Comparative Medicine Lab, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
- School of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - Andrew Atkinson
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Petros Kottas
- School of Physics and Astronomy, University of Manchester, Manchester, UK
| | - Filip Perde
- National Institute of Legal Medicine, Bucharest, Romania
| | - Fatemeh Jafarzadeh
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Mike Bateman
- The Visible Heart Laboratory, University of Minnesota, Minneapolis, USA
| | - Paul A Iaizzo
- The Visible Heart Laboratory, University of Minnesota, Minneapolis, USA
| | - Jichao Zhao
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Henggui Zhang
- School of Physics and Astronomy, University of Manchester, Manchester, UK
| | - Robert H Anderson
- Institute of Genetic Medicine, University of Newcastle, Newcastle, UK
| | - Jonathan C Jarvis
- School of Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
| | - Halina Dobrzynski
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
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Abstract
Cardiac arrhythmias are a leading cause of morbidity and mortality. Currently available therapeutic options lack sufficient efficacy and safety. Gene therapy has been proposed for treatment of cardiac arrhythmias. This review will discuss the current state of development for arrhythmia gene therapy. So far, all published studies are short-term, proof-of-concept animal studies. Potential replacement of cardiac pacemakers has been shown for combination gene therapy using the HCN2 gene and either the gene for adenylate cyclase, the skeletal muscle isoform of the sodium channel, or a dominant negative mutant of the potassium channel responsible for resting membrane potential. Atrial fibrillation has been prevented by gene transfer of either a dominant negative mutant of a repolarizing potassium channel, a gap junction, or an siRNA directed against caspase 3. Inherited arrhythmia syndromes have been corrected by replacement of the causative genes. Post-infarct ventricular tachycardia has been reduced by gene therapy with the skeletal muscle sodium channel and connexins and eliminated with the dominant negative mutant of the potassium channel responsible for resting membrane potential. These ideas show considerable promise. Long-term efficacy and safety studies are required to see if they can become viable therapies.
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Affiliation(s)
- J Kevin Donahue
- University of Massachusetts Medical School, Division of Cardiology, 55 Lake Ave. North, Worcester, MA 01655, United States.
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Moghtadaei M, Jansen HJ, Mackasey M, Rafferty SA, Bogachev O, Sapp JL, Howlett SE, Rose RA. The impacts of age and frailty on heart rate and sinoatrial node function. J Physiol 2016; 594:7105-7126. [PMID: 27598221 DOI: 10.1113/jp272979] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 08/24/2016] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS Sinoatrial node (SAN) function declines with age; however, not all individuals age at the same rate and health status can vary from fit to frail. Frailty was quantified in young and aged mice using a non-invasive frailty index so that the impacts of age and frailty on heart rate and SAN function could be assessed. SAN function was impaired in aged mice due to alterations in electrical conduction, changes in SAN action potential morphology and fibrosis in the SAN. Changes in SAN function, electrical conduction, action potential morphology and fibrosis were correlated with, and graded by, frailty. This study shows that mice of the same chronological age have quantifiable differences in health status that impact heart rate and SAN function and that these differences in health status can be identified using our frailty index. ABSTRACT Sinoatrial node (SAN) dysfunction increases with age, although not all older adults are affected in the same way. This is because people age at different rates and individuals of the same chronological age vary in health status from very fit to very frail. Our objective was to determine the impacts of age and frailty on heart rate (HR) and SAN function using a new model of frailty in ageing mice. Frailty, which was quantified in young and aged mice using a frailty index (FI), was greater in aged vs. young mice. Intracardiac electrophysiology demonstrated that HR was reduced whereas SAN recovery time (SNRT) was prolonged in aged mice; however, both parameters showed heteroscedasticity suggesting differences in health status among mice of similar chronological age. Consistent with this, HR and corrected SNRT were correlated with, and graded by, FI score. Optical mapping of the SAN demonstrated that conduction velocity (CV) was reduced in aged hearts in association with reductions in diastolic depolarization (DD) slope and action potential (AP) duration. In agreement with in vivo results, SAN CV, DD slope and AP durations all correlated with FI score. Finally, SAN dysfunction in aged mice was associated with increased interstitial fibrosis and alterations in expression of matrix metalloproteinases, which also correlated with frailty. These findings demonstrate that age-related SAN dysfunction occurs in association with electrical and structural remodelling and that frailty is a critical determinant of health status of similarly aged animals that correlates with changes in HR and SAN function.
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Affiliation(s)
- Motahareh Moghtadaei
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Hailey J Jansen
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Martin Mackasey
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Sara A Rafferty
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Oleg Bogachev
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - John L Sapp
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.,Division of Cardiology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Susan E Howlett
- Department of Pharmacology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Robert A Rose
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.,School of Biomedical Engineering, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada
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Murphy C, Lazzara R. Current concepts of anatomy and electrophysiology of the sinus node. J Interv Card Electrophysiol 2016; 46:9-18. [PMID: 27142063 DOI: 10.1007/s10840-016-0137-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 04/20/2016] [Indexed: 10/21/2022]
Abstract
The sinoatrial node, or sinus node, of humans is the principal pacemaker of the heart. Over the last century, studies have unraveled the complex molecular architecture of the sinus node and the expression of unique ion channels within its specialized myocytes. Aim of this review is to describe the embriology, the anatomy, the histology and the electrophisiology of the sinus node.
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Affiliation(s)
- Cliona Murphy
- University of Oklahoma Health Sciences Center, Heart Rhythm Institute, Oklahoma City, OK, USA.
| | - Ralph Lazzara
- University of Oklahoma Health Sciences Center, Heart Rhythm Institute, Oklahoma City, OK, USA
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41
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Csepe TA, Zhao J, Hansen BJ, Li N, Sul LV, Lim P, Wang Y, Simonetti OP, Kilic A, Mohler PJ, Janssen PML, Fedorov VV. Human sinoatrial node structure: 3D microanatomy of sinoatrial conduction pathways. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:164-78. [PMID: 26743207 DOI: 10.1016/j.pbiomolbio.2015.12.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 12/10/2015] [Accepted: 12/18/2015] [Indexed: 01/09/2023]
Abstract
INTRODUCTION Despite a century of extensive study on the human sinoatrial node (SAN), the structure-to-function features of specialized SAN conduction pathways (SACP) are still unknown and debated. We report a new method for direct analysis of the SAN microstructure in optically-mapped human hearts with and without clinical history of SAN dysfunction. METHODS Two explanted donor human hearts were coronary-perfused and optically-mapped. Structural analyses of histological sections parallel to epicardium (∼13-21 μm intervals) were integrated with optical maps to create 3D computational reconstructions of the SAN complex. High-resolution fiber fields were obtained using 3D Eigen-analysis of the structure tensor, and used to analyze SACP microstructure with a fiber-tracking approach. RESULTS Optical mapping revealed normal SAN activation of the atria through a lateral SACP proximal to the crista terminalis in Heart #1 but persistent SAN exit block in diseased Heart #2. 3D structural analysis displayed a functionally-observed SAN border composed of fibrosis, fat, and/or discontinuous fibers between SAN and atria, which was only crossed by several branching myofiber tracts in SACP regions. Computational 3D fiber-tracking revealed that myofiber tracts of SACPs created continuous connections between SAN #1 and atria, but in SAN #2, SACP region myofiber tracts were discontinuous due to fibrosis and fat. CONCLUSIONS We developed a new integrative functional, structural and computational approach that allowed for the resolution of the specialized 3D microstructure of human SACPs for the first time. Application of this integrated approach will shed new light on the role of the specialized SAN microanatomy in maintaining sinus rhythm.
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Affiliation(s)
- Thomas A Csepe
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Jichao Zhao
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Brian J Hansen
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Ning Li
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Lidiya V Sul
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Praise Lim
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Yufeng Wang
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Orlando P Simonetti
- Department of Biomedical Informatics, College of Medicine, The Ohio State University, Columbus, OH, USA; Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Ahmet Kilic
- Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Peter J Mohler
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Paul M L Janssen
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Vadim V Fedorov
- Department of Physiology & Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Davis Heart & Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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42
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Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
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Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
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Joung B, Chen PS. Function and dysfunction of human sinoatrial node. Korean Circ J 2015; 45:184-91. [PMID: 26023305 PMCID: PMC4446811 DOI: 10.4070/kcj.2015.45.3.184] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 03/23/2015] [Accepted: 03/26/2015] [Indexed: 11/11/2022] Open
Abstract
Sinoatrial node (SAN) automaticity is jointly regulated by a voltage (cyclic activation and deactivation of membrane ion channels) and Ca2+ clocks (rhythmic spontaneous sarcoplasmic reticulum Ca2+ release). Using optical mapping in Langendorff-perfused canine right atrium, we previously demonstrated that the β-adrenergic stimulation pushes the leading pacemaker to the superior SAN, which has the fastest activation rate and the most robust late diastolic intracellular calcium (Cai) elevation. Dysfunction of the superior SAN is commonly observed in animal models of heart failure and atrial fibrillation (AF), which are known to be associated with abnormal SAN automaticity. Using the 3D electroanatomic mapping techniques, we demonstrated that superior SAN served as the earliest atrial activation site (EAS) during sympathetic stimulation in healthy humans. In contrast, unresponsiveness of superior SAN to sympathetic stimulation was a characteristic finding in patients with AF and SAN dysfunction, and the 3D electroanatomic mapping technique had better diagnostic sensitivity than corrected SAN recovery time testing. However, both tests have significant limitations in detecting patients with symptomatic sick sinus syndrome. Recently, we reported that the location of the EAS can be predicted by the amplitudes of P-wave in the inferior leads. The inferior P-wave amplitudes can also be used to assess the superior SAN responsiveness to sympathetic stimulation. Inverted or isoelectric P-waves at baseline that fail to normalize during isoproterenol infusion suggest SAN dysfunction. P-wave morphology analyses may be helpful in determining the SAN function in patients at risk of symptomatic sick sinus syndrome.
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Affiliation(s)
- Boyoung Joung
- Division of Cardiology, Department of Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Peng-Sheng Chen
- The Krannert Institute of Cardiology and the Division of Cardiology, Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
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Csepe TA, Kalyanasundaram A, Hansen BJ, Zhao J, Fedorov VV. Fibrosis: a structural modulator of sinoatrial node physiology and dysfunction. Front Physiol 2015; 6:37. [PMID: 25729366 PMCID: PMC4325882 DOI: 10.3389/fphys.2015.00037] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Accepted: 01/24/2015] [Indexed: 01/01/2023] Open
Abstract
Heart rhythm is initialized and controlled by the Sinoatrial Node (SAN), the primary pacemaker of the heart. The SAN is a heterogeneous multi-compartment structure characterized by clusters of specialized cardiomyocytes enmeshed within strands of connective tissue or fibrosis. Intranodal fibrosis is emerging as an important modulator of structural and functional integrity of the SAN pacemaker complex. In adult human hearts, fatty tissue and fibrosis insulate the SAN from the hyperpolarizing effect of the surrounding atria while electrical communication between the SAN and right atrium is restricted to discrete SAN conduction pathways. The amount of fibrosis within the SAN is inversely correlated with heart rate, while age and heart size are positively correlated with fibrosis. Pathological upregulation of fibrosis within the SAN may lead to tachycardia-bradycardia arrhythmias and cardiac arrest, possibly due to SAN reentry and exit block, and is associated with atrial fibrillation, ventricular arrhythmias, heart failure and myocardial infarction. In this review, we will discuss current literature on the role of fibrosis in normal SAN structure and function, as well as the causes and consequences of SAN fibrosis upregulation in disease conditions.
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Affiliation(s)
- Thomas A Csepe
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center Columbus, OH, USA
| | - Anuradha Kalyanasundaram
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center Columbus, OH, USA
| | - Brian J Hansen
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center Columbus, OH, USA
| | - Jichao Zhao
- Auckland Bioengineering Institute, The University of Auckland Auckland, New Zealand
| | - Vadim V Fedorov
- Department of Physiology and Cell Biology, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center Columbus, OH, USA
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Unudurthi SD, Wolf RM, Hund TJ. Role of sinoatrial node architecture in maintaining a balanced source-sink relationship and synchronous cardiac pacemaking. Front Physiol 2014; 5:446. [PMID: 25505419 PMCID: PMC4244803 DOI: 10.3389/fphys.2014.00446] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Accepted: 10/31/2014] [Indexed: 11/21/2022] Open
Abstract
Normal heart rhythm (sinus rhythm) depends on regular activity of the sinoatrial node (SAN), a heterogeneous collection of specialized myocytes in the right atrium. SAN cells, in general, possess a unique electrophysiological profile that promotes spontaneous electrical activity (automaticity). However, while automaticity is required for normal pacemaking, it is not necessarily sufficient. Less appreciated is the importance of the elaborate structure of the SAN complex for proper pacemaker function. Here, we review the important structural features of the SAN with a focus on how these elements help manage a precarious balance between electrical charge generated by the SAN (“source”) and the charge needed to excite the surrounding atrial tissue (“sink”). We also discuss how compromised “source-sink” balance due, for example to fibrosis, may promote SAN dysfunction, characterized by slow and/or asynchronous pacemaker activity and even failure, in the setting of cardiovascular disease (e.g., heart failure, atrial fibrillation). Finally, we discuss implications of the “source-sink” balance in the SAN complex for cell and gene therapies aimed at creating a biological pacemaker as replacement or bridge to conventional electronic pacemakers.
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Affiliation(s)
- Sathya D Unudurthi
- Department of Biomedical Engineering, College of Engineering, The Ohio State University Columbus, OH, USA ; The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center Columbus, OH, USA
| | - Roseanne M Wolf
- Department of Mathematics, The University of Dubuque Dubuque, IA, USA
| | - Thomas J Hund
- Department of Biomedical Engineering, College of Engineering, The Ohio State University Columbus, OH, USA ; The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center Columbus, OH, USA ; Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University Wexner Medical Center Columbus, OH, USA
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Labarthe S, Bayer J, Coudiere Y, Henry J, Cochet H, Jais P, Vigmond E. A bilayer model of human atria: mathematical background, construction, and assessment. Europace 2014; 16 Suppl 4:iv21-iv29. [DOI: 10.1093/europace/euu256] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Abstract
In a normal human life span, the heart beats about 2 to 3 billion times. Under diseased conditions, a heart may lose its normal rhythm and degenerate suddenly into much faster and irregular rhythms, called arrhythmias, which may lead to sudden death. The transition from a normal rhythm to an arrhythmia is a transition from regular electrical wave conduction to irregular or turbulent wave conduction in the heart, and thus this medical problem is also a problem of physics and mathematics. In the last century, clinical, experimental, and theoretical studies have shown that dynamical theories play fundamental roles in understanding the mechanisms of the genesis of the normal heart rhythm as well as lethal arrhythmias. In this article, we summarize in detail the nonlinear and stochastic dynamics occurring in the heart and their links to normal cardiac functions and arrhythmias, providing a holistic view through integrating dynamics from the molecular (microscopic) scale, to the organelle (mesoscopic) scale, to the cellular, tissue, and organ (macroscopic) scales. We discuss what existing problems and challenges are waiting to be solved and how multi-scale mathematical modeling and nonlinear dynamics may be helpful for solving these problems.
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Affiliation(s)
- Zhilin Qu
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Correspondence to: Zhilin Qu, PhD, Department of Medicine, Division of Cardiology, David Geffen School of Medicine at UCLA, A2-237 CHS, 650 Charles E. Young Drive South, Los Angeles, CA 90095, Tel: 310-794-6050, Fax: 310-206-9133,
| | - Gang Hu
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Alan Garfinkel
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Department of Integrative Biology and Physiology, University of California, Los Angeles, California 90095, USA
| | - James N. Weiss
- Department of Medicine (Cardiology), David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA
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Lou Q, Hansen BJ, Fedorenko O, Csepe TA, Kalyanasundaram A, Li N, Hage LT, Glukhov AV, Billman GE, Weiss R, Mohler PJ, Györke S, Biesiadecki BJ, Carnes CA, Fedorov VV. Upregulation of adenosine A1 receptors facilitates sinoatrial node dysfunction in chronic canine heart failure by exacerbating nodal conduction abnormalities revealed by novel dual-sided intramural optical mapping. Circulation 2014; 130:315-24. [PMID: 24838362 DOI: 10.1161/circulationaha.113.007086] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Although sinoatrial node (SAN) dysfunction is a hallmark of human heart failure (HF), the underlying mechanisms remain poorly understood. We aimed to examine the role of adenosine in SAN dysfunction and tachy-brady arrhythmias in chronic HF. METHODS AND RESULTS We applied multiple approaches to characterize SAN structure, SAN function, and adenosine A1 receptor expression in control (n=17) and 4-month tachypacing-induced chronic HF (n=18) dogs. Novel intramural optical mapping of coronary-perfused right atrial preparations revealed that adenosine (10 μmol/L) markedly prolonged postpacing SAN conduction time in HF by 206 ± 99 milliseconds (versus 66 ± 21 milliseconds in controls; P=0.02). Adenosine induced SAN intranodal conduction block or microreentry in 6 of 8 dogs with HF versus 0 of 7 controls (P=0.007). Adenosine-induced SAN conduction abnormalities and automaticity depression caused postpacing atrial pauses in HF versus control dogs (17.1 ± 28.9 versus 1.5 ± 1.3 seconds; P<0.001). Furthermore, 10 μmol/L adenosine shortened atrial repolarization and led to pacing-induced atrial fibrillation in 6 of 7 HF versus 0 of 7 control dogs (P=0.002). Adenosine-induced SAN dysfunction and atrial fibrillation were abolished or prevented by adenosine A1 receptor antagonists (50 μmol/L theophylline/1 μmol/L 8-cyclopentyl-1,3-dipropylxanthine). Adenosine A1 receptor protein expression was significantly upregulated during HF in the SAN (by 47 ± 19%) and surrounding atrial myocardium (by 90 ± 40%). Interstitial fibrosis was significantly increased within the SAN in HF versus control dogs (38 ± 4% versus 23 ± 4%; P<0.001). CONCLUSIONS In chronic HF, adenosine A1 receptor upregulation in SAN pacemaker and atrial cardiomyocytes may increase cardiac sensitivity to adenosine. This effect may exacerbate conduction abnormalities in the structurally impaired SAN, leading to SAN dysfunction, and potentiate atrial repolarization shortening, thereby facilitating atrial fibrillation. Atrial fibrillation may further depress SAN function and lead to tachy-brady arrhythmias in HF.
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Affiliation(s)
- Qing Lou
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Brian J Hansen
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Olga Fedorenko
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Thomas A Csepe
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Anuradha Kalyanasundaram
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Ning Li
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Lori T Hage
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Alexey V Glukhov
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - George E Billman
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Raul Weiss
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Peter J Mohler
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Sándor Györke
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Brandon J Biesiadecki
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Cynthia A Carnes
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.)
| | - Vadim V Fedorov
- From the Department of Physiology and Cell Biology (Q.L., B.J.H., O.F., T.A.C., A.K., N.L., L.T.H., A.V.G., G.E.B., P.J.M., S.G., B.J.B., V.V.F.), Davis Heart & Lung Research Institute (Q.L., A.K., G.E.B., R.W., P.J.M., S.G., B.J.B., C.A.C., V.V.F.), and Department of Internal Medicine (R.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus, OH; Mental Health Research Institute and National Research Tomsk Polytechnic University, Tomsk, Russia (O.F.); and College of Pharmacy, The Ohio State University, Columbus (C.A.C.).
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Affiliation(s)
- Gwilym M Morris
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility
- Department of Cardiology, The Royal Melbourne Hospital
| | - Jonathan M Kalman
- Department of Cardiology, The Royal Melbourne Hospital
- Department of Medicine, Melbourne University
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Azer J, Hua R, Krishnaswamy PS, Rose RA. Effects of natriuretic peptides on electrical conduction in the sinoatrial node and atrial myocardium of the heart. J Physiol 2013; 592:1025-45. [PMID: 24344164 DOI: 10.1113/jphysiol.2013.265405] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Natriuretic peptides, including B-type and C-type natriuretic peptide (BNP and CNP), are powerful regulators of the cardiovascular system; however, their electrophysiological effects in the heart, particularly in the sinoatrial node (SAN), are incompletely understood. We have used high-resolution optical mapping to measure the effects of BNP and CNP, and the roles of natriuretic peptide receptors (NPR-A, NPR-B and NPR-C), on electrical conduction within the SAN and atrial myocardium. In basal conditions BNP and CNP (50-500 nm) increased conduction velocity (CV) within the SAN by ∼30% at the high dose and shifted the initial exit site superiorly. These effects sped conduction from the SAN to the surrounding atrial myocardium and were mediated by the NPR-A and NPR-B receptors. In the presence of isoproterenol (1 μm) the NPR-C receptor made a major contribution to the effects of BNP and CNP in the heart. In these conditions BNP, CNP and the NPR-C agonist cANF each decreased SAN CV and shifted the initial exit site inferiorly. The effects of cANF (30% reduction) were larger than BNP or CNP (∼15% reduction), indicating that BNP and CNP activate multiple natriuretic peptide receptors. In support of this, the inhibitory effects of BNP were absent in NPR-C knockout mice, where BNP instead elicited a further increase (∼25%) in CV. Measurements in externally paced atrial preparations demonstrate that the effects of natriuretic peptides on CV are partially independent of changes in cycle length. These data provide detailed novel insight into the complex effects of natriuretic peptides and their receptors on electrical conduction in the heart.
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Affiliation(s)
- John Azer
- Department of Physiology and Biophysics, Dalhousie University, Sir Charles Tupper Medical Building - Room 4J, 5850 College Street, PO Box 15000, Halifax, Nova Scotia, Canada, B3H 4R2.
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