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Burnicka-Turek O, Trampel KA, Laforest B, Broman MT, Khan Z, Rytkin E, Li B, Schaffer E, Gadek M, Shen KM, Efimov IR, Moskowitz IP. Coordinated Tbx3 / Tbx5 transcriptional control of the adult ventricular conduction system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.29.610377. [PMID: 39257760 PMCID: PMC11383707 DOI: 10.1101/2024.08.29.610377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2024]
Abstract
The cardiac conduction system (CCS) orchestrates the electrical impulses that enable coordinated contraction of the cardiac chambers. The T-box transcription factors TBX3 and TBX5 are required for cardiac conduction system development and associated with overlapping and distinct human cardiac conduction system diseases. We evaluated the coordinated role of Tbx3 and Tbx5 in the murine ventricular conduction system (VCS). We engineered a compound Tbx3:Tbx5 conditional knockout allele for both genes located in cis on mouse chromosome 5. Conditional deletion of both T-box transcriptional factors in the ventricular conduction system, using the VCS-specific Mink:Cre, caused loss of VCS function and molecular identity. Combined Tbx3 and Tbx5 deficiency in the adult VCS led to conduction defects, including prolonged PR and QRS intervals and elevated susceptibility to ventricular tachycardia. These electrophysiologic defects occurred prior to detectable alterations in cardiac contractility or histologic morphology, indicative of a primary conduction system defect. Tbx3:Tbx5 double knockout VCS cardiomyocytes revealed a transcriptional shift towards non-CCS-specialized working myocardium, suggesting reprogramming of their cellular identity. Furthermore, optical mapping revealed a loss of VCS-specific conduction system propagation. Collectively, these findings indicate that Tbx3 and Tbx5 coordinate to control VCS molecular fate and function, with implications for understanding cardiac conduction disorders in humans.
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Affiliation(s)
- Ozanna Burnicka-Turek
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Katy A Trampel
- Departments of Biomedical Engineering, Northwestern University, Chicago, IL 60611, USA
| | - Brigitte Laforest
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Michael T Broman
- Department of Medicine, Section of Cardiology, University of Chicago, Chicago, IL, 60637, USA
| | - Zoheb Khan
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Eric Rytkin
- Departments of Biomedical Engineering, Northwestern University, Chicago, IL 60611, USA
| | - Binjie Li
- Departments of Biomedical Engineering, Northwestern University, Chicago, IL 60611, USA
| | - Ella Schaffer
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Margaret Gadek
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Kaitlyn M Shen
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Igor R Efimov
- Departments of Biomedical Engineering, Northwestern University, Chicago, IL 60611, USA
| | - Ivan P Moskowitz
- Departments of Pediatrics, Pathology, and Human Genetics, University of Chicago, Chicago, IL 60637, USA
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2
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Kennedy HL. Progress in Cardiac Conduction Disease and the Emergence of Artificial Intelligence in Epidemiological Research. JACC. ADVANCES 2024; 3:101007. [PMID: 39129985 PMCID: PMC11312773 DOI: 10.1016/j.jacadv.2024.101007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Affiliation(s)
- Harold L. Kennedy
- Department of Medicine and Cardiovascular Disease, University of Missouri School of Medicine, Columbia, Missouri, USA
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3
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Lee C, Xu S, Samad T, Goodyer WR, Raissadati A, Heinrich P, Wu SM. The cardiac conduction system: History, development, and disease. Curr Top Dev Biol 2024; 156:157-200. [PMID: 38556422 DOI: 10.1016/bs.ctdb.2024.02.006] [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] [Indexed: 04/02/2024]
Abstract
The heart is the first organ to form during embryonic development, establishing the circulatory infrastructure necessary to sustain life and enable downstream organogenesis. Critical to the heart's function is its ability to initiate and propagate electrical impulses that allow for the coordinated contraction and relaxation of its chambers, and thus, the movement of blood and nutrients. Several specialized structures within the heart, collectively known as the cardiac conduction system (CCS), are responsible for this phenomenon. In this review, we discuss the discovery and scientific history of the mammalian cardiac conduction system as well as the key genes and transcription factors implicated in the formation of its major structures. We also describe known human diseases related to CCS development and explore existing challenges in the clinical context.
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Affiliation(s)
- Carissa Lee
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States
| | - Sidra Xu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States
| | - Tahmina Samad
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, United States; Department of Pediatrics, Stanford University, Stanford, CA, United States
| | - William R Goodyer
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, United States
| | - Alireza Raissadati
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Division of Pediatric Cardiology, Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, United States
| | - Paul Heinrich
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Regenerative Medicine in Cardiovascular Diseases, First Department of Medicine, Cardiology, Klinikum Rechts der Isar, Technical University of Munich, School of Medicine and Health, Munich, Germany
| | - Sean M Wu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA, United States; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA, United States; Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, CA, United States.
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4
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Inokaitis H, Pauziene N, Pauza DH. The distribution of sinoatrial nodal cells and their innervation in the pig. Anat Rec (Hoboken) 2023; 306:2333-2344. [PMID: 35643929 DOI: 10.1002/ar.24998] [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: 03/03/2022] [Revised: 04/28/2022] [Accepted: 05/05/2022] [Indexed: 11/08/2022]
Abstract
The sinoatrial node (SAN) has been the object of interest of various studies. In experimental neurocardiology, the real challenge is the choice of the most appropriate animal model. Pig is routinely used animal due to its size and physiological features. Despite this, the anatomy and innervation of the pig SAN are not completely examined. This study analyses the distribution of SAN cells and their innervation in whole-mount preparations and the cross-sections of the pig right atrium. Our findings revealed the differences in the distribution of the SAN cells and their innervation pattern between pigs and other animals. The pig SAN myocytes were distributed around the root of the anterior vena cava. A meshwork of nerve fibers (NFs) in this area was four-fold denser compared to other right atrial areas and contained the adrenergic (positive for TH), cholinergic (positive for ChAT), nitrergic (positive for nNOS), and potentially sensory (positive for SP) NFs. The SAN area contained 98 ± 10 ganglia that involved 21 ± 2 neuronal somata per ganglion. The determined chemical phenotypes of ganglionic cells demonstrate their diversity in the pig SAN area as there were identified neuronal somata positive for ChAT, nNOS, TH, and simultaneously for ChAT/nNOS and ChAT/TH. Small intensively fluorescent cells were also abundant. The broad distribution of SAN cells, the chemical diversity, and the high density of neural components in the SAN area are comparable to the human one and, therefore, the pig may be considered as the appropriate animal model for experimental cardiology.
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Affiliation(s)
- Hermanas Inokaitis
- Faculty of Medicine, Institute of Anatomy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Neringa Pauziene
- Faculty of Medicine, Institute of Anatomy, Lithuanian University of Health Sciences, Kaunas, Lithuania
| | - Dainius H Pauza
- Faculty of Medicine, Institute of Anatomy, Lithuanian University of Health Sciences, Kaunas, Lithuania
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5
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De Almeida MC. Heinrich Ewald Hering's discovery of the heart pacemaker: Hering, Tawara and Aschoff's search for its morphological basis, the sinoatrial node, and why they failed. Anat Sci Int 2023:10.1007/s12565-023-00711-z. [PMID: 36944867 DOI: 10.1007/s12565-023-00711-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 02/23/2023] [Indexed: 03/23/2023]
Abstract
Two groups of investigators investigated the heart pacemaker and its morphological basis in the early twentieth century. The first group was formed by Henrich Ewald Hering (physiologist), Sunao Tawara and Ludwig Aschoff (morphologists). The second group was composed of James Mackenzie (general practitioner and clinical investigator), Arthur Keith and Martin Flack (morphologists). These groups were formed almost at the same time in 1903. Their work resulted in the discovery of the atrioventricular node and Purkinje network (Sunao Tawara, in 1906), heart pacemaker (H E Hering, in 1907) and sinoatrial node (Keith and Flack, in 1907). Here, it is shown how the interconnections of the concurrent works of these groups resulted in the discovery not only of the function, but also of the structure of the sinoatrial node.
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Affiliation(s)
- Marcos C De Almeida
- Department of Genetics and Morphology, Brasilia's University, Campus Asa Norte, Brasilia, CEP 70910-900, Brazil.
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6
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Chaturvedi P, Kalani A, Chaturvedi P, Kalani K, Verma VK, Tyagi SC. Exercise mitigates calpain induced Purkinje cell loss in diabetes. Life Sci 2022; 308:120982. [PMID: 36150460 DOI: 10.1016/j.lfs.2022.120982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 09/15/2022] [Accepted: 09/16/2022] [Indexed: 11/30/2022]
Abstract
Calpain-1 is a ubiquitous calcium dependent cysteine protease and found in cytoplasm as well as mitochondria. We have earlier reported that active calpain-1 is translocated from cytosol to mitochondria and activates MMP9. Calpain-1 activation is detrimental to the heart in several different ways, but there is little evidence that it can degrade Purkinje cell protein (PCP-4) and impair contractility in diabetes. Our hypothesis is that in diabetes, PCP-4 is degraded by calpain-1, causing contractile dysfunction that can be mitigated by exercise. To test this hypothesis, we recruited four groups of mice, 1) db/+ control, 2) db/+ with exercise, 3) db/db, 4) db/db with exercise. The mice were exercised on treadmill for 8 weeks as per American Veterinary Research Guidelines. Adding calcium to isolated cardiomyocytes caused them to lose shape and die. Compared with live myocytes, we observed high calpain-1 levels as well as significantly lower levels of PCP-4 and increased levels of calmodulin and calmodulin kinase II (CaMKII) in dead myocytes. We used the CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats) plasmid to knock down calpain-1 in HL-1 myocytes which restored the levels of PCP-4 along with calmodulin and CaMKII. In vivo, we found upregulated levels of calpain-1 in db/db mice (diabetic) as compared to db/+ which were mitigated in the exercised mice. Conclusively our data strongly suggests that in diabetes there is high induction of calpain-1 with degrades PCP-4, a protein important for contractility and exercise can mitigate this.
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Affiliation(s)
- Pankaj Chaturvedi
- Department of Physiology and Biophysics, University of Louisville, KY, USA
| | - Anuradha Kalani
- Department of Physiology and Biophysics, University of Louisville, KY, USA; Department of Life Sciences and Biotechnology, Chhatrapati Shahu Ji Maharaj University, Kanpur, U.P., India.
| | - Poonam Chaturvedi
- Department of Physiotherapy, Lovely Professional University, Phagwara, Punjab, India
| | - Komal Kalani
- Department of Chemistry, Biotechnology Sciences and Engineering Building, University of Texas at San Antonio, San Antonio, TX, USA
| | - Vinod K Verma
- Department of Life Sciences and Biotechnology, Chhatrapati Shahu Ji Maharaj University, Kanpur, U.P., India
| | - Suresh C Tyagi
- Department of Physiology and Biophysics, University of Louisville, KY, USA
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7
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Arshad A, Atkinson AJ. A 21st century view of the anaotmy of the cardiac conduction system. TRANSLATIONAL RESEARCH IN ANATOMY 2022. [DOI: 10.1016/j.tria.2022.100204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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8
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Remme CA. Getting to the heart of rhythm: A century of progress. Physiol Rev 2022; 102:1553-1567. [PMID: 35343827 DOI: 10.1152/physrev.00043.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The human heart beats over eighty thousand times a day, and the average person's heart may have beaten up to 3 billion times by the age of 80. During the early stages of pregnancy, the heart beat provides the first visual and auditory sign of life of the foetus. Conversely, the first audible sound that the foetus is likely to hear is the heart beat of the mother. How fitting then, that at the "birth" Physiological Reviews the very first article published in 1921 written by Eyster and Meek addressed "The origin and conduction of the heart beat".1 In their insightful review, the authors discussed the landmark discoveries made from the mid-19th century on the electrical function of the heart. Now, a hundred years later, at the start of the next century of Physiological Reviews, an update on the huge progress made in the "exciting" field of cardiac electrophysiology is warranted. Guided by a number of excellent reviews published in Physiological Reviews since 1921 as well as a large body of literature, an overview of the important advancements made on the topic is provided here.
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Affiliation(s)
- Carol Ann Remme
- Amsterdam UMC, location University of Amsterdam, Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
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New Insights into the Development and Morphogenesis of the Cardiac Purkinje Fiber Network: Linking Architecture and Function. J Cardiovasc Dev Dis 2021; 8:jcdd8080095. [PMID: 34436237 PMCID: PMC8397066 DOI: 10.3390/jcdd8080095] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 07/30/2021] [Accepted: 08/03/2021] [Indexed: 12/30/2022] Open
Abstract
The rapid propagation of electrical activity through the ventricular conduction system (VCS) controls spatiotemporal contraction of the ventricles. Cardiac conduction defects or arrhythmias in humans are often associated with mutations in key cardiac transcription factors that have been shown to play important roles in VCS morphogenesis in mice. Understanding of the mechanisms of VCS development is thus crucial to decipher the etiology of conduction disturbances in adults. During embryogenesis, the VCS, consisting of the His bundle, bundle branches, and the distal Purkinje network, originates from two independent progenitor populations in the primary ring and the ventricular trabeculae. Differentiation into fast-conducting cardiomyocytes occurs progressively as ventricles develop to form a unique electrical pathway at late fetal stages. The objectives of this review are to highlight the structure–function relationship between VCS morphogenesis and conduction defects and to discuss recent data on the origin and development of the VCS with a focus on the distal Purkinje fiber network.
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10
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Yu S, Chen H, Li H. Transient left septal fascicular block in the scenario of ST-segment elevation myocardial infarction. Anatol J Cardiol 2021; 25:588-589. [PMID: 34369887 DOI: 10.5152/anatoljcardiol.2021.93490] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Shandong Yu
- Department of Cardiology, Cardiovascular Center, Beijing Friendship Hospital, Capital Medical University; Beijing-China
| | - Hui Chen
- Department of Cardiology, Cardiovascular Center, Beijing Friendship Hospital, Capital Medical University; Beijing-China
| | - Hongwei Li
- Department of Cardiology, Cardiovascular Center, Beijing Friendship Hospital, Capital Medical University; Beijing-China
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11
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Barber F, Langfield P, Lozano M, Garcia-Fernandez I, Duchateau J, Hocini M, Haissaguerre M, Vigmond E, Sebastian R. Estimation of Personalized Minimal Purkinje Systems From Human Electro-Anatomical Maps. IEEE TRANSACTIONS ON MEDICAL IMAGING 2021; 40:2182-2194. [PMID: 33856987 DOI: 10.1109/tmi.2021.3073499] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The Purkinje system is a heart structure responsible for transmitting electrical impulses through the ventricles in a fast and coordinated way to trigger mechanical contraction. Estimating a patient-specific compatible Purkinje Network from an electro-anatomical map is a challenging task, that could help to improve models for electrophysiology simulations or provide aid in therapy planning, such as radiofrequency ablation. In this study, we present a methodology to inversely estimate a Purkinje network from a patient's electro-anatomical map. First, we carry out a simulation study to assess the accuracy of the method for different synthetic Purkinje network morphologies and myocardial junction densities. Second, we estimate the Purkinje network from a set of 28 electro-anatomical maps from patients, obtaining an optimal conduction velocity in the Purkinje network of 1.95 ± 0.25 m/s, together with the location of their Purkinje-myocardial junctions, and Purkinje network structure. Our results showed an average local activation time error of 6.8±2.2 ms in the endocardium. Finally, using the personalized Purkinje network, we obtained correlations higher than 0.85 between simulated and clinical 12-lead ECGs.
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12
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Gómez-Torres F, Estupiñán HY, Ruíz-Sauri A. Identification to cardiac conduction cells in humans and pigs according to their zonal distribution, using histological, immunohistochemical and morphometric study. Res Vet Sci 2021; 138:137-147. [PMID: 34144281 DOI: 10.1016/j.rvsc.2021.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 05/23/2021] [Accepted: 06/07/2021] [Indexed: 10/21/2022]
Abstract
Histologically, the cardiac conduction network is formed of electrically isolated subendocardial fibers that comprise specialized cells with fewer myofibrils and mitochondria than cardiomyocytes. Our aim is to uncover regional variations of cardiac conduction fibers through histological and morphometric study in a porcine and human model. We analyzed five male adult human hearts and five male pig hearts. The left ventricles were dissected and sectioned in the axial plane into three parts: basal, middle third and apex regions. Cardiac conduction fibers study was carried out using hematoxylin-eosin and Masson's trichrome staining, and cardiac conduction cells and their junctions were identified using desmin, and a PAS method. Cardiac conduction fibers were difficult to pinpoint in humans, mostly showing a darker color or equal to cardiomyocytes. Cardiac conduction fibers in humans were in the subendocardium and in pigs in the myocardium and subendocardium. Cardiac conduction fibers were located mainly in the septal region in both humans and pigs. In our morphometric analysis, we were able to determine that cardiac conduction cells in humans (18.52 +/- 5.41 μm) and pigs (21.32 +/- 6.45 μm) were large, compared to cardiomyocytes. Conduction fiber-myocardial junctions were present in 10% in humans and 24.2% in pigs. The performance of immunohistochemical methods made it possible to improve the identification of cardiac conduction cells in the species studied. Study of cardiac conduction fibers and cells and their myocardial junctions is vital to gain insight into their normal distribution in the species analyzed, and thus advance the use of pigs in experimental models of the cardiac conduction system in humans.
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Affiliation(s)
- Fabián Gómez-Torres
- Department of Pathology, Faculty of Medicine, Universitat de Valencia, Av. de Blasco Ibáñez, 15, 46010 Valencia, Spain; Department of Basic Sciences, Medicine School, Universidad Industrial de Santander, Cra 32 # 29-31, 68002 Bucaramanga, Colombia.
| | - H Yesid Estupiñán
- Department of Basic Sciences, Medicine School, Universidad Industrial de Santander, Cra 32 # 29-31, 68002 Bucaramanga, Colombia; Department of Laboratory Medicine, Clinical Research Center, Karolinska Institute, Karolinska University Hospital Huddinge, SE-141 86 Huddinge, Sweden.
| | - Amparo Ruíz-Sauri
- Department of Pathology, Faculty of Medicine, Universitat de Valencia, Av. de Blasco Ibáñez, 15, 46010 Valencia, Spain; INCLIVA Biomedical Research Institute, Av. de Blasco Ibáñez, 17, 46010 Valencia, Spain.
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13
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Scherlag BJ. The ligament of Marshall: A historical perspective. Heart Rhythm 2021; 18:1088-1089. [PMID: 33940196 DOI: 10.1016/j.hrthm.2021.04.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 04/23/2021] [Indexed: 10/21/2022]
Affiliation(s)
- Benjamin J Scherlag
- Division of Cardiovascular Services, Department of Medicine, The Oklahoma University Health Sciences Center, Oklahoma City, Oklahoma.
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14
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Gómez-Torres FA, Estupiñán HY, Ruíz-Saurí A. Morphometric analysis of cardiac conduction fibers in horses and dogs, a comparative histological and immunohistochemical study with findings in human hearts. Res Vet Sci 2021; 135:200-216. [PMID: 33618179 DOI: 10.1016/j.rvsc.2021.02.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 01/04/2021] [Accepted: 02/14/2021] [Indexed: 11/28/2022]
Abstract
The principal function of the ventricular conduction system is rapid electrical activation of the ventricles. The aim of this study is to conduct a morphometric study to pinpoint the morphological parameters that define cardiac conduction cells, allowing us to distinguish them from other cells. Five male horse hearts and five male dog hearts were used in the study. The hearts were fixed in a 5% formaldehyde solution. Histological sections of 5 μm thickness were acquired and stained with hematoxylin-eosin and Masson's trichrome and cardiac conduction cells and their junctions were identified by desmin, connexin 40 and a PAS method. We found statistically significant differences in cardiac conduction fibers density and thickness, which was much higher in horses than in dogs (p = 0.000 for both values). By comparing the measured parameters of the cells in both species, we determined that cardiac conduction cells area and diameters were greater in horses than in dogs (p = 0.000 for all values). In dogs there are more junctions (30.8%) than in horses (26.1%), a statistically significant difference (p = 0.041). Our findings regarding the cardiac conduction fibers distribution in the animal species studied becomes new knowledge that contributes to the morphological study of this component of the cardiac conduction system and also makes it possible to locate exactly the site with the highest density of cardiac conduction fibers as a contribution to the cardiological study of these structures that lead to the prevention of ventricular arrhythmias and the identification of their treatment site.
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Affiliation(s)
- F A Gómez-Torres
- Department of Pathology, Faculty of Medicine, 1st floor, Universitat de Valencia, Av. de Blasco Ibáñez, 15, 46010 Valencia, Spain; Department of Basic Sciences, School of Medicine, Universidad Industrial de Santander, Cra 32 # 29-31, 68002 Bucaramanga, Colombia.
| | - H Y Estupiñán
- Department of Basic Sciences, School of Medicine, Universidad Industrial de Santander, Cra 32 # 29-31, 68002 Bucaramanga, Colombia; Department of Laboratory Medicine, Clinical Research Center, Karolinska Institute, Karolinska University Hospital Huddinge, SE-141 86 Huddinge, Sweden.
| | - A Ruíz-Saurí
- Department of Pathology, Faculty of Medicine, 1st floor, Universitat de Valencia, Av. de Blasco Ibáñez, 15, 46010 Valencia, Spain; INCLIVA Biomedical Research Institute, Av. de Blasco Ibáñez, 17, 46010 Valencia, Spain.
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15
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Christoffels V, Jensen B. Cardiac Morphogenesis: Specification of the Four-Chambered Heart. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a037143. [PMID: 31932321 DOI: 10.1101/cshperspect.a037143] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Early heart morphogenesis involves a process in which embryonic precursor cells are instructed to form a cyclic contracting muscle tube connected to blood vessels, pumping fluid. Subsequently, the heart becomes structurally complex and its size increases several orders of magnitude to functionally keep up with the demands of the growing organism. Programmed transcriptional regulatory networks control the early steps of cardiac development. However, already during the early stages of its assembly, the heart tube starts to produce electrochemical potentials, contractions, and flow, which are transduced into signals that feed back into the process of morphogenesis itself. Heart morphogenesis, thus, involves the interplay between progressively changing genetic networks, function, and shape. Morphogenesis is evolutionarily conserved, but species-specific differences occur and in mouse, for instance, distinct phases of development become overlapping and compounded in an extremely fast gestation. Here, we review the early morphogenesis of the chambered heart that maintains a circulation supporting development of an organism rapidly growing in size and requirements.
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Affiliation(s)
- Vincent Christoffels
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam 1105AZ, The Netherlands
| | - Bjarke Jensen
- Department of Medical Biology, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam 1105AZ, The Netherlands
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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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Burnicka-Turek O, Broman MT, Steimle JD, Boukens BJ, Petrenko NB, Ikegami K, Nadadur RD, Qiao Y, Arnolds DE, Yang XH, Patel VV, Nobrega MA, Efimov IR, Moskowitz IP. Transcriptional Patterning of the Ventricular Cardiac Conduction System. Circ Res 2020; 127:e94-e106. [PMID: 32290757 PMCID: PMC8328577 DOI: 10.1161/circresaha.118.314460] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
RATIONALE The heartbeat is organized by the cardiac conduction system (CCS), a specialized network of cardiomyocytes. Patterning of the CCS into atrial node versus ventricular conduction system (VCS) components with distinct physiology is essential for the normal heartbeat. Distinct node versus VCS physiology has been recognized for more than a century, but the molecular basis of this regional patterning is not well understood. OBJECTIVE To study the genetic and genomic mechanisms underlying node versus VCS distinction and investigate rhythm consequences of failed VCS patterning. METHODS AND RESULTS Using mouse genetics, we found that the balance between T-box transcriptional activator, Tbx5, and T-box transcriptional repressor, Tbx3, determined the molecular and functional output of VCS myocytes. Adult VCS-specific removal of Tbx5 or overexpression of Tbx3 re-patterned the fast VCS into slow, nodal-like cells based on molecular and functional criteria. In these cases, gene expression profiling showed diminished expression of genes required for VCS-specific fast conduction but maintenance of expression of genes required for nodal slow conduction physiology. Action potentials of Tbx5-deficient VCS myocytes adopted nodal-specific characteristics, including increased action potential duration and cellular automaticity. Removal of Tbx5 in vivo precipitated inappropriate depolarizations in the atrioventricular (His)-bundle associated with lethal ventricular arrhythmias. TBX5 bound and directly activated cis-regulatory elements at fast conduction channel genes required for fast physiological characteristics of the VCS action potential, defining the identity of the adult VCS. CONCLUSIONS The CCS is patterned entirely as a slow, nodal ground state, with a T-box dependent, physiologically dominant, fast conduction network driven specifically in the VCS. Disruption of the fast VCS gene regulatory network allowed nodal physiology to emerge, providing a plausible molecular mechanism for some lethal ventricular arrhythmias.
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Affiliation(s)
- Ozanna Burnicka-Turek
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, USA
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Michael T. Broman
- Department of Medicine, The University of Chicago, Chicago, IL, 60637, USA
| | - Jeffrey D. Steimle
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, USA
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Bastiaan J. Boukens
- Department of Biomedical Engineering, George Washington University, Washington, DC 20052, USA
- Department of Medical Biology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Nataliya B. Petrenko
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Penn Cardiovascular Institute, Philadelphia, PA 19104, USA
| | - Kohta Ikegami
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, USA
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Rangarajan D. Nadadur
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, USA
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Yun Qiao
- Department of Biomedical Engineering, George Washington University, Washington, DC 20052, USA
| | - David E. Arnolds
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, USA
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Xinan H. Yang
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, USA
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Vickas V. Patel
- Discovery Medicine, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - Marcelo A. Nobrega
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Igor R. Efimov
- Department of Biomedical Engineering, George Washington University, Washington, DC 20052, USA
| | - Ivan P. Moskowitz
- Department of Pediatrics, University of Chicago, Chicago, IL 60637, USA
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
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18
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Toward detection of conduction tissue during cardiac surgery: Light at the end of the tunnel? Heart Rhythm 2020; 17:2200-2207. [PMID: 32659372 DOI: 10.1016/j.hrthm.2020.07.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 07/02/2020] [Accepted: 07/02/2020] [Indexed: 11/22/2022]
Abstract
Postoperative conduction block requiring lifetime pacemaker placement continues to be a considerable source of morbidity for patients undergoing repair of congenital heart defects. Damage to the cardiac conduction system (CCS) during surgical procedures is thought to be a major cause of conduction block. Intraoperative identification and avoidance of the CCS is thus a key strategy to improve surgical outcomes. A number of approaches have been developed to avoid conduction tissue damage and mitigate morbidity. Here we review the historical and contemporary approaches for identification of conduction tissue during cardiac surgery. The established approach for intraoperative identification is based on anatomic landmarks established in extensive histologic studies of normal and diseased heart. We focus on landmarks to identify the sinus and atrioventricular nodes during cardiac surgery. We also review technologies explored for intraoperative tissue identification, including electrical impedance measurements and electrocardiography. We describe new optical approaches, in particular, and optical spectroscopy and fiberoptic confocal microscopy (FCM) for identification of CCS regions and working myocardium during surgery. As a template for translation of future technology developments, we describe research and regulatory pathways to translate FCM for cardiac surgery. We suggest that along with more robust approaches to surgeon training, including awareness of fundamental anatomic studies, optical approaches such as FCM show promise in aiding surgeons with repairs of heart defects. In particular, for complex defects, these approaches can complement landmark-based identification of conduction tissue and thus help to avoid injury to the CCS due to surgical procedures.
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19
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Kuhtz-Buschbeck JP, Schaefer J, Wilder N, Wolze WT. The origin of the heartbeat and theories of muscle contraction. Physiological concepts and conflicts in the 19th century. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 159:3-9. [PMID: 32622835 DOI: 10.1016/j.pbiomolbio.2020.05.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 04/27/2020] [Accepted: 05/28/2020] [Indexed: 11/19/2022]
Abstract
The origin of the incessant rhythmical heartbeat and the mechanism of muscle contraction have fascinated scientists over centuries. This short review outlines physiological explanations that were discussed in the 19th century starting with Albrecht von Haller (1708-1777), an 18th century physiologist who proposed that the heart has an intrinsic irritability. He argued that under normal conditions the inflow of blood stimulates the heart muscle to contract by mechanical touch and distension. Johannes Müller (1800-1858, physiologist in Bonn and Berlin) contended that the influence of the sympathetic nerve, specifically the activity of intracardiac ganglia, is the foremost cause of the heartbeat. Walter H. Gaskell and Theodor Engelmann (physiologists in Cambridge and Utrecht, respectively) independently criticized this neurogenic theory. They reported experimental evidence that supported the myogenic theory of the origin of the heartbeat, which has been accepted since about 1900. The concept of cardiac mechano-sensitivity, which can be traced back to A. von Haller, is currently resurging. Concerning mechanisms of contraction, Edward A. Schäfer (1850-1935), histologist and physiologist in Edinburgh, described differences between cardiac and skeletal muscle and coined the term sarcomere. Based on microscopic studies of cross-striated muscle, Schäfer outlined a detailed and plausible mechanism of muscle contraction in 1892. He put forward that during muscle shortening the "clear part of the muscle substance" (actin) might pass into longitudinal canals, which exist between the "sarcous elements" (myosin). His model foresaw fundamental elements of the sliding filament model, which was discovered by the Huxleys about 60 years later.
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Affiliation(s)
| | - Jochen Schaefer
- International Institute for Theoretical Cardiology, Kiel, Germany
| | - Nicolaus Wilder
- Institut für Pädagogik, Christian-Albrechts-Universität Kiel, Germany
| | - Wilhelm T Wolze
- Zentrum für konstruktive Erziehungswissenschaften, Christian-Albrechts-Universität Kiel, Germany
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20
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Johnson JK, Cottle BK, Mondal A, Hitchcock R, Kaza AK, Sachse FB. Localization of the sinoatrial and atrioventricular nodal region in neonatal and juvenile ovine hearts. PLoS One 2020; 15:e0232618. [PMID: 32379798 PMCID: PMC7205220 DOI: 10.1371/journal.pone.0232618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 04/17/2020] [Indexed: 11/18/2022] Open
Abstract
Localization of the components of the cardiac conduction system (CCS) is essential for many therapeutic procedures in cardiac surgery and interventional cardiology. While histological studies provided fundamental insights into CCS localization, this information is incomplete and difficult to translate to aid in intraprocedural localization. To advance our understanding of CCS localization, we set out to establish a framework for quantifying nodal region morphology. Using this framework, we quantitatively analyzed the sinoatrial node (SAN) and atrioventricular node (AVN) in ovine with postmenstrual age ranging from 4.4 to 58.3 months. In particular, we studied the SAN and AVN in relation to the epicardial and endocardial surfaces, respectively. Using anatomical landmarks, we excised the nodes and adjacent tissues, sectioned those at a thickness of 4 μm at 100 μm intervals, and applied Masson's trichrome stain to the sections. These sections were then imaged, segmented to identify nodal tissue, and analyzed to quantify nodal depth and superficial tissue composition. The minimal SAN depth ranged between 20 and 926 μm. AVN minimal depth ranged between 59 and 1192 μm in the AVN extension region, 49 and 980 μm for the compact node, and 148 and 888 μm for the transition to His Bundle region. Using a logarithmic regression model, we found that minimal depth increased logarithmically with age for the AVN (R2 = 0.818, P = 0.002). Also, the myocardial overlay of the AVN was heterogeneous within different regions and decreased with increasing age. Age associated alterations of SAN minimal depth were insignificant. Our study presents examples of characteristic tissue patterns superficial to the AVN and within the SAN. We suggest that the presented framework provides quantitative information for CCS localization. Our studies indicate that procedural methods and localization approaches in regions near the AVN should account for the age of patients in cardiac surgery and interventional cardiology.
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Affiliation(s)
- Jordan K. Johnson
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, Utah, United States of America
| | - Brian K. Cottle
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, Utah, United States of America
| | - Abhijit Mondal
- Cardiac Surgery, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Robert Hitchcock
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
| | - Aditya K. Kaza
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
- Cardiac Surgery, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Frank B. Sachse
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
- Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, Utah, United States of America
- * E-mail:
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21
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De Almeida MC, Sanchez-Quintana D, Anderson RH. Sunao Tawara : further musings on his tribulations in providing the basis for the modern-day understanding of cardiac electrophysiology. Anat Sci Int 2020; 95:381-386. [PMID: 32078150 DOI: 10.1007/s12565-020-00530-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Accepted: 02/04/2020] [Indexed: 11/30/2022]
Abstract
Sunao Tawara, who was born in 1873 and died in 1952, is considered the father of modern cardiac electrophysiology. He published his monumental monograph describing the atrioventricular conduction axis in 1906. He achieved this task in the face of multiple tribulations as a doctoral student working in a cultural environment that was not his own. Although his letters underscoring the publication of the monograph have been published, little emphasis has been placed on the potential problems he encountered in bringing his task to fruition. For example, it was not until the final 6 months of his studies that he resolved the issue of the connection between the atrioventricular bundle and the so called "Purkinje cardiomyocytes". His exchanges with his mentor, Ludwig Aschoff, emphasized that the difficulties he encountered in making the connection caused him quite some turmoil. We believe that this issue, and others that he identified in his correspondence, are worthy of further attention.
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Affiliation(s)
- Marcos C De Almeida
- Department of Genetics and Morphology, Brasilia's University, Campus Asa Norte, Brasília, Cep: 70910-900, Brazil.
| | - Damian Sanchez-Quintana
- Department of Human Anatomy and Cell Biology, Faculty of Medicine, University of Extremadura, Badajoz, Spain
| | - Robert H Anderson
- Institute of Bioscience, Newcastle University, Newcastle-upon-Tyne, UK
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22
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Anderson RH, Mori S, Spicer DE, Sanchez-Quintana D, Jensen B. The Anatomy, Development, and Evolution of the Atrioventricular Conduction Axis. J Cardiovasc Dev Dis 2018; 5:jcdd5030044. [PMID: 30135383 PMCID: PMC6162790 DOI: 10.3390/jcdd5030044] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 08/16/2018] [Accepted: 08/19/2018] [Indexed: 12/22/2022] Open
Abstract
It is now well over 100 years since Sunao Tawara clarified the location of the axis of the specialised myocardium responsible for producing coordinated ventricular activation. Prior to that stellar publication, controversies had raged as to how many bundles crossed the place of the atrioventricular insulation as found in mammalian hearts, as well as the very existence of the bundle initially described by Wilhelm His Junior. It is, perhaps surprising that controversies continue, despite the multiple investigations that have taken place since the publication of Tawara’s monograph. For example, we are still unsure as to the precise substrates for the so-called slow and fast pathways into the atrioventricular node. Much has been done, nonetheless, to characterise the molecular make-up of the specialised pathways, and to clarify their mechanisms of development. Of this work itself, a significant part has emanated from the laboratory coordinated for a quarter of a century by Antoon FM Moorman. In this review, which joins the others in recognising the value of his contributions and collaborations, we review our current understanding of the anatomy, development, and evolution of the atrioventricular conduction axis.
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Affiliation(s)
- Robert H Anderson
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne NE1 4EP, UK.
| | - Shumpei Mori
- Division of Cardiovascular Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Hyogo, Japan.
| | - Diane E Spicer
- Department of Pediatric Cardiology, University of Florida, Gainesville, FL 32610, USA.
| | - Damian Sanchez-Quintana
- Department of Anatomy and Cell Biology, Faculty of Medicine, University of Extremadura, 06006 Badajoz, Spain.
| | - Bjarke Jensen
- University of Amsterdam, Amsterdam UMC, Department of Medical Biology, Amsterdam Cardiovascular Sciences, Meibergdreef 15, 1105AZ Amsterdam, The Netherlands.
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23
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24
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Oh IY, Cha MJ, Lee TH, Seo JW, Oh S. Unsolved Questions on the Anatomy of the Ventricular Conduction System. Korean Circ J 2018; 48:1081-1096. [PMID: 30403014 PMCID: PMC6221866 DOI: 10.4070/kcj.2018.0335] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Accepted: 10/22/2018] [Indexed: 11/11/2022] Open
Abstract
We reviewed the anatomical characteristics of the conduction system in the ventricles of human and ungulate hearts and then raised some questions to be answered by clinical and anatomical studies in the future. The ventricular conduction system is a 3-dimensional structure as compared to the 2-dimensional character of the atrial conduction system. The proximal part consisting of the atrioventricular node, the bundle of His and fascicles are groups of conducting cells surrounded by fibrous connective tissue so as to insulate from the underlying myocardium. Their location and morphological characters are well established. The bundle of His is a cord like structure but the left and right fascicles are broad at the proximal and branching at the distal part. The more distal part of fascicles and Purkinje system are linear networks of conducting cells at the immediate subendocardium but the intra-mural network is detected at the inner half of the ventricular wall. The papillary muscle also harbors Purkinje system not in the deeper part. It is hard to recognize histologically in human hearts but conducting cells as well as Purkinje cells are easily recognized in ungulate hearts. Further observation on human and ungulate hearts with myocardial infarct, we could find preserved Purkinje system at the subendocardium in contrast to the damaged system at the deeper myocardium. Further studies are necessary on the anatomical characteristics of this peripheral conduction system so as to correlate the clinical data on hearts with ventricular arrhythmias.
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Affiliation(s)
- Il Young Oh
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Myung Jin Cha
- Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
| | - Tae Hui Lee
- Department of Pathology, Mediplex Sejong Hospital, Incheon, Korea
| | - Jeong Wook Seo
- Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.
| | - Seil Oh
- Division of Cardiology, Department of Internal Medicine, Seoul National University Hospital, Seoul, Korea
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25
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Nawroj AI, Dollar AM. Shape Control of Compliant, Articulated Meshes: Towards Modular Active-Cell Robots (MACROs). IEEE Robot Autom Lett 2017. [DOI: 10.1109/lra.2017.2714146] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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26
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Nawroj AI, Swensen JP, Dollar AM. Toward Modular Active-Cell Robots (MACROs): SMA Cell Design and Modeling of Compliant, Articulated Meshes. IEEE T ROBOT 2017. [DOI: 10.1109/tro.2017.2693393] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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27
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Garcia-Bustos V, Sebastian R, Izquierdo M, Molina P, Chorro FJ, Ruiz-Sauri A. A quantitative structural and morphometric analysis of the Purkinje network and the Purkinje-myocardial junctions in pig hearts. J Anat 2017; 230:664-678. [PMID: 28256093 DOI: 10.1111/joa.12594] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2016] [Indexed: 12/20/2022] Open
Abstract
The morpho-functional properties of the distal section of the cardiac Purkinje network (PN) and the Purkinje-myocardial junctions (PMJs) are fundamental to understanding the sequence of electrical activation in the heart. The overall structure of the system has already been described, and several computational models have been developed to gain insight into its involvement in cardiac arrhythmias or its interaction with implantable devices, such as pacemakers. However, anatomical descriptions of the PN in the literature have not enabled enough improvements in the accuracy of anatomical-based electrophysiological simulations of the PN in 3D hearts models. In this work, we study the global distribution and morphological properties of the PN, with special emphasis on the cellular and architectural characterization of its intramural branching structure, mesh-like sub-endocardial network, and the PMJs in adult pig hearts by both histopathological and morphometric evaluation. We have defined three main patterns of PMJ: contact through cell bodies, contact through cell prolongations either thick or piliform, and contact through transitional cells. Moreover, from hundreds of micrographs, we quantified the density of PMJs and provided data for the basal/medial/apical regions, anterior/posterior/septal/lateral regions and myocardial/sub-endocardial distribution. Morphometric variables, such as Purkinje cell density and thickness of the bundles, were also analyzed. After combining the results of these parameters, a different septoanterior distribution in the Purkinje cell density was observed towards the cardiac apex, which is associated with a progressive thinning of the conduction bundles and the posterolateral ascension of intramyocardial terminal scattered fibers. The study of the PMJs revealed a decreasing trend towards the base that may anatomically explain the early apical activation. The anterolateral region contains the greatest number of contacts, followed by the anterior and septal regions. This supports the hypothesis that thin distal Purkinje bundles create a junction-rich network that may be responsible for the quick apical depolarization. The PN then ascends laterally and spreads through the anterior and medial walls up to the base. We have established the first morphometric study of the Purkinje system, and provided quantitative and objective data that facilitate its incorporation into the development of models beyond gross and variable pathological descriptions, and which, after further studies, could be useful in the characterization of pathological processes or therapeutic procedures.
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Affiliation(s)
- V Garcia-Bustos
- Department of Pathology, Faculty of Medicine, Universitat de Valencia, Valencia, Spain
| | - R Sebastian
- Computational Multiscale Simulation Lab, Universitat de Valencia, Valencia, Spain
| | - M Izquierdo
- INCLIVA Biomedical Research Institute, Valencia, Spain.,Cardiology Unit, Hospital Clinico Universitario de Valencia, Valencia, Spain
| | - P Molina
- Department of Pathology, Faculty of Medicine, Universitat de Valencia, Valencia, Spain
| | - F J Chorro
- INCLIVA Biomedical Research Institute, Valencia, Spain.,Cardiology Unit, Hospital Clinico Universitario de Valencia, Valencia, Spain
| | - A Ruiz-Sauri
- Department of Pathology, Faculty of Medicine, Universitat de Valencia, Valencia, Spain.,INCLIVA Biomedical Research Institute, Valencia, Spain
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28
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Marks ED, Kumar A. Thymosin β4: Roles in Development, Repair, and Engineering of the Cardiovascular System. VITAMINS AND HORMONES 2016; 102:227-49. [PMID: 27450737 DOI: 10.1016/bs.vh.2016.04.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The burden of cardiovascular disease is a growing worldwide issue that demands attention. While many clinical trials are ongoing to test therapies for treating the heart after myocardial infarction (MI) and heart failure, there are few options doctors able to currently give patients to repair the heart. This eventually leads to decreased ventricular contractility and increased systemic disease, including vascular disorders that could result in stroke. Small peptides such as thymosin β4 (Tβ4) are upregulated in the cardiovascular niche during fetal development and after injuries such as MI, providing increased neovasculogenesis and paracrine signals for endogenous stem cell recruitment to aid in wound repair. New research is looking into the effects of in vivo administration of Tβ4 through injections and coatings on implants, as well as its effect on cell differentiation. Results so far demonstrate Tβ4 administration leads to robust increases in angiogenesis and wound healing in the heart after MI and the brain after stroke, and can differentiate adult stem cells toward the cardiac lineage for implantation to the heart to increase contractility and survival. Future work, some of which is currently in clinical trials, will demonstrate the in vivo effect of these therapies on human patients, with the goal of helping the millions of people worldwide affected by cardiovascular disease.
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Affiliation(s)
- E D Marks
- Nanomedicine Research Laboratory, University of Delaware, Newark, DE, United States
| | - A Kumar
- Nanomedicine Research Laboratory, University of Delaware, Newark, DE, United States.
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29
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Logantha SJRJ, Stokke MK, Atkinson AJ, Kharche SR, Parveen S, Saeed Y, Sjaastad I, Sejersted OM, Dobrzynski H. Ca(2+)-Clock-Dependent Pacemaking in the Sinus Node Is Impaired in Mice with a Cardiac Specific Reduction in SERCA2 Abundance. Front Physiol 2016; 7:197. [PMID: 27313537 PMCID: PMC4889599 DOI: 10.3389/fphys.2016.00197] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 05/17/2016] [Indexed: 12/23/2022] Open
Abstract
Background: The sarcoplasmic reticulum Ca2+-ATPase (SERCA2) pump is an important component of the Ca2+-clock pacemaker mechanism that provides robustness and flexibility to sinus node pacemaking. We have developed transgenic mice with reduced cardiac SERCA2 abundance (Serca2 KO) as a model for investigating SERCA2's role in sinus node pacemaking. Methods and Results: In Serca2 KO mice, ventricular SERCA2a protein content measured by Western blotting was 75% (P < 0.05) lower than that in control mice (Serca2 FF) tissue. Immunofluorescent labeling of SERCA2a in ventricular, atrial, sinus node periphery and center tissue sections revealed 46, 45, 55, and 34% (all P < 0.05 vs. Serca2 FF) lower labeling, respectively and a mosaic pattern of expression. With telemetric ECG surveillance, we observed no difference in basal heart rate, but the PR-interval was prolonged in Serca2 KO mice: 49 ± 1 vs. 40 ± 1 ms (P < 0.001) in Serca2 FF. During exercise, heart rate in Serca2 KO mice was elevated to 667 ± 22 bpm, considerably less than 780 ± 17 bpm (P < 0.01) in Serca2 FF. In isolated sinus node preparations, 2 mM Cs+ caused bradycardia that was equally pronounced in Serca2 KO and Serca2 FF (32 ± 4% vs. 29 ± 5%), indicating no change in the pacemaker current, If. Disabling the Ca2+-clock with 2 μM ryanodine induced bradycardia that was less pronounced in Serca2 KO preparations (9 ± 1% vs. 20 ± 3% in Serca2 FF; P < 0.05), suggesting a disrupted Ca2+-clock. Mathematical modeling was used to dissect the effects of membrane- and Ca2+-clock components on Serca2 KO mouse heart rate and sinus node action potential. Computer modeling predicted a slowing of heart rate with SERCA2 downregulation and the heart rate slowing was pronounced at >70% reduction in SERCA2 activity. Conclusions:Serca2 KO mice show a disrupted Ca2+-clock-dependent pacemaker mechanism contributing to impaired sinus node and atrioventricular node function.
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Affiliation(s)
| | - Mathis K Stokke
- Institute for Experimental Medical Research, Oslo University Hospital and University of OsloOslo, Norway; Center for Heart Failure Research, University of OsloOslo, Norway; Clinic for Internal Medicine, Lovisenberg Deaconess Hospital ASOslo, Norway
| | - Andrew J Atkinson
- Institute of Cardiovascular Sciences, University of Manchester Manchester, UK
| | - Sanjay R Kharche
- Institute of Cardiovascular Sciences, University of Manchester Manchester, UK
| | - Sajida Parveen
- Institute of Cardiovascular Sciences, University of Manchester Manchester, UK
| | - Yawer Saeed
- Institute of Cardiovascular Sciences, University of Manchester Manchester, UK
| | - Ivar Sjaastad
- Institute for Experimental Medical Research, Oslo University Hospital and University of OsloOslo, Norway; Center for Heart Failure Research, University of OsloOslo, Norway
| | - Ole M Sejersted
- Institute for Experimental Medical Research, Oslo University Hospital and University of OsloOslo, Norway; Center for Heart Failure Research, University of OsloOslo, Norway
| | - Halina Dobrzynski
- Institute of Cardiovascular Sciences, University of Manchester Manchester, UK
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Loukas M, Youssef P, Gielecki J, Walocha J, Natsis K, Tubbs RS. History of cardiac anatomy: A comprehensive review from the egyptians to today. Clin Anat 2016; 29:270-84. [DOI: 10.1002/ca.22705] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 02/19/2016] [Indexed: 11/08/2022]
Affiliation(s)
- Marios Loukas
- Department of Anatomical Sciences; School of Medicine, St George's University; Grenada West Indies
| | - Pamela Youssef
- Department of Anatomical Sciences; School of Medicine, St George's University; Grenada West Indies
| | - Jerzy Gielecki
- Department of Anatomy; Varmia and Mazuria Medical School; Olsztyn Poland
| | - Jerzy Walocha
- Department of Anatomy; Jagelonian University Medical School; Krakow Poland
| | - Kostantinos Natsis
- School of Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki; Thessaloniki Greece
| | - R. Shane Tubbs
- Department of Anatomical Sciences; School of Medicine, St George's University; Grenada West Indies
- Seattle Science Foundation; Seattle Washington
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Vigmond EJ, Stuyvers BD. Modeling our understanding of the His-Purkinje system. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:179-88. [PMID: 26740015 DOI: 10.1016/j.pbiomolbio.2015.12.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 12/18/2015] [Accepted: 12/22/2015] [Indexed: 01/25/2023]
Abstract
The His-Purkinje System (HPS) is responsible for the rapid electric conduction in the ventricles. It relays electrical impulses from the atrioventricular node to the muscle cells and, thus, coordinates the contraction of ventricles in order to ensure proper cardiac pump function. The HPS has been implicated in the genesis of ventricular tachycardia and fibrillation as a source of ectopic beats, as well as forming distinct portions of reentry circuitry. Despite its importance, it remains much less well characterized, structurally and functionally, than the myocardium. Notably, important differences exist with regard to cell structure and electrophysiology, including ion channels, intracellular calcium handling, and gap junctions. Very few computational models address the HPS, and the majority of organ level modeling studies omit it. This review will provide an overview of our current knowledge of structure and function (including electrophysiology) of the HPS. We will review the most recent advances in modeling of the system from the single cell to the organ level, with considerations for relevant interspecies distinctions.
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Affiliation(s)
- Edward J Vigmond
- LIRYC, Institute of Electrophysiology and Cardiac Modeling, Hôpital Xavier Arnozan, avenue Haut-Lévèque, 33600 Pessac, France; Institut de Mathématiques de Bordeaux, Université de Bordeaux, 351, cours de la Libération, F 33 405 Talence, France; Department of Electrical and Computer Engineering, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.
| | - Bruno D Stuyvers
- LIRYC, Institute of Electrophysiology and Cardiac Modeling, Hôpital Xavier Arnozan, avenue Haut-Lévèque, 33600 Pessac, France; Université de Bordeaux, 351, cours de la Libération, F 33 405 Talence, France; Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Phillip Drive, St. John's, NL A1B 3V6, Canada.
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Lammers WJEP, Stephen B, Al-Sultan MA, Subramanya SB, Blanks AM. The location of pacemakers in the uteri of pregnant guinea pigs and rats. Am J Physiol Regul Integr Comp Physiol 2015; 309:R1439-46. [PMID: 26377559 DOI: 10.1152/ajpregu.00187.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 09/01/2015] [Indexed: 01/31/2023]
Abstract
The pregnant uterus is a smooth muscle organ whose pattern of contraction is dictated by the propagation of electrical impulses. Such electrical activity may originate from one or more pacemakers, but the location of these sites has not yet been determined. To detect the location of the pacemaker in the gravid uterus, two approaches were used: 1) determine the site from where the contraction started using isolated uteri from the pregnant guinea pig, and videotape their contractions; and 2) record, in isolated uteri from pregnant term rats, with 240 extracellular electrodes simultaneously, and determine where the electrical bursts started. In both the contractile and electrophysiological experiments, there was not a single, specific pacemaker area. However, most contractions (guinea pig 87%) and bursts (rat 76%) started close to the mesometrial border (mean 2.7 ± 4.0 mm SD in guinea pigs and 1.3 ± 1.4 mm in rats). In addition, in the rat, most sites of initiations were located closer to the ovarial end of the horn (mean distance from the ovarial end 6.0 ± 6.2 mm SD), whereas such an orientation was not seen in the guinea pig. In both guinea pig and rat uteri at term, there is not one specific pacemaker area. Rather, contractile and electrical activity may arise from any site, with the majority starting close to the mesometrial border. Furthermore, in the rat, most activities started at the ovarial end of the horn. This may suggest a slightly different pattern of contraction in both species.
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Affiliation(s)
- Wim J E P Lammers
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates; and
| | - Betty Stephen
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates; and
| | - Mahmood Ahmed Al-Sultan
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates; and
| | - Sandeep B Subramanya
- Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates; and
| | - Andrew M Blanks
- Division of Translational and Systems Medicine, Warwick Medical School, Clinical Sciences Research Laboratory, Coventry, United Kingdom
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Ungulates heart model: a study of the Purkinje network using India ink injection, transparent specimens and computer tomography. Anat Sci Int 2014; 90:240-50. [DOI: 10.1007/s12565-014-0255-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Accepted: 09/16/2014] [Indexed: 11/25/2022]
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SEM, TEM, and IHC Analysis of the Sinus Node and Its Implications for the Cardiac Conduction System. ANATOMY RESEARCH INTERNATIONAL 2013; 2013:961459. [PMID: 24282640 PMCID: PMC3825050 DOI: 10.1155/2013/961459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 09/12/2013] [Accepted: 09/17/2013] [Indexed: 11/17/2022]
Abstract
More than 100 years after the discovery of the sinus node (SN) by Keith and Flack, the function and structure of the SN have not been completely established yet. The anatomic architecture of the SN has often been described as devoid of an organized structure; the origin of the sinus impulse is still a matter of debate, and a definite description of the long postulated internodal specialized tract conducting the impulse from the SN to the atrioventricular node (AVN) is still missing. In our previously published study, we proposed a morphologically ordered structure for the SN. As a confirmation of what was presented then, we have added the results of additional observations regarding the structural particularities of the SN. We investigated the morphology of the sinus node in the human hearts of healthy individuals using histochemical, immunohistochemical, optical, and electron microscopy (SEM, TEM). Our results confirmed that the SN presents a previously unseen highly organized architecture.
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Li J, Wang K, Zuo W, Lu W, Zhang H. Construction of 3D Realistic Purkinje System: A Locally Linear Embedding-Based Method. J BIOL SYST 2011. [DOI: 10.1142/s0218339010003664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The geometry of canine ventricle with purkinje system provides the data basis for the simulation and analysis of the mechanisms of ventricular pathophysiology. The acquisition of the geometry of the purkinje system, however, is very challenging, and traditional construction approaches are mainly based on modeling using fractal geometry. In this paper, we propose a novel locally linear embedding (LLE)-based method to construct 3D anatomical purkinje system of the canine left ventricle (LV). First, we collect the 2D purkinje system data in a canine ventricle and extract the endocardial surface of the canine left ventricle from 3D canine ventricle. Then, LLE is used to map the 3D geometry of the endocardial surface to a 2D subspace, and the 2D purkinje system data is further embedded into this 2D subspace. Finally, LLE is adopted to map both the 3D geometry of the endocardial surface and the 2D purkinje system data back to the 3D space. An experiment is designed to verify the effectiveness of the LLE-based construction method. The proposed method approaches is promising in restoring realistic purkinje system of the left canine ventricle.
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Affiliation(s)
- Jie Li
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
| | - Kuanquan Wang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
| | - Wangmeng Zuo
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
| | - Weigang Lu
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, China
| | - Henggui Zhang
- School of Physics and Astronomy, The University of Manchester, Manchester, UK
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37
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Atkinson A, Inada S, Li J, Tellez JO, Yanni J, Sleiman R, Allah EA, Anderson RH, Zhang H, Boyett MR, Dobrzynski H. Anatomical and molecular mapping of the left and right ventricular His–Purkinje conduction networks. J Mol Cell Cardiol 2011; 51:689-701. [DOI: 10.1016/j.yjmcc.2011.05.020] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2010] [Revised: 05/23/2011] [Accepted: 05/25/2011] [Indexed: 12/12/2022]
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38
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Rabbit-specific ventricular model of cardiac electrophysiological function including specialized conduction system. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2011; 107:90-100. [PMID: 21672547 DOI: 10.1016/j.pbiomolbio.2011.05.002] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 05/27/2011] [Indexed: 11/20/2022]
Abstract
The function of the ventricular specialized conduction system in the heart is to ensure the coordinated electrical activation of the ventricles. It is therefore critical to the overall function of the heart, and has also been implicated as an important player in various diseases, including lethal ventricular arrhythmias such as ventricular fibrillation and drug-induced torsades de pointes. However, current ventricular models of electrophysiology usually ignore, or include highly simplified representations of the specialized conduction system. Here, we describe the development of an image-based, species-consistent, anatomically-detailed model of rabbit ventricular electrophysiology that incorporates a detailed description of the free-running part of the specialized conduction system. Techniques used for the construction of the geometrical model of the specialized conduction system from a magnetic resonance dataset and integration of the system model into a ventricular anatomical model, developed from the same dataset, are described. Computer simulations of rabbit ventricular electrophysiology are conducted using the novel anatomical model and rabbit-specific membrane kinetics to investigate the importance of the components and properties of the conduction system in determining ventricular function under physiological conditions. Simulation results are compared to panoramic optical mapping experiments for model validation and results interpretation. Full access is provided to the anatomical models developed in this study.
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KARAGUEUZIAN HRAYRS. How Does Cholinergic Activation Slow Down Sinus Node Automaticity?“Diastolic Voltage Oscillations” vs. “Calcium Clock” Mechanisms. J Cardiovasc Electrophysiol 2011; 22:81-3. [DOI: 10.1111/j.1540-8167.2010.01866.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
Abstract: Pacemaking is a basic physiological process, and the cellular mechanisms involved in this function have always attracted the keen attention of investigators. The "funny" (I(f)) current, originally described in sinoatrial node myocytes as an inward current activated on hyperpolarization to the diastolic range of voltages, has properties suitable for generating repetitive activity and for modulating spontaneous rate. The degree of activation of the funny current determines, at the end of an action potential, the steepness of phase 4 depolarization; hence, the frequency of action potential firing. Because I(f) is controlled by intracellular cAMP and is thus activated and inhibited by beta-adrenergic and muscarinic M2 receptor stimulation, respectively, it represents a basic physiological mechanism mediating autonomic regulation of heart rate. Given the complexity of the cellular processes involved in rhythmic activity, an exact quantification of the extent to which I(f) and other mechanisms contribute to pacemaking is still a debated issue; nonetheless, a wealth of information collected since the current was first described more than 30 years ago clearly agrees to identify I(f) as a major player in both generation of spontaneous activity and rate control. I(f)- dependent pacemaking has recently advanced from a basic, physiologically relevant concept, as originally described, to a practical concept that has several potentially useful clinical applications and can be valuable in therapeutically relevant conditions. Typically, given their exclusive role in pacemaking, f-channels are ideal targets of drugs aiming to pharmacological control of cardiac rate. Molecules able to bind specifically to and block f-channels can thus be used as pharmacological tools for heart rate reduction with little or no adverse cardiovascular side effects. Indeed a selective f-channel inhibitor, ivabradine, is today commercially available as a tool in the treatment of stable chronic angina. Also, several loss-of-function mutations of HCN4 (hyperpolarization-activated, cyclic-nucleotide gated 4), the major constitutive subunit of f-channels in pacemaker cells, are known today to cause rhythm disturbances, such as for example inherited sinus bradycardia. Finally, gene- or cell-based methods for in situ delivery of f-channels to silent or defective cardiac muscle represent novel approaches for the development of biological pacemakers eventually able to replace electronic devices.
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Affiliation(s)
- Dario DiFrancesco
- University of Milano, Department of Biomolecular Sciences and Biotechnology, The PaceLab, via Celoria 26, 20133 Milano, Italy.
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41
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Yanagawa N, Nakajima Y. A simple dissection method for the conduction system of the human heart. ANATOMICAL SCIENCES EDUCATION 2009; 2:78-80. [PMID: 19215062 DOI: 10.1002/ase.67] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A simple dissection guide for the conduction system of the human heart is shown. The atrioventricular (AV) node, AV bundle, and right bundle branch were identified in a formaldehyde-fixed human heart. The sinu-atrial (SA) node could not be found, but the region in which SA node was contained was identified using the SA nodal artery. Gross anatomical observation of the conduction system is useful for understanding the structure and function of the heart.
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Affiliation(s)
- Nariaki Yanagawa
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Osaka City University, Abenoku, Osaka, Japan
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42
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Abstract
The heart automaticity is a fundamental physiological function in higher organisms. The spontaneous activity is initiated by specialized populations of cardiac cells generating periodical electrical oscillations. The exact cascade of steps initiating the pacemaker cycle in automatic cells has not yet been entirely elucidated. Nevertheless, ion channels and intracellular Ca(2+) signaling are necessary for the proper setting of the pacemaker mechanism. Here, we review the current knowledge on the cellular mechanisms underlying the generation and regulation of cardiac automaticity. We discuss evidence on the functional role of different families of ion channels in cardiac pacemaking and review recent results obtained on genetically engineered mouse strains displaying dysfunction in heart automaticity. Beside ion channels, intracellular Ca(2+) release has been indicated as an important mechanism for promoting automaticity at rest as well as for acceleration of the heart rate under sympathetic nerve input. The potential links between the activity of ion channels and Ca(2+) release will be discussed with the aim to propose an integrated framework of the mechanism of automaticity.
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Affiliation(s)
- Matteo E Mangoni
- Institute of Functional Genomics, Department of Physiology, Centre National de la Recherche Scientifique UMR5203, INSERM U661, University of Montpellier I and II, Montpellier, France.
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Affiliation(s)
- Mark E Silverman
- Department of Medicine, Piedmont Hospital and Emory University School of Medicine and the Fuqua Heart Center, Piedmont Hospital, Atlanta, Georgia 30309, USA.
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44
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Loukas M, Clarke P, Tubbs RS, Kapos T, Trotz M. The His family and their contributions to cardiology. Int J Cardiol 2008; 123:75-8. [PMID: 17433467 DOI: 10.1016/j.ijcard.2006.12.070] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Accepted: 12/31/2006] [Indexed: 11/18/2022]
Abstract
Few families in medicine can claim that more than one of their members contributed significantly to modern-day clinical and research practices. The Swiss family of His can assert that two of their number, Wilhelm His Sr. (1831-1904) and Wilhelm His Jr. (1863-1934) made advancements in medicine that still have an impact on many areas of research and clinical practice today. In 1865, His focused on embryology research and he introduced the term "endothelium" from his observations in embryology. His invented the microtome in 1866, and named the axonal appendages as dendrites. On the other hand His Jr., in 1893, published a 35-page article that described the activity of the embryonic heart and how this understanding is important in comprehending actions in the adult heart. This article contains the description of his best-known discovery, the now eponymous Bundle of His. Modern researchers and clinicians should consider the importance of the work of both Wilhelm His Sr. and Wilhelm His Jr. Advancements in embryological, histological and cardiovascular electrophysiology research can all trace some input back to this father and son.
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Affiliation(s)
- Marios Loukas
- Department of Anatomical Sciences, St. George's University, School of Medicine, True Blue Campus, West Indies, Grenada.
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45
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Swenne CA, Schalij MJ. Pacemaking in the AV node. Heart Rhythm 2007; 4:1336-7. [PMID: 17905340 DOI: 10.1016/j.hrthm.2007.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2007] [Indexed: 10/23/2022]
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46
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Silverman ME, Hollman A. Discovery of the sinus node by Keith and Flack: on the centennial of their 1907 publication. Heart 2007; 93:1184-7. [PMID: 17890694 PMCID: PMC2000948 DOI: 10.1136/hrt.2006.105049] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/10/2006] [Indexed: 11/03/2022] Open
Abstract
In 1839, Jan Evangelista Purkinje discovered a net of gelatinous fibres in the subendocardium of the heart. Walter Gaskell in the 1880s observed that the impulse of the heart began in the sinus venosus, and that this region had the most rhythmic ability. A conducting bundle between the atrium and the ventricle was found by Wilhelm His, Jr in 1893. In 1906, Sunao Tawara found a "complex knoten" of tissue at the proximal end of the His bundle. He concluded that this was the inception of an electrical conducting system which continued from the AV node through the bundle of His, divided into the bundle branches, and terminated as the Purkinje fibres. The collaboration of Arthur Keith and Martin Flack led to discovery of the sinus node, finalising the discovery of the electrical system of the heart and providing an anatomical answer to the baffling mystery: "Why does the heart beat?"
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Affiliation(s)
- Mark E Silverman
- The Fuqua Heart Center of Piedmont Hospital and the Department of Medicine of Emory University, Atlanta, Georgia, USA.
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47
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Baruscotti M, Robinson RB. Electrophysiology and pacemaker function of the developing sinoatrial node. Am J Physiol Heart Circ Physiol 2007; 293:H2613-23. [PMID: 17827259 DOI: 10.1152/ajpheart.00750.2007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sinoatrial node performs its task as a cardiac impulse generator throughout the life of the organism, but this important function is not a constant. Rather, there are significant developmental changes in the expression and function of ion channels and other cellular elements, which lead to a postnatal slowing of heart rate and may be crucial to the reliable functioning of the node during maturation. In this review, we provide an overview of current knowledge regarding these changes, with the main focus placed on maturation of the ion channel expression profile. Studies on Na(+) and pacemaker currents have shown that their contribution to automaticity is greater in the newborn than in the adult, but this age-dependent decrease is at least partially opposed by an increased contribution of L-type Ca(2+) current. Whereas information regarding age-dependent changes in other transmembrane currents within the sinoatrial node are lacking, there are data on other relevant parameters. These include an increase in the nodal content of fibroblasts and in the area of nonexpression of connexin43, considered a molecular marker of nodal tissue. Although much remains to be done before a comprehensive view of the developmental biology of the node is available, important evidence in support of a molecular interpretation of developmental slowing of the intrinsic sinoatrial rate is beginning to emerge.
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Affiliation(s)
- Mirko Baruscotti
- Laboratory of Molecular Physiology and Neurobiology, Department of Biomolecular Sciences and Biotechnology, University of Milano, Milan, Italy
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48
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Tusscher KHWJT, Panfilov AV. Modelling of the ventricular conduction system. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2007; 96:152-70. [PMID: 17910889 DOI: 10.1016/j.pbiomolbio.2007.07.026] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The His-Purkinje conduction system initiates the normal excitation of the ventricles and is a major component of the specialized conduction system of the heart. Abnormalities and propagation blocks in the Purkinje system result in abnormal excitation of the heart. Experimental findings suggest that the Purkinje network plays an important role in ventricular tachycardia and fibrillation, which is the major cause of sudden cardiac death. Nowadays an important area in the study of cardiac arrhythmias is anatomically accurate modelling. The majority of current anatomical models have not included a description of the Purkinje network. As a consequence, these models cannot be used to study the important role of the Purkinje system in arrhythmia initiation and maintenance. In this article we provide an overview of previous work on modelling of the Purkinje system and report on the development of a His-Purkinje system for our human ventricular model. We use the model to simulate the normal activation pattern as well as abnormal activation patterns resulting from bundle branch block and bundle branch reentry.
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Affiliation(s)
- K H W J Ten Tusscher
- Department of Theoretical Biology, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
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49
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Abstract
The cardiac conduction system (CCS) is a specialized tissue network that initiates and maintains a rhythmic heartbeat. The CCS consists of several functional subcomponents responsible for producing a pacemaking impulse and distributing action potentials across the heart in a coordinated manner. The formation of the distinct subcomponents of the CCS occurs within a precise temporal and spatial framework; thereby assuring that as the system matures from a tubular to a complex chambered organ, a rhythmic heartbeat is always maintained. Therefore, a defect in differentiation of any CCS component would lead to severe rhythm disturbances. Recent molecular, cell biological and physiological approaches have provided fresh and unexpected perspectives of the relationships between cell fate, gene expression and differentiation of specialized function within the developing myocardium. In particular, biomechanical forces created by the heartbeat itself have important roles in the inductive patterning and functional integration of the developing conduction system. This new understanding of the cellular origin and molecular induction of CCS tissues during embryogenesis may provide the foundation for tissue engineering, replacement and repair of these essential cardiac tissues in the future.
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Affiliation(s)
- Takashi Mikawa
- University of California San Francisco, Cardiovascular Research Institute, Box 2711, Rock Hall Room 384D, 1550 4th Street, San Francisco, CA 94158-2324, United States.
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50
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Affiliation(s)
- Marios Loukas
- Department of Anatomical Sciences, St George's University, Grenad, West Indies.
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