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Salavatian S, Robbins EM, Kuwabara Y, Castagnola E, Cui XT, Mahajan A. Real-time in vivo thoracic spinal glutamate sensing during myocardial ischemia. Am J Physiol Heart Circ Physiol 2023; 325:H1304-H1317. [PMID: 37737733 PMCID: PMC10908408 DOI: 10.1152/ajpheart.00299.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 09/18/2023] [Accepted: 09/18/2023] [Indexed: 09/23/2023]
Abstract
In the spinal cord, glutamate serves as the primary excitatory neurotransmitter. Monitoring spinal glutamate concentrations offers valuable insights into spinal neural processing. Consequently, spinal glutamate concentration has the potential to emerge as a useful biomarker for conditions characterized by increased spinal neural network activity, especially when uptake systems become dysfunctional. In this study, we developed a multichannel custom-made flexible glutamate-sensing probe for the large-animal model that is capable of measuring extracellular glutamate concentrations in real time and in vivo. We assessed the probe's sensitivity and specificity through in vitro and ex vivo experiments. Remarkably, this developed probe demonstrates nearly instantaneous glutamate detection and allows continuous monitoring of glutamate concentrations. Furthermore, we evaluated the mechanical and sensing performance of the probe in vivo, within the pig spinal cord. Moreover, we applied the glutamate-sensing method using the flexible probe in the context of myocardial ischemia-reperfusion (I/R) injury. During I/R injury, cardiac sensory neurons in the dorsal root ganglion transmit excitatory signals to the spinal cord, resulting in sympathetic activation that potentially leads to fatal arrhythmias. We have successfully shown that our developed glutamate-sensing method can detect this spinal network excitation during myocardial ischemia. This study illustrates a novel technique for measuring spinal glutamate at different spinal cord levels as a surrogate for the spinal neural network activity during cardiac interventions that engage the cardio-spinal neural pathway.NEW & NOTEWORTHY In this study, we have developed a new flexible sensing probe to perform an in vivo measurement of spinal glutamate signaling in a large animal model. Our initial investigations involved precise testing of this probe in both in vitro and ex vivo environments. We accurately assessed the sensitivity and specificity of our glutamate-sensing probe and demonstrated its performance. We also evaluated the performance of our developed flexible probe during the insertion and compared it with the stiff probe during animal movement. Subsequently, we used this innovative technique to monitor the spinal glutamate signaling during myocardial ischemia and reperfusion that can cause fatal ventricular arrhythmias. We showed that glutamate concentration increases during the myocardial ischemia, persists during the reperfusion, and is associated with sympathoexcitation and increases in myocardial substrate excitability.
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Affiliation(s)
- Siamak Salavatian
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Elaine Marie Robbins
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Yuki Kuwabara
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Elisa Castagnola
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Xinyan Tracy Cui
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Center for Neural Basis of Cognition, Pittsburgh, Pennsylvania, United States
- McGowan Institute for Regenerative Medicine, Pittsburgh, Pennsylvania, United States
| | - Aman Mahajan
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
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2
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Haugsten Hansen M, Sadredini M, Hasic A, Eriksen M, Stokke MK. Myocardial oxidative stress is increased in early reperfusion, but systemic antioxidative therapy does not prevent ischemia-reperfusion arrhythmias in pigs. Front Cardiovasc Med 2023; 10:1223496. [PMID: 37823177 PMCID: PMC10562584 DOI: 10.3389/fcvm.2023.1223496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 09/14/2023] [Indexed: 10/13/2023] Open
Abstract
Background Arrhythmias in the early phase of reperfusion after myocardial infarction (MI) are common, and can lead to hemodynamic instability or even cardiac arrest. Reactive oxygen species (ROS) are thought to play a key role in the underlying mechanisms, but evidence from large animal models is scarce, and effects of systemic antioxidative treatment remain contentious. Methods MI was induced in 7 male and 7 female pigs (Norwegian landrace, 35-40 kg) by clamping of the left anterior descending artery (LAD) during open thorax surgery. Ischemia was maintained for 90 min, before observation for 1 h after reperfusion. Pigs were randomized 1:1 in an operator-blinded fashion to receive either i.v. N-acetylcysteine (NAC) from 70 min of ischemia and onwards, or 0.9% NaCl as a control. Blood samples and tissue biopsies were collected at baseline, 60 min of ischemia, and 5 and 60 min of reperfusion. ECG and invasive blood pressure were monitored throughout. Results The protocol was completed in 11 pigs. Oxidative stress, as indicated by immunoblotting for Malondialdehyde in myocardial biopsies, was increased at 5 min of reperfusion compared to baseline, but not at 60 min of reperfusion, and not reduced with NAC. We found no significant differences in circulating biomarkers of myocardial necrosis, nor in the incidence of idioventricular rhythm (IVR), non-sustained ventricular tachycardia (NSVT), ventricular tachycardia (VT) or ventricular fibrillation (VF) between NAC-treated and control pigs during reperfusion. Conclusion Myocardial oxidation was increased early after reperfusion in a porcine model of MI, but systemic antioxidative treatment did not protect against reperfusion arrhythmias.
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Affiliation(s)
- Marie Haugsten Hansen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Mani Sadredini
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Almira Hasic
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Morten Eriksen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
| | - Mathis Korseberg Stokke
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway
- KG Jebsen Centre for Cardiac Research, University of Oslo, Oslo, Norway
- Department of Cardiology, Oslo University Hospital Rikshospitalet, Oslo, Norway
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3
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Oknińska M, Mączewski M, Mackiewicz U. Ventricular arrhythmias in acute myocardial ischaemia-Focus on the ageing and sex. Ageing Res Rev 2022; 81:101722. [PMID: 36038114 DOI: 10.1016/j.arr.2022.101722] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 08/17/2022] [Accepted: 08/20/2022] [Indexed: 01/31/2023]
Abstract
Annually, approximately 17 million people die from cardiovascular diseases worldwide, half of them suddenly. The most common direct cause of sudden cardiac death is ventricular arrhythmia triggered by an acute coronary syndrome (ACS). The study summarizes the knowledge of the mechanisms of arrhythmia onset during ACS in humans and in animal models and factors that may influence the susceptibility to life-threatening arrhythmias during ACS with particular focus on the age and sex. The real impact of age and sex on the arrhythmic susceptibility within the setting of acute ischaemia is masked by the fact that ACSs result from coronary artery disease appearing with age much earlier among men than among women. However, results of researches show that in ageing process changes with potential pro-arrhythmic significance, such as increased fibrosis, cardiomyocyte hypertrophy, decrease number of gap junction channels, disturbances of the intracellular Ca2+ signalling or changes in electrophysiological parameters, occur independently of the development of cardiovascular diseases and are more severe in male individuals. A review of the literature also indicates a marked paucity of research in this area in female and elderly individuals. Greater awareness of sex differences in the aging process could help in the development of personalized prevention methods targeting potential pro-arrhythmic factors in patients of both sexes to reduce mortality during the acute phase of myocardial infarction. This is especially important in an era of aging populations in which women will predominate due to their longer lifespan.
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Affiliation(s)
- Marta Oknińska
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Marymoncka 99/103, 01-813 Warsaw, Poland
| | - Michał Mączewski
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Marymoncka 99/103, 01-813 Warsaw, Poland
| | - Urszula Mackiewicz
- Department of Clinical Physiology, Centre of Postgraduate Medical Education, Marymoncka 99/103, 01-813 Warsaw, Poland.
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4
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Zhang H, Yu H, Walcott GP, Rogers JM. Ectopic foci do not co-locate with ventricular epicardial stretch during early acute regional ischemia in isolated pig hearts. Physiol Rep 2022; 10:e15492. [PMID: 36259098 PMCID: PMC9579492 DOI: 10.14814/phy2.15492] [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: 06/27/2022] [Revised: 09/16/2022] [Accepted: 09/27/2022] [Indexed: 11/07/2022] Open
Abstract
Ectopic activation during early acute regional ischemia may initiate fatal reentrant arrhythmias. However, the origin of this ectopy remains poorly understood. Studies suggest that systolic stretch arising from dyskinesia in ischemic tissue may cause ectopic depolarization due to cardiac mechanosensitivity. The aim of this study was to investigate the link between mechanical stretch and ectopic electrical activation during early acute regional ischemia. We used a recently developed optical mapping technique capable of simultaneous imaging of mechanical deformation and electrical activation in isolated hearts. Eight domestic swine hearts were prepared in left ventricular working mode (LVW), in which the left ventricle was loaded and contracting. In an additional eight non-working (NW) hearts, contraction was pharmacologically suppressed with blebbistatin and the left ventricle was not loaded. In both groups, the left anterior descending coronary artery was tied below the first diagonal branch. Positive mechanical stretch (bulging) during systole was observed in the ischemic zones of LVW, but not NW, hearts. During ischemia phase 1a (0-15 min post-occlusion), LVW hearts had more ectopic beats than NW hearts (median: 19, interquartile range: 10-28 vs. median: 2, interquartile range: 1-6; p = 0.02); but the difference during phase 1b (15-60 min post-occlusion) was not significant (median: 27, interquartile range: 22-42 vs. median: 16, interquartile range: 12-31; p = 0.37). Ectopic beats arose preferentially from the ischemic border zone in both groups (p < 0.01). In LVW hearts, local mechanical stretch was only occasionally co-located with ectopic foci (9 of 69 ectopic beats). Despite the higher rate of ectopy observed in LVW hearts during ischemia phase 1a, the ectopic beats generally did not arise by the hypothesized mechanism in which ectopic foci are generated by co-local epicardial mechanical stretch.
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Affiliation(s)
- Hanyu Zhang
- Department of Biomedical EngineeringUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Han Yu
- Department of Biomedical EngineeringUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Gregory P. Walcott
- Department of MedicineUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Jack M. Rogers
- Department of Biomedical EngineeringUniversity of Alabama at BirminghamBirminghamAlabamaUSA
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5
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de Lepper AGW, Buck CMA, van 't Veer M, Huberts W, van de Vosse FN, Dekker LRC. From evidence-based medicine to digital twin technology for predicting ventricular tachycardia in ischaemic cardiomyopathy. JOURNAL OF THE ROYAL SOCIETY, INTERFACE 2022; 19:20220317. [PMID: 36128708 DOI: 10.1098/rsif.2022.0317] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Survivors of myocardial infarction are at risk of life-threatening ventricular tachycardias (VTs) later in their lives. Current guidelines for implantable cardioverter defibrillators (ICDs) implantation to prevent VT-related sudden cardiac death is solely based on symptoms and left ventricular ejection fraction. Catheter ablation of scar-related VTs is performed following ICD therapy, reducing VTs, painful shocks, anxiety, depression and worsening heart failure. We postulate that better prediction of the occurrence and circuit of VT, will improve identification of patients at risk for VT and boost preventive ablation, reducing mortality and morbidity. For this purpose, multiple time-evolving aspects of the underlying pathophysiology, including the anatomical substrate, triggers and modulators, should be part of VT prediction models. We envision digital twins as a solution combining clinical expertise with three prediction approaches: evidence-based medicine (clinical practice), data-driven models (data science) and mechanistic models (biomedical engineering). This paper aims to create a mutual understanding between experts in the different fields by providing a comprehensive description of the clinical problem and the three approaches in an understandable manner, leveraging future collaborations and technological innovations for clinical decision support. Moreover, it defines open challenges and gains for digital twin solutions and discusses the potential of hybrid modelling.
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Affiliation(s)
| | - Carlijn M A Buck
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Marcel van 't Veer
- Department of Cardiology, Catharina Hospital, Eindhoven, The Netherlands.,Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Wouter Huberts
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.,Department of Biomedical Engineering, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| | - Frans N van de Vosse
- Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
| | - Lukas R C Dekker
- Department of Cardiology, Catharina Hospital, Eindhoven, The Netherlands.,Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands
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6
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Han Y, Xiong C, Zhang LZ, Wang YD, Yang G, Guo Z. Antagonism of N/OFQ attenuates externalization of β1-adrenergic receptor and ventricular arrhythmias in acute myocardial ischemia rat model. Eur J Pharmacol 2022; 929:175139. [PMID: 35809655 DOI: 10.1016/j.ejphar.2022.175139] [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: 04/29/2022] [Revised: 07/02/2022] [Accepted: 07/02/2022] [Indexed: 11/18/2022]
Abstract
Nociceptin/orphanin FQ (N/OFQ) and adrenergic activations play roles in promoting cardiac arrhythmia in acute myocardial ischemia but whether N/OFQ and β1-adrenergic activities interact and how they interact in the arrhythmogenesis are still unknown. We designed this study to investigate the potential interaction of N/OFQ and β1-adrenergic activities and the underlying mechanism in arrhythmogenesis in acute myocardial ischemia. Ventricular arrhythmia was evaluated in anaesthetized rats following permanent coronary artery occlusion (CAO), in presence and absence of UFP-101 (a selective antagonist of N/OFQ receptor). The changes of β1-adrenergic receptor (β1-AR) in plasma membrane of cardiomyocytes were quantitatively evaluated and the relations with the alterations of phosphorylated Raf kinase inhibitor protein (p-RKIP) and phosphorylated connexin 43 (p-Cx43) were investigated. The ventricular arrhythmia was 59% less in the animals pre-treated with UFP-101 than the placebo-treated control (difference of means = -2.41; 95% confidence interval (CI) -2.84 to -1.99; P < 0.001). Meanwhile, p-RKIP and membrane β1-AR in the myocardium were downregulated by 59% and 24%, respectively (p-RKIP: difference of means = -6.91; 95% CI -8.38 to -5.45; P < 0.001; membrane β1-AR difference of means = -27.06; 95% CI -29.89 to -24.23; P < 0.001). Artificial upregulation of RKIP by didymin significant increased β1-AR in plasma membrane of the cardiomyocytes in the animals prone to ventricular arrhythmia. The findings may suggest that activation of N/OFQ receptor in acute myocardial ischemia induces upregulation of p-RKIP, externalization of β1-adrenergic receptor and downregulation of p-Cx43 in the cardiomyocytes, which promotes ventricular arrhythmia.
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Affiliation(s)
- Yi Han
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China; Department of Anaesthesia, Second Hospital of Shanxi Medical University, 382 Wuyi Road, Taiyuan, 030001, Shanxi, China
| | - Chang Xiong
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China
| | - Lin-Zhong Zhang
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China; Department of Anaesthesia, Second Hospital of Shanxi Medical University, 382 Wuyi Road, Taiyuan, 030001, Shanxi, China
| | - Yi-Di Wang
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China
| | - Guang Yang
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China
| | - Zheng Guo
- College of Anaesthesia, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China; Department of Anaesthesia, Second Hospital of Shanxi Medical University, 382 Wuyi Road, Taiyuan, 030001, Shanxi, China; Key Laboratory of Cellular Physiology (Shanxi Medical University), National Education Commission, Shanxi Medical University, 86 Xinjiannan Road, Taiyuan, 030001, Shanxi, China.
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7
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Hoogendijk MG, Géczy T, Yap SC, Szili-Torok T. Pathophysiological Mechanisms of Premature Ventricular Complexes. Front Physiol 2020; 11:406. [PMID: 32528299 PMCID: PMC7247859 DOI: 10.3389/fphys.2020.00406] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 04/06/2020] [Indexed: 11/29/2022] Open
Abstract
Premature ventricular complexes (PVCs) are the most common ventricular arrhythmia. Despite the high prevalence, the cause of PVCs remains elusive in most patients. A better understanding of the underlying pathophysiological mechanism may help to steer future research. This review aims to provide an overview of the potential pathophysiological mechanisms of PVCs and their differentiation.
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Affiliation(s)
- Mark G Hoogendijk
- Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Tamás Géczy
- Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Sing-Chien Yap
- Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Tamas Szili-Torok
- Department of Cardiology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
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Quinn TA, Kohl P. Cardiac Mechano-Electric Coupling: Acute Effects of Mechanical Stimulation on Heart Rate and Rhythm. Physiol Rev 2020; 101:37-92. [PMID: 32380895 DOI: 10.1152/physrev.00036.2019] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The heart is vital for biological function in almost all chordates, including humans. It beats continually throughout our life, supplying the body with oxygen and nutrients while removing waste products. If it stops, so does life. The heartbeat involves precise coordination of the activity of billions of individual cells, as well as their swift and well-coordinated adaption to changes in physiological demand. Much of the vital control of cardiac function occurs at the level of individual cardiac muscle cells, including acute beat-by-beat feedback from the local mechanical environment to electrical activity (as opposed to longer term changes in gene expression and functional or structural remodeling). This process is known as mechano-electric coupling (MEC). In the current review, we present evidence for, and implications of, MEC in health and disease in human; summarize our understanding of MEC effects gained from whole animal, organ, tissue, and cell studies; identify potential molecular mediators of MEC responses; and demonstrate the power of computational modeling in developing a more comprehensive understanding of ‟what makes the heart tick.ˮ.
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Affiliation(s)
- T Alexander Quinn
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Peter Kohl
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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9
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Cameron BA, Kai H, Kaihara K, Iribe G, Quinn TA. Ischemia Enhances the Acute Stretch-Induced Increase in Calcium Spark Rate in Ventricular Myocytes. Front Physiol 2020; 11:289. [PMID: 32372969 PMCID: PMC7179564 DOI: 10.3389/fphys.2020.00289] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 03/16/2020] [Indexed: 12/20/2022] Open
Abstract
Introduction: In ventricular myocytes, spontaneous release of calcium (Ca2+) from the sarcoplasmic reticulum via ryanodine receptors (“Ca2+ sparks”) is acutely increased by stretch, due to a stretch-induced increase of reactive oxygen species (ROS). In acute regional ischemia there is stretch of ischemic tissue, along with an increase in Ca2+ spark rate and ROS production, each of which has been implicated in arrhythmogenesis. Yet, whether there is an impact of ischemia on the stretch-induced increase in Ca2+ sparks and ROS has not been investigated. We hypothesized that ischemia would enhance the increase of Ca2+ sparks and ROS that occurs with stretch. Methods: Isolated ventricular myocytes from mice (male, C57BL/6J) were loaded with fluorescent dye to detect Ca2+ sparks (4.6 μM Fluo-4, 10 min) or ROS (1 μM DCF, 20 min), exposed to normal Tyrode (NT) or simulated ischemia (SI) solution (hyperkalemia [15 mM potassium], acidosis [6.5 pH], and metabolic inhibition [1 mM sodium cyanide, 20 mM 2-deoxyglucose]), and subjected to sustained stretch by the carbon fiber technique (~10% increase in sarcomere length, 15 s). Ca2+ spark rate and rate of ROS production were measured by confocal microscopy. Results: Baseline Ca2+ spark rate was greater in SI (2.54 ± 0.11 sparks·s−1·100 μm−2; n = 103 cells, N = 10 mice) than NT (0.29 ± 0.05 sparks·s−1·100 μm−2; n = 33 cells, N = 9 mice; p < 0.0001). Stretch resulted in an acute increase in Ca2+ spark rate in both SI (3.03 ± 0.13 sparks·s−1·100 μm−2; p < 0.0001) and NT (0.49 ± 0.07 sparks·s−1·100 μm−2; p < 0.0001), with the increase in SI being greater than NT (+0.49 ± 0.04 vs. +0.20 ± 0.04 sparks·s−1·100 μm−2; p < 0.0001). Baseline rate of ROS production was also greater in SI (1.01 ± 0.01 normalized slope; n = 11, N = 8 mice) than NT (0.98 ± 0.01 normalized slope; n = 12, N = 4 mice; p < 0.05), but there was an acute increase with stretch only in SI (+12.5 ± 2.6%; p < 0.001). Conclusion: Ischemia enhances the stretch-induced increase of Ca2+ sparks in ventricular myocytes, with an associated enhancement of stretch-induced ROS production. This effect may be important for premature excitation and/or in the development of an arrhythmogenic substrate in acute regional ischemia.
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Affiliation(s)
- Breanne A Cameron
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Hiroaki Kai
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Keiko Kaihara
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Gentaro Iribe
- Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, Okayama, Japan.,Department of Physiology, Asahikawa Medical University, Asahikawa, Japan
| | - T Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada.,School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
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10
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Nesmith HW, Zhang H, Rogers JM. Optical mapping of electromechanics in intact organs. Exp Biol Med (Maywood) 2019; 245:368-373. [PMID: 31842618 DOI: 10.1177/1535370219894942] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Optical mapping has become a widely used and important method in cardiac electrophysiology. The method typically uses voltage-sensitive fluorescent dyes and high-speed cameras to image propagation of electrical waves. However, signals are highly susceptible to artifact caused by motion of the target organ. Consequently, cardiac optical mapping is traditionally performed in isolated, perfused organs whose contraction has been pharmacologically arrested. This has prevented optical mapping from being used to study interactions between electrical and mechanical motion. However, recently, a number of groups have developed methods to implement cardiac optical mapping in the presence of motion. These methods employ two basic strategies: (1) compensate for motion by measuring it or (2) ratiometry. In ratiometry, two signals are recorded from each site. The signals have differing sensitivity to membrane potential, but common motion artifact, which can be cancelled by taking the ratio of the two signals. Some methods use both of these strategies. Methods that measure motion have the additional advantage that this information can be used to quantify the organ’s mechanical function. Doing so enables combined “electromechanical mapping,” which allows optical study of electromechanical interactions. By allowing recording in the presence of motion, the new methods open the door to optical recording in in-vivo preparations. In addition, it is possible to implement electromechanical optical mapping techniques in organ systems other than the heart. For example, it was recently shown that optical mapping of slow wave propagation in the swine stomach is feasible. Such studies have the potential to uncover new information on the role of dysrhythmic slow wave propagation in gastric motility disorders. Impact statement Electrical and mechanical functions in the heart are bidirectionally coupled, yet are usually studied separately because of the different instrumentation technologies that are used in the two areas. Optical mapping is a powerful and widespread tool for imaging electrical propagation, but has traditionally required mechanical function to be arrested. Recently new methods have been devised that enable optical mapping to be performed in beating hearts and also to simultaneously quantify mechanical function. These new technologies promise to yield new information about electromechanical interactions in normal and pathological settings. They are also beginning to find application in other organ systems such as the gastrointestinal tract where they may provide new insight into motility disorders.
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Affiliation(s)
- Haley W Nesmith
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Hanyu Zhang
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jack M Rogers
- Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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11
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Sattler SM, Skibsbye L, Linz D, Lubberding AF, Tfelt-Hansen J, Jespersen T. Ventricular Arrhythmias in First Acute Myocardial Infarction: Epidemiology, Mechanisms, and Interventions in Large Animal Models. Front Cardiovasc Med 2019; 6:158. [PMID: 31750317 PMCID: PMC6848060 DOI: 10.3389/fcvm.2019.00158] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Accepted: 10/18/2019] [Indexed: 12/22/2022] Open
Abstract
Ventricular arrhythmia and subsequent sudden cardiac death (SCD) due to acute myocardial infarction (AMI) is one of the most frequent causes of death in humans. Lethal ventricular arrhythmias like ventricular fibrillation (VF) prior to hospitalization have been reported to occur in more than 10% of all AMI cases and survival in these patients is poor. Identification of risk factors and mechanisms for VF following AMI as well as implementing new risk stratification models and therapeutic approaches is therefore an important step to reduce mortality in people with high cardiovascular risk. Studying spontaneous VF following AMI in humans is challenging as it often occurs unexpectedly in a low risk subgroup. Large animal models of AMI can help to bridge this knowledge gap and are utilized to investigate occurrence of arrhythmias, involved mechanisms and therapeutic options. Comparable anatomy and physiology allow for this translational approach. Through experimental focus, using state-of-the-art technologies, including refined electrical mapping equipment and novel pharmacological investigations, valuable insights into arrhythmia mechanisms and possible interventions for arrhythmia-induced SCD during the early phase of AMI are now beginning to emerge. This review describes large experimental animal models of AMI with focus on first AMI-associated ventricular arrhythmias. In this context, epidemiology of first AMI, arrhythmogenic mechanisms and various potential therapeutic pharmacological targets will be discussed.
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Affiliation(s)
- Stefan Michael Sattler
- Department of Cardiology, Heart Centre, Copenhagen University Hospital, Copenhagen, Denmark.,Medical Department I, University Hospital Grosshadern, LMU Munich, Munich, Germany
| | - Lasse Skibsbye
- Department of Exploratory Toxicology, H. Lundbeck A/S, Copenhagen, Denmark
| | - Dominik Linz
- Medical Department III, Universitätsklinikum des Saarlandes, Homburg, Germany.,Centre for Heart Rhythm Disorders, South Australian Health and Medical Research Institute, Royal Adelaide Hospital, University of Adelaide, Adelaide, SA, Australia
| | - Anniek Frederike Lubberding
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacob Tfelt-Hansen
- Department of Cardiology, Heart Centre, Copenhagen University Hospital, Copenhagen, Denmark.,Department of Forensic Medicine, Faculty of Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Jespersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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12
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Zhang H, Walcott GP, Rogers JM. Effects of gadolinium on cardiac mechanosensitivity in whole isolated swine hearts. Sci Rep 2018; 8:10506. [PMID: 30002391 PMCID: PMC6043572 DOI: 10.1038/s41598-018-28743-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/28/2018] [Indexed: 12/13/2022] Open
Abstract
Mechanical stimulation can elicit electrical activation of the heart. This mechanosensitivity can start life-threatening arrhythmias (commotio cordis) or terminate them (precordial thump). Mechanosensitivity may also be involved in arrhythmogenesis in other settings. Stretch-activated ion channels (SACs) are thought to be important in mechanosensitivity and a number of agents that block them have been identified. Such agents could potentially be used as tools in experimental investigation of mechanosensitivity. However, studies using them in intact-heart preparations have yielded inconsistent results. In the present study, we used isolated, perfused hearts from 25-35 kg pigs and a computer-controlled device that repeatably delivered focal mechanical stimuli. The concentration-dependent ability of the SAC blocker gadolinium to suppress mechanical activation was assessed by the success rate of mechanical stimulation and by the delay between successful mechanical stimulation and electrical activation. In six hearts, perfusate was recirculated. In an additional six hearts, perfusate was not recirculated to prevent gadolinium from forming complexes with metabolic waste and possibly precipitating. Gadolinium did not suppress mechanically-induced activation. Although gadolinium has been shown to be an effective SAC blocker in isolated cells, using it to probe the role of mechanical stimulation in whole heart preparations should be done with great caution.
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Affiliation(s)
- Hanyu Zhang
- University of Alabama at Birmingham, Department of Biomedical Engineering, Birmingham, 35294, United States of America
| | - Gregory P Walcott
- University of Alabama at Birmingham, Division of Cardiovascular Disease, Department of Medicine, Birmingham, 35294, United States of America
| | - Jack M Rogers
- University of Alabama at Birmingham, Department of Biomedical Engineering, Birmingham, 35294, United States of America.
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Mechano-electrical feedback in the clinical setting: Current perspectives. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:365-375. [DOI: 10.1016/j.pbiomolbio.2017.06.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 06/01/2017] [Accepted: 06/02/2017] [Indexed: 12/13/2022]
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Schönleitner P, Schotten U, Antoons G. Mechanosensitivity of microdomain calcium signalling in the heart. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017. [PMID: 28648626 DOI: 10.1016/j.pbiomolbio.2017.06.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In cardiac myocytes, calcium (Ca2+) signalling is tightly controlled in dedicated microdomains. At the dyad, i.e. the narrow cleft between t-tubules and junctional sarcoplasmic reticulum (SR), many signalling pathways combine to control Ca2+-induced Ca2+ release during contraction. Local Ca2+ gradients also exist in regions where SR and mitochondria are in close contact to regulate energetic demands. Loss of microdomain structures, or dysregulation of local Ca2+ fluxes in cardiac disease, is often associated with oxidative stress, contractile dysfunction and arrhythmias. Ca2+ signalling at these microdomains is highly mechanosensitive. Recent work has demonstrated that increasing mechanical load triggers rapid local Ca2+ releases that are not reflected by changes in global Ca2+. Key mechanisms involve rapid mechanotransduction with reactive oxygen species or nitric oxide as primary signalling molecules targeting SR or mitochondria microdomains depending on the nature of the mechanical stimulus. This review summarizes the most recent insights in rapid Ca2+ microdomain mechanosensitivity and re-evaluates its (patho)physiological significance in the context of historical data on the macroscopic role of Ca2+ in acute force adaptation and mechanically-induced arrhythmias. We distinguish between preload and afterload mediated effects on local Ca2+ release, and highlight differences between atrial and ventricular myocytes. Finally, we provide an outlook for further investigation in chronic models of abnormal mechanics (eg post-myocardial infarction, atrial fibrillation), to identify the clinical significance of disturbed Ca2+ mechanosensitivity for arrhythmogenesis.
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Affiliation(s)
- Patrick Schönleitner
- Dept of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
| | - Uli Schotten
- Dept of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands
| | - Gudrun Antoons
- Dept of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, The Netherlands.
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Barrabés JA, Inserte J, Rodríguez-Sinovas A, Ruiz-Meana M, Garcia-Dorado D. Early regional wall distension is strongly associated with vulnerability to ventricular fibrillation but not arrhythmia triggers following coronary occlusion in vivo. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:387-393. [PMID: 28579517 DOI: 10.1016/j.pbiomolbio.2017.05.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 05/28/2017] [Accepted: 05/29/2017] [Indexed: 10/19/2022]
Abstract
Wall stress may favor ischemic ventricular arrhythmias, yet its association with ventricular fibrillation (VF) or ventricular ectopy has been inconsistent among studies and its potential arrhythmogenicity across the cardiac cycle is unclear. In 91 open-chest pigs undergoing 40-50 min left anterior descending artery occlusion, we assessed the association between diastolic or systolic distension of the ischemic area and the incidence of ventricular premature beats (VPBs) and VF. End-diastolic segment length (EDL) and systolic bulging ([maximum systolic length-EDL] × 100/EDL) were measured by ultrasonic crystals. Fifteen minutes after occlusion, EDL increased to 112.7 ± 5.6% of baseline (P < 0.001) and systolic bulging averaged 3.4 ± 2.2%. Median VPB number was 52 (IQR, 16-110), 2 (0-7) in phase Ia and 49 (13-94) in phase Ib. VF occurred in 26 animals (28.6%), the first episode appearing 24 ± 6 min after occlusion. EDL increase was associated with subsequent VF (115.9 ± 5.7 and 111.4 ± 5.1% in animals with and without VF, P < 0.001) and with the number of VF episodes (P = 0.001) but not with VPB number, overall (r = 0.028, P = 0.801) or in phases Ia or Ib. Systolic bulging was related neither to VF occurrence (3.2 ± 2.2 and 3.5 ± 2.2%, respectively, P = 0.561) nor to VBP number (r = 0.095, P = 0.397). EDL increase predicted VF after adjusting for ischemic area size and K+ levels (odds ratio for 1% increase: 1.17, 95%CI 1.06-1.29, P = 0.001). Thus, diastolic regional ventricular distension predicts VF occurrence after coronary occlusion whereas neither diastolic nor systolic distension is associated with ventricular ectopy, which suggests that distension favors VF by acting on the arrhythmic substrate but not on arrhythmia triggers.
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Affiliation(s)
- José A Barrabés
- Hospital Universitari Vall d'Hebron & Research Institute, Universitat Autònoma de Barcelona, Barcelona, CIBER-CV, Spain.
| | - Javier Inserte
- Hospital Universitari Vall d'Hebron & Research Institute, Universitat Autònoma de Barcelona, Barcelona, CIBER-CV, Spain
| | - Antonio Rodríguez-Sinovas
- Hospital Universitari Vall d'Hebron & Research Institute, Universitat Autònoma de Barcelona, Barcelona, CIBER-CV, Spain
| | - Marisol Ruiz-Meana
- Hospital Universitari Vall d'Hebron & Research Institute, Universitat Autònoma de Barcelona, Barcelona, CIBER-CV, Spain
| | - David Garcia-Dorado
- Hospital Universitari Vall d'Hebron & Research Institute, Universitat Autònoma de Barcelona, Barcelona, CIBER-CV, Spain
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Cepiel A, Noszczyk-Nowak A, Pasławski R, Janiszewski A, Pasławska U. Intracardiac electrophysiological conduction parameters in adult dogs. Vet Q 2017; 37:91-97. [DOI: 10.1080/01652176.2017.1309599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Affiliation(s)
- Alicja Cepiel
- Department of Internal Medicine and Clinic of Diseases of Horses, Dogs and Cats, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - Agnieszka Noszczyk-Nowak
- Department of Internal Medicine and Clinic of Diseases of Horses, Dogs and Cats, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - Robert Pasławski
- Department and Clinic of Internal and Occupational Diseases and Hypertension, Wroclaw Medical University, Wroclaw, Poland
| | - Adrian Janiszewski
- Centre for Experimental Diagnostics and Biomedical Innovations, Wroclaw, Poland
| | - Urszula Pasławska
- Department of Internal Medicine and Clinic of Diseases of Horses, Dogs and Cats, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
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Abstract
In this review, the pro- and anti-arrhythmic effects of a diet rich in fish oil fatty acids and of hypercholesterolemia will be discussed in relation to two major mechanisms of arrhythmogenesis (triggered activity and re-entry). Whereas a diet rich in fish oil is pro-arrhythmic in relation to re-entry based arrhythmias (as occur in acute myocardial ischemia) and anti-arrhythmic in relation to triggered activity based arrhythmias (as occur in heart failure), the reverse is true for hypercholesterolemia. Changing the lipid composition of cardiomyocytes likely has powerful pro- or anti-arrhythmic consequences, depending on the mechanism of arrhythmias, and has corresponding therapeutic potential.
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Affiliation(s)
- R Coronel
- Dept. Exp. Cardiology, Academic Medical Center, Amsterdam, The Netherlands; IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, F-33600 Pessac Bordeaux, France.
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18
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Porta A, Barrabés JA, Candell-Riera J, Agulló L, Aguadé-Bruix S, de León G, Figueras J, Garcia-Dorado D. Plasma B-type natriuretic peptide levels are poorly related to the occurrence of ischemia or ventricular arrhythmias during symptom-limited exercise in low-risk patients. Arch Med Sci 2016; 12:341-8. [PMID: 27186178 PMCID: PMC4848363 DOI: 10.5114/aoms.2016.59258] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 02/03/2015] [Indexed: 12/15/2022] Open
Abstract
INTRODUCTION The usefulness of B-type natriuretic peptide (BNP) as a marker of ischemia is controversial. BNP levels have predicted arrhythmias in various settings, but it is unknown whether they are related to exercise-induced ischemic ventricular arrhythmias. MATERIAL AND METHODS We analyzed in 63 patients (64 ±14 years, 65% male, 62% with known coronary disease) undergoing exercise stress single-photon emission computed tomography (SPECT) the association between plasma BNP values (before and 15 min after exercise) and the occurrence of ischemia or ventricular arrhythmias during the test. RESULTS Exercise test (8.1 ±2.7 min, 7.4 ±8.1 metabolic equivalents, 82 ±12% of maximal predicted heart rate) induced reversible perfusion defects in 23 (36%) patients. Eight (13%) patients presented significant arrhythmias (≥ 7 ventricular premature complexes/min, couplets, or non-sustained ventricular tachycardia during exercise or in the first minute of recovery). Median baseline BNP levels were 17.5 (12.4-66.4) pg/ml in patients developing scintigraphic ischemia and 45.6 (13.2-107.4) pg/ml in those without ischemia (p = 0.137). The BNP levels increased after exercise (34.4 (15.3-65.4)% increment over baseline, p < 0.001), but the magnitude of this increase was not related to SPECT positivity (35.7 (18.8-65.4)% vs. 27.9 (5.6-64.0)% in patients with and without ischemia, respectively, p = 0.304). No significant association was found between BNP values (at baseline or their change during the test) and ventricular arrhythmias. CONCLUSIONS Plasma BNP values - at baseline or after exercise - were not associated with myocardial ischemia or with ventricular arrhythmia during exercise SPECT. These results highlight the limited usefulness of this biomarker to assess acute ischemia.
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Affiliation(s)
- Andreu Porta
- Servicio de Cardiología, Hospital Universitari Vall d'Hebron, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - José A Barrabés
- Servicio de Cardiología, Hospital Universitari Vall d'Hebron, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Jaume Candell-Riera
- Servicio de Cardiología, Hospital Universitari Vall d'Hebron, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Luis Agulló
- Servicio de Cardiología, Hospital Universitari Vall d'Hebron, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Santiago Aguadé-Bruix
- Servicio de Medicina Nuclear, Hospital Universitari Vall d'Hebron, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Gustavo de León
- Servicio de Medicina Nuclear, Hospital Universitari Vall d'Hebron, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Jaume Figueras
- Servicio de Cardiología, Hospital Universitari Vall d'Hebron, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - David Garcia-Dorado
- Servicio de Cardiología, Hospital Universitari Vall d'Hebron, VHIR, Universitat Autònoma de Barcelona, Barcelona, Spain
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Wilder CDE, Masoud R, Yazar D, O'Brien BA, Eykyn TR, Curtis MJ. Contractile function assessment by intraventricular balloon alters the ability of regional ischaemia to evoke ventricular fibrillation. Br J Pharmacol 2016; 173:39-52. [PMID: 26377788 PMCID: PMC4813384 DOI: 10.1111/bph.13332] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 09/04/2015] [Accepted: 09/10/2015] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE In drug research using the rat Langendorff heart preparation, it is possible to study left ventricular (LV) contractility using an intraventricular balloon (IVB), and arrhythmogenesis during coronary ligation-induced regional ischaemia. Assessing both concurrently would halve animal requirements. We aimed to test the validity of this approach. EXPERIMENTAL APPROACH The electrocardiogram (ECG) and LV function (IVB) were recorded during regional ischaemia of different extents in a randomized and blinded study. KEY RESULTS IVB-induced proarrhythmia was anticipated, but in hearts with an ischaemic zone (IZ) made deliberately small, an inflated IVB reduced ischaemia-induced ventricular fibrillation (VF) incidence as a trend. Repeating studies in hearts with large IZs revealed the effect to be significant. There were no changes in QT interval or other variables that might explain the effect. Insertion of an IVB that was minimally inflated had no effect on any variable compared with 'no IVB' controls. The antiarrhythmic effect of verapamil (a positive control drug) was unaffected by IVB inflation. Removal of an inflated (but not a non-inflated) IVB caused a release of lactate commensurate with reperfusion of an endocardial/subendocardial layer of IVB-induced ischaemia. This was confirmed by intracellular (31) phosphorus ((31) P) nuclear magnetic resonance (NMR) spectroscopy. CONCLUSIONS AND IMPLICATIONS IVB inflation does not inhibit VF suppression by a standard drug, but it has profound antiarrhythmic effects of its own, likely to be due to inflation-induced localized ischaemia. This means rhythm and contractility cannot be assessed concurrently by this approach, with implications for drug discovery and safety assessment.
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Affiliation(s)
| | - Radwa Masoud
- Cardiovascular
DivisionKing's College LondonLondonUK
| | - Duygu Yazar
- Cardiovascular
DivisionKing's College LondonLondonUK
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Barrabés JA, Inserte J, Agulló L, Rodríguez-Sinovas A, Alburquerque-Béjar JJ, Garcia-Dorado D. Effects of the Selective Stretch-Activated Channel Blocker GsMtx4 on Stretch-Induced Changes in Refractoriness in Isolated Rat Hearts and on Ventricular Premature Beats and Arrhythmias after Coronary Occlusion in Swine. PLoS One 2015; 10:e0125753. [PMID: 25938516 PMCID: PMC4418727 DOI: 10.1371/journal.pone.0125753] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/26/2015] [Indexed: 01/19/2023] Open
Abstract
Mechanical factors may contribute to ischemic ventricular arrhythmias. GsMtx4 peptide, a selective stretch-activated channel blocker, inhibits stretch-induced atrial arrhythmias. We aimed to assess whether GsMtx4 protects against ventricular ectopy and arrhythmias following coronary occlusion in swine. First, the effects of 170-nM GsMtx4 on the changes in the effective refractory period (ERP) induced by left ventricular (LV) dilatation were assessed in 8 isolated rat hearts. Then, 44 anesthetized, open-chest pigs subjected to 50-min left anterior descending artery occlusion and 2-h reperfusion were blindly allocated to GsMtx4 (57 μg/kg iv. bolus and 3.8 μg/kg/min infusion, calculated to attain the above concentration in plasma) or saline, starting 5-min before occlusion and continuing until after reflow. In rat hearts, LV distension induced progressive reductions in ERP (35±2, 32±2, and 29±2 ms at 0, 20, and 40 mmHg of LV end-diastolic pressure, respectively, P<0.001) that were prevented by GsMTx4 (33±2, 33±2, and 32±2 ms, respectively, P=0.002 for the interaction with LV end-diastolic pressure). Pigs receiving GsMtx4 had similar number of ventricular premature beats during the ischemic period as control pigs (110±28 vs. 103±21, respectively, P=0.842). There were not significant differences among treated and untreated animals in the incidence of ventricular fibrillation (13.6 vs. 22.7%, respectively, P=0.696) or tachycardia (36.4 vs. 50.0%, P=0.361) or in the number of ventricular tachycardia episodes during the occlusion period (1.8±0.7 vs. 5.5±2.6, P=0.323). Thus, GsMtx4 administered under these conditions does not suppress ventricular ectopy following coronary occlusion in swine. Whether it might protect against malignant arrhythmias should be tested in studies powered for these outcomes.
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Affiliation(s)
- José A. Barrabés
- Servicio de Cardiología, Hospital Universitari Vall d’Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona, Spain
- * E-mail:
| | - Javier Inserte
- Servicio de Cardiología, Hospital Universitari Vall d’Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Luis Agulló
- Servicio de Cardiología, Hospital Universitari Vall d’Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Antonio Rodríguez-Sinovas
- Servicio de Cardiología, Hospital Universitari Vall d’Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Juan J. Alburquerque-Béjar
- Servicio de Cardiología, Hospital Universitari Vall d’Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona, Spain
| | - David Garcia-Dorado
- Servicio de Cardiología, Hospital Universitari Vall d’Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona, Barcelona, Spain
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Ramirez E, Saiz J, Romero L, Ferrero JM, Trenor B. In silico ischaemia-induced reentry at the Purkinje-ventricle interface. Europace 2014; 16:444-51. [PMID: 24569899 DOI: 10.1093/europace/eut386] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
AIMS This computational modelling work illustrates the influence of hyperkalaemia and electrical uncoupling induced by defined ischaemia on action potential (AP) propagation and the incidence of reentry at the Purkinje-ventricle interface in mammalian hearts. METHODS AND RESULTS Unidimensional and bidimensional models of the Purkinje-ventricle subsystem, including ischaemic conditions (defined as phase 1B) in the ventricle and an ischaemic border zone, were developed by altering several important electrophysiological parameters of the Luo-Rudy AP model of the ventricular myocyte. Purkinje electrical activity was modelled using the equations of DiFrancesco and Noble. Our study suggests that an extracellular potassium concentration [K(+)]o >14 mM and a slight decrease in intercellular coupling induced by ischaemia in ventricle can cause conduction block from Purkinje to ventricle. Under these conditions, propagation from ventricle to Purkinje is possible. Thus, unidirectional block (UDB) and reentry can result. When conditions of UDB are met, retrograde propagation with a long delay (320 ms) may re-excite Purkinje cells, and give rise to a reentrant pathway. This induced reentry may be the origin of arrhythmias observed in phase 1B ischaemia. CONCLUSION In a defined setting of ischaemia (phase 1B), a small amount of uncoupling between ventricular cells, as well as between Purkinje and ventricular tissue, may induce UDBs and reentry. Hyperkalaemia is also confirmed to be an important factor in the genesis of reentrant rhythms, since it regulates the range of coupling in which UDBs may be induced.
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Affiliation(s)
- Esteban Ramirez
- Laboratorio de Bioingenieria, Departamento de Ingenieria Electrica y Electronica, Instituto Tecnologico de Cuautla, Cuautla, Morelos 62745, Mexico
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Han Y, Guo Z, Wang LL, Zhang LZ, Yao TP. Antagonism of endogenous nociceptin/orphanin FQ inhibits infarction-associated ventricular arrhythmias via PKC-dependent mechanism in rats. Br J Pharmacol 2014; 170:614-23. [PMID: 23869704 DOI: 10.1111/bph.12310] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 07/02/2013] [Accepted: 07/12/2013] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND AND PURPOSE Evidence indicates nociceptin/orphanin FQ (N/OFQ) may participate in the pathology of cardiac arrhythmias associated with myocardial infarction. But the role of N/OFQ in the arrhythmogenesis in acute myocardial infarction is unclear. The aim of this study was to investigate the effects of endogenous N/OFQ on infarction-associated arrhythmias. EXPERIMENTAL APPROACH The expression of N/OFQ, PKC activity and ventricular arrhythmias in presence and absence of UFP-101, a specific antagonist of N/OFQ receptor, were examined following permanent coronary artery occlusion in anaesthetized rats. The effect of N/OFQ on action potential duration was examined in isolated rat cardiomyocytes. KEY RESULTS It was observed that N/OFQ was increased by 41% in the myocardium after coronary artery occlusion (P < 0.01 vs. control). Pretreatment with UFP-101 (10(-7) mol·kg(-1) , i.v.) reduced the incidence of ventricular ectopic beats by 70% and ventricular tachycardia by 51% respectively (all P < 0.05 vs. control). Meanwhile, PKC activity was elevated in the rats treated with UFP-101 (by 35%, P < 0.05 vs. control). A selective PKC inhibitor, calphostin C, completely abolished the anti-arrhythmic effects of UFP-101 (P < 0.01). N/OFQ (at 10(-11) , 10(-9) and 1 × 10(-7) mol·L(-1) ) shortened the action potential duration by 3% (P > 0.05), 10% (P < 0.05) and 22% (P < 0.01), respectively, via N/OFQ receptor. CONCLUSIONS AND IMPLICATIONS Antagonism of endogenous N/OFQ produces anti-arrhythmic effects on ventricular arrhythmias in acute myocardial infarction, possibly via modulating PKC activity and action potential of myocytes.
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Affiliation(s)
- Y Han
- Department of Anesthesiology, Shanxi Medical University, Second Hospital of Shanxi Medical University, Taiyuan, China
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23
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The importance of non-uniformities in mechano-electric coupling for ventricular arrhythmias. J Interv Card Electrophysiol 2013; 39:25-35. [DOI: 10.1007/s10840-013-9852-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 10/16/2013] [Indexed: 12/31/2022]
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Wang LL, Han Y, Guo Z, Han SQ, Liu T. Esmolol activates endogenous neurokinin activity inhibiting infarction-induced arrhythmias in rats: Novel mechanisms of anti-arrhythmia. ACTA ACUST UNITED AC 2013; 186:116-22. [DOI: 10.1016/j.regpep.2013.08.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 07/26/2013] [Accepted: 08/13/2013] [Indexed: 10/26/2022]
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The Lambeth Conventions (II): Guidelines for the study of animal and human ventricular and supraventricular arrhythmias. Pharmacol Ther 2013; 139:213-48. [DOI: 10.1016/j.pharmthera.2013.04.008] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 04/01/2013] [Indexed: 12/17/2022]
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Barrabés JA, Figueras J, Candell-Riera J, Agulló L, Inserte J, Garcia-Dorado D. La distensión de la región isquémica predice una mayor inducibilidad de fibrilación ventricular tras la oclusión coronaria en el modelo porcino. Rev Esp Cardiol 2013. [DOI: 10.1016/j.recesp.2012.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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27
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Retroalimentación mecanoeléctrica del miocardio isquémico: un juego que modula su capacidad fibrilatoria. Rev Esp Cardiol (Engl Ed) 2013. [DOI: 10.1016/j.recesp.2012.09.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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28
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Calvo D, Jalife J. Mechanoelectric feedback in the ischemic myocardium: an interplay that modulates susceptibility to fibrillation. ACTA ACUST UNITED AC 2013; 66:168-70. [PMID: 24775449 DOI: 10.1016/j.rec.2012.09.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 09/29/2012] [Indexed: 11/16/2022]
Affiliation(s)
- David Calvo
- Unidad de Arritmias, Hospital Universitario Central de Asturias, Oviedo, Asturias, Spain
| | - José Jalife
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, United States.
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Distension of the ischemic region predicts increased ventricular fibrillation inducibility following coronary occlusion in swine. ACTA ACUST UNITED AC 2012; 66:171-6. [PMID: 24775450 DOI: 10.1016/j.rec.2012.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 08/01/2012] [Indexed: 11/21/2022]
Abstract
INTRODUCTION AND OBJECTIVES Distension of the ischemic region has been related to an increased incidence of spontaneous ventricular arrhythmias following coronary occlusion. This study analyzed whether regional ischemic distension predicts increased ventricular fibrillation inducibility after coronary occlusion in swine. METHODS In 18 anesthetized, open-chest pigs, the left anterior descending coronary artery was ligated for 60 min. Myocardial segment length in the ischemic region was monitored by means of ultrasonic crystals. Programmed stimulation was applied at baseline and then continuously between 10 and 60 min after coronary occlusion. RESULTS Coronary occlusion induced a rapid increase in end-diastolic length in the ischemic region, which reached 109.4% (0.9%) of baseline values 10 min after occlusion (P<.001). On average, 6.6 (0.5) stimulation protocols were completed and 5.4 (0.6) ventricular fibrillation episodes induced between 10 and 60 min of coronary occlusion. Neither baseline serum potassium levels nor the size of the ischemic region were significantly related to ventricular fibrillation inducibility. In contrast, the increase in end-diastolic length 10 min after coronary occlusion was associated directly (r=0.67; P=.002) with the number of induced ventricular fibrillation episodes and inversely (r=-0.55; P=.018) with the number of extrastimuli needed for ventricular fibrillation induction. CONCLUSIONS Regional ischemic expansion predicts increased ventricular fibrillation inducibility following coronary occlusion. These results highlight the potential influence of mechanical factors, acting not only on the triggers but also on the substrate, in the genesis of malignant ventricular arrhythmias during acute ischemia.
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Romero D, Ringborn M, Demidova M, Koul S, Laguna P, Platonov PG, Pueyo E. Characterization of ventricular depolarization and repolarization changes in a porcine model of myocardial infarction. Physiol Meas 2012; 33:1975-91. [DOI: 10.1088/0967-3334/33/12/1975] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Jie X, Rodriguez B, Trayanova N. The ischemic heart: what causes ectopic beating? CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2012; 2005:7194-7. [PMID: 17281937 DOI: 10.1109/iembs.2005.1616168] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The mechanisms by which spontaneous electrical activity originates in the ischemic heart and leads to arrhythmia remain unknown, however mechanical stretch of the diseased region has been hypothesized to play a role. The goal of this study is to investigate the conditions that favor the initiation of stretch-induced premature beats in the ischemic heart. We employ a mathematical model of the ischemic cell subjected to stretch. The study found that upon stretch, spontaneous beats occur in the ischemic cell, which are due to the stretch-induced re-activation of the L-type calcium current.
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Affiliation(s)
- Xiao Jie
- Department of Biomedical Engineering, Tulane University, New Orleans, LA 70118, USA
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Opthof T, Sutton P, Coronel R, Wright S, Kallis P, Taggart P. The Association of Abnormal Ventricular Wall Motion and Increased Dispersion of Repolarization in Humans is Independent of the Presence of Myocardial Infarction. Front Physiol 2012; 3:235. [PMID: 22783201 PMCID: PMC3388480 DOI: 10.3389/fphys.2012.00235] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2011] [Accepted: 06/11/2012] [Indexed: 11/13/2022] Open
Abstract
Abnormal ventricular wall motion is a strong clinical predictor of sudden, arrhythmic, cardiac death. Dispersion in repolarization is a prerequisite for the initiation of re-entrant arrhythmia. We hypothesize that regionally decreased wall motion is associated with heterogeneity of repolarization. We measured local activation times, activation-recovery intervals (ARIs, surrogate for action potential duration), and repolarization times using a multielectrode grid at nine segments on the left ventricular epicardium in 23 patients undergoing coronary artery surgery. Regional wall motion was simultaneously assessed using intraoperative transesophageal echocardiography. Three groups were discriminated: (1) Patients with normal wall motion (n = 11), (2) Patients with one or more hypokinetic segments (n = 6), (3) Patients with one or more akinetic or dyskinetic segments (n = 6). The average ARI was similar in all groups (251 ± 3.7 ms, ±SEM). Dispersion of ARIs between the nine segments was significantly increased in the hypokinetic (84 ± 7.4 ms, p < 0.005) and akinetic/dyskinetic group (94 ± 3.5 ms, p < 0.0005) compared with the normal group (49 ± 5.1 ms), independent from the presence of myocardial infarction. Repolarization heterogeneity occurred primarily in the normally contracting regions of the hearts with abnormal wall motion. An almost maximal increased dispersion of repolarization was observed when there was only a single hypokinetic segment. We conclude that inhomogeneous wall motion abnormality of even moderate severity is associated with increased repolarization inhomogeneity, independent from the presence of infarction.
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Affiliation(s)
- Tobias Opthof
- Experimental Cardiology Group, Center for Heart Failure Research, Academic Medical Center Amsterdam, Netherlands
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Miura M, Hattori T, Murai N, Nagano T, Nishio T, Boyden PA, Shindoh C. Regional increase in extracellular potassium can be arrhythmogenic due to nonuniform muscle contraction in rat ventricular muscle. Am J Physiol Heart Circ Physiol 2012; 302:H2301-9. [PMID: 22447939 DOI: 10.1152/ajpheart.01161.2011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In the ischemic myocardium, extracellular potassium ([K(+)](o)) increases to ≥20 mmol/l. To determine how lethal arrhythmias occur during ischemia, we investigated whether the increased spatial pattern of [K(+)](o), i.e., a regional or a global increase, affects the incidence of arrhythmias. Force, sarcomere length, membrane potential, and nonuniform intracellular Ca(2+) ([Ca(2+)](i)) were measured in rat ventricular trabeculae. A "regional" or "global" increase in [K(+)](o) was produced by exposing a restricted region of muscle to a jet of 30 mmol/l KCl or by superfusing trabeculae with a solution containing 30 mmol/l KCl, respectively. The increase in [Ca(2+)](i) (Ca(CW)) during Ca(2+) waves was measured (24°C, 3.0 mmol/l [Ca(2+)](o)). A regional increase in [K(+)](o) caused nonuniform [Ca(2+)](i) and contraction. In the presence of isoproterenol, the regional increase in [K(+)](o) induced sustained arrhythmias in 10 of 14 trabeculae, whereas the global increase did not induce such arrhythmias. During sustained arrhythmias, Ca(2+) surged within the jet-exposed region. In the absence of isoproterenol, the regional increase in [K(+)](o) increased Ca(CW), whereas the global increase decreased it. This increase in Ca(CW) with the regional increase in [K(+)](o) was not suppressed by 100 μmol/l streptomycin, whereas it was suppressed by 1) a combination of 10 μmol/l cilnidipine and 3 μmol/l SEA0400; 2) 20 mmol/l 2,3-butanedione monoxime; and 3) 10 μmol/l blebbistatin. A regional but not a global increase in [K(+)](o) induces sustained arrhythmias, probably due to nonuniform excitation-contraction coupling. The same mechanism may underlie arrhythmias during ischemia.
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Affiliation(s)
- Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai, Japan.
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Sánchez JA, Rodríguez-Sinovas A, Fernández-Sanz C, Ruiz-Meana M, García-Dorado D. Effects of a reduction in the number of gap junction channels or in their conductance on ischemia-reperfusion arrhythmias in isolated mouse hearts. Am J Physiol Heart Circ Physiol 2011; 301:H2442-53. [PMID: 21949115 DOI: 10.1152/ajpheart.00540.2011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
A transient reduction of cell coupling during reperfusion limits myocardial necrosis, but little is known about its arrhythmogenic effects during ischemia-reperfusion. Thus, we analyzed the effect of an extreme reduction in the number of gap junction channels or in their unitary conductance on ventricular arrhythmias during myocardial ischemia-reperfusion. Available gap junction uncouplers have electrophysiological effects independent from their uncoupling actions. Thus, isolated hearts from Cx43(Cre-ER(T)/fl) mice treated with 4-hydroxytamoxifen (4-OHT), from Cx43KI32 mice [in which connexin (Cx)43 was replaced with Cx32], and from control animals were submitted to regional ischemia and reperfusion, and spontaneous and induced ventricular arrhythmias were monitored. In additional hearts, changes in activation time and electrical impedance during global ischemia-reperfusion were assessed. In contrast to treatment with 4-OHT, replacement of Cx43 with Cx32 did not modify baseline activation time or electrical impedance. However, the number of extrasistole and ventricular tachyarrhythmias was higher in isolated hearts from Cx43KI32 and 4-OHT-treated Cx43(Cre-ER(T)/fl) animals versus wild-type animals during normoxia, ischemia (12.29 ± 3.26 and 52.17 ± 22.51 vs. 3.00 ± 1.46 spontaneous tachyarrhythmias, P < 0.05), and reperfusion. The impairment in conduction during ischemia was steeper in isolated hearts from Cx43KI32 animals, whereas changes in myocardial impedance were attenuated during ischemia in both transgenic models, suggesting altered cell-to-cell coupling at baseline. In conclusion, both reduction of Cx43 with 4-OHT and replacement of Cx43 by less-conductive Cx32 were arrhythmogenic under normoxia and ischemia-reperfusion, despite no major effects on baseline electrical properties. These results suggest that modifications in gap junction communication silent under normal conditions may be arrhythmogenic during ischemia-reperfusion.
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Affiliation(s)
- Jose A Sánchez
- Laboratorio de Cardiología Experimental, Vall d’Hebron University Hospital, Barcelona, Spain
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Odenstedt J, Linderoth B, Bergfeldt L, Ekre O, Grip L, Mannheimer C, Andréll P. Spinal cord stimulation effects on myocardial ischemia, infarct size, ventricular arrhythmia, and noninvasive electrophysiology in a porcine ischemia–reperfusion model. Heart Rhythm 2011; 8:892-8. [DOI: 10.1016/j.hrthm.2011.01.029] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 01/12/2011] [Indexed: 12/26/2022]
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Fujimatsu T, Nitta T, Osawa H, Shimizu K. Serial changes in epicardial electrograms during and after a coronary artery occlusion. Gen Thorac Cardiovasc Surg 2010; 58:323-30. [PMID: 20628847 DOI: 10.1007/s11748-010-0590-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 01/25/2010] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Suddenly occurring ventricular tachyarrhythmias are a complication during off-pump coronary artery bypass (OPCAB) surgery, potentially leading to the need for conversion to on-pump surgery. We examined serial changes in the spatial dispersion of the electrical activity and refractoriness at the myocardial ischemia border zones during and after coronary occlusion. METHODS Unipolar epicardial electrograms were continuously recorded from the anterior left ventricle at the border zones during and after a 10-min occlusion of the left anterior descending (LAD) coronary artery in 22 patients undergoing OPCAB. The local electrogram amplitude and local refractoriness were evaluated by the unipolar peak-to-peak amplitude (UPPA) and activation recovery interval (ARI), respectively. The spatial dispersion of the electrical activity and refractoriness were examined using the coefficient of variation of these parameters. RESULTS No sustained ventricular tachyarrhythmias occurred in any patients. The UPPA dispersion significantly increased up to 5 min after the LAD occlusion and then returned to a nonsignificant level and again increased after reperfusion. The ARI dispersion gradually increased after the LAD occlusion, reached a significantly increased level 3 min after the occlusion, and stayed at a significantly increased level for at least 5 min after the reperfusion. CONCLUSION There were unique serial changes in the spatial dispersion of the electrical activity and refractoriness at the myocardial ischemia border zones during and after coronary occlusions. Continuous monitoring of these parameters may be useful for predicting the critical electrophysiological conditions prone to the occurrence of ventricular tachyarrhythmias in patients undergoing OPCAB.
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Oikonomidis DL, Baltogiannis GG, Kolettis TM. Do endothelin receptor antagonists have an antiarrhythmic potential during acute myocardial infarction? Evidence from experimental studies. J Interv Card Electrophysiol 2010; 28:157-65. [DOI: 10.1007/s10840-010-9493-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Accepted: 05/05/2010] [Indexed: 11/24/2022]
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Jie X, Trayanova NA. Mechanisms for initiation of reentry in acute regional ischemia phase 1B. Heart Rhythm 2009; 7:379-86. [PMID: 20097623 DOI: 10.1016/j.hrthm.2009.11.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Accepted: 11/10/2009] [Indexed: 12/15/2022]
Abstract
BACKGROUND During phase 1B of acute regional ischemia, the subepicardial and subendocardial layers coupled to the inexcitable midmyocardium remain viable. OBJECTIVE The purpose of this study was to examine how the degree of hyperkalemia in the surviving layers, the lateral width of border zone between the normal tissue and the central ischemic zone, and the degree of cellular uncoupling between the surviving layers and the midmyocardium contribute to initiation of reentry. METHODS Simulations were conducted on the state-of-the-art model of rabbit ventricles with realistic representation of the spatial distribution of the ischemic insult. RESULTS Hyperkalemia in the surviving layers led to induction of reentry by increasing refractoriness and slowing conduction in the layers. Such reentries were formed solely in the subepicardium. A minimal level of hyperkalemia was required for induction of reentry. Progress increase in hyperkalemia led to a biphasic change in vulnerability to reentry. For each level of hyperkalemia, increased cellular uncoupling between subepicardium and midmyocardium increased inducibility of reentry by restoring subepicardial tissue excitability via blocking midmyocardial electrotonic effect. In addition, increased lateral width of the border zone prevented inducibility of reentry as conduction block occurred in the central ischemic zone when the wave propagated across the border zone from the normal zone. CONCLUSION The degree of hyperkalemia in the surviving subepicardium, the lateral width of border zone, and cellular uncoupling between the subepicardium and midmyocardium determine dispersion of refractoriness, conduction velocity, excitability, and, therefore, inducibility of reentry during phase 1B.
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Affiliation(s)
- Xiao Jie
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, Maryland, USA
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Jie X, Gurev V, Trayanova N. Mechanisms of mechanically induced spontaneous arrhythmias in acute regional ischemia. Circ Res 2009; 106:185-92. [PMID: 19893011 DOI: 10.1161/circresaha.109.210864] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
RATIONALE Although ventricular premature beats (VPBs) during acute regional ischemia have been linked to mechanical stretch of ischemic tissue, whether and how ischemia-induced mechanical dysfunction can induce VPBs and facilitate their degradation into reentrant arrhythmias has not been yet addressed. OBJECTIVE This study used a novel multiscale electromechanical model of the rabbit ventricles to investigate the origin of and the substrate for spontaneous arrhythmias arising from ischemia-induced electrophysiological and mechanical changes. METHODS AND RESULTS Two stages of ischemia were simulated. Dynamic mechanoelectrical feedback was modeled as spatially and temporally nonuniform membrane currents through mechanosensitive channels, the conductances of which depended on local strain rate. Our results reveal that both strains and strain rates were significantly larger in the central ischemic zone than in the border zone. However, in both ischemia stages, a VPB originated from the ischemic border in the left ventricular apical endocardium because of mechanically induced suprathreshold depolarizations. It then traveled fully intramurally until emerging from the ischemic border on the anterior epicardium. Reentry was formed only in the advanced ischemia stage as the result of a widened temporal excitable gap. Mechanically induced delayed afterdepolarization-like events contributed to the formation of reentry by further decreasing the already reduced-by-hyperkalemia local excitability, causing extended conduction block lines and slowed conduction in the ischemic region. CONCLUSIONS Mechanically induced membrane depolarizations in the ischemic region are the mechanism by which mechanical activity contributes to both the origin of and substrate for spontaneous arrhythmias under the conditions of acute regional ischemia.
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Affiliation(s)
- Xiao Jie
- Department of Biomedical Engineering and Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD 21218, USA
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Ivabradine induces an increase in ventricular fibrillation threshold during acute myocardial ischemia: an experimental study. J Cardiovasc Pharmacol 2009; 52:548-54. [PMID: 19034029 DOI: 10.1097/fjc.0b013e3181913df4] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Tachycardia often facilitates ischemic ventricular fibrillation (VF). OBJECTIVE This study assessed the impact of ivabradine (IVA), a selective inhibitor of the cardiac pacemaker If current, on ventricular fibrillation threshold (VFT) during acute myocardial ischemia. METHODS The experiments were conducted on a total of 54 domestic pigs. Myocardial ischemia was induced in anesthetized pigs by total 1-minute coronary occlusion at baseline and then on 2 occasions after intravenous administration of saline or 0.5 mg/kg of IVA. VF was triggered by electrical stimuli of increasing intensity at a fixed rate. Heart rate (HR), VFT, monophasic action potential duration, and peak of the time derivative of left ventricular pressure (LV dP/dt max) were monitored on each occasion. The activity of mitochondrial succinodehydrogenase was measured on heart sections. RESULTS Compared with controls, IVA induced a 31% reduction in HR, a 2.9-fold increase in VFT, and prevented ischemia-induced monophasic action potential duration shortening (+1 +/- 12 vs. -14 +/- 11 milliseconds) without affecting peak LV dP/dt. This beneficial effect on VFT was mainly due to HR reduction and was accompanied by a significant reduction in the hypoxic area (26% +/- 1% vs. 38% +/- 1%, P < 0.0001). CONCLUSION HR reduction and the decrease in myocardial damage induced by IVA protected against primary ischemic VF without altering myocardial contractility.
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Ischemic preconditioning protects against arrhythmogenesis through maintenance of both active as well as passive electrical properties in ischemic canine hearts. J Electrocardiol 2008; 40:S150-9. [PMID: 17993314 DOI: 10.1016/j.jelectrocard.2007.06.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2007] [Revised: 05/15/2007] [Accepted: 06/05/2007] [Indexed: 11/21/2022]
Abstract
BACKGROUND The mechanisms for the antiarrhythmogenic effects of preconditioning in ischemic hearts, although well demonstrated, are not clear. We measured indices of activation and repolarization using data from a high-resolution epicardial sock electrode array in preconditioned (PC) and non-PC hearts in an attempt to gain further insight into protective mechanisms. METHODS AND RESULTS Five canine hearts were subjected to a coronary artery occlusion lasting at least 1 hour, and 5 were subjected to a similar occlusion preceded by a preconditioning protocol. Epicardial electrograms were recorded using a 490-electrode sock. Representative beats were selected at intervals of 1 minute for analysis. The mean ST elevation for the PC group both rose slowly after occlusion and also resolved more slowly than the non-PC group. Electrocardiographic markers for propagation such as Total Activation Time, the QRSRMS width, and magnitude of steepest downstroke of the QRS complex all showed that the PC group maintained conduction velocity initially and also varied less dramatically than the control group. The regression line slope computed on a scatter plot of QT width vs cycle length was 0.23 for the PC group and 0.58 for non-PC. During occlusion, the incidence of premature ventricular contractions (PVCs) peaked at approximately 17 minutes followed by a second peak at approximately 27 minutes in the non-PC group, the PC group showed similar peaks at approximately 24 and approximately 53 minutes respectively. CONCLUSION The slower rate of resolution of ST elevation in PC hearts suggests a delay in gap junction closure, thus maintaining intracellular resistivity and reducing the likelihood of arrhythmia. The speed of conduction is adequately maintained during the early stages of ischemia in PC hearts. The mQTi-mRR regression line, a surrogate measure of rate dependency of repolarization (restitution), has a lower slope in the PC case, thus suggesting a mechanism of reduced arrhythmogenesis. The conclusions are supported by a delay of peak PVCs in PC hearts.
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[Relation between QT dispersion, left ventricle systolic function and frequency of ventricular arrhythmias in coronary patients]. SRP ARK CELOK LEK 2007; 135:395-400. [PMID: 17929530 DOI: 10.2298/sarh0708395s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
INTRODUCTION QT dispersion (QTd) is a measure of non-homogeneous repolarisation of the myocardium and is used as an indicator of arrhythmogenicity. OBJECTIVE The aim of this study was to assess the relation between QT dispersion, left ventricle systolic function and frequency of ventricular arrhythmias in coronary patients. METHOD We studied 290 coronary patients, 72 with angina pectoris and 218 after myocardial infarction. Eighty-one coronary patients had frequent and complex ventricular arrhythmias (out of them 19 had ventricular tachycardia) and 209 were without arrhythmias or with infrequent ventricular premature contractions (VPC < or = 10/h). In all patients, QT dispersion, exercise test, 24-hour Holter monitoring and echocardiographic examination were performed. RESULTS Patients with frequent and complex ventricular arrhythmias had significantly higher values of QTd (71.8 +/- 25.5 vs 55.6 +/- 21.7 ms; p < 0.001), corrected QT dispersion (QTdc: 81.3 +/- 31.5 vs. 60.3 +/- 26.1 ms; p < 0.001 ), left ventricular end-diastolic diameter (LVEDd: 56.2 +/- 6.9 vs. 53.4 +/- 6.2 mm; p < 0.001) and left ventricular end-systolic diameter (LVESd: 39.5 +/- 6.2 vs. 36.0 +/- 6.3 mm; p < 0.001), and significantly lower values of left ventricular ejection fraction (LVEF: 47.7 +/- 13.9 vs. 55.9 +/- 11.6%; p < 0.001) in comparison to those without arrhythmias or with infrequent VPC. Patients with VT had significantly higher values of QTd and QTdc in comparison to other patients with frequent and complex ventricular arrhythmias (83.8 +/- 17.1 vs. 69.4 +/- 26.2 ms; p < 0.02 for QTd; 101.1 +/- 23.9: 77.6 +/- 31.4 ms; p < 0.005 for QTdc). There is a significant negative correlation of QTd and QTdc with LVEF, and a significant positive correlation of QTd and QTdc with inside dimensions of the left ventricle, in patients with frequent and complex ventricular arrhythmias. CONCLUSION The study demonstrated that patients with frequent and complex ventricular arrhythmias had significantly higher values of QTd and QTdc, as well as a higher degree of left ventricle systolic dysfunction in comparison to those without arrhythmias or with infrequent VPC.
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Luqman N, Sung RJ, Wang CL, Kuo CT. Myocardial ischemia and ventricular fibrillation: pathophysiology and clinical implications. Int J Cardiol 2006; 119:283-90. [PMID: 17166606 DOI: 10.1016/j.ijcard.2006.09.016] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Revised: 07/31/2006] [Accepted: 09/24/2006] [Indexed: 10/23/2022]
Abstract
Ventricular fibrillation (VF) and myocardial ischemia are inseparable. The first clinical manifestation of myocardial ischemia or infarction may be sudden cardiac death in 20-25% of patients. The occurrence of potentially lethal arrhythmia is the end result of a cascade of pathophysiological abnormalities that result from complex interactions between coronary vascular events, myocardial injury, and changes in autonomic tone, metabolic conditions and ionic state of the myocardium. It is also related to the time from the onset of ischemia. Within the first few minutes there is abundant ventricular arrhythmogenesis usually lasting for 30 min. Triggers for ischemic VF occur at the border zone or regionally ischemic heart. The border zone of ischemia is the predominant site of fragmentation. Acute ischemia opens K(ATP) channels and causes acidosis and hypoxia of myocardial cells leading to a large dispersion in repolarization across the border zone. Abnormalities of intracellular Ca2+ handling also occur in the first few minutes of acute myocardial ischemia and may be an important cause of arrhythmias in human coronary artery disease. Substrate on the other hand transforms triggers into VF and serves to maintain it through fragmentation of waves in the ischemic zone. Thrombin levels, stretch, catecholamine, genetic predisposition, etc. are some of these factors. Reentry models described are spiral wave reentry, 3 dimensional rotors, reentry around 'M' cells and figure-of-eight reentry. Continuing efforts to better understand these arrhythmias will help identify patients of myocardial ischemia prone to arrhythmias.
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Affiliation(s)
- Nazar Luqman
- The Department of Cardiology, RIPAS Hospital, Brunei Darussalam
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Abstract
Proper mechanical and electrical coupling of cardiomyocytes is crucial for normal propagation of the electrical impulse throughout the working myocardium. Various proteins on the surface of cardiomyocytes are responsible for the integration of structural information and cell-cell communication. Increasing evidence from diseased myocardium and animal models indicates that alteration in electrical coupling via gap junctions is a critical determinant in the development of an arrhythmogenic substrate. What is less clear is how gap junctions are maintained and regulated in the working myocardium. In this review, we present data from human disease and animal models that support the idea that cell adhesion proteins regulate the stability of the gap junction protein, connexin.
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Affiliation(s)
- Jifen Li
- Jifen Li, MD, PhD, Center for Research on Reproduction and Women’s Health, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Vickas V. Patel
- Vickas V. Patel, MD, PhD, Division of Cardiovascular Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
| | - Glenn L. Radice
- Glenn L. Radice, PhD, Center for Research on Reproduction and Women’s Health, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
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Barrabés JA, Garcia-Dorado D, Agulló L, Rodríguez-Sinovas A, Padilla F, Trobo L, Soler-Soler J. Intracoronary infusion of Gd3+ into ischemic region does not suppress phase Ib ventricular arrhythmias after coronary occlusion in swine. Am J Physiol Heart Circ Physiol 2005; 290:H2344-50. [PMID: 16387793 DOI: 10.1152/ajpheart.00917.2005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Increased mechanical tension in the ischemic region during acute coronary occlusion might favor the occurrence of phase Ib ventricular arrhythmias. We aimed to investigate whether intracoronary administration of Gd(3+), a stretch-activated channel blocker, into the ischemic zone reduces the incidence of these arrhythmias. In thiopental-anesthetized, open-chest pigs, the left anterior descending coronary artery (LAD) was ligated for 45 or 48 min. Phosphate-free, HEPES-buffered saline bubbled with 100% N(2) was infused into the ischemic region for 4 min, starting 5 min (series A; n = 16) or 20 min (series B; n = 16) after coronary occlusion, at a rate doubling the baseline blood flow. Animals were blindly allocated to receive 40 muM Gd(3+) or only the buffer during the final 2 min of the infusion. There were no differences between groups with respect to hemodynamic variables, plasma K(+) levels, or size of the ischemic region. In neither series was the number of phase Ib premature ventricular beats reduced by Gd(3+) (46 +/- 20 in untreated vs. 91 +/- 37 in Gd(3+)-treated animals in series A and 19 +/- 7 vs. 22 +/- 13, respectively, in series B; both P = not significant). The occurrence of ventricular tachycardia or fibrillation was significantly associated with the magnitude of early ischemic expansion of the LAD region, as measured by ultrasonic crystals, but was also not prevented by Gd(3+). These results argue against a major role of stretch-activated channels inside the area at risk in the genesis of phase Ib ischemic ventricular arrhythmias.
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Affiliation(s)
- José A Barrabés
- Servicio de Cardiología, Hospital Universitari Vall d'Hebron, Pg. Vall d'Hebron 119-129, E-08035 Barcelona, Spain
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Li L, Nikolski V, Wallick DW, Efimov IR, Cheng Y. Mechanisms of enhanced shock-induced arrhythmogenesis in the rabbit heart with healed myocardial infarction. Am J Physiol Heart Circ Physiol 2005; 289:H1054-68. [PMID: 15879480 DOI: 10.1152/ajpheart.01253.2004] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Shock-induced vulnerability and defibrillation have been mostly studied in structurally normal hearts. However, defibrillation therapy is normally applied to patients with diseased hearts, frequently those with prior myocardial infarction (MI). Shock-induced vulnerability and defibrillation have not been well studied under this condition. We sought to examine the mechanisms of shock-induced arrhythmogenesis and arrhythmia maintenance in a rabbit model of healed MI (4 wk or more postinfarction). Ligation of the lateral division or posterolateral division of the left coronary artery at a level of 40-70% from the apex was performed 53 +/- 21 days before acute experiments. Shock-induced vulnerability was assessed in infarcted (n = 8) and structurally normal (n = 8) hearts by delivering internal monophasic shocks at different shock strengths and delivery phases. Electrical activities from the anterior epicardium during shock application and during shock-induced arrhythmias were optically recorded and quantitatively analyzed. Ligation resulted in a transmural left ventricular free wall infarction mainly located at the apical region with a consistent endocardial border zone (BZ) as confirmed by histological studies. There were significant increases in the incidence, severity, and duration of shock-induced arrhythmias in the infarcted hearts versus controls due to 1) postshock break-excitation wavefronts that frequently originated near the infarction BZ and 2) the existence of an infarction BZ that created an anatomic reentry pathway and facilitated arrhythmia maintenance. In conclusion, the infarction BZ contributes to both increased shock-induced arrhythmogenesis and arrhythmia maintenance in the rabbit model of healed MI.
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Affiliation(s)
- Li Li
- Department of Cardiovascular Medicine, Desk FF10, Cleveland Clinic Foundation, 9500 Euclid Ave., Cleveland, OH 44195, USA
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Janse MJ, Coronel R, Wilms-Schopman FJG, de Groot JR. Mechanical effects on arrhythmogenesis: from pipette to patient. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2003; 82:187-95. [PMID: 12732278 DOI: 10.1016/s0079-6107(03)00015-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Mechanical stimuli delivered to the precordium can, if strong enough and timed at the beginning of the T-wave, induce ventricular premature beats or runs of ventricular tachycardia and even fibrillation. On the other hand, there are reports that a properly timed "chest thump" can terminate ventricular tachycardia, or can act as pacemaker stimuli during an episode of asystole. It is likely that in these cases mechanical energy is translated to an electrical stimulus. There are more subtle ways in which mechanical stimuli, mediated by stretch, can exert electrophysiological effects, and the most common name to describe these effects is mechanoelectrical feedback. Most studies have concentrated on acute stretch or dilatation, while the effects of chronic stretch, which may clinically be more important, are difficult to evaluate since they are accompanied by other factors, such as hypertrophy, heart failure, fibrosis, neurohumeral disturbances, and electrolyte abnormalities, all of which have arrhythmogenic effects. There are a number of ion channels that are activated following stretch. Stretch during diastole usually leads to a depolarization, resembling a delayed afterdepolarization, which may reach threshold and initiate a ventricular premature beat. Stretch during systole usually shortens the action potential, but action potential prolongation, resulting in early afterdepolarizations has been described as well. The arrhythmias during acute myocardial ischaemia occur in two phases: the 1A phase between 2 and 10 min following coronary artery occlusion, and the 1B phase between 18 and 30 min. Experiments will be described, indicating that the ventricular premature beats of the 1B phase, which may induce ventricular fibrillation, are caused by stretch of the border between ischaemic and normal myocardium. Briefly, 1B arrhythmias are much less frequent in the isolated perfused heart than in the heart in situ, but in working, ejecting isolated hearts, the number of 1B arrhythmias is similar to those in the in situ heart. The ventricular premature beats have a focal origin at the border, and they occur more often after a pause-induced potentiated contraction.
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Affiliation(s)
- Michiel J Janse
- Academic Meidcal Center, Cardiovascular Research and Experimental and Molecular Cardiology Group, Cardiovascular Research Institute, Room J 1-27 Meibergdreef 9, 1105, Amsterdam, Netherlands.
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