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Majumder R. In silico thermal control of spiral wave dynamics in excitable cardiac tissue. BIOPHYSICAL REPORTS 2024; 4:100170. [PMID: 38960373 DOI: 10.1016/j.bpr.2024.100170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 06/26/2024] [Accepted: 06/28/2024] [Indexed: 07/05/2024]
Abstract
Self-organizing spiral waves of excitation occur in many complex excitable systems. In the heart, for example, they are associated with the occurrence of fatal cardiac arrhythmias such as tachycardia and fibrillation, which can lead to sudden cardiac death. The control of these waves is therefore necessary for the treatment of the disease. In this letter, I present an innovative approach to control cardiac arrhythmias using low (nonfreezing) temperatures. This approach differs from all previous established techniques in that it involves no drugs, no genetic modification, no injection of foreign bodies, no application of voltage shocks (high or low, single or pulsed), and no curative damage to the heart. It relies on regional cooling of cardiac tissue to create a transient inhomogeneity in the electrophysiological properties. This inhomogeneity can then be manipulated to control the dynamics of the reentrant waves. This approach is, to my knowledge, the most sustainable theoretical proposal for the treatment of cardiac arrhythmias in the clinic.
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Crispino A, Loppini A, Uzelac I, Iravanian S, Bhatia NK, Burke M, Filippi S, Fenton FH, Gizzi A. A cross species thermoelectric and spatiotemporal analysis of alternans in live explanted hearts using dual voltage-calcium fluorescence optical mapping. Physiol Meas 2024; 45:065001. [PMID: 38772394 DOI: 10.1088/1361-6579/ad4e8f] [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: 11/20/2023] [Accepted: 05/21/2024] [Indexed: 05/23/2024]
Abstract
Objective.Temperature plays a crucial role in influencing the spatiotemporal dynamics of the heart. Electrical instabilities due to specific thermal conditions typically lead to early period-doubling bifurcations and beat-to-beat alternans. These pro-arrhythmic phenomena manifest in voltage and calcium traces, resulting in compromised contractile behaviors. In such intricate scenario, dual optical mapping technique was used to uncover unexplored multi-scale and nonlinear couplings, essential for early detection and understanding of cardiac arrhythmia.Approach.We propose a methodological analysis of synchronized voltage-calcium signals for detecting alternans, restitution curves, and spatiotemporal alternans patterns under different thermal conditions, based on integral features calculation. To validate our approach, we conducted a cross-species investigation involving rabbit and guinea pig epicardial ventricular surfaces and human endocardial tissue under pacing-down protocols.Main results.We show that the proposed integral feature, as the area under the curve, could be an easily applicable indicator that may enhance the predictability of the onset and progression of cardiac alternans. Insights into spatiotemporal correlation analysis of characteristic spatial lengths across different heart species were further provided.Significance.Exploring cross-species thermoelectric features contributes to understanding temperature-dependent proarrhythmic regimes and their implications on coupled spatiotemporal voltage-calcium dynamics. The findings provide preliminary insights and potential strategies for enhancing arrhythmia detection and treatment.
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Affiliation(s)
- Anna Crispino
- Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Alessandro Loppini
- Department of Medicine and Surgery, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Ilija Uzelac
- Virginia Commonwealth University, Richmond, VA, United States of America
| | - Shahriar Iravanian
- Department of Cardiovascular Medicine, Emory University School of Medicine, Atlanta, GA, United States of America
| | - Neal K Bhatia
- Department of Cardiovascular Medicine, Emory University School of Medicine, Atlanta, GA, United States of America
| | - Michael Burke
- Department of Cardiovascular Medicine, Emory University School of Medicine, Atlanta, GA, United States of America
| | - Simonetta Filippi
- Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
| | - Flavio H Fenton
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States of America
| | - Alessio Gizzi
- Department of Engineering, Università Campus Bio-Medico di Roma, Rome, Italy
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3
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Li L, Ye W, Li Y, Chen Y, Zeng J. Intraoperative accidental hypothermia as a probable cause of malignant ventricular arrhythmias in an elderly patient undergoing transurethral resection of prostate: A case report. Heliyon 2023; 9:e19006. [PMID: 37600405 PMCID: PMC10432956 DOI: 10.1016/j.heliyon.2023.e19006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 07/23/2023] [Accepted: 08/04/2023] [Indexed: 08/22/2023] Open
Abstract
Background Intraoperative hypothermia is a common but severe condition that is defined as a core body temperature below 36 °C. Accidental hypothermia can produce coagulopathy, immunosuppression and peripheral hypoperfusion that can ultimately lead to life-threatening ventricular arrhythmias and vital organ injury, and it is significantly associated with perioperative complications and mortality. Case description We report the case of an 82-year-old man who presented with persistent ventricular tachycardia intraoperatively due to accidental hypothermia. The patient was diagnosed with benign prostatic hypertrophy and scheduled for transurethral resection of the prostate. Laboratory tests showed moderate anemia, and echocardiography indicated mild tricuspid and mitral regurgitation. The patient received general anesthesia with endotracheal intubation. Four hours after the start of surgery, the patient developed sudden ventricular tachycardia with severe hypotension. Arterial blood gas sampling indicated that there was no disturbance of electrolytes, acid-base balance or excessive bleeding. The rectal temperature was measured immediately, and the core temperature was 32 °C. The patient received antiarrhythmic therapy and rewarming measures. No additional ventricular arrhythmias appeared after the core temperature rose to 35 °C and the blood pressure returned to normal. The patient was transferred to the intensive care unit after surgery for further observation and was moved to the general ward the next day. He was discharged 4 days later without significant organ damage. Conclusions Intraoperative hypothermia may increase ventricular arrhythmia risk, especially in elderly patients. Surgeons and anesthesiologists should pay more attention to preventing and reversing accidental hypothermia, necessitating aggressive efforts to maintain normothermia during surgery.
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Affiliation(s)
| | | | - Yongxing Li
- Department of Anesthesiology, The Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Yingzhen Chen
- Department of Anesthesiology, The Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
| | - Jianfeng Zeng
- Department of Anesthesiology, The Sun Yat-sen Memorial Hospital of Sun Yat-sen University, Guangzhou, China
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Crispino A, Loppini A, Chionuma H, Uzelac I, Filippi S, Fenton FH, Gizzi A. Innovative Characterization of Alternans Onset and Development in Dual Voltage-Calcium Whole-Heart Optical Mapping Signals at Multiple Thermal States. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38083080 DOI: 10.1109/embc40787.2023.10340581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Cardiac electrical dynamics show complex space-time instabilities, like period-doubling bifurcation and beat-to-beat alternans, known to occur as pro-arrhythmic phenomena and linked to membrane voltage and intracellular calcium kinetics. Besides, cellular ionic dynamics are critically affected by temperature oscillations, further enhancing the complexity of such arrhythmias precursors that lead to irregular cardiac contraction. In this complex scenario, fluorescence dual optical mapping techniques allow the unveiling of nonlinear and multi-scale couplings. In this contribution, we propose a novel methodological analysis of synchronous dual voltage-calcium traces obtained from whole rabbit hearts for (i) detecting alternans onset and evolution, (ii) characterizing novel restitution curves, and (iii) defining spatio-temporal alternans patterns at four thermal states. We validate our approach against well-accepted analyses considering complete pacing-down restitution protocols. The proposed methodology computes integral features, e.g., area under the curve, suggesting that a novel, easy-to-use indicator, may advance predictability on alternans onset and evolution, further providing insights into spatio-temporal cardiac analyses.Clinical Relevance- This work introduces new methods for the early detection of cardiac alternans onset and development as precursors of arrhythmias and fibrillation at different temperatures.
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Kharche SR, Lemoine S, Tamasi T, Hur L, So A, McIntyre CW. Therapeutic Hypothermia Reduces Peritoneal Dialysis Induced Myocardial Blood Flow Heterogeneity and Arrhythmia. Front Med (Lausanne) 2021; 8:700824. [PMID: 34395480 PMCID: PMC8362929 DOI: 10.3389/fmed.2021.700824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/30/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Moderate therapeutic hypothermia (TH) is a well-recognized cardio-protective strategy. The instillation of fluid into the peritoneum provides an opportunity to deliver moderate hypothermia as primary prevention against cardiovascular events. We aimed to to investigate both cardiac perfusion consequences (overall blood flow and detailed assessment of perfusion heterogeneity) and subsequently simulate the associated arrhythmic risk for patients undergoing peritoneal dialysis (PD) induced TH. Methods: Patients underwent high resolution myocardial perfusion scanning using high resolution 256 slice CT scanning, at rest and with adenosine stress. The first visit using the patient's usual PD regimen, on the second visit the same regime was utilized but with cooled peritoneal dialysate at 32°C. Myocardial blood flow (MBF) was quantified from generated perfusion maps, reconstructed in 3D. MBF heterogeneity was assessed by fractal dimension (FD) measurement on the 3D left ventricular reconstruction. Arrhythmogenicity was quantified from a sophisticated computational simulation using a multi-scale human 3D ventricle wedge electrophysiological computational model. Results: We studied 7 PD patients, mean age of 60 ± 7 and mean vintage dialysis of 23.6 ± 17.6 months. There were no significant different in overall segmental MBF between normothermic condition (NT) and TH. MBF heterogeneity was significantly decreased (-14%, p = 0.03) at rest and after stress (-14%, p = 0.03) when cooling was applied. Computational simulation showed that TH allowed a normalization of action potential, QT duration and T wave. Conclusion: TH-PD results in moderate hypothermia leading to a reduction in perfusion heterogeneity and simulated risk of non-terminating malignant ventricular arrhythmias.
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Affiliation(s)
- Sanjay R Kharche
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada.,Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Sandrine Lemoine
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada
| | - Tanya Tamasi
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada
| | - Lisa Hur
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada
| | - Aaron So
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Imaging Program, Lawson Health Research Institute, London, ON, Canada
| | - Christopher W McIntyre
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada.,Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
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6
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Majumder R, Mohamed Nazer AN, Panfilov AV, Bodenschatz E, Wang Y. Electrophysiological Characterization of Human Atria: The Understated Role of Temperature. Front Physiol 2021; 12:639149. [PMID: 34366877 PMCID: PMC8346027 DOI: 10.3389/fphys.2021.639149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/01/2021] [Indexed: 11/13/2022] Open
Abstract
Ambient temperature has a profound influence on cellular electrophysiology through direct control over the gating mechanisms of different ion channels. In the heart, low temperature is known to favor prolongation of the action potential. However, not much is known about the influence of temperature on other important characterization parameters such as the resting membrane potential (RMP), excitability, morphology and characteristics of the action potential (AP), restitution properties, conduction velocity (CV) of signal propagation, etc. Here we present the first, detailed, systematic in silico study of the electrophysiological characterization of cardiomyocytes from different regions of the normal human atria, based on the effects of ambient temperature (5-50°C). We observe that RMP decreases with increasing temperature. At ~ 48°C, the cells lose their excitability. Our studies show that different parts of the atria react differently to the same changes in temperature. In tissue simulations a drop in temperature correlated positively with a decrease in CV, but the decrease was region-dependent, as expected. In this article we show how this heterogeneous response can provide an explanation for the development of a proarrhythmic substrate during mild hypothermia. We use the above concept to propose a treatment strategy for atrial fibrillation that involves severe hypothermia in specific regions of the heart for a duration of only ~ 200 ms.
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Affiliation(s)
- Rupamanjari Majumder
- Laboratory for Fluid Physics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
| | | | - Alexander V Panfilov
- World-Class Research Center "Digital Biodesign and Personalized Healthcare", Sechenov University, Moscow, Russia.,Department of Physics and Astronomy, Ghent University, Ghent, Belgium.,Laboratory of Computational Biology and Medicine, Ural Federal University, Yekaterinburg, Russia
| | - Eberhard Bodenschatz
- Laboratory for Fluid Physics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany.,Laboratory of Atomic and Solid-State Physics and Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, United States
| | - Yong Wang
- Laboratory for Fluid Physics, Pattern Formation and Biocomplexity, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, Göttingen, Germany
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7
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Loppini A, Barone A, Gizzi A, Cherubini C, Fenton FH, Filippi S. Thermal effects on cardiac alternans onset and development: A spatiotemporal correlation analysis. Phys Rev E 2021; 103:L040201. [PMID: 34005953 PMCID: PMC8202768 DOI: 10.1103/physreve.103.l040201] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/09/2021] [Indexed: 01/08/2023]
Abstract
Alternans of cardiac action potential duration represent critical precursors for the development of life-threatening arrhythmias and sudden cardiac death. The system's thermal state affects these electrical disorders requiring additional theoretical and experimental efforts to improve a patient-specific clinical understanding. In such a scenario, we generalize a recent work from Loppini et al. [Phys. Rev. E 100, 020201(R) (2019)PREHBM2470-004510.1103/PhysRevE.100.020201] by performing an extended spatiotemporal correlation study. We consider high-resolution optical mapping recordings of canine ventricular wedges' electrical activity at different temperatures and pacing frequencies. We aim to recommend the extracted characteristic length as a potential predictive index of cardiac alternans onset and evolution within a wide range of system states. In particular, we show that a reduction of temperature results in a drop of the characteristic length, confirming the impact of thermal instabilities on cardiac dynamics. Moreover, we theoretically investigate the use of such an index to identify and predict different alternans regimes. Finally, we propose a constitutive phenomenological law linking conduction velocity, characteristic length, and temperature in view of future numerical investigations.
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Affiliation(s)
- Alessandro Loppini
- Department of Engineering, Campus Bio-Medico University of Rome, 00128 Rome, Italy
| | - Alessandro Barone
- Department of Engineering, Campus Bio-Medico University of Rome, 00128 Rome, Italy
| | - Alessio Gizzi
- Department of Engineering, Campus Bio-Medico University of Rome, 00128 Rome, Italy
| | - Christian Cherubini
- Department of Science and Technology for Humans and the Environment and ICRA, Campus Bio-Medico University of Rome, 00128 Rome, Italy and International Center for Relativistic Astrophysics Network-ICRANet, 65122 Pescara, Italy
| | - Flavio H. Fenton
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Simonetta Filippi
- Department of Engineering and ICRA, Campus Bio-Medico University of Rome, 00128 Rome, Italy and International Center for Relativistic Astrophysics Network-ICRANet, 65122 Pescara, Italy
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8
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Herndon C, Astley HC, Owerkowicz T, Fenton FH. Defibrillate You Later, Alligator: Q10 Scaling and Refractoriness Keeps Alligators from Fibrillation. Integr Org Biol 2021; 3:obaa047. [PMID: 33977229 PMCID: PMC8101277 DOI: 10.1093/iob/obaa047] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Effective cardiac contraction during each heartbeat relies on the coordination of an electrical wave of excitation propagating across the heart. Dynamically induced heterogeneous wave propagation may fracture and initiate reentry-based cardiac arrhythmias, during which fast-rotating electrical waves lead to repeated self-excitation that compromises cardiac function and potentially results in sudden cardiac death. Species which function effectively over a large range of heart temperatures must balance the many interacting, temperature-sensitive biochemical processes to maintain normal wave propagation at all temperatures. To investigate how these species avoid dangerous states across temperatures, we optically mapped the electrical activity across the surfaces of alligator (Alligator mississippiensis) hearts at 23°C and 38°C over a range of physiological heart rates and compare them with that of rabbits (Oryctolagus cuniculus). We find that unlike rabbits, alligators show minimal changes in wave parameters (action potential duration and conduction velocity) which complement each other to retain similar electrophysiological wavelengths across temperatures and pacing frequencies. The cardiac electrophysiology of rabbits accommodates the high heart rates necessary to sustain an active and endothermic metabolism at the cost of increased risk of cardiac arrhythmia and critical vulnerability to temperature changes, whereas that of alligators allows for effective function over a range of heart temperatures without risk of cardiac electrical arrhythmias such as fibrillation, but is restricted to low heart rates. Synopsis La contracción cardíaca efectiva durante cada latido del corazón depende de la coordinación de una onda eléctrica de excitación que se propaga a través del corazón. Heterogéidades inducidas dinámicamente por ondas de propagación pueden resultar en fracturas de las ondas e iniciar arritmias cardíacas basadas en ondas de reingreso, durante las cuales ondas espirales eléctricas de rotación rápida producen una autoexcitación repetida que afecta la función cardíaca y pude resultar en muerte súbita cardíaca. Las especies que funcionan eficazmente en una amplia gama de temperaturas cardíacas deben equilibrar los varios procesos bioquímicos que interactúan, sensibles a la temperatura para mantener la propagación normal de ondas a todas las temperaturas. Para investigar cómo estas especies evitan los estados peligrosos a través de las temperaturas, mapeamos ópticamente la actividad eléctrica a través de las superficies de los corazones de caimanes (Alligator mississippiensis) a 23°C and 38°C sobre un rango de frecuencias fisiológicas del corazón y comparamos con el de los conejos (Oryctolagus cuniculus). Encontramos que a diferencia de los conejos, los caimanes muestran cambios mínimos en los parámetros de onda (duración potencial de acción y velocidad de conducción) que se complementan entre sí para retener longitudes de onda electrofisiológicas similares a través de los rangos de temperaturas y frecuencias de ritmo. La electrofisiología cardíaca de los conejos acomoda las altas frecuencias cardíacas necesarias para mantener un metabolismo activo y endotérmico a costa de un mayor riesgo de arritmia cardíaca y vulnerabilidad crítica a los cambios de temperatura, mientras que la de los caimanes permite un funcionamiento eficaz en una serie de temperaturas cardíacas sin riesgo de arritmias eléctricas cardíacas como la fibrilación, pero está restringida a bajas frecuencias cardíacas.
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Affiliation(s)
- Conner Herndon
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
| | - Henry C Astley
- Department of Biology, Biomimicry Research & Innovation Center, University of Akron, Akron, OH, USA
| | - Tomasz Owerkowicz
- Department of Biology, California State University, San Bernardino, CA, USA
| | - Flavio H Fenton
- School of Physics, Georgia Institute of Technology, Atlanta, GA, USA
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Wu CI, Lu YY, Chen YC, Lin FZ, Huang JH, Lin YK, Higa S, Chan CS, Liu CM, Chen SA, Chen YJ. The AMP-activated protein kinase modulates hypothermia-induced J wave. Eur J Clin Invest 2020; 50:e13247. [PMID: 32307703 DOI: 10.1111/eci.13247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 04/09/2020] [Accepted: 04/12/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND The mechanism underlying the occurrence of the J wave in low temperature remains unclear. However, low temperature is associated with metabolic disorder and 5' AMP-activated protein kinase (AMPK), which modulates ionic currents and cardiac metabolism. This study investigated whether AMPK regulation can modulate the occurrence of the J wave at low temperature. METHODS Unipolar and bipolar leads were used to record monophasic action potential (the endocardium and epicardium) and pseudo-electrocardiograms (inferior leads) to study the cardiac electrical activity. Measurements were taken in isolated Langendorff rabbit hearts at both 30℃ and 37℃ before and after administration of 4-aminopyridine (an ultrarapid delayed rectifier potassium current inhibitor, IKur , 50 µmol L-1 ), PF06409577 (an AMPK activator, 1 µmol L-1 ), compound C (an AMPK inhibitor, 10 µmol L-1 ) and glibenclamide (an ATP-sensitive inward rectifier potassium channel inhibitor, IKATP , 20 µmol L-1 ). RESULTS The amplitude of the J wave (2.46 ± 0.34 mV vs. 1.11 ± 0.23 mV, P < .01) at 30℃ (n = 15) was larger than that at 37℃ (n = 15). PF06409577 (1 µmol L-1 ) increased the J waves at both 30℃ and 37℃. In contrast, compound C (10 µmol L-1 ) reduced J wave at both 37℃ and 30℃. Low-temperature-induced J waves were individually suppressed by 4-AP (50 µmol L-1 ) and glibenclamide (20 µmol L-1 ). CONCLUSIONS AMPK inhibition reduces low-temperature-induced J waves and possible ventricular arrhythmogenesis by modulating IKATP and IKur channels.
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Affiliation(s)
- Cheng-I Wu
- Heart Rhythm Center, Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yen-Yu Lu
- Division of Cardiovascular Medicine, Department of Internal Medicine, Cathay General Hospital, Taipei, Taiwan
| | - Yao-Chang Chen
- Department of Biomedical Engineering and Institute of Physiology, National Defense Medical Center, Taipei, Taiwan
| | - Feng-Zhi Lin
- Grade Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Jen-Hung Huang
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Yung-Kuo Lin
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Satoshi Higa
- Cardiac Electrophysiology and Pacing Laboratory, Division of Cardiovascular Medicine, Makiminato Central Hospital, Okinawa, Japan
| | - Chao-Shun Chan
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Chih-Min Liu
- Heart Rhythm Center, Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Shih-Ann Chen
- Heart Rhythm Center, Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yi-Jen Chen
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.,Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.,Cardiovacular Research Center, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
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10
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Loppini A, Cherubini C, Bertolaso M, Filippi S. Breaking down calcium timing in heterogenous cells populations. Biosystems 2020; 191-192:104117. [DOI: 10.1016/j.biosystems.2020.104117] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 01/17/2020] [Accepted: 02/12/2020] [Indexed: 12/21/2022]
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11
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Welsh AJ, Delgado C, Lee-Trimble C, Kaboudian A, Fenton FH. Simulating waves, chaos and synchronization with a microcontroller. CHAOS (WOODBURY, N.Y.) 2019; 29:123104. [PMID: 31893636 PMCID: PMC7195869 DOI: 10.1063/1.5094351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 10/22/2019] [Indexed: 05/12/2023]
Abstract
The spatiotemporal dynamics of complex systems have been studied traditionally and visualized numerically using high-end computers. However, due to advances in microcontrollers, it is now possible to run what once were considered large-scale simulations using a very small and inexpensive single integrated circuit that can furthermore send and receive information to and from the outside world in real time. In this paper, we show how microcontrollers can be used to perform simulations of nonlinear ordinary differential equations with spatial coupling and to visualize their dynamics using arrays of light-emitting diodes and/or touchscreens. We demonstrate these abilities using three different models: two reaction-diffusion models (one neural and one cardiac) and a generic model of network oscillators. These models are commonly used to simulate various phenomena in biophysical systems, including bifurcations, waves, chaos, and synchronization. We also demonstrate how simple it is to integrate real-time user interaction with the simulations by showing examples with a light sensor, touchscreen, and web browser.
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Affiliation(s)
- Andrea J Welsh
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Cristian Delgado
- Facultad de Ciencias, Universidad Nacional Autònoma de México, Distrito Federal 04510, Mexico
| | | | - Abouzar Kaboudian
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Flavio H Fenton
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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12
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Cheng QY, Yang MC, Wu J, Jia XL, Xiao C, Lian T, Zhang SZ. Reduced cardiac ischemia/reperfusion injury by hypothermic reperfusion via activation of transient receptor potential M8 channel. Life Sci 2019; 232:116658. [PMID: 31310758 DOI: 10.1016/j.lfs.2019.116658] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/05/2019] [Accepted: 07/12/2019] [Indexed: 01/23/2023]
Abstract
AIMS To investigate the cardioprotective effects of hypothermic (25 °C) reperfusion on ischemia/reperfusion injury and the role of transient potential channel M8 (TRPM8) in this process. MAIN METHODS Western blot and real-time PCR were used to monitor the expression of TRPM8 in myocardium. Myocardial ischemia/reperfusion injury was induced by 30 min of global ischemia followed by 120 min of reperfusion in Langendorff-perfused hearts from Sprague-Dawley rats. The reperfusion was either normothermic (37 °C) or hypothermic (25 °C). Infarct size and left ventricular function were assessed, and lactate dehydrogenase (LDH), superoxide dismutase (SOD), and malondialdehyde (MDA) in the coronary effluent were measured spectrophotometrically, and cardiomyocyte apoptosis was detected by TUNEL assay. The expression of TRPM8, Bcl-2, Bax, cleaved capspase-3, RhoA, and ROCK2 was quantified. KEY FINDINGS TRPM8 protein and mRNA were expressed in rat myocardium. Hypothermic reperfusion decreased the infarct size, LDH activity, MDA content, apoptosis, and expression of Bax, cleaved caspase-3, RhoA, and ROCK2 compared with normothermic reperfusion. These effects were associated with improved recovery of left ventricular contractility, and were reduced by BCTC, a TRPM8 antagonist. Ischemia/reperfusion injury and the increased expression of Bax, caspase-3, RhoA, and ROCK2 induced by normothermic reperfusion were reduced by Icilin, a TRPM8 agonist. SIGNIFICANCE Hypothermic reperfusion at 25 °C has cardioprotective effects against ischemia/reperfusion injury via activation of TRPM8 to inhibit the oxidative stress-related RhoA/ROCK2 signal pathway.
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Affiliation(s)
- Quan-Yi Cheng
- Department of Physiology, Medical College of China Three Gorges University, 8 Daxue Road, Yichang 443002, China
| | - Meng-Cheng Yang
- Department of Physiology, Medical College of China Three Gorges University, 8 Daxue Road, Yichang 443002, China
| | - Jing Wu
- Department of Physiology, Medical College of China Three Gorges University, 8 Daxue Road, Yichang 443002, China
| | - Xiao-Li Jia
- Department of Physiology, Medical College of China Three Gorges University, 8 Daxue Road, Yichang 443002, China
| | - Chao Xiao
- Department of Physiology, Medical College of China Three Gorges University, 8 Daxue Road, Yichang 443002, China
| | - Ting Lian
- Department of Physiology, Medical College of China Three Gorges University, 8 Daxue Road, Yichang 443002, China
| | - Shi-Zhong Zhang
- Department of Physiology, Medical College of China Three Gorges University, 8 Daxue Road, Yichang 443002, China.
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13
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Belhamadia Y, Grenier J. Modeling and simulation of hypothermia effects on cardiac electrical dynamics. PLoS One 2019; 14:e0216058. [PMID: 31050666 PMCID: PMC6499428 DOI: 10.1371/journal.pone.0216058] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 04/12/2019] [Indexed: 11/18/2022] Open
Abstract
Previous experimental evidence has shown the effect of temperature on the action potential duration (APD). It has also been demonstrated that regional cooling of the heart can prolong the APD and promote the termination of ventricular tachycardia. The aim of this study is to demonstrate the effect of hypothermia in suppressing cardiac arrhythmias using numerical modeling. For this purpose, we developed a mathematical model that couples Pennes’ bioheat equation and the bidomain model to simulate the effect of heat on the cardiac action potential. The simplification of the proposed heat–bidomain model to the heat–monodomain model is provided. A suitable numerical scheme for this coupling, based on a time adaptive mesh finite element method, is also presented. First, we performed two-dimensional numerical simulations to study the effect of heat on a regular electrophysiological wave, with the comparison of the calculated and experimental values of Q10. Then, we demonstrated the effect of global hypothermia in suppressing single and multiple spiral waves.
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Affiliation(s)
- Youssef Belhamadia
- Department of Mathematics and Statistics, American University of Sharjah, Sharjah, United Arab Emirates
- * E-mail:
| | - Justin Grenier
- Department of Biomedical Engineering, University of Alberta, Edmonton, Canada
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14
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Kaboudian A, Cherry EM, Fenton FH. Large-scale Interactive Numerical Experiments of Chaos, Solitons and Fractals in Real Time via GPU in a Web Browser. CHAOS, SOLITONS, AND FRACTALS 2019; 121:6-29. [PMID: 34764627 PMCID: PMC8580290 DOI: 10.1016/j.chaos.2019.01.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The study of complex systems has emerged as an important field with many discoveries still to be made. Computer simulation and visualization provide important tools for studying complex dynamics including chaos, solitons, and fractals, but available computing power has been a limiting factor. In this work, we describe a novel and highly efficient computing and visualization paradigm using a Web Graphics Library (WebGL 2.0) methodology along with our newly developed library (Abubu.js). Our approach harnesses the power of widely available and highly parallel graphics cards while maintaining ease of use by simplifying programming through hiding implementation details, running in a web browser without the need for compilation, and avoiding the use of plugins. At the same time, it allows for interactivity, such as changing parameter values on the fly, and its computing is so fast that zooming in on a region of a fractal like the Mandelbrot set can incur no delay despite having to recalculate values for the entire plane. We demonstrate our approach using a wide range of complex systems that display dynamics from fractals to standing and propagating waves in 1, 2 and 3 dimensions. We also include some models with instabilities that can lead to chaotic dynamics. For all the examples shown here we provide links to the codes for anyone to use, modify and further develop with other models. Overall, the enhanced visualization and computation capabilities provided by WebGL together with Abubu.js have great potential to facilitate new discoveries about complex systems.
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15
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Malki G, Zlochiver S. Cardiac spiral wave drifting due to spatial temperature gradients - A numerical study. Med Eng Phys 2018; 61:69-80. [PMID: 30201284 DOI: 10.1016/j.medengphy.2018.08.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 06/16/2018] [Accepted: 08/26/2018] [Indexed: 01/07/2023]
Abstract
Cardiac rotors are believed to be a major driver source of persistent atrial fibrillation (AF), and their spatiotemporal characterization is essential for successful ablation procedures. However, electrograms guided ablation have not been proven to have benefit over empirical ablation thus far, and there is a strong need of improving the localization of cardiac arrhythmogenic targets for ablation. A new approach for characterize rotors is proposed that is based on induced spatial temperature gradients (STGs), and investigated by theoretical study using numerical simulations. We hypothesize that such gradients will cause rotor drifting due to induced spatial heterogeneity in excitability, so that rotors could be driven towards the ablating probe. Numerical simulations were conducted in single cell and 2D atrial models using AF remodeled kinetics. STGs were applied either linearly on the entire tissue or as a small local perturbation, and the major ion channel rate constants were adjusted following Arrhenius equation. In the AF-remodeled single cell, recovery time increased exponentially with decreasing temperatures, despite the marginal effect of temperature on the action potential duration. In 2D models, spiral waves drifted with drifting velocity components affected by both temperature gradient direction and the spiral wave rotation direction. Overall, spiral waves drifted towards the colder tissue region associated with global minimum of excitability. A local perturbation with a temperature of T = 28 °C was found optimal for spiral wave attraction for the studied conditions. This work provides a preliminary proof-of-concept for a potential prospective technique for rotor attraction. We envision that the insights from this study will be utilize in the future in the design of a new methodology for AF characterization and termination during ablation procedures.
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Affiliation(s)
- Guy Malki
- Department of Biomedical Engineering, Faculty of Engineering, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel
| | - Sharon Zlochiver
- Department of Biomedical Engineering, Faculty of Engineering, Tel-Aviv University, Ramat-Aviv, Tel-Aviv 69978, Israel.
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16
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Foster J, Mauger AR, Govus A, Hewson D, Taylor L. Acetaminophen (Paracetamol) Induces Hypothermia During Acute Cold Stress. Clin Drug Investig 2018; 37:1055-1065. [PMID: 28766264 DOI: 10.1007/s40261-017-0560-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Acetaminophen is an over-the-counter drug used to treat pain and fever, but it has also been shown to reduce core temperature (T c) in the absence of fever. However, this side effect is not well examined in humans, and it is unknown if the hypothermic response to acetaminophen is exacerbated with cold exposure. OBJECTIVE To address this question, we mapped the thermoregulatory responses to acetaminophen and placebo administration during exposure to acute cold (10 °C) and thermal neutrality (25 °C). METHODS Nine healthy Caucasian males (aged 20-24 years) participated in the experiment. In a double-blind, randomised, repeated measures design, participants were passively exposed to a thermo-neutral or cold environment for 120 min, with administration of 20 mg/kg lean body mass acetaminophen or a placebo 5 min prior to exposure. T c, skin temperature (T sk), heart rate, and thermal sensation were measured every 10 min, and mean arterial pressure was recorded every 30 min. Data were analysed using linear mixed effects models. Differences in thermal sensation were analysed using a cumulative link mixed model. RESULTS Acetaminophen had no effect on T c in a thermo-neutral environment, but significantly reduced T c during cold exposure, compared with a placebo. T c was lower in the acetaminophen compared with the placebo condition at each 10-min interval from 80 to 120 min into the trial (all p < 0.05). On average, T c decreased by 0.42 ± 0.13 °C from baseline after 120 min of cold exposure (range 0.16-0.57 °C), whereas there was no change in the placebo group (0.01 ± 0.1 °C). T sk, heart rate, thermal sensation, and mean arterial pressure were not different between conditions (p > 0.05). CONCLUSION This preliminary trial suggests that acetaminophen-induced hypothermia is exacerbated during cold stress. Larger scale trials seem warranted to determine if acetaminophen administration is associated with an increased risk of accidental hypothermia, particularly in vulnerable populations such as frail elderly individuals.
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Affiliation(s)
- Josh Foster
- Institute for Sport and Physical Activity Research, University of Bedfordshire, Bedford, UK. .,Environmental Ergonomics Research Centre, Loughborough University, Loughborough, UK.
| | - Alexis R Mauger
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent, Chatham Maritime, UK
| | - Andrew Govus
- Department of Health Sciences, Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden
| | - David Hewson
- Institute for Health Research, University of Bedfordshire, Luton, UK
| | - Lee Taylor
- ASPETAR, Qatar Orthopaedic and Sports Medicine Hospital, Athlete Health and Performance Research Centre, Aspire Zone, Doha, Qatar.,School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
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17
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Muszkiewicz A, Liu X, Bueno-Orovio A, Lawson BAJ, Burrage K, Casadei B, Rodriguez B. From ionic to cellular variability in human atrial myocytes: an integrative computational and experimental study. Am J Physiol Heart Circ Physiol 2017; 314:H895-H916. [PMID: 29351467 PMCID: PMC6008144 DOI: 10.1152/ajpheart.00477.2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Variability refers to differences in physiological function between individuals, which may translate into different disease susceptibility and treatment efficacy. Experiments in human cardiomyocytes face wide variability and restricted tissue access; under these conditions, computational models are a useful complementary tool. We conducted a computational and experimental investigation in cardiomyocytes isolated from samples of the right atrial appendage of patients undergoing cardiac surgery to evaluate the impact of variability in action potentials (APs) and subcellular ionic densities on Ca2+ transient dynamics. Results showed that 1) variability in APs and ionic densities is large, even within an apparently homogenous patient cohort, and translates into ±100% variation in ionic conductances; 2) experimentally calibrated populations of models with wide variations in ionic densities yield APs overlapping with those obtained experimentally, even if AP characteristics of the original generic model differed significantly from experimental APs; 3) model calibration with AP recordings restricts the variability in ionic densities affecting upstroke and resting potential, but redundancy in repolarization currents admits substantial variability in ionic densities; and 4) model populations constrained with experimental APs and ionic densities exhibit three Ca2+ transient phenotypes, differing in intracellular Ca2+ handling and Na+/Ca2+ membrane extrusion. These findings advance our understanding of the impact of variability in human atrial electrophysiology. NEW & NOTEWORTHY Variability in human atrial electrophysiology is investigated by integrating for the first time cellular-level and ion channel recordings in computational electrophysiological models. Ion channel calibration restricts current densities but not cellular phenotypic variability. Reduced Na+/Ca2+ exchanger is identified as a primary mechanism underlying diastolic Ca2+ fluctuations in human atrial myocytes.
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Affiliation(s)
- Anna Muszkiewicz
- Department of Computer Science, University of Oxford , Oxford , United Kingdom
| | - Xing Liu
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital , Oxford , United Kingdom
| | | | - Brodie A J Lawson
- ARC Centre of Excellence for Mathematical and Statistical Frontiers, School of Mathematical Sciences, Queensland University of Technology , Brisbane, Queensland , Australia.,School of Mathematics, Queensland University of Technology , Brisbane, Queensland , Australia
| | - Kevin Burrage
- Department of Computer Science, University of Oxford , Oxford , United Kingdom.,ARC Centre of Excellence for Mathematical and Statistical Frontiers, School of Mathematical Sciences, Queensland University of Technology , Brisbane, Queensland , Australia.,School of Mathematics, Queensland University of Technology , Brisbane, Queensland , Australia
| | - Barbara Casadei
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital , Oxford , United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford , Oxford , United Kingdom
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18
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Uzelac I, Ji YC, Hornung D, Schröder-Scheteling J, Luther S, Gray RA, Cherry EM, Fenton FH. Simultaneous Quantification of Spatially Discordant Alternans in Voltage and Intracellular Calcium in Langendorff-Perfused Rabbit Hearts and Inconsistencies with Models of Cardiac Action Potentials and Ca Transients. Front Physiol 2017; 8:819. [PMID: 29104543 PMCID: PMC5655020 DOI: 10.3389/fphys.2017.00819] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 10/05/2017] [Indexed: 02/03/2023] Open
Abstract
Rationale: Discordant alternans, a phenomenon in which the action potential duration (APDs) and/or intracellular calcium transient durations (CaDs) in different spatial regions of cardiac tissue are out of phase, present a dynamical instability for complex spatial dispersion that can be associated with long-QT syndrome (LQTS) and the initiation of reentrant arrhythmias. Because the use of numerical simulations to investigate arrhythmic effects, such as acquired LQTS by drugs is beginning to be studied by the FDA, it is crucial to validate mathematical models that may be used during this process. Objective: In this study, we characterized with high spatio-temporal resolution the development of discordant alternans patterns in transmembrane voltage (Vm) and intracellular calcium concentration ([Cai]+2) as a function of pacing period in rabbit hearts. Then we compared the dynamics to that of the latest state-of-the-art model for ventricular action potentials and calcium transients to better understand the underlying mechanisms of discordant alternans and compared the experimental data to the mathematical models representing Vm and [Cai]+2 dynamics. Methods and Results: We performed simultaneous dual optical mapping imaging of Vm and [Cai]+2 in Langendorff-perfused rabbit hearts with higher spatial resolutions compared with previous studies. The rabbit hearts developed discordant alternans through decreased pacing period protocols and we quantified the presence of multiple nodal points along the direction of wave propagation, both in APD and CaD, and compared these findings with results from theoretical models. In experiments, the nodal lines of CaD alternans have a steeper slope than those of APD alternans, but not as steep as predicted by numerical simulations in rabbit models. We further quantified several additional discrepancies between models and experiments. Conclusions: Alternans in CaD have nodal lines that are about an order of magnitude steeper compared to those of APD alternans. Current action potential models lack the necessary coupling between voltage and calcium compared to experiments and fail to reproduce some key dynamics such as, voltage amplitude alternans, smooth development of calcium alternans in time, conduction velocity and the steepness of the nodal lines of APD and CaD.
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Affiliation(s)
- Ilija Uzelac
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States
| | - Yanyan C. Ji
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States
| | - Daniel Hornung
- Max Planck Institute for Dynamics and Self-Organization, Gottingen, Germany
| | | | - Stefan Luther
- Max Planck Institute for Dynamics and Self-Organization, Gottingen, Germany
| | - Richard A. Gray
- Center for Device and Radiological Health, Food and Drug Administration, Silver Spring, MD, United States
| | - Elizabeth M. Cherry
- School of Mathematical Sciences, Rochester Institute of Technology, Rochester, NY, United States
| | - Flavio H. Fenton
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States
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19
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Collet A, Bragard J, Dauby PC. Temperature, geometry, and bifurcations in the numerical modeling of the cardiac mechano-electric feedback. CHAOS (WOODBURY, N.Y.) 2017; 27:093924. [PMID: 28964162 DOI: 10.1063/1.5000710] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This article characterizes the cardiac autonomous electrical activity induced by the mechanical deformations in the cardiac tissue through the mechano-electric feedback. A simplified and qualitative model is used to describe the system and we also account for temperature effects. The analysis emphasizes a very rich dynamics for the system, with periodic solutions, alternans, chaotic behaviors, etc. The possibility of self-sustained oscillations is analyzed in detail, particularly in terms of the values of important parameters such as the dimension of the system and the importance of the stretch-activated currents. It is also shown that high temperatures notably increase the parameter ranges for which self-sustained oscillations are observed and that several attractors can appear, depending on the location of the initial excitation of the system. Finally, the instability mechanisms by which the periodic solutions are destabilized have been studied by a Floquet analysis, which has revealed period-doubling phenomena and transient intermittencies.
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Affiliation(s)
- A Collet
- GIGA In silico medicine, Liège University, B-4000 Liège, Belgium
| | - J Bragard
- Physics and Applied Math. Dept., Universidad de Navarra, Pamplona E-31080, Spain
| | - P C Dauby
- GIGA In silico medicine, Liège University, B-4000 Liège, Belgium
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20
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Gizzi A, Loppini A, Ruiz-Baier R, Ippolito A, Camassa A, La Camera A, Emmi E, Di Perna L, Garofalo V, Cherubini C, Filippi S. Nonlinear diffusion and thermo-electric coupling in a two-variable model of cardiac action potential. CHAOS (WOODBURY, N.Y.) 2017; 27:093919. [PMID: 28964112 DOI: 10.1063/1.4999610] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This work reports the results of the theoretical investigation of nonlinear dynamics and spiral wave breakup in a generalized two-variable model of cardiac action potential accounting for thermo-electric coupling and diffusion nonlinearities. As customary in excitable media, the common Q10 and Moore factors are used to describe thermo-electric feedback in a 10° range. Motivated by the porous nature of the cardiac tissue, in this study we also propose a nonlinear Fickian flux formulated by Taylor expanding the voltage dependent diffusion coefficient up to quadratic terms. A fine tuning of the diffusive parameters is performed a priori to match the conduction velocity of the equivalent cable model. The resulting combined effects are then studied by numerically simulating different stimulation protocols on a one-dimensional cable. Model features are compared in terms of action potential morphology, restitution curves, frequency spectra, and spatio-temporal phase differences. Two-dimensional long-run simulations are finally performed to characterize spiral breakup during sustained fibrillation at different thermal states. Temperature and nonlinear diffusion effects are found to impact the repolarization phase of the action potential wave with non-monotone patterns and to increase the propensity of arrhythmogenesis.
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Affiliation(s)
- A Gizzi
- Department of Engineering, University Campus Bio-Medico of Rome, Unit of Nonlinear Physics and Mathematical Modeling, Via A. del Portillo 21, 00128 Rome, Italy
| | - A Loppini
- Department of Engineering, University Campus Bio-Medico of Rome, Unit of Nonlinear Physics and Mathematical Modeling, Via A. del Portillo 21, 00128 Rome, Italy
| | - R Ruiz-Baier
- Mathematical Institute, University of Oxford, Woodstock Road, OX2 6GG Oxford, United Kingdom
| | - A Ippolito
- Department of Engineering, University Campus Bio-Medico of Rome, Unit of Nonlinear Physics and Mathematical Modeling, Via A. del Portillo 21, 00128 Rome, Italy
| | - A Camassa
- Department of Engineering, University Campus Bio-Medico of Rome, Unit of Nonlinear Physics and Mathematical Modeling, Via A. del Portillo 21, 00128 Rome, Italy
| | - A La Camera
- Department of Engineering, University Campus Bio-Medico of Rome, Unit of Nonlinear Physics and Mathematical Modeling, Via A. del Portillo 21, 00128 Rome, Italy
| | - E Emmi
- Department of Engineering, University Campus Bio-Medico of Rome, Unit of Nonlinear Physics and Mathematical Modeling, Via A. del Portillo 21, 00128 Rome, Italy
| | - L Di Perna
- Department of Engineering, University Campus Bio-Medico of Rome, Unit of Nonlinear Physics and Mathematical Modeling, Via A. del Portillo 21, 00128 Rome, Italy
| | - V Garofalo
- Department of Engineering, University Campus Bio-Medico of Rome, Unit of Nonlinear Physics and Mathematical Modeling, Via A. del Portillo 21, 00128 Rome, Italy
| | - C Cherubini
- Department of Engineering, University Campus Bio-Medico of Rome, Unit of Nonlinear Physics and Mathematical Modeling, Via A. del Portillo 21, 00128 Rome, Italy
| | - S Filippi
- Department of Engineering, University Campus Bio-Medico of Rome, Unit of Nonlinear Physics and Mathematical Modeling, Via A. del Portillo 21, 00128 Rome, Italy
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21
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Kienast R, Handler M, Stöger M, Baumgarten D, Hanser F, Baumgartner C. Modeling hypothermia induced effects for the heterogeneous ventricular tissue from cellular level to the impact on the ECG. PLoS One 2017; 12:e0182979. [PMID: 28813535 PMCID: PMC5558962 DOI: 10.1371/journal.pone.0182979] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 07/27/2017] [Indexed: 11/18/2022] Open
Abstract
Hypothermia has a profound impact on the electrophysiological mechanisms of the heart. Experimental investigations provide a better understanding of electrophysiological alterations associated with cooling. However, there is a lack of computer models suitable for simulating the effects of hypothermia in cardio-electrophysiology. In this work, we propose a model that describes the cooling-induced electrophysiological alterations in ventricular tissue in a temperature range from 27°C to 37°C. To model the electrophysiological conditions in a 3D left ventricular tissue block it was essential to consider the following anatomical and physiological parameters in the model: the different cell types (endocardial, M, epicardial), the heterogeneous conductivities in longitudinal, transversal and transmural direction depending on the prevailing temperature, the distinct fiber orientations and the transmural repolarization sequences. Cooling-induced alterations on the morphology of the action potential (AP) of single myocardial cells thereby are described by an extension of the selected Bueno-Orovio model for human ventricular tissue using Q10 temperature coefficients. To evaluate alterations on tissue level, the corresponding pseudo electrocardiogram (pECG) was calculated. Simulations show that cooling-induced AP and pECG-related parameters, i.e. AP duration, morphology of the notch of epicardial AP, maximum AP upstroke velocity, AP rise time, QT interval, QRS duration and J wave formation are in good accordance with literature and our experimental data. The proposed model enables us to further enhance our knowledge of cooling-induced electrophysiological alterations from cellular to tissue level in the heart and may help to better understand electrophysiological mechanisms, e.g. in arrhythmias, during hypothermia.
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Affiliation(s)
- Roland Kienast
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
- * E-mail:
| | - Michael Handler
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
| | - Markus Stöger
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
| | - Daniel Baumgarten
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
- Institute of Biomedical Engineering and Informatics, Technische Universität Ilmenau, Ilmenau, Germany
| | - Friedrich Hanser
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
| | - Christian Baumgartner
- Institute of Electrical and Biomedical Engineering, UMIT–University for Health Sciences, Medical Informatics and Technology, Hall, Tyrol, Austria
- Institute of Health Care Engineering with European Testing Center of Medical Devices, Graz University of Technology, Graz, Austria
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22
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Gizzi A, Loppini A, Cherry EM, Cherubini C, Fenton FH, Filippi S. Multi-band decomposition analysis: application to cardiac alternans as a function of temperature. Physiol Meas 2017; 38:833-847. [DOI: 10.1088/1361-6579/aa64af] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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23
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Chavez LO, Leon M, Einav S, Varon J. Editor's Choice- Inside the cold heart: A review of therapeutic hypothermia cardioprotection. EUROPEAN HEART JOURNAL-ACUTE CARDIOVASCULAR CARE 2016; 6:130-141. [PMID: 26714973 DOI: 10.1177/2048872615624242] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Targeted temperature management has been originally used to reduce neurological injury and improve outcome in patients after out-of-hospital cardiac arrest. Myocardial infarction remains a major cause of death in the world and several investigators are studying the effect of mild therapeutic hypothermia during an acute cardiac ischemic injury. A search on MEDLINE, Scopus and EMBASE databases was conducted to obtain data regarding the cardioprotective properties of therapeutic hypothermia. Preclinical studies have shown that therapeutic hypothermia provides a cardioprotective effect in animals. The proposed pathways for the cardioprotective effects of therapeutic hypothermia include stabilization of mitochondrial permeability, production of nitric oxide, equilibration of reactive oxygen species, and calcium channels homeostasis. Clinical trials in humans have yielded controversial results. Current trials are therefore seeking to combine therapeutic hypothermia with other treatment modalities in order to improve the outcomes of patients with acute ischemic injury. This article provides a review of the hypothermia effects on the cardiovascular system, from the basic science of physiological changes in the human body and molecular mechanisms of cardioprotection to the bench of clinical trials with therapeutic hypothermia in patients with acute ischemic injury.
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Affiliation(s)
- Luis O Chavez
- 1 University General Hospital, Houston, USA.,2 Universidad Autonoma de Baja California, Facultad de Medicina y Psicología, Tijuana, Mexico
| | - Monica Leon
- 1 University General Hospital, Houston, USA.,3 Universidad Popular Autonoma del Estado de Puebla, Facultad de Medicina Puebla, Mexico
| | - Sharon Einav
- 4 Shaare Zedek Medical Center and Hadassah-Hebrew University Faculty of Medicine, Jerusalem, Israel
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24
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Arteyeva NV, Azarov JE. The Role of Transmural Repolarization Gradient in the Inversion of Cardiac Electric Field: Model Study of ECG in Hypothermia. Ann Noninvasive Electrocardiol 2016; 22. [PMID: 27018036 DOI: 10.1111/anec.12360] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 01/24/2016] [Accepted: 02/11/2016] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND The changes in ventricular repolarization gradients lead to significant alterations of the electrocardiographic body surface T waves up to the T wave inversion. However, the contribution of a specific gradient remains to be elucidated. The objective of the present investigation was to study the role of the transmural repolarization gradient in the inversion of the body surface T wave with a mathematical model of the hypothermia-induced changes of ventricular repolarization. METHODS By means of mathematical simulation, we set the hypothermic action potential duration (APD) distribution on the rabbit ventricular epicardium as it was previously experimentally documented. Then the parameters of the body surface potential distribution were tested with the introduction of different scenarios of the endocardial and epicardial APD behavior in hypothermia resulting in the unchanged, reversed or enlarged transmural repolarization gradient. RESULTS The reversal of epicardial repolarization gradients (apicobasal, anterior-posterior and interventricular) caused the inversion of the T waves regardless of the direction of the transmural repolarization gradient. However, the most realistic body surface potentials were obtained when the endocardial APDs were not changed under hypothermia while the epicardial APDs prolonged. This produced the reversed and increased transmural repolarization gradient in absolute magnitude. The body surface potentials simulated under the unchanged transmural gradient were reduced in comparison to those simulated under the reversed transmural gradient. CONCLUSIONS The simulations demonstrated that the transmural repolarization gradient did not play a crucial role in the cardiac electric field inversion under hypothermia, but its magnitude and direction contribute to the T wave amplitude.
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Affiliation(s)
- Natalia V Arteyeva
- Laboratory of Cardiac Physiology, Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia
| | - Jan E Azarov
- Laboratory of Cardiac Physiology, Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia.,Department of Physiology, Medical Institute of Syktyvkar State University, Syktyvkar, Russia.,Department of Cardiology, Lund University, Lund, Sweden
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Severi S, Rodriguez B, Zaza A. Computational cardiac electrophysiology is ready for prime time. Europace 2014; 16:382-3. [DOI: 10.1093/europace/euu044] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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