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Hoang JD, van Weperen VYH, Kang KW, Jani NR, Swid MA, Chan CA, Lokhandwala ZA, Lux RL, Vaseghi M. Antiarrhythmic Mechanisms of Epidural Blockade After Myocardial Infarction. Circ Res 2024; 135:e57-e75. [PMID: 38939925 PMCID: PMC11257785 DOI: 10.1161/circresaha.123.324058] [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: 11/29/2023] [Accepted: 06/18/2024] [Indexed: 06/29/2024]
Abstract
BACKGROUND Thoracic epidural anesthesia (TEA) has been shown to reduce the burden of ventricular tachycardia in small case series of patients with refractory ventricular tachyarrhythmias and cardiomyopathy. However, its electrophysiological and autonomic effects in diseased hearts remain unclear, and its use after myocardial infarction is limited by concerns for potential right ventricular dysfunction. METHODS Myocardial infarction was created in Yorkshire pigs (N=22) by left anterior descending coronary artery occlusion. Approximately, six weeks after myocardial infarction, an epidural catheter was placed at the C7-T1 vertebral level for injection of 2% lidocaine. Right and left ventricular hemodynamics were recorded using Millar pressure-conductance catheters, and ventricular activation recovery intervals (ARIs), a surrogate of action potential durations, by a 56-electrode sock and 64-electrode basket catheter. Hemodynamics and ARIs, baroreflex sensitivity and intrinsic cardiac neural activity, and ventricular effective refractory periods and slope of restitution (Smax) were assessed before and after TEA. Ventricular tachyarrhythmia inducibility was assessed by programmed electrical stimulation. RESULTS TEA reduced inducibility of ventricular tachyarrhythmias by 70%. TEA did not affect right ventricular-systolic pressure or contractility, although left ventricular-systolic pressure and contractility decreased modestly. Global and regional ventricular ARIs increased, including in scar and border zone regions post-TEA. TEA reduced ARI dispersion specifically in border zone regions. Ventricular effective refractory periods prolonged significantly at critical sites of arrhythmogenesis, and Smax was reduced. Interestingly, TEA significantly improved cardiac vagal function, as measured by both baroreflex sensitivity and intrinsic cardiac neural activity. CONCLUSIONS TEA does not compromise right ventricular function in infarcted hearts. Its antiarrhythmic mechanisms are mediated by increases in ventricular effective refractory period and ARIs, decreases in Smax, and reductions in border zone electrophysiological heterogeneities. TEA improves parasympathetic function, which may independently underlie some of its observed antiarrhythmic mechanisms. This study provides novel insights into the antiarrhythmic mechanisms of TEA while highlighting its applicability to the clinical setting.
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Affiliation(s)
- Jonathan D Hoang
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, Los Angeles, CA
- Neurocardiology Research Center of Excellence, UCLA, Los Angeles, CA
- UCLA Molecular Cellular and Integrative Physiology Interdepartmental Program, Los Angeles, CA
| | - Valerie YH van Weperen
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, Los Angeles, CA
- Neurocardiology Research Center of Excellence, UCLA, Los Angeles, CA
| | - Ki-Woon Kang
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, Los Angeles, CA
- Neurocardiology Research Center of Excellence, UCLA, Los Angeles, CA
| | - Neil R Jani
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, Los Angeles, CA
- Neurocardiology Research Center of Excellence, UCLA, Los Angeles, CA
| | - Mohammed A Swid
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, Los Angeles, CA
- Neurocardiology Research Center of Excellence, UCLA, Los Angeles, CA
| | - Christopher A Chan
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, Los Angeles, CA
- Neurocardiology Research Center of Excellence, UCLA, Los Angeles, CA
| | - Zulfiqar Ali Lokhandwala
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, Los Angeles, CA
- Neurocardiology Research Center of Excellence, UCLA, Los Angeles, CA
| | - Robert L Lux
- Department of Medicine, University of Utah, Salt Lake City, Utah
| | - Marmar Vaseghi
- University of California, Los Angeles (UCLA) Cardiac Arrhythmia Center, Los Angeles, CA
- Neurocardiology Research Center of Excellence, UCLA, Los Angeles, CA
- UCLA Molecular Cellular and Integrative Physiology Interdepartmental Program, Los Angeles, CA
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Hoang JD, van Weperen VY, Kang KW, Jani NR, Swid MA, Chan CA, Lokhandwala ZA, Lux RL, Vaseghi M. Thoracic epidural blockade after myocardial infarction benefits from anti-arrhythmic pathways mediated in part by parasympathetic modulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.14.585127. [PMID: 38559001 PMCID: PMC10980055 DOI: 10.1101/2024.03.14.585127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Background Thoracic epidural anesthesia (TEA) has been shown to reduce the burden of ventricular tachyarrhythmias (VT) in small case-series of patients with refractory VT and cardiomyopathy. However, its electrophysiological and autonomic effects in diseased hearts remain unclear and its use after myocardial infarction (MI) is limited by concerns for potential RV dysfunction. Methods MI was created in Yorkshire pigs ( N =22) by LAD occlusion. Six weeks post-MI, an epidural catheter was placed at the C7-T1 vertebral level for injection of 2% lidocaine. RV and LV hemodynamics were recorded using Millar pressure-conductance catheters, and ventricular activation-recovery intervals (ARIs), a surrogate of action potential durations, by a 56-electrode sock and 64-electrode basket catheter. Hemodynamics and ARIs, baroreflex sensitivity (BRS) and intrinsic cardiac neural activity, and ventricular effective refractory periods (ERP) and slope of restitution (S max ) were assessed before and after TEA. VT/VF inducibility was assessed by programmed electrical stimulation. Results TEA reduced inducibility of VT/VF by 70%. TEA did not affect RV-systolic pressure or contractility, although LV-systolic pressure and contractility decreased modestly. Global and regional ventricular ARIs increased, including in scar and border zone regions post-TEA. TEA reduced ARI dispersion specifically in border zone regions. Ventricular ERPs prolonged significantly at critical sites of arrhythmogenesis, and S max was reduced. Interestingly, TEA significantly improved cardiac vagal function, as measured by both BRS and intrinsic cardiac neural activity. Conclusion TEA does not compromise RV function in infarcted hearts. Its anti-arrhythmic mechanisms are mediated by increases in ventricular ERP and ARIs, decreases in S max , and reductions in border zone heterogeneity. TEA improves parasympathetic function, which may independently underlie some of its observed anti-arrhythmic mechanisms. This study provides novel insights into the anti-arrhythmic mechanisms of TEA, while highlighting its applicability to the clinical setting. Abstract Illustration Myocardial infarction is known to cause cardiac autonomic dysfunction characterized by sympathoexcitation coupled with reduced vagal tone. This pathological remodeling collectively predisposes to ventricular arrhythmia. Thoracic epidural anesthesia not only blocks central efferent sympathetic outflow, but by also blocking ascending projections of sympathetic afferents, relieving central inhibition of vagal function. These complementary autonomic effects of thoracic epidural anesthesia may thus restore autonomic balance, thereby improving ventricular electrical stability and suppressing arrhythmogenesis. DRG=dorsal root ganglion, SG=stellate ganglion.
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Jungtanasomboon P, Nussaro S, Winwan H, Suebthawinkul P, Boonpala P, Dong VNK, Saengklub N, Kumphune S, Panyasing Y, Kijtawornrat A. Vericiguat preserved cardiac function and mitochondrial quality in a rat model of mitral regurgitation. Life Sci 2023; 328:121929. [PMID: 37437403 DOI: 10.1016/j.lfs.2023.121929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 06/30/2023] [Accepted: 07/08/2023] [Indexed: 07/14/2023]
Abstract
AIMS New drugs for heart failure (HF) that target restoring the impaired NO-sGC-cGMP pathway are being developed. We aimed to investigate the effects of vericiguat, an sGC stimulator, on cardiac function, blood pressure (BP), cardiac mitochondrial quality, and cardiac fibrosis in rat models of chronic mitral regurgitation (MR). MATERIALS AND METHODS We surgically induced MR in 20 Sprague-Dawley rats and performed sham procedures on 10 rats (negative control). Four weeks post-surgery, we randomly divided the MR rats into two groups: MR group and MR + vericiguat group. Vericiguat (0.5 mg/kg, PO) was administered once a day via oral gavage for 8 weeks, while the sham and MR groups received equivalent volumes of drinking water instead. We took echocardiography and BP measurements at baseline (4 weeks post-surgery) and at the end of study (8 weeks after treatment). At the study end, all rats were euthanized and their hearts were immediately collected, weighed, and used for histopathology and mitochondrial quality assessments. KEY FINDINGS Vericiguat preserved cardiac functions and structural remodeling in the MR rats, with significantly lower systolic BPs than baseline values (P < 0.05). Additionally, vericiguat significantly improved the mitochondrial quality by attenuating ROS production, depolarization and swelling when comparing the values in both groups (P < 0.05). The fibrosis area also significantly decreased in the MR + vericiguat group (P < 0.05). SIGNIFICANCE Vericiguat demonstrated cardioprotective effects on cardiac function, BP, and fibrosis by preserving mitochondrial quality in rats with HF due to MR.
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Affiliation(s)
- Peeraya Jungtanasomboon
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Surunchana Nussaro
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Hathaichanok Winwan
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Patcharapol Suebthawinkul
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Pakit Boonpala
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Van Nhut Khanh Dong
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Nakkawee Saengklub
- Department of Physiology, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand
| | - Sarawut Kumphune
- Biomedical Engineering Institute (BMEI), Chiang Mai University, Chiang Mai, Thailand
| | - Yaowalak Panyasing
- Department of Pathology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Anusak Kijtawornrat
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand; Chulalongkorn University Laboratory Animal Center (CULAC), Bangkok, Thailand.
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Han J, Taberner AJ, Loiselle DS, Tran K. Cardiac efficiency and Starling's Law of the Heart. J Physiol 2022; 600:4265-4285. [PMID: 35998082 PMCID: PMC9826111 DOI: 10.1113/jp283632] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 08/18/2022] [Indexed: 01/11/2023] Open
Abstract
The formulation by Starling of The Law of the Heart states that 'the [mechanical] energy of contraction, however measured, is a function of the length of the muscle fibre'. Starling later also stated that 'the oxygen consumption of the isolated heart … is determined by its diastolic volume, and therefore by the initial length of its muscular fibres'. This phrasing has motivated us to extend Starling's Law of the Heart to include consideration of the efficiency of contraction. In this study, we assessed both mechanical efficiency and crossbridge efficiency by studying the heat output of isolated rat ventricular trabeculae performing force-length work-loops over ranges of preload and afterload. The combination of preload and afterload allowed us, using our modelling frameworks for the end-systolic zone and the heat-force zone, to simulate cases by recreating physiologically feasible loading conditions. We found that across all cases examined, both work output and change of enthalpy increased with initial muscle length; hence it can only be that the former increases more than the latter to yield increased mechanical efficiency. In contrast, crossbridge efficiency increased with initial muscle length in cases where the extent of muscle shortening varied greatly with preload. We conclude that the efficiency of cardiac contraction increases with increasing initial muscle length and preload. An implication of our conclusion is that the length-dependent activation mechanism underlying the cellular basis of Starling's Law of the Heart is an energetically favourable process that increases the efficiency of cardiac contraction. KEY POINTS: Ernest Starling in 1914 formulated the Law of the Heart to describe the mechanical property of cardiac muscle whereby force of contraction increases with muscle length. He subsequently, in 1927, showed that the oxygen consumption of the heart is also a function of the length of the muscle fibre, but left the field unclear as to whether cardiac efficiency follows the same dependence. A century later, the field has gained an improved understanding of the factors, including the distinct effects of preload and afterload, that affect cardiac efficiency. This understanding presents an opportunity for us to investigate the elusive length-dependence of cardiac efficiency. We found that, by simulating physiologically feasible loading conditions using a mechano-energetics framework, cardiac efficiency increased with initial muscle length. A broader physiological importance of our findings is that the underlying cellular basis of Starling's Law of the Heart is an energetically favourable process that yields increased efficiency.
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Affiliation(s)
- June‐Chiew Han
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand
| | - Andrew J. Taberner
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand,Department of Engineering ScienceUniversity of AucklandAucklandNew Zealand
| | - Denis S. Loiselle
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand,Department of PhysiologyUniversity of AucklandAucklandNew Zealand
| | - Kenneth Tran
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand
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Pichayapaiboon P, Tantisuwat L, Boonpala P, Saengklub N, Boonyarattanasoonthorn T, Khemawoot P, Kijtawornrat A. Pharmacodynamics and Pharmacokinetics of Injectable Pimobendan and Its Metabolite, O-Desmethyl-Pimobendan, in Healthy Dogs. Front Vet Sci 2021; 8:656902. [PMID: 34490386 PMCID: PMC8417876 DOI: 10.3389/fvets.2021.656902] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 07/30/2021] [Indexed: 11/13/2022] Open
Abstract
Objectives: This study was designed to thoroughly evaluate the effects of bolus pimobendan at a dose of 0.15 mg/kg on cardiac functions, hemodynamics, and electrocardiographic parameters together with the pharmacokinetic profile of pimobendan and its active metabolite, o-desmethyl-pimobendan (ODMP), in anesthetized dogs. Methods: Nine beagle dogs were anesthetized and instrumented to obtain left ventricular pressures, aortic pressures, cardiac outputs, right atrial pressures, pulmonary arterial pressures, pulmonary capillary wedge pressures, electrocardiograms. After baseline data were collected, dogs were given a single bolus of pimobendan, and the pharmacodynamic parameters were obtained at 10, 20, 30, 60, and 120 min. Meanwhile, the venous blood was collected at baseline and 2, 5, 10, 20, 30, 60, 120, 180, 360, and 1,440 min after administration for the determination of pharmacokinetic parameters. Results: Compared with baseline measurements, the left ventricular inotropic indices significantly increased in response to intravenous pimobendan, as inferred from the maximum rate of rise in the left ventricular pressure and the contractility index. Conversely, the left ventricular lusitropic parameters significantly decreased, as inferred from the maximum rate of fall in the left ventricular pressure and the left ventricular relaxation time constant. Significant increases were also noted in cardiac output and systolic blood pressure. Decreases were observed in the systemic vascular resistance, pulmonary vascular resistance, left ventricular end-diastolic pressure, pulmonary capillary wedge pressure, right atrial pressure, and pulmonary arterial pressure. The heart rate increased, but the PQ interval decreased. There was no arrhythmia during the observed period (2 h). The mean maximum plasma concentration (in μg/L) for ODMP was 30.0 ± 8.8. Pimobendan exerted large volume of distribution ~9 L/kg. Conclusions: Intravenous pimobendan at the recommended dose for dogs increased cardiac contraction and cardiac output, accelerated cardiac relaxation but decreased both vascular resistances. These mechanisms support the use of injectable pimobendan in acute heart failure.
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Affiliation(s)
- Poonavit Pichayapaiboon
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Lalida Tantisuwat
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Pakit Boonpala
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
| | - Nakkawee Saengklub
- Department of Physiology, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand
| | | | - Phisit Khemawoot
- Faculty of Medicine Ramathibodi Hospital, Chakri Naruebodindra Medical Institute, Mahidol University, Bangkok, Thailand
| | - Anusak Kijtawornrat
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand
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Carll AP, Salatini R, Pirela SV, Wang Y, Xie Z, Lorkiewicz P, Naeem N, Qian Y, Castranova V, Godleski JJ, Demokritou P. Inhalation of printer-emitted particles impairs cardiac conduction, hemodynamics, and autonomic regulation and induces arrhythmia and electrical remodeling in rats. Part Fibre Toxicol 2020; 17:7. [PMID: 31996220 PMCID: PMC6990551 DOI: 10.1186/s12989-019-0335-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 12/29/2019] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Using engineered nanomaterial-based toners, laser printers generate aerosols with alarming levels of nanoparticles that bear high bioactivity and potential health risks. Yet, the cardiac impacts of printer-emitted particles (PEPs) are unknown. Inhalation of particulate matter (PM) promotes cardiovascular morbidity and mortality, and ultra-fine particulates (< 0.1 μm aerodynamic diameter) may bear toxicity unique from larger particles. Toxicological studies suggest that PM impairs left ventricular (LV) performance; however, such investigations have heretofore required animal restraint, anesthesia, or ex vivo preparations that can confound physiologic endpoints and/or prohibit LV mechanical assessments during exposure. To assess the acute and chronic effects of PEPs on cardiac physiology, male Sprague Dawley rats were exposed to PEPs (21 days, 5 h/day) while monitoring LV pressure (LVP) and electrocardiogram (ECG) via conscious telemetry, analyzing LVP and heart rate variability (HRV) in four-day increments from exposure days 1 to 21, as well as ECG and baroreflex sensitivity. At 2, 35, and 70 days after PEPs exposure ceased, rats received stress tests. RESULTS On day 21 of exposure, PEPs significantly (P < 0.05 vs. Air) increased LV end systolic pressure (LVESP, + 18 mmHg) and rate-pressure-product (+ 19%), and decreased HRV indicating sympathetic dominance (root means squared of successive differences [RMSSD], - 21%). Overall, PEPs decreased LV ejection time (- 9%), relaxation time (- 3%), tau (- 5%), RMSSD (- 21%), and P-wave duration (- 9%). PEPs increased QTc interval (+ 5%) and low:high frequency HRV (+ 24%; all P < 0.05 vs. Air), while tending to decrease baroreflex sensitivity and contractility index (- 15% and - 3%, P < 0.10 vs. Air). Relative to Air, at both 2 and 35 days after PEPs, ventricular arrhythmias increased, and at 70 days post-exposure LVESP increased. PEPs impaired ventricular repolarization at 2 and 35 days post-exposure, but only during stress tests. At 72 days post-exposure, PEPs increased urinary dopamine 5-fold and protein expression of ventricular repolarizing channels, Kv1.5, Kv4.2, and Kv7.1, by 50%. CONCLUSIONS Our findings suggest exposure to PEPs increases cardiovascular risk by augmenting sympathetic influence, impairing ventricular performance and repolarization, and inducing hypertension and arrhythmia. PEPs may present significant health risks through adverse cardiovascular effects, especially in occupational settings, among susceptible individuals, and with long-term exposure.
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Affiliation(s)
- Alex P. Carll
- Department of Physiology, School of Medicine, University of Louisville, Louisville, KY USA
- Christina Lee Brown Envirome Institute, University of Louisville, Louisville, KY USA
- Center for Nanotechnology and Nanotoxicology. Department of Environmental Health, T.H. Chan School of Public Health, Harvard University, 665 Huntington Avenue, Room 1310, Boston, MA 02115 USA
| | - Renata Salatini
- Department of Physiology, School of Medicine, University of Louisville, Louisville, KY USA
- Department of Surgery, University of Sao Paulo Medical School, Sao Paulo, Brazil
| | - Sandra V. Pirela
- Center for Nanotechnology and Nanotoxicology. Department of Environmental Health, T.H. Chan School of Public Health, Harvard University, 665 Huntington Avenue, Room 1310, Boston, MA 02115 USA
| | - Yun Wang
- Center for Nanotechnology and Nanotoxicology. Department of Environmental Health, T.H. Chan School of Public Health, Harvard University, 665 Huntington Avenue, Room 1310, Boston, MA 02115 USA
- Department of Occupational and Environmental Health Sciences,School of Public Health, Peking University, Beijing, People’s Republic of China
| | - Zhengzhi Xie
- Christina Lee Brown Envirome Institute, University of Louisville, Louisville, KY USA
| | - Pawel Lorkiewicz
- Christina Lee Brown Envirome Institute, University of Louisville, Louisville, KY USA
| | - Nazratan Naeem
- Christina Lee Brown Envirome Institute, University of Louisville, Louisville, KY USA
| | - Yong Qian
- Pathology and Physiology Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, WV USA
| | - Vincent Castranova
- Department of Pharmaceutical Sciences/Mary Babb Randolph Cancer Center, West Virginia University, Morgantown, WV USA
| | - John J. Godleski
- Center for Nanotechnology and Nanotoxicology. Department of Environmental Health, T.H. Chan School of Public Health, Harvard University, 665 Huntington Avenue, Room 1310, Boston, MA 02115 USA
| | - Philip Demokritou
- Center for Nanotechnology and Nanotoxicology. Department of Environmental Health, T.H. Chan School of Public Health, Harvard University, 665 Huntington Avenue, Room 1310, Boston, MA 02115 USA
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Promising approach for the preclinical assessment of cardiac risks using left ventricular pressure-volume loop analyses in anesthetized monkeys. J Pharmacol Toxicol Methods 2017; 84:1-10. [DOI: 10.1016/j.vascn.2016.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 10/07/2016] [Accepted: 10/12/2016] [Indexed: 11/23/2022]
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Morissette P, Regan C, Fitzgerald K, Gerenser P, Travis J, Wang S, Fanelli P, Sannajust F. Shortening of the electromechanical window in the ketamine/xylazine-anesthetized guinea pig model to assess pro-arrhythmic risk in early drug development. J Pharmacol Toxicol Methods 2016; 81:171-82. [DOI: 10.1016/j.vascn.2016.06.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 05/23/2016] [Accepted: 06/04/2016] [Indexed: 11/26/2022]
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Saengklub N, Youngblood B, Del Rio C, Sawangkoon S, Hamlin RL, Kijtawornrat A. Short-term effects of oral dronedarone administration on cardiac function, blood pressure and electrocardiogram in conscious telemetry dogs. J Vet Med Sci 2016; 78:977-85. [PMID: 26922916 PMCID: PMC4937158 DOI: 10.1292/jvms.15-0481] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dronedarone is a multichannel blocking antiarrhythmic drug that has been used for management of atrial
fibrillation in humans, but the data in veterinary medicine are inadequate. The objective of this study was to
determine the short-term effects of oral dronedarone on cardiac inotropy and lusitropy, blood pressure and
electrocardiogram (ECG) in healthy dogs. A total of 6 beagle dogs were instrumented with telemetry units and
sono-micrometry crystals to obtain left ventricular pressure-volume relationship, mean blood pressure (MBP)
and ECG. Dogs were given orally dronedarone (20 mg/kg, twice per day) for 7 days. All parameters were obtained
hourly at 4–8 hr after the first dose and at 12-, 96- (day 4) and 168-hr (day 7) after dosing. The results
showed that dronedarone had no effect on inotropy and lusitropy, while it significantly lengthened PQ interval
(P<0.001) and lowered MBP (P<0.05). Dronedarone also tended to
reduce cardiac output (P=0.237) and heart rate (P=0.057). These results
suggested that short-term effects of oral dronedarone administration at a dose of 20 mg/kg, twice per day,
produced negative dromotropy with minimal effect on cardiac function in conscious dogs.
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Affiliation(s)
- Nakkawee Saengklub
- Graduate Student in the Program of Animal Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
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Saengklub N, Limprasutr V, Sawangkoon S, Buranakarl C, Hamlin RL, Kijtawornrat A. Acute effects of intravenous dronedarone on electrocardiograms, hemodynamics and cardiac functions in anesthetized dogs. J Vet Med Sci 2015; 78:177-86. [PMID: 26346474 PMCID: PMC4785105 DOI: 10.1292/jvms.15-0413] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Dronedarone is a class III antiarrhythmic that has been used for management of atrial fibrillation in humans, but limited information was found in dogs. The objective of this study was to determine the acute effects of escalating concentrations of dronedarone on electrocardiograms (ECG), hemodynamics and cardiac mechanics in healthy dogs. A total of 7 beagle dogs were anesthetized with isoflurane and instrumented to obtain lead II ECG, pressures at ascending aorta, right atrium, pulmonary artery and left ventricle, and left ventricular pressure-volume relationship. Five dogs were given vehicle and followed by escalating doses of dronedarone (0.5, 1.0 and 2.5 mg/kg, 15 min for each dose), and two dogs were used as a vehicle-treated control. All parameters were measured at 15 min after the end of each dose. The results showed that all parameters in vehicle-treated dogs were unaltered. Dronedarone at 2.5 mg/kg significantly lengthened PQ interval (P<0.01), reduced cardiac output (P<0.01) and increased systemic vascular resistance (P<0.01). Dronedarone produced negative inotropy assessed by significantly lowered end-systolic pressure-volume relationship, preload recruitable stroke work, contractility index and dP/dtmax. It also impaired diastolic function by significantly increased end-diastolic pressure-volume relationship, tau and dP/dtmin. These results suggested that acute effects of dronedarone produced negative dromotropy, inotropy and lusitropy in anesthetized dogs. Care should be taken when given dronedarone to dogs, especially when the patients have impaired cardiac function.
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Affiliation(s)
- Nakkawee Saengklub
- Graduate Student in the Program of Animal Physiology, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
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Klein SK, Redfern WS. Cardiovascular safety risk assessment for new candidate drugs from functional and pathological data: Conference report. J Pharmacol Toxicol Methods 2015; 76:1-6. [PMID: 26126834 DOI: 10.1016/j.vascn.2015.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 06/24/2015] [Indexed: 02/03/2023]
Abstract
This is a report on a 2-day joint meeting between the British Society of Toxicological Pathology (BSTP) and the Safety Pharmacology Society (SPS) held in the UK in November 2013. Drug induced adverse effects on the cardiovascular system are associated with the attrition of more marketed and candidate drugs than any other safety issue. The objectives of this meeting were to foster inter-disciplinary approaches to address cardiovascular risk assessment, improve understanding of the respective disciplines, and increase awareness of new technologies. These aims were achieved. This well attended meeting covered both 'purely functional' cardiovascular adverse effects of drugs (e.g., electrophysiological and haemodynamic changes) as well as adverse effects encompassing both functional and pathological changes. Most of the presentations focused on nonclinical safety data, with information on translation to human where known. To reflect the content of the presentations we have cited key references and review articles.
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Affiliation(s)
- Stephanie K Klein
- Drug Safety & Metabolism, Alderley Park, Macclesfield, Cheshire SK10 4TG, United Kingdom
| | - Will S Redfern
- Drug Safety & Metabolism, Alderley Park, Macclesfield, Cheshire SK10 4TG, United Kingdom.
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Transmural dispersion of repolarization and cardiac remodeling in ventricles of rabbit with right ventricular hypertrophy. J Pharmacol Toxicol Methods 2014; 71:129-36. [PMID: 25305588 DOI: 10.1016/j.vascn.2014.09.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 09/26/2014] [Accepted: 09/30/2014] [Indexed: 11/23/2022]
Abstract
INTRODUCTION Recent publications demonstrated that rabbits with right ventricular hypertrophy (RVH) possess high sensitivity and specificity for drug-induced arrhythmias. However, the underlying mechanism has not been elucidated. This study aimed to evaluate RVH induced changes in cardiac remodeling especially the transmural dispersion of repolarization (TDR), epicardial monophasic action potentials (MAP), and hERG mRNA expression in rabbits. METHODS New Zealand White rabbits (n=13) were divided into 2 groups: sham operated (SHAM, n=6) and pulmonary artery banding (PAB, n=7). PAB was induced by narrowing the pulmonary artery. Twenty weeks after surgery, hemodynamic, cardiac function, electrocardiograms, and MAP were obtained from PAB compared with SHAM. After measurement, rabbits were sacrificed to collect ventricular myocardium for histopathological analysis and measurement of hERG mRNA expression by real time PCR. RESULTS After 20weeks, the % HW to BW ratio of whole heart and right ventricle (RV) and left and right ventricular free wall thickness was significantly increased in PAB when compared with those in SHAM. PAB has a significant electrical remodeling as demonstrated by lengthening of QT, QTc intervals, and increased Tp-Te duration. PAB also has a significant functional remodeling verified by decreased contractility index of RV and lengthened time constant of relaxation of LV. MAP of RV epicardium was significantly shortened in PAB consistently with increased hERG mRNA expression at the epicardium of RV. DISCUSSION The rabbit with PAB demonstrates cardiac remodeling diastolic and systolic dysfunctions. These rabbits also demonstrate increased TDR and electrical remodeling related to the change of hERG mRNA expression which may be prone to develop arrhythmias.
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