1
|
Qiu B, Wang Y, Li C, Guo H, Xu Y. Utility of the JT Peak Interval and the JT Area in Determining the Proarrhythmic Potential of QT-Shortening Agents. J Cardiovasc Pharmacol Ther 2018; 24:160-171. [PMID: 30092655 DOI: 10.1177/1074248418791999] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Drug-induced long QT increases the risk of ventricular tachyarrhythmia known as torsades de pointes (TdP). Many biomarkers have been used to predict TdP. At present, however, there are few biomarkers for arrhythmias induced by QT-shortening drugs. The objective of the present study was to identify the best biomarkers for predicting arrhythmias caused by the 4 potassium channel openers ICA-105574, NS-1643, R-L3, and pinacidil. Our results showed that, at higher concentrations, all 4 potassium channel openers induced ventricular tachycardia (VT) and ventricular fibrillation (VF) in Langendorff-perfused guinea pig hearts, but not in rabbit hearts. The electrocardiography parameters were measured including QT/QTc, JT peak, Tp-e interval, JT area, short-term beat-to-beat QT interval variability (STV), and index of cardiac electrophysiological balance (iCEB). We found that the potassium channel openers at test concentrations shortened the QT/QTc and the JT peak interval and increased the JT area. Nevertheless, even at proarrhythmic concentrations, they did not always change STV, Tp-e, or iCEB. Receiver operating characteristic curve analysis showed that the JT peak interval representing the early repolarization phase and the JT area reflecting the dispersion of ventricular repolarization were the best predictors of VT/VF. Action potential recordings in guinea pig papillary muscle revealed that except for pinacidil, the potassium channel openers shortened APD30 in a concentration-dependent manner. They also evoked early or delayed afterdepolarizations at fast pacing rates. Patch-clamp recordings in guinea pig ventricular cardiomyocytes showed that the potassium channel openers enhanced the total outward currents during the early phase of action potential repolarization, especially at proarrhythmic concentrations. We concluded that the JT peak interval and the JT area are surrogate biomarkers identifying the risk of proarrhythmia associated with the administration of QT-shortening agents. The acceleration of early-phase repolarization and the increased dispersion of ventricular repolarization may contribute to the occurrence of arrhythmias.
Collapse
Affiliation(s)
- Bo Qiu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Shijiazhuang, Hebei, China.,The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, Hebei, China.,Hebei General Hospital, Shijiazhuang, China
| | - Yuhong Wang
- Institute of Materia Medica, Chinese Academy of Medical Sciences and Beijing Union Medical College, Beijing, China
| | - Congxin Li
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Shijiazhuang, Hebei, China.,The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, Hebei, China
| | - Huicai Guo
- Department of Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Yanfang Xu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Shijiazhuang, Hebei, China.,The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, Hebei, China
| |
Collapse
|
2
|
Li M, Chadda KR, Matthews GDK, Marr CM, Huang CLH, Jeevaratnam K. Cardiac electrophysiological adaptations in the equine athlete-Restitution analysis of electrocardiographic features. PLoS One 2018. [PMID: 29522557 PMCID: PMC5844547 DOI: 10.1371/journal.pone.0194008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Exercising horses uniquely accommodate 7–8-fold increases in heart rate (HR). The present experiments for the first time analysed the related adaptations in action potential (AP) restitution properties recorded by in vivo telemetric electrocardiography from Thoroughbred horses. The horses were subjected to a period of acceleration from walk to canter. The QRS durations, and QT and TQ intervals yielded AP conduction velocities, AP durations (APDs) and diastolic intervals respectively. From these, indices of active, λ = QT/(QRS duration), and resting, λ0 = TQ/(QRS duration), AP wavelengths were calculated. Critical values of QT and TQ intervals, and of λ and λ0 at which plots of these respective pairs of functions showed unity slope, were obtained. These were reduced by 38.9±2.7% and 86.2±1.8%, and 34.1±3.3% and 85.9±1.2%, relative to their resting values respectively. The changes in λ were attributable to falls in QT interval rather than QRS duration. These findings both suggested large differences between the corresponding critical (129.1±10.8 or 117.4±5.6 bpm respectively) and baseline HRs (32.9±2.1 (n = 7) bpm). These restitution analyses thus separately identified concordant parameters whose adaptations ensure the wide range of HRs over which electrophysiological activation takes place in an absence of heart block or arrhythmias in equine hearts. Since the horse is amenable to this in vivo electrophysiological analysis and displays a unique wide range of heart rates, it could be a novel cardiac electrophysiology animal model for the study of sudden cardiac death in human athletes.
Collapse
Affiliation(s)
- Mengye Li
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Karan R. Chadda
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | | | - Celia M. Marr
- Rossdales Equine Hospital and Diagnostic Centre, Exning, Suffolk, United Kingdom
| | - Christopher L.-H. Huang
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
- Division of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Kamalan Jeevaratnam
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
- * E-mail:
| |
Collapse
|
3
|
Therapeutic effects of a taurine-magnesium coordination compound on experimental models of type 2 short QT syndrome. Acta Pharmacol Sin 2018; 39:382-392. [PMID: 29072257 DOI: 10.1038/aps.2017.86] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 05/19/2017] [Indexed: 01/21/2023] Open
Abstract
Short QT syndrome (SQTS) is a genetic arrhythmogenic disease that can cause malignant arrhythmia and sudden cardiac death. The current therapies for SQTS have application restrictions. We previously found that Mg· (NH2CH2CH2SO3)2· H2O, a taurine-magnesium coordination compound (TMCC) exerted anti-arrhythmic effects with low toxicity. In this study we established 3 different models to assess the potential anti-arrhythmic effects of TMCC on type 2 short QT syndrome (SQT2). In Langendorff guinea pig-perfused hearts, perfusion of pinacidil (20 μmol/L) significantly shortened the QT interval and QTpeak and increased rTp-Te (P<0.05 vs control). Subsequently, perfusion of TMCC (1-4 mmol/L) dose-dependently increased the QT interval and QTpeak (P<0.01 vs pinacidil). TMCC perfusion also reversed the rTp-Te value to the normal range. In guinea pig ventricular myocytes, perfusion of trapidil (1 mmol/L) significantly shortened the action potential duration at 50% (APD50) and 90% repolarization (APD90), which was significantly reversed by TMCC (0.01-1 mmol/L, P<0.05 vs trapidil). In HEK293 cells that stably expressed the outward delayed rectifier potassium channels (IKs), perfusion of TMCC (0.01-1 mmol/L) dose-dependently inhibited the IKs current with an IC50 value of 201.1 μmol/L. The present study provides evidence that TMCC can extend the repolarization period and inhibit the repolarizing current, IKs, thereby representing a therapeutic candidate for ventricular arrhythmia in SQT2.
Collapse
|
4
|
Limprasutr V, Saengklub N, Meedech P, Kijtawornrat A, Hamlin RL. Characteristics of electromechanical window in anesthetized rabbit models of short QT and long QT syndromes. J Toxicol Sci 2018; 42:579-587. [PMID: 28904293 DOI: 10.2131/jts.42.579] [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] [Indexed: 11/02/2022]
Abstract
The current regulatory guidelines recommend the use of QT interval to assess the risk of arrhythmogenic potential of new chemical entities. Recently, the electromechanical window (EMW), the difference in duration between electrical and mechanical systole, has been proposed as markers for drug-induced torsades de pointes (TdP); however, data of EMW in short QT model are not available. This study aimed to characterize the EMW as a marker for drug-induced ventricular arrhythmias in anesthetized rabbit model of long QT syndrome type 2 (LQT2) and short QT syndrome (SQTS) infused with reference compounds known to lengthen or shorten QT intervals. After rabbits were anesthetized with isoflurane, body surface electrocardiograms and left ventricular pressure were recorded. The LQT2 was produced by intravenous infusion with dofetilide (n = 6), quinidine (n = 6) and sotalol (n = 6) whereas the SQTS was induced by intravenous escalating concentrations of nicorandil (n = 7), pinacidil (n = 5) and cromakalim (n = 5). The EMW in anesthetized rabbits ranged from 1.3 to 53.3 msec. All three drugs known to lengthen QT intervals prolonged QT and QTcF interval while the EMW was markedly decreased to negative values. Pinacidil significantly produced QT and QTcF shortening and significantly abbreviated the EMW (p < 0.05). This study demonstrated that the EMW is associated with QT intervals (p < 0.001). It is negative in the presence of QT-prolonging drugs while it is more positive in the presence of QT-shortening drugs. The results suggest that the EMW in anesthetized rabbits can be used in drug safety evaluation in addition to the QT interval.
Collapse
Affiliation(s)
- Vudhiporn Limprasutr
- Department of Veterinary Physiology, Faculty of Veterinary Science, Chulalongkorn University, Thailand
| | - Nakkawee Saengklub
- Department of Physiology, Faculty of Pharmacy, Mahidol University, Thailand
| | - Pradtana Meedech
- Department of Veterinary Physiology, Faculty of Veterinary Science, Chulalongkorn University, Thailand
| | - Anusak Kijtawornrat
- Department of Veterinary Physiology, Faculty of Veterinary Science, Chulalongkorn University, Thailand.,Research clusters: Research Study and Testing of Drug's Effect Related to Cardiovascular System in Laboratory Animals, Chulalongkorn University, Thailand
| | | |
Collapse
|
5
|
Limprasutr V, Pirintr P, Kijtawornrat A, Hamlin RL. An increasing electromechanical window is a predictive marker of ventricular fibrillation in anesthetized rabbit with ischemic heart. Exp Anim 2017; 67:175-183. [PMID: 29162767 PMCID: PMC5955749 DOI: 10.1538/expanim.17-0100] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The QTc interval is widely used in Safety Pharmacological studies to predict arrhythmia
risk, and the electromechanical window (EMW) and short-term variability of QT intervals
(STVQT) have been studied as new biomarkers for drug-induced Torsades de
Pointes (TdP). However, the use of EMW and STVQT to predict ventricular
fibrillation (VF) has not been elucidated. This study aimed to evaluate EMW and
STVQT to predict VF in anesthetized rabbit model of VF. VF was induced by
ligation of the left anterior descending and a descending branch of the left circumflex
coronary arteries in a sample population of rabbits (n=18). VF was developed 55.6%
(10/18). In rabbit with VF, the EMW was significantly higher than in rabbits without VF
(96.3 ± 15.6 ms and 49.5 ± 5.6 ms, respectively, P<0.05).
STVQT had significantly increased before the onset of VF in rabbits that
experienced VF, but not in rabbits that did not experience VF (11.7 ± 1.8 ms and 3.7 ± 0.4
ms, respectively, P<0.05). The EMW and STVQT had better
predictive power for VF with higher sensitivity and specificity than the QTc measure. The
result suggested that the increasing of EMW, as well as the elevation of STVQT,
can potentially be used as biomarkers for predicting of VF.
Collapse
Affiliation(s)
- Vudhiporn Limprasutr
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, 39 Henri Dunant Road, Wang Mai, Pathumwan, Bangkok 10330, Thailand
| | - Prapawadee Pirintr
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, 39 Henri Dunant Road, Wang Mai, Pathumwan, Bangkok 10330, Thailand.,Department of Veterinary Biosciences and Veterinary Public Health, Faculty of Veterinary Medicine, Chiang Mai University, 155 Tumbon Mae Hiae, Muang, Chiang Mai 50100, Thailand
| | - Anusak Kijtawornrat
- Department of Physiology, Faculty of Veterinary Science, Chulalongkorn University, 39 Henri Dunant Road, Wang Mai, Pathumwan, Bangkok 10330, Thailand.,Research clusters: research study and testing of drug's effect related to cardiovascular system in laboratory animals, Chulalongkorn University, 39 Henri Dunant Road, Wang Mai, Pathumwan, Bangkok 10330, Thailand
| | - Robert L Hamlin
- QTest Labs, LLC. 6456 Fiesta Drive, Columbus, Ohio 43235, USA
| |
Collapse
|
6
|
Abstract
Short QT syndrome is a malignant cardiac disease characterized by the presence of ventricular tachyarrhythmias leading to syncope and sudden cardiac death. Currently, international guidelines establish diagnostic criteria when QTc is below 340 ms. This entity is one of the main diseases responsible for sudden cardiac death in the pediatric population. In recent years, clinical, genetic and molecular advances in pathophysiological mechanisms related to short QT syndrome have improved diagnosis, risk stratification, and preventive measures. Despite these advances, automatic implantable cardiac defibrillator remains the most effective measure. Currently, six genes have been associated with short QT syndrome, which account for nearly 60% of clinically diagnosed families. Here, we review the main clinical hallmarks of the disease, focusing on the pediatric population.
Collapse
|
7
|
Malik M. Drug-Induced QT/QTc Interval Shortening: Lessons from Drug-Induced QT/QTc Prolongation. Drug Saf 2016; 39:647-59. [DOI: 10.1007/s40264-016-0411-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
8
|
Ware WA, Reina-Doreste Y, Stern JA, Meurs KM. Sudden death associated with QT interval prolongation and KCNQ1 gene mutation in a family of English Springer Spaniels. J Vet Intern Med 2015; 29:561-8. [PMID: 25779927 PMCID: PMC4895492 DOI: 10.1111/jvim.12550] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Revised: 12/22/2014] [Accepted: 01/06/2015] [Indexed: 01/04/2023] Open
Abstract
Background A 5‐year‐old, healthy English Springer Spaniel died suddenly 4 months after delivering a litter of 7 puppies. Within 4 months of the dam's death, 3 offspring also died suddenly. Hypothesis Abnormal cardiac repolarization, caused by an inherited long QT syndrome, is thought to be responsible for arrhythmias leading to sudden death in this family. Animals Four remaining dogs from the affected litter and 11 related dogs. Methods Physical examination and resting ECG were done on the littermates and 9 related dogs. Additional tests on some or all littermates included echocardiogram with Doppler, Holter monitoring, and routine serum biochemistry. Blood for DNA sequencing was obtained from all 15 dogs. Results Three of 4 littermates examined, but no other dogs, had prolonged QT intervals with unique T‐wave morphology. DNA sequencing of the KCNQ1 gene identified a heterozygous single base pair mutation, unique to these 3 dogs, which changes a conserved amino acid from threonine to lysine and is predicted to change protein structure. Conclusions and Clinical Importance This family represents the first documentation in dogs of spontaneous familial QT prolongation, which was associated with a KCNQ1 gene mutation and sudden death. Although the final rhythm could not be documented in these dogs, their phenotypic manifestations of QT interval prolongation and abnormal ECG restitution suggested increased risk for sudden arrhythmic death. The KCNQ1 gene mutation identified is speculated to impair the cardiac repolarizing current IKs, similar to KCNQ1 mutations causing long QT syndrome 1 in humans.
Collapse
Affiliation(s)
- W A Ware
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA
| | | | | | | |
Collapse
|
9
|
Del Rio CL, Clymer BD, Billman GE. Myocardial electrotonic response to submaximal exercise in dogs with healed myocardial infarctions: evidence for β-adrenoceptor mediated enhanced coupling during exercise testing. Front Physiol 2015; 6:25. [PMID: 25698976 PMCID: PMC4318283 DOI: 10.3389/fphys.2015.00025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 01/15/2015] [Indexed: 11/13/2022] Open
Abstract
INTRODUCTION Autonomic neural activation during cardiac stress testing is an established risk-stratification tool in post-myocardial infarction (MI) patients. However, autonomic activation can also modulate myocardial electrotonic coupling, a known factor to contribute to the genesis of arrhythmias. The present study tested the hypothesis that exercise-induced autonomic neural activation modulates electrotonic coupling (as measured by myocardial electrical impedance, MEI) in post-MI animals shown to be susceptible or resistant to ventricular fibrillation (VF). METHODS Dogs (n = 25) with healed MI instrumented for MEI measurements were trained to run on a treadmill and classified based on their susceptibility to VF (12 susceptible, 9 resistant). MEI and ECGs were recorded during 6-stage exercise tests (18 min/test; peak: 6.4 km/h @ 16%) performed under control conditions, and following complete β-adrenoceptor (β-AR) blockade (propranolol); MEI was also measured at rest during escalating β-AR stimulation (isoproterenol) or overdrive-pacing. RESULTS Exercise progressively increased heart rate (HR) and reduced heart rate variability (HRV). In parallel, MEI decreased gradually (enhanced electrotonic coupling) with exercise; at peak exercise, MEI was reduced by 5.3 ± 0.4% (or -23 ± 1.8Ω, P < 0.001). Notably, exercise-mediated electrotonic changes were linearly predicted by the degree of autonomic activation, as indicated by changes in either HR or in HRV (P < 0.001). Indeed, β-AR blockade attenuated the MEI response to exercise while direct β-AR stimulation (at rest) triggered MEI decreases comparable to those observed during exercise; ventricular pacing had no significant effects on MEI. Finally, animals prone to VF had a significantly larger MEI response to exercise. CONCLUSIONS These data suggest that β-AR activation during exercise can acutely enhance electrotonic coupling in the myocardium, particularly in dogs susceptible to ischemia-induced VF.
Collapse
Affiliation(s)
- Carlos L Del Rio
- Department of Physiology and Cell Biology, The Ohio State University Columbus, OH, USA ; Department of Electrical and Computer Engineering, The Ohio State University Columbus, OH, USA ; Safety Pharmacology, QTest Labs Columbus, OH, USA
| | - Bradley D Clymer
- Department of Electrical and Computer Engineering, The Ohio State University Columbus, OH, USA ; Biomedical Engineering, The Ohio State University Columbus, OH, USA
| | - George E Billman
- Department of Physiology and Cell Biology, The Ohio State University Columbus, OH, USA ; Davis Heart and Lung Research Institute, The Ohio State University Columbus, OH, USA
| |
Collapse
|
10
|
Li L, Zheng X, Dosdall DJ, Huang J, Pogwizd SM, Ideker RE. Long-duration ventricular fibrillation exhibits 2 distinct organized states. Circ Arrhythm Electrophysiol 2013; 6:1192-9. [PMID: 24243784 DOI: 10.1161/circep.113.000459] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Previous studies showed that endocardial activation during long-duration ventricular fibrillation (VF) exhibits organized activity. We identified and quantified the different types of organized activity. METHODS AND RESULTS Two 64-electrode basket catheters were inserted, respectively, into the left ventricle and right ventricle of dogs to record endocardial activation from the endocardium during 7 minutes of VF (controls, n=6). The study was repeated with the K(ATP) channel opener pinacidil (n=6) and the calcium channel blocker flunarizine (n=6). After 2 minutes of VF without drugs, 2 highly organized left ventricular endocardial activation patterns were observed: (1) ventricular electric synchrony pattern, in which endocardial activation arose focally and either had a propagation sequence similar to sinus rhythm or arose near papillary muscles, and (2) stable pattern, in which activation was regular and repeatable, sometimes forming a stable re-entrant circuit around the left ventricular apex. Between 3 and 7 minutes of VF, the percent of time ventricular electric synchrony was present was control=25%, flunarizine=24% (P=0.44), and pinacidil=0.1% (P<0.001) and the percent of time stable pattern was present was control=71%, flunarizine=48% (P<0.001), and pinacidil=56% (P<0.001). The remainder of the time, nonstable re-entrant activation with little repeatability was present. CONCLUSIONS After 3 minutes, VF exhibits 2 highly organized endocardial activation patterns 96% of the time, one potentially arising focally in the Purkinje system that was prevented with a K(ATP) channel opener but not a calcium channel blocker and the other potentially arising from a stable re-entrant circuit near the apical left ventricular endocardium.
Collapse
Affiliation(s)
- Li Li
- Departments of Medicine, Biomedical Engineering, and Physiology, University of Alabama at Birmingham; and Department of Internal Medicine, CARMA Center, University of Utah, Salt Lake City
| | | | | | | | | | | |
Collapse
|
11
|
Shah RR, Bjerregaard P, Gussak I. Drug-induced QT interval shortening: an emerging component in integrated assessment of cardiac safety of drugs. J Electrocardiol 2011; 43:386-9. [PMID: 20728017 DOI: 10.1016/j.jelectrocard.2010.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Indexed: 11/16/2022]
|