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Canine svt

Erik R Larson, John E Porterfield, Sandeep Sagar, Juan Marmol-Velez, Manoj Panday, Daniel Escobedo, Joel Michalek, Yongjian Ouyang, Jonathan W Valvano, John A Pearce, Marc D Feldman
BACKGROUND: Implantable cardioverter-defibrillators monitor intracardiac electrograms (EGMs) to discriminate between ventricular and supraventricular tachycardias. The incidence of inappropriate shocks remains high because of misclassification of the tachycardia in an otherwise hemodynamically stable individual. Coupling EGMs with an assessment of left ventricular (LV) stroke volume (SV) could help in gauging hemodynamics during an arrhythmia and reducing inappropriate shocks. OBJECTIVE: The purpose of this study was to use the admittance method to accurately derive LV SV...
November 2014: Heart Rhythm: the Official Journal of the Heart Rhythm Society
Hideki Okunishi, Keiko Shimoura, Dang-Qiao Wang, Eiichi Kakizoe
Potential risks of cyclohexanol (CH) and cyclohexanediol (CHD) isomers, which are the metabolites derived from cilexetil ester side-chain of several prodrugs such as antibiotics (e.g. cefotiam hexetil) and an antihypertensive agent (candesartan cilexetil), were examined in beagles that were made congestive heart failure (CHF) by rapid ventricular pacing. The following three experiments tested the cardiac effects of i.v. doses of: (1) the metabolites alone, (2) the metabolites under the digoxin-induced bradycardia, and (3) the metabolites given concomitantly with digoxin (0...
October 2002: Pharmacological Research: the Official Journal of the Italian Pharmacological Society
David Amar, Paul M Heerdt, Robert J Korst, Hao Zhang, Hai Nguyen
UNLABELLED: Because advanced age is the strongest independent risk factor for the development of supraventricular arrhythmias after lung resection, we compared the incidence and premorbid events of supraventricular arrhythmias after pneumonectomy in young and elderly dogs with the aim of better understanding potential age-related arrhythmogenic mechanisms. Right pneumonectomy was performed in 15 male mongrel dogs ("old" > or =8 yr [n = 8], "young" <4 yr [n = 7]) and the electrocardiogram continuously recorded by an implantable telemetry system for 1 wk before euthanizing...
May 2002: Anesthesia and Analgesia
H Schmitt, C Cabo, J C Coromilas, A L Wit
INTRODUCTION: Azimilide blocks the slow (I(Ks)) and fast (I(Kr)) components of the delayed rectifier potassium channel. It also has blocking effects on sodium (I(Na)) and calcium currents (I(CaL)). Its effects on reentrant circuits in infarct border zones causing ventricular tachyarrhythmias are unknown. METHODS AND RESULTS: Activation in reentrant circuits causing sustained ventricular tachycardia (SVT) and the initial polymorphic tachycardia that leads to ventricular fibrillation (VF) was mapped in the epicardial border zone (EBZ) of 4-day-old canine infarcts...
September 2001: Journal of Cardiovascular Electrophysiology
J He, M W Conklin, J D Foell, M R Wolff, R A Haworth, R Coronado, T J Kamp
OBJECTIVE: Persistent supraventricular tachycardia leads to the development of a dilated cardiomyopathy with impairment of excitation-contraction (EC) coupling. Since the initial trigger for EC coupling in ventricular muscle is the influx of Ca(2+) through L-type Ca(2+) channels (I(Ca)) in the transverse tubules (T-tubules), we determined if the density of the T-tubule system and L-type Ca(2+) channels change in canine tachycardia pacing-induced cardiomyopathy. METHODS: Confocal imaging of isolated ventricular myocytes stained with the membrane dye Di-8-ANEPPS was used to image the T-tubule system, and standard whole-cell patch clamp techniques were used to measure I(Ca) and intramembrane charge movement...
February 1, 2001: Cardiovascular Research
D Clemett, A Markham
Azimilide is a potassium channel antagonist that, in contrast to existing class III antiarrhythmic agents, blocks both the rapidly (I(Kr)) and slowly (I(Ks)) activating components of the delayed rectifier potassium current. In animal and clinical studies, azimilide prolonged repolarisation by increasing the action potential duration and effective refractory period. In animal models, azimilide was effective in terminating both atrial and ventricular arrhythmias. Azimilide also demonstrated antifibrillatory efficacy in a canine model of sudden cardiac death...
February 2000: Drugs
N J Weissman, G A Rose, G P Foster, M H Picard
OBJECTIVES: This study sought to test whether the physiologic advantage of a prolonged dobutamine stage during stress echocardiography can be effectively combined with a clinically practical infusion protocol. BACKGROUND: Dobutamine has a half-life of 2 min and requires up to 10 min to achieve steady state. Despite these known pharmacodynamics, dobutamine stress echocardiography is routinely performed by advancing doses at 3-min intervals. Canine studies have shown that dobutamine stress echocardiography end points will occur at a lower dose if each stage is prolonged, but these findings have yet to be used in the clinical setting...
March 1, 1997: Journal of the American College of Cardiology
D D Hodgkin, G L Pierpont, K R Hildebrand, C C Gornick
This study evaluated the electrophysiologic effects of a pulsed iontophoretic drug-delivery system when used in the coronary arteries. Prevention of acute thrombosis and restenosis after intravascular procedures may be enhanced by high concentrations of therapeutic agents within the vessel wall. A new intravascular drug-delivery system uses iontophoresis to maximize local tissue concentrations of drug. However, the electrophysiologic effects of such a system in coronary arteries are unknown. An iontophoretic membrane balloon-tipped catheter was placed fluoroscopically in the mid left anterior descending coronary artery of 10 anesthetized dogs...
January 1997: Journal of Cardiovascular Pharmacology
E J Ciaccio, A L Wit, M M Scheinman, S M Dunn, M Akay, J Coromilas
Ventricular tachycardia caused by reentrant excitation can lead to cardiac arrest and sudden death. Drug treatment and surgical procedures have been used with limited effectiveness. Catheter ablation methods are more promising because they are less invasive than surgery. Although ablation has come to be highly effective in the treatment of supraventricular tachycardias, the overall success rate remains low for ventricular tachycardias, which may be due in part to an inaccurate localization of the reentrant pathway...
1995: Journal of Electrocardiology
I Aidonidis, J Brachmann, I Rizos, A Zacharoulis, I Stavridis, P Toutouzas, W K├╝bler
Myocardial infarction was produced in 27 anesthetized dogs by ligating the left anterior descending (LAD) coronary artery proximal to the septal branch. Nineteen of these animals survived the operation and were studied by programmed stimulation in a random sequence between the third and seventh days after the infarct. Complete electrophysiologic testing was implemented in each animal prior to and after single doses of either alinidine (1 mg/kg IV) or zatebradine (0.5 mg/kg IV). Alinidine prevented reinduction of sustained ventricular tachycardia (SVT) in only 2 of 9 dogs and zatebradine in 1 of 8 dogs...
August 1995: Cardiovascular Drugs and Therapy
I Aidonidis, I Rizos, T Hilbel, W Kuebler, J Brachmann
To evaluate the antiarrhythmic efficacy of l-sotalol and bisoprolol on inducible ventricular arrhythmias, conscious dogs with 4- to 8-day-old myocardial infarction were studied by programmed electrical stimulation. Direct recordings from infarcted and adjacent normal subepicardium were made using a specially designed composite electrode. From 18 dogs developing sustained ventricular tachycardia (sVT) during control stimulation, l-sotalol (1.5 mg/kg i.v.) prevented reinducibility of sVT in 10 animals, while in seven other animals it significantly reduced the rate of tachycardia...
July 1994: Journal of Molecular and Cellular Cardiology
G M Ansel, J P Meimer, S D Nelson
Sinus tachycardia facilitates ventricular conduction delay and sustained ventricular tachyarrhythmias during tricyclic antidepressant overdose. We hypothesized that impeding sinus tachycardia with the specific bradycardia agent, UL-FS 49, would reduce the incidence of ventricular tachyarrhythmia caused by tricyclic antidepressant overdose and tested this hypothesis in a canine model of ventricular tachycardia (VT) induced by graded amitriptyline infusion (0.5-1.0 mg/kg/min) during continuous hemodynamic monitoring...
August 1994: Journal of Cardiovascular Pharmacology
J P Moak, R A Friedman, A Garson
Electrode catheter ablation (ECA) of atrial muscle may be a useful technique for the treatment of drug-refractory supraventricular tachycardias originating in the right atrial free wall (RAFW). We performed this study in order to determine: (1) the safety of electrical shocks applied to the RAFW and (2) the early and late anatomic effects of ECA. Twelve beagle puppies, ranging in age from 2.0 to 7.5 months and weighting 2.3 to 8.0 kg, underwent electrical ablation of the RAFW, using energy doses of 100 to 400 J...
June 1987: American Heart Journal
T Sakai, S Ogawa, M Hosokawa, T Miyazaki, K Sakurai, Y Nakamura
Flecainide has been reported to be effective in suppressing chronic ventricular arrhythmias in clinical studies, but the electrophysiological mechanisms of its action are not understood. We therefore studied its effects on re-entrant ventricular arrhythmias in eight dogs with 7 day old infarction. Epicardial mapping and local refractory periods were obtained using 48 channel bipolar electrodes attached to the epicardium. Epicardial conduction velocity was significantly depressed by flecainide (2 intravenously), from 49...
March 1989: Cardiovascular Research
G J Klein, G M Guiraudon, D G Perkins, A D Sharma, D L Jones
Elective subtotal injury to the AV node-His bundle region may create a negative dromotropic effect to provide a therapeutic advantage in some patients with supraventricular tachycardia without creating complete AV block. We examined the effects of cryosurgery to the AV nodal region, varying temperature and time using a 15 mm circular cryoprobe applied directly to the canine AV node-His bundle region. Twelve dogs were anesthetized and the heart was exposed through a right thoracotomy. Electrophysiological data obtained included conduction intervals, incremental pacing, and extrastimulus testing...
September 1985: Pacing and Clinical Electrophysiology: PACE
M Hirai, M J Burgess
The effects of changes in paced cycle length alone and changes in both paced cycle length and site of pacing on canine cardiac surface QRST isoarea maps were studied. The correlations between QRST isoarea maps acquired during right ventricular pacing at 900 ms and 700 ms averaged 0.97. The correlations between maps acquired during RV pacing at 900 ms and 500 ms averaged 0.94. The root mean square value of QRST areas progressively decreased as cycle length was decreased from 900 ms to 700 ms and then to 500 ms...
July 1991: Journal of Electrocardiology
M Talajic, C Villemaire, D Papadatos, R Lemery, D Roy, S Nattel
Cycle length alternation (CLA) is commonly observed during supraventricular tachycardia (SVT) onset and termination. The present study was designed to gain insights into the mechanism and potential clinical relevance of CLA by comparing computer simulations of tachycardia to directly observed behavior in a canine model of AV reentrant tachycardia (AVRT). The computer model was based on the hypothesis that CLA is secondary to feedback between AV nodal output during SVT and subsequent AV nodal input, and used the measured anterograde AV nodal recovery curve (AV vs A1A2) to predict sequential AV and RR intervals during SVT...
March 1990: Pacing and Clinical Electrophysiology: PACE
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