Electrophysiological and proarrhythmic parameters in transmural canine left-ventricular needle biopsies.
This study was designed to validate the use of small, transmural, left-ventricular biopsies in the dog for investigations of electrophysiological and proarrhythmic properties of the heart. This technique could facilitate pharmacological in vitro testing in remodelled hearts of both man and animal. Small, transmural, semi-cylindrical, left-ventricular biopsies from dogs with normal sinus rhythm (SR) were characterized electrophysiologically and compared with biopsies from electrically remodelled hearts from dogs with chronic, complete AV-block (CAVB). In at least five biopsy segments recordings were made to determine the action potential duration (APD), the transmural gradient of repolarization, the maximal transmural dispersion (deltatM(max)) and presence of early after-depolarizations (EADs) at different pacing cycle lengths (PCLs) in the absence and presence of a class-III agent, ibutilide (10(-6) M). The biopsies showed stable and normal AP characteristics, a conduction velocity of 0.22 +/- 0.05 m/s and normal frequency dependence of the APD. The location of the longest APD varied, thus creating transmural repolarization gradients with differing morphology. Ibutilide prolonged the APD, accentuated repolarization gradients and induced EADs. CAVB biopsies had significantly longer APDs, a larger dispersion of repolarization and showed more EADs in the presence of ibutilide than SR biopsies. We conclude that this biopsy technique provides coherent and valid transmural electrophysiological data in dogs under various conditions.
Verduyn
S Cora
SC
Department of Cardiology, Cardiovascular Research Institute Maastricht, Academic Hospital Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands.
Jungschleger
Jérôme G M
JG
Stengl
Milan
M
Spätjens
Roel L H M G
RL
Beekman
Jet D M
JD
Vos
Marc A
MA
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D001707:Biopsy, Needle / Q000295:instrumentation / Q000379:methods; D004285:Dogs; D004594:Electrophysiology; D005260:Female; D006352:Heart Ventricles / Q000166:cytology* / Q000187:drug effects; D008297:Male; D015203:Reproducibility of Results; D013449:Sulfonamides / Q000494:pharmacology; D016276:Ventricular Function
D000889:Anti-Arrhythmia Agents; D013449:Sulfonamides; C067192:ibutilide