title: Verapamil and tiapamil in prevention of ventricular fibrillation in pigs with coronary ligation. Comparative effects on left ventricular function.
abstract: Antiarrhythmic and hemodynamic effects of the calcium channel antagonist verapamil were compared with those of tiapamil, a congener, in open-chest pigs with anterior descending coronary artery ligation. Tiapamil (6 mg/kg i.v.) decreased the incidence of ventricular fibrillation to 4 of 10 versus 22 of 25 in controls (p less than 0.05) and maintained left ventricular dP/dtmax after ligation (predrug value: 2,312 +/- 112 mm Hg/sec; 20 minutes after ligation: 2,139 +/- 229 mm Hg/sec). Tiapamil increased blood flow in the peripheral ischemic zone (24 +/- 3.2% vs. 16.9 +/- 1.6% of preligation value in controls, p less than 0.05) as well as in the peri-ischemic and nonischemic zones (153.9 +/- 12.7% and 186.3 +/- 17.1%, respectively; both p less than 0.0001 vs. 97.9 +/- 5% and 91.3 +/- 4.7% in controls). Verapamil (0.6 mg/kg i.v.) decreased the incidence of ventricular fibrillation to 0 of 7 versus 22 of 25 in controls (p less than 0.005); left ventricular dP/dtmax decreased from 2,062 +/- 144 to 1,060 +/- 168 mm Hg/sec (p less than 0.0001). Verapamil did not change blood flow in the peripheral, peri-ischemic, or nonischemic zones. Thus, tiapamil, and not verapamil, decreased ischemic ventricular fibrillation while maintaining left ventricular mechanical function. Verapamil congeners warrant further evaluation as antiarrhythmic agents in acute myocardial ischemia.
authors: Ischaemic Heart Disease Research Unit, Medical Research Council, Cape Town, South Africa.
authors: C A
authors: CA
authors: Muller
authors: L H
authors: LH
authors: Opie
authors: C W
authors: CW
authors: Hamm
authors: M
authors: M
authors: Peisach
authors: C A
authors: CA
authors: Pineda
authors: F T
authors: FT
authors: Thandroyen
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000601:surgery; D005260:Female; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics / Q000187:drug effects*; D008026:Ligation; D008297:Male; D009203:Myocardial Infarction / Q000503:physiopathology*; D011437:Propylamines / Q000627:therapeutic use*; D013552:Swine; D013976:Tiapamil Hydrochloride; D014693:Ventricular Fibrillation / Q000517:prevention & control*; D014700:Verapamil / Q000627:therapeutic use*
chemical_list: D011437:Propylamines; D014700:Verapamil; D013976:Tiapamil Hydrochloride