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Antiarrhythmic and hemodynamic effects of calcium channel blocking agents during coronary arterial reperfusion

1981; Elsevier BV; Volume: 48; Issue: 1 Linguagem: Inglês

10.1016/0002-9149(81)90573-7

1879-1913

Lair G.T. Ribeiro, Tedd A. Brandon, Thomas L. DeBauche, Peter R. Maroko, Richard R. Miller,

Cardiac Arrhythmias and Treatments

To determine the comparative actions of the calcium channel blocking agents verapamil and nifedipine on coronary flow and ventricular arrhythmias during myocardial reperfusion, 24 open chest dogs underwent proximal occlusion of the left anterior descending coronary artery. Regional myocardial blood flow (ml/mln per 100 g) was quantltated by microspheres (strontium [85Sr]and cerium [141Ce]) 20 minutes after coronary occlusion and 10 minutes after reperfusion. Dogs were randomly assigned to one of three groups 20 minutes after coronary occlusion: (1) control group (n = 8); (2) dogs given intravenous verapamil (n = 8), 0.2 mg/kg body weight in 5 minutes followed by an infusion of 0.01 mg/kg per min; or (3) dogs given nifedipine (n = 8), 100 μg/kg in 5 minutes followed by an infusion of 3 μg/kg per min. Ten minutes after reperfusion, transmural regional myocardial blood flow in the ischemic zone was unchanged by verapamil and nifedipine (p = not significant [NS]versus control value). The endocardial/epicardial ratio in the hyperemlc zone tended to be lowered by the calcium blocking agents compared with that observed in control animals. Coronary resistance during reperfusion was similar (p = NS) in animals treated with verapamil and nifedipine. Ventricular tachycardia or fibrillation occurred in six dogs In the control group (tachycardia in three and fibrillation in three). Among dogs given verapamil, none had ventricular tachycardia and one of eight had ventricular fibrillation (p <0.05 versus control value). Four of the eight dogs given nifedipine, had ventricular tachycardia (two dogs) or fibrillation (two dogs) (p = NS versus control and verapamil values). Thus, verapamil and nifedipine had similar effects on central and coronary hemodynamics during myocardial reperfusion. However, verapamil, in contrast to nifedipine, decreased reperfusion ventricular arrhythmias. These data suggest that despite similar calcium channel blocking actions, verapamil and nifedipine possess different antiarrhythmic effects.