Nifedipine with and without propranolol in the treatment of myocardial ischemia: effect on ventricular arrhythmias and recovery of regional wall function.
Sudden reperfusion of ischemic myocardium has been related to an extension of damage, due to sudden increases in transmembrane calcium fluxes. When the calcium slow channel blocker nifedipine (1 microgram kg-1 min-1 i.v.) was infused just prior to release of a 30 min partial obstruction of the left anterior descending coronary artery (LAD) in anesthetized pigs, recovery of regional function was better (75%) than in untreated animals (50%). The number of reperfusion arrhythmias was also significantly lower in the treated animals. In another series of experiments, ventricular fibrillation occurred in 80% of the untreated animals within 10 min after the complete acute occlusion of the LAD. Animals pretreated with propranolol (0.5 mg kg-1 i.v. bolus + infusion) or nifedipine (0.05 microgram kg-1 min-1 i.c.) showed a similar high incidence of ventricular fibrillation. However, when the administration of these drugs was combined, 60% of the animals survived three periods (10 min) of intermittent myocardial ischemia. When the continuous infusion of nifedipine was preceded by a bolus of 2.0 microgram kg-1, sufficient to abolish systolic wall thickening completely, the incidence of ventricular fibrillation was also reduced. Recovery of regional function was nearly complete in these animals.
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000517:prevention & control*; D003327:Coronary Disease / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D006321:Heart / Q000503:physiopathology*; D009206:Myocardium / Q000473:pathology; D009543:Nifedipine / Q000627:therapeutic use*; D011433:Propranolol / Q000627:therapeutic use*; D013552:Swine; D014693:Ventricular Fibrillation / Q000517:prevention & control
D011433:Propranolol; D009543:Nifedipine