Age-dependent cardiovascular effects of verapamil in newborn swine

Abstract

Since there are limited studies concerning the hemodynamic effects of verapamil in pediatric patients, cardiovascular effects of clinical doses (100 or 300 μg/kg) of verapamil, given as a 2-min intravenous infusion, were examined in sodium pentobarbital anesthetized swine, aged 1 day (n = 15) and 2 wk (n = 18). Aortic and left ventricular pressures, index of left ventricular contractility, heart rate, and phasic superior mesenteric, renal, and femoral arterial flows were recorded; mean aortic pressure and vascular resistances were calculated. Maximum changes in cardiovascular function (mean %A ± SEM) occurred at the end of the infusion. Mean aortic pressure and index of left ventricular contractility decreased in all animals; responses were larger in magnitude with the higher dose. By 30 min after infusion of 300 μg/kg verapamil had ended, mean aortic pressure in both 1 day and 2 wk olds and index of left ventricular contractility and femoral flow in 1 day olds were still decreased. During infusion of verapamil, heart rate decreased (—11.6 ± 2.9) to the high dose in 1 day olds but increased (+6.4 ± 2.7) to 100 and 300 Mg/kg verapamil in 2 wk olds. After infusion of 300 jug/kg verapamil ended, heart rate decreased and reached the nadir (—10.0 ± 2.9) by 10 min in 2 wk olds. Decreases in renal resistance (—7.6 ± 1.7) were not dose dependent while superior mesenteric resistance decreased (—12.9 ± 2.7) only to low dose verapamil in 2 wk olds. In 1 day olds decreases in renal and superior mesenteric resistance were not sustained throughout the infusion. The results indicate that verapamil has both age- and dose-dependent cardiovascular effects in newborn swine and suggest that verapamil be used with caution in infants. © 1986 International Pediatric Research Foundation, Inc.