Regional wall motion from radiopaque markers after intravenous and intracoronary injections of nifedipine.

SlUMMARY In 11 patients, 1 mg of i.v. nifedipine was administered over 3 minutes and regional wall motion was studied during atrial pacing. The dominant effect of nifedipine at basal heart rate (HR) was a lowering of peak left ventricular pressure (152 to 128 mm Hg) with an increase in HR from 70 to 86 beats/min. During pacing, nifedipine produced (p < 0.02) a similar reduction in pressure at all rates, which is a mechanism reduc- ing or sparing myocardial oxygen consumption. At the highest paced rate, the maximal velocity (Vmax) of the contractile element was significantly (p < 0.02) increased from 61 to 68 sec-' and the regional shortening frac- tions were increased over the entire pacing range: basal HR, 13.7% to 14.6% (p < 0.025); HR 120 beats/min, 11.6% to 13.5% (p < 0.005); maximal HR, 10.9% to 11.8% (p < 0.05). No evidence of a negative inotropic effect after i.v. administration of nifedipine was observed, myocardial oxygen consumption was probably reduced and there was an increase in regional function.