THE EFFECT OF NIFEDIPINE ON VENTRICULOARTERIAL COUPLING IN OLD MYOCARDIAL-INFARCTION

The effect of nifedipine on ventriculoarterial coupling was examined i n 8 patients with old myocardial infarction who showed a depressed eje ction fraction (37+/-7%). Left ventricular (LV) pressure and LV volume were determined simultaneously by micromanometer and conductance cath eter, respectively. We measured the slope (Ees) of the end-systolic pr essure-volume relation during transient inferior vena caval occlusion, the slope (Ea) of the end-systolic pressure-stroke volume relation, t he ratio of Ea to Ees (Ea/Ees), and the work efficiency (the ratio of external work to the systolic pressure-volume area) at baseline and af ter the sublingual administration of nifedipine (10 mg). Nifedipine sl ightly increased the heart rate from 71+/-14 to 78+/-17 beats/min. Alt hough nifedipine had little effect on Ees (2.54+/-0.68 vs 2.47+/-0.62 mmHg/ml/m(2), ns), it significantly decreased Ea from 3.47+/-1.16 to 2 .37+/-0.54 mmHg/ml/m(2). Consequently, Ea/Ees decreased from 1.42+/-0. 47 to 0.97+/-0.31 and work efficiency increased from 48+/-12 to 59+/-1 3% after nifedipine administration. These data suggest that nifedipine reduces afterload (Ea) and improves left ventriculoarterial coupling without depressing left ventricular contractility in patients with fai ling hearts due to old myocardial infarction.