Abstract
<h2>Abstract</h2> The effects of verapamil, 0.145 mg/kg body weight, administered intravenously in a bolus injection followed by 0.005 mg/kg per min, on cardiovascular hemodynamics and on ventricular ejection fraction, determined with gated cardiac blood pool scanning, were studted in 25 patients, 8 with acute myocardial infarction and 17 with symptomatic coronary artery disease who were undergoing diagnostic cardiac catheterization. The mean (± standard deviation) plasma verapamil level, determined with a gas liquid chromatographic technique utilizing a nitrogen detector, was 161 ± 47 <i>ng</i>/<i>ml</i> (n = 8) during steady state conditions of drug infusion. In 15 patients with stable coronary artery disease having a normal or moderately reduced ejection fraction, verapamil reduced mean arterial pressure (−16 <i>percent</i>, <i>probability</i> [p] < 0.001), systemic vascular resistance (−23 <i>percent</i>, p < 0.001), stroke work index (−13 <i>percent</i>, p < 0.02), with no significant change in pulmonary vascular resistance, ejection fraction or heart rate; cardiac index was increased (+11 <i>percent</i>, p < 0.001) as was the stroke volume index (+7 <i>percent</i>, p < 0.01) and mean capillary wedge pressure (+10 <i>percent</i>, p < 0.01). In the seven patients with uncomplicated infarction, there was no effect on ejection fraction, heart rate or pulmonary vascular resistance. There was a decrease in systemic vascular resistance (−22 <i>percent</i>, p < 0.01) and mean arterial pressure (−16 <i>percent</i>, p < 0.01) with an increase in cardiac index (+27 <i>percent</i>, p < 0.05), stroke volume index (+4 <i>percent</i>, p < 0.05) and mean capillary wedge pressure (+17 <i>percent</i>, p < 0.02). In three patients, one wlth acute infarction and two with coronary artery disease, having a severely reduced ejection fraction and elevated mean capillary wedge pressure (20 mm Hg or greater), mean arterial pressure decreased markedly with a fall in stroke volume index and an abrupt increase in the mean pulmonary capillary wedge pressure. These findings were associated with clinical evidence of heart failure and dyspnea. It is concluded that (1) in patients with cardiac disease having a mild to moderate decrease in left ventricular ejection fraction accompanied by a normal or mildly elevated mean pulmonary capillary wedge pressure, the intrinsic depressant effect of verapamil is offset almost entirely by its potent vasodilator proporties, but (2) in patients with a severely reduced ejection fraction and a high pulmonary capillary wedge pressure, the depressant effects of the compound become clinically apparent with sudden further increases in pulmonary capillary wedge pressure and a decrease in stroke volume and mean arterial pressure.
Published Version
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