Cardiac depression by intravenous disopyramide in patients with left ventricular dysfunction.

The hemodynamic effects of disopyramide phosphate were studied in nine patients with left ventricular dysfunction. After control measurements, administration of a 2 mg/kg bolus of disopyramide phosphate over 5 or 15 minutes was followed by a 20 minute 0.4 mg/kg/hour infusion and a 15 minute recovery period. Response to the 5 and 15 minute bolus injection was similar. Maximum hemodynamic effects occurred immediately after the bolus was given; there were decrements in systolic pressure (142 to 124 mm Hg)(p less than 0.005), cardiac index (2.5 to 1.8 liters/min/m2)(p less than 0.001) and stroke index (29.4 to 20.6 ml/beat/m2)(p less than 0.001), and increases in right atrial pressure (9 to 12 mm Hg)(p less than 0.005) and total peripheral resistance (21.2 to 25.7 U)(p less than 0.005). Two studies had to be terminated after the bolus was given due to profound hemodynamic deterioration. In the remainder, the systolic pressure returned to control by the end of the infusion, whereas the mean arterial pressure increasd significantly (92 to 96 mm Hg)(p less than 0.01). Little further change in mean arterial pressure, cardiac and stroke index, and total peripheral resistance occurred during the recovery period. These data indicated that intravenous disopyramide phosphate is a potent cardiac depressant when given over 5 to 15 minutes to patients with left ventricular dysfunction. It is concluded that disopyramide should not be administered to such patients unless conventional therapy fails. In such circumstances it should be used with extreme caution and careful monitoring.