ACUTE EFFECTS OF CONVENTIONAL ORAL DOSE OF DISOPYRAMIDE ON LEFT ATRIAL AND VENTRICULAR FUNCTIONS

Disopyramide, an antiarrhythmic drug, is known to impair cardiac funct ion, but acute cardiac effects of conventional oral dose of disopyrami de are not well known. To examine the extent of acute cardiac effects of daily oral dose of disopyramide, we gave 150 mg of disopyramide to thirteen patients with normal or impaired cardiac function, and observ ed cardiac function on an hourly basis for 3 hours after baseline peri od. The serum level of disopyramide reached a therapeutic level (2.0-5 .0 mug/ml) mostly 1 hour after administration. Doppler-echocardiograph ically determined left ventricular ejection fraction, and the ratio of the peak early filling velocity to the peak atrial filling velocity i n left ventricular inflow velocity remained unchanged throughout the e xperimental period. Other hemodynamic variables, such as blood pressur e and heart rate remained unchanged. We conclude that daily oral dose of disopyramide appears to have no significant effects on cardiac func tion after administration. Disopyramide seems to be safe and may not b e necessarily withheld from patients who need it, when hemodynamic var iables are to be measured.