[The effect of disopyramide of left ventricular function: an echocardiographic study of the extent and time course...

Seven healthy volunteers were evaluated for changes in left ventricular function after a therapeutic intravenous dose of Disopyramide (2 mg/kg, maximum 150 mg given over 5 min) and, subsequently, under oral maintenance therapy (200 mg every 6 h for 3 days). Parameters of left ventricular function were determined by Echocardiography. Measurements were taken before injection, 5--25 min after intravenous Disopyramide in intervals of 5 min and 120 min after the last oral dose of the drug. Peak changes occurred 5 min after termination of injection and included increases in mean arterial pressure (10%), heart rate (22%) and endsystolic ventricular diameter (30%) and decreases in percentage (43%) and mean velocity (36%) of diameter shortening, decreases of systolic thickness and percentage of thickening of left posterior wall (27 and 43% respectively) and of interventricular septum (15 and 22% respectively) as well as a decrease of the relative thickness of left ventricular wall (40%) and of left posterior (36%) and septal (39%) amplitude. After 20 min changes in all parameters were significantly less than 5 min after injection but still significantly greater than under oral maintenance therapy. After 25 min measurements differed from those under oral Disopyramide only slightly. At both times, however, all parameters were significantly different from control values. Thus, Disopyramide given intravenously and orally in therapeutic dosage is a potent myocardial depressant in man. As the acute negative inotropic effect of intravenous Disopyramide might be of clinical importance in patients with decreased myocardial function a slow injection over 15--20 min and a dose reduction is recommended in these cases.