Hemodynamic effects of disopyramide at rest and during exercise in normal subjects

The hemodynamlc effects of disopyramide phosphate, 2.0 mg/kg body weight, given intravenously over a period of five minutes were studied at rest and during exercise in ten patients without clinical or anglographlc evidence of heart disease. Following disopyramide, the resting cardiac index was lower (4.0 ± 0.6 vs 4.3 ± 0.6 iners/min/m2, mean ± 1 SO, P <0.05), while left ventricular end-dlastollc pressure (16 ± 4 vs 11 ± 4 mm Hg, P <0.001), pulmonary arterial (PA) mean pressure (20 ± 5 vs 17 ± 5 mm Hg, P <0.05), and brachlal arterial (BA) mean pressure (105 ± 8 vs 96 ± 7 mm Hg, P <0.05) were higher than the pre-infuslon resting values. During exercise, there was no change in left ventricular end-diastollc pressure while cardiac index rose from 4.0 ± 0.6 to 6.5 ± 0.6 itters/mln/m2 (P <0.001) and left ventricular stroke work index increased from 62 ± 19 to 84 ± 22 gm/beat/m2 (P <0.001). The normal hemodynamlc response during exercise after disopyramide despite the apparent depression of left ventricular function at rest probably reflects the positive inotroplc effect of enhanced sympathoad-renergic activity.