Effects of ouabain on early ventricular relaxation in patients with acute myocardial infarction.

The effects of the administration of ouabain on the peak negative left ventriculat (LV) dP/dt were studied in 14 patients with acute myocardial infarction. Prior to administration of ouabain, negative LV dP/at was lower than previously reported for patients without coronary arterial disease. One hour after administration of ouabain, significant (P less than 0.05) increases in peak positive LV dP/dt and maximal velocity of contractile-element shortening and decreases in LV diastolic pressure were present. These changes were associated with small and insignificant increases in negative LV dP/dt. Early LV relaxation rate is impaired in patients with acute myocardial infarction; however, the reduction in LV diastolic pressures which occurs after administration of ouabain does not appear to be due to an increase in the rate of early LV relaxation but rather is probably related to improved contractility.