Circulatory response to prenalterol in normal subjects and in patients with primary congestive cardiomyopathy

Experimental pharmacology indicates that prenalterol is a selective beta 1-adrenoceptor activator. In 5 normal individuals, 15 minutes after the drug (infused at a dose of 15 micrograms/kg over 5 min) the following circulatory changes were seen: a) increase of cardiac index (+31%), heart rate, stroke index, systolic aortic pressure, left and right ventricular mean rate of ejection and mean rate of the pressure rise in either ventricle during the pre-ejection phase; b) reduction of systemic vascular resistance (-18%), appearance, built-up and disappearance times in the left ventricular dye dilution curves. Pulmonary systolic, diastolic and wedge pressures and vascular resistance did not vary consistently. The circulatory effects persisted almost unchanged 30 minutes after the infusion. In a group of 5 patients with heart failure due to primary congestive cardiomyopathy, refractory to conventional therapy, the haemodynamic response to prenalterol (infused at a dose of 30 micrograms/kg over 5 min) was qualitatively similar to that of normal subjects in 3 cases. In 2 other patients cardiac performance deteriorated. The reasons for this paradoxical effect were not identified. These preliminary results suggest that prenalterol is a p...Continue Reading