Haemodynamic effects of prazosin in CHF.

The acute haemodynamic effects of oral prazosin have been studied, at cardiac catheterization, in 11 patients with CHF. In all patients there was a significant fall in left ventricular end-diastolic pressure, mean aortic and pulmonary artery pressure and systemic vascular resistance, 60 minutes after 3.5 mg of prazosin. There was no significant change in heart rate but there was a significant increase in cardiac index and left ventricular stroke work index. The patients received chronic therapy with prazosin one mg 3 times a day and CO was measured serially by the nitrous oxide whole body plethysmograph method. There was s sustained increase in cardiac index of 82% during the 8 week study period. Twelve months after the initial haemodynamic study 5 patients had improved sufficiently to return to normal work. A further 3 patients were improved symptomatically but were unable to return to their previous employment. Three patients died of a myocardial infarction. Prazosin has proved to be beneficial in CHF resistant to digitalis and diuretics.