[Hemodynamic changes caused by prazocin in patients with uncomplicated arterial hypertension]

Hemodynamic changes produced by prazosin were evaluated in 19 patients with mild non complicated essential hypertension using M mode echocardiography. Patients received an initial dose of the drug of 0.5 mg tid, which was augmented gradually. As a whole, arterial pressure was reduced significantly. Heart rate did not show changes. Telediastolic and stroke volumes augmented significantly (p less than 0.05) and consequently cardiac output was increased. Systemic vascular resistance decreased notably (p less than 0.01). Left ventricular function indexes (EF, % shortening, Vcf) were not modified at all. These findings suggest that prazosin is a good antihypertensive drug and its actions upon the different hemodynamic parameters in normal and non complicated hypertensive patients are complex. Generally, it decreases systemic vascular resistance, without modification of contractility. Decreases in afterload were evident and something interesting, in contrast with other papers, is the demonstration of an augmented telediastolic volume, which indicates that the venodilatator effect with the consecutive decrease in blood return to the heart is masked by other effects. Nevertheless, it is necessary to perform a more detailed study with more sensitive methods in order to elucidate the complex hemodynamic interactions produced by prazosin in patients with mild non complicated essential hypertension.