The Effect of Vasodilator Therapy on Systolic and Diastolic Time Intervals in Congestive Heart Failure

Abstract

To determine the effects of vasodilator drugs on systolic and diastolic time intervals in patients with congestive heart failure, these noninvasive measurements were made in 50 patients with moderately severe disease before and after vasodilator therapy. These data were compared with direct hemodynamic measurements obtained simultaneously from a flow-directed triple-lumen pulmonary artery catheter placed in each patient. Oral vasodilators included isosorbide dinitrate 20 mg (n-8), hydralazine 75 mg (n-8), and 100 mg (n-8), and first-dose prazosin 2 mg (n-8) and 5 mg (n-8). Ten additional patients received intravenous dose-response infusions of isosorbide dinitrate, nitroglycerin, and nitroprusside. Increases in cardiac output and stroke volume effected a decrease (improvement) in the systolic time interval parameter of ventricular performance, PEP/LVET. The correlation coefficient for vasodilator-induced changes in cardiac output vs changes in PEP/LVET was -0.82 (P less than 0.05) and for changes in stroke volume and PEP/LVET was -0.75 (P less than 0.05). In general, the diastolic time period was not significantly affected by these drugs. The systolic time intervals are a simple and useful method for evaluation of vasodilator therapy in patients with congestive heart failure.