Cardiocirculatory actions of trimazosin and sodium nitroprusside in ischemic heart disease

Although postload-reducing drugs are effective vasodilators in chronic congestive heart failure, the clinical application of the approach to ambulatory patient management remains difficult. We compared the hemodynamic effects of the new oral systemic vasodilator trimazosin (TZ) with those of nitroprusside (NP). Both TZ (172 mg) and NP (46 μg/min) decreased mean blood pressure modestly (P < 0.001), while causing considerable decline in elevated left ventricular filling pressure (TZ from 30 to 24 mm Hg; NP from 31 to 20 mm Hg; both P < 0.001). TZ also raised the low cardiac index (CI) of 2.02 to 2.59 l/min/M² (P < 0.001), whereas NP elevated CI from 2.16 to 2.96 l/min/M² (P < 0.001). Both drugs lowered (P < 0.05) total systemic vascular resistance and pressure time/minute while enhancing (P < 0.01) stroke work index. The drugs diminished forearm venous tone (P < 0.02) and forearm vascular resistance (P < 0.01) concomitantly with elevation of forearm blood flow (P < 0.05). Thus, TZ induced qualitatively similar marked augmentation of cardiac function to that by NP. These encouraging hemodynamic findings indicate that TZ may be beneficial to patients undergoing ambulatory vasodilator therapy of severe chronic congestive heart failure.