Efficacy of ambulatory systemic vasodilator therapy with oral prazosin in chronic refractory heart failure. Concomitant relief of pulmonary congestion and elevation of pump output demonstrated by improvements in symptomatology, exercise tolerance, hemodynamics and echocardiography.

Abstract

2. Powell WJ Jr, DiBona DR, Flores J, Leaf A: The protective effect of hyperosmotic mannitol in myocardial ischemia and necrosis. Circulation 54: 603, 1976 graphic end-diastolic dimension fell (5.7 to 5.4 cm, P < 0.001) while shortening fraction increased (27.6 to 30.2%, P < 0.005). Treadmill exercise duration increased from 209 to 317 seconds (P < 0.001). Symptoms diminished throughout the duration of follow-up (mean 94 days) with improvement in NYHA functional class (3.7 to 2.2, P < 0.001). Thus, prazosin possesses sustained nitroprusside-like balanced dilator actions on the systemic arterial and venous systems and is effective in the ambulatory management of chronic severe heart failure.agent are related to its equal relaxation of the vascular smooth muscle of both the peripheral resistance and the capacitance vessels.23 As the result of this balanced dilator action on the systemic venous and arterial beds, ventricular preload reduction is accompanied by decline in aortic impedance, thereby leading to relief of pulmonary congestion simultaneously with enhancement of cardiac output. However, attempts to continue the benefits of such balanced ventricular unloading therapy in ambulatory patients with chronic heart failure have been difficult because of the lack of an oral vasodilator drug with both arteriolar and venous relaxing properties. Thus the nitrates, which principally cause venodilation, are capable of reducing ventricular preload and pulmonary congestion3' 13,14,16,19,[23][24][25][26] but lack consistent effects on systemic impedance and therefore produce minimal alterations of cardiac output

Muscle metaboreflex-induced coronary vasoconstriction limits ventricular contractility during dynamic exercise in heart failure

“…Short-term clinical results have shown that prazosin therapy provides favorable hemodynamic responses such as reduced pulmonary venous congestion, improved end-diastolic and -systolic volumes, increased CBF, CO, and improved New York Heart Association functional class (4,6,9,11,17,22,41,43,57). However, these responses were attenuated in the long-term (11,17), and there was no improvement in mortality (9).…”

“…However, these responses were attenuated in the long-term (11,17), and there was no improvement in mortality (9). Another concern with the long-term clinical use of prazosin is the possible attenuation of ventricular preload below that of optimal filling pressure (6). The systemic effects of prazosin may also complicate its clinical usefulness.…”

Comparison of haemodynamic effects of oral hydralazine and prazosin hydrochloride in patients with chronic congestive heart failure.

“…With accumulated experience, it is apparent that though most vasodilators produce qualitatively similar haemodynamic effects, the magnitude of the responses may differ significantly. Recently, the haemodynamic effects of two vasodilators, hydralazine and prazosin, have been investigated in different groups of patients with chronic congestive heart failure and beneficial responses to both drugs have been reported (Chatterjee et al, 1976b;Franciosa et al, 1977;Miller et al, 1977;Awan et al, 1977). 'This work was supported in part by a NHLBI Program Project grant.…”

Pharmacotherapy of congestive heart failure

“…Results showed a significant decrease in the left ventricular end-diastolic dimension, significant increases in the mean velocity of circumferential fiber shortening (an index of left ventricular systolic function) and in exercise time, and significant improvement in New York Heart Association functional class. 9 The most damaging information concerning the efficacy of prazosin in left ventricular failure was provided by Packer and coworkers10in 1979. These investigators administered three consecutive 5-mg doses then one 10-mg dose of prazosin orally, waiting long enough between each dose (generally six to eight hours) for hemodynamic values to return to control levels.…”