Importance of venodilation during long-term vasodilator therapy of chronic left ventricular failure.

Vasodilators with different sites of action are used for long-term therapy of congestive heart failure, and selection of agents based on acute hemodynamic effects has been recommended. We compared the acute hemodynamic effects (by Swan-Ganz catheterization) and long-term responses (maximal oxygen uptake during exercise) associated with isosorbide dinitrate, a predominant venodilator, captopril, an arterial and venous dilator, and minoxidil, an arterial dilator, in 22 patients with congestive heart failure. In eight patients isosorbide dinitrate reduced pulmonary wedge pressure by 29% +/- 8% acutely (p less than .001) without significantly changing cardiac index or systemic vascular resistance. In eight patients captopril acutely reduced pulmonary wedge pressure by 42% +/- 22% (p less than .001) and systemic vascular resistance by 27% +/- 12% (p less than .01), while raising cardiac index by 19% +/- 18% (p less than .02). In six patients minoxidil raised cardiac index acutely by 38% +/- 30% (p less than .05) and reduced systemic vascular resistance by 35% +/- 12% (p less than .05) without changing pulmonary wedge pressure. After 2-5 months vasodilator administration maximal exercise oxygen uptake was increased by 7 +/- 3 ml/min/kg on isosorbide dinitrate (p less than .01), by 3 +/- 2 ml/min/kg on captopril (p less than .01), and by only 1 +/- 2 ml/min/kg on minoxidil (ns). Thus exercise capacity improved only during administration of drugs with venodilating action, failing to change during treatment with the arterial dilator despite a reduction in systemic vascular resistance. Predominantly arterial dilators alone may not be suitable for long-term vasodilator therapy for heart failure, and the regimens used should include venodilating agents.