Selection of vasodilator drugs for patients with severe chronic heart failure: an approach based on a new classification.

Although vasodilator drugs are of proven worth in the management of patients with severe heart failure, a useful system of classification of vasodilator drugs has not yet been devised. The traditional system of classification based on the dominant arterial and/or venous sites of action as determined by limb plethysmography has major conceptual and practical limitations. This article discusses the merits of a new classification format based on pharmacological mechanisms of action. According to this new system, vasodilator drugs can be divided into two groups: (1) direct-acting agonists (hydralazine, minoxidil, nitrates and nitroprusside) which demonstrate dose-dependent responses and generalised vasodilator effects, and thus require invasive monitoring for dose titration; and (2) neurohumoral antagonists (prazosin, trimazosin, phentolamine, captopril and teprotide), whose effects are qualitatively and quantitatively independent of the dose administered, show marked regional heterogeneity and have characteristic temporal patterns of response. This new classification system permits the rational formulation of clinical recommendations concerning the choice of a vasodilator drug for patients with severe chronic heart failure. However, widespread application of this new classification system awaits the development of reliable means of identifying patients with neurohumoral-dependent vasoconstriction without the necessity of a therapeutic trial.