Vasodilators in acute heart failure.

Most patients with acute heart failure present with increased left ventricular filling pressure and high or normal blood pressure; only a minority present with cardiogenic shock. In this context, therapy with vasodilators in the acute setting can improve both hemodynamics and symptoms. Vasodilators are usually given in conjunction with diuretics, although much of the acute effect of loop diuretics may be due to venodilation. Currently available agents include nitroglycerin, nitroprusside, and nesiritide. Nitroglycerin relieves pulmonary congestion primarily through direct venodilation, but may dilate coronary arteries and increase collateral blood flow at higher doses, an effect desirable in patients with ischemia. Tachyphylaxis may develop, necessitating incremental dosing. The major adverse effects of nitrates are hypotension and headache. Nitroprusside is a balanced arterial and venous vasodilator with a very short half-life, facilitating rapid titration. Afterload reduction lowers blood pressure and can increase stroke volume. The major complications of nitroprusside therapy are hypotension, and toxicity from accumulation of cyanide or thiocyanate, usually in patients with renal insufficiency treated for more than 24 h. Nesiritide, a recombinant form of human B-type natriuretic peptide (BNP), is a venous and arterial vasodilator that may also potentiate the effect of concomitant diuretics. Hypotension is the most common side effect. In addition, meta-analyses have suggested that nesiritide may worsen renal function and decrease survival at 30 days compared to conventional therapies. Resolution of these concerns awaits completion of appropriately powered prospective clinical trials. Angiotensin-converting enzyme (ACE) inhibitors have vasodilatory effects, but intravenous infusion of enalapril within 24 h of ischemic chest pain is not recommended. Oral ACE inhibition may be used to reduce afterload in other settings if blood pressure permits. Use of calcium antagonists in acute heart failure is not recommended.