Management of Acute Heart Failure

MANAGEMENT OF ACUTE HEART FAILURE

Acute heart failure occurs frequently in patients with chronic failure. Such episodes are usually associated with increased exertion, emotion, excess salt intake, nonadherence to medical therapy, or increased metabolic demand occasioned by fever, anemia, etc. A particularly common and important cause of acute failure—with or without chronic failure—is acute myocardial infarction.Patients with acute myocardial infarction are best treated with emergency revascularization using either coronary angioplasty and a stent, or a thrombolytic agent. Even with revascularization, acute failure may develop in such patients. Many of the signs and symp-toms of acute and chronic failure are identical, but their therapies diverge because of the need for more rapid response and the rela-tively greater frequency and severity of pulmonary vascular congestion in the acute form.

Measurements of arterial pressure, cardiac output, stroke work index, and pulmonary capillary wedge pressure are particularly useful in patients with acute myocardial infarction and acute heart failure. Such patients can be usefully characterized on the basis of three hemodynamic measurements: arterial pressure, left ventricu-lar filling pressure, and cardiac index. When filling pressure is greater than 15 mm Hg and stroke work index is less than 20 g-m/m², the mortality rate is high. Intermediate levels of these two variables imply a much better prognosis.

Intravenous treatment is the rule in acute heart failure. Among diuretics, furosemide is the most commonly used. Dopamine or dobutamine are positive inotropic drugs with prompt onset andshort durations of action; they are most useful in patients with severe hypotension. Levosimendan has been approved for use in acute failure in Europe, and noninferiority has been demonstrated against dobutamine. Vasodilators in use in patients with acute decompensation include nitroprusside, nitroglycerine, and nesiritide. Reduction in afterload often improves ejection fraction, but improved survival has not been documented. A small subset of patients in acute heart failure will have hyponatremia, presum-ably due to increased vasopressin activity. A V_1a and V₂ receptor antagonist, conivaptan, is approved for parenteral treatment of euvolemic hyponatremia. Several clinical trials have indicated that this drug and related V₂ antagonists (tolvaptan) may have a ben-eficial effect in some patients with acute heart failure and hypona-tremia. Thus far, vasopressin antagonists do not seem to reduce mortality.