congestive heart failure, inability of the heart to expel sufficient blood to keep pace with the metabolic demands of the body. In the healthy individual the heart can tolerate large increases of workload for a considerable length of time. Cardiac failure results from conditions, e.g., coronary artery disease, hypertensive heart disease (see hypertension), valvular insufficiency, and rheumatic heart disease, that interfere with the nutrition and oxygenation of the heart muscle itself. Congestive heart failure develops in 50% to 60% of patients with such disorders, and it can be either acute or chronic. If the heart has time to compensate, the heart muscle may become hypertrophic (enlarged); this is caused by structural changes that impede blood flow and impair the ability of the heart to relax. Eventually the great demand for oxygen by the heart muscle cells cannot be met, and cell death results. Either the left or right ventricle alone may fail first, although combined failure is most common and almost always eventually occurs. Left ventricular failure is marked by shortness of breath (dyspnea), often accompanied by cough; pulmonary congestion and edema are evident. Failure of the right ventricle produces systemic edema, reflecting hepatic and visceral engorgement. Diagnosis is often confirmed by echocardiography. Treatment of cardiac failure usually includes dietary changes, restrictions on physical activity, rest, oxygenation, measures to improve myocardial contractility, and correction of arrhythmias. Restriction on sodium intake and the administration of diuretics (the dosages of which depend on the patient's weight) are used to remove excess sodium and water from the body. Digitalis is often prescribed to increase the speed and force of cardiac contractions, and ACE inhibitors are used to decrease peripheral vascular resistance, making heart pumping easier and more effective.