A 65-year-old man developed shortness of breath with exertion several weeks after experiencing a viral illness.* This was accompanied by swelling of the feet and ankles and increasing fatigue. On physical examination he is now found to be mildly short of breath lying down, but feels better sitting upright. Pulse is 105 bpm and regular, and blood pressure is 110/70 mm Hg. Crackles are noted at both lung bases, and his jugular venous pressure is elevated. The liver is enlarged, and there is 3+ edema of the ankles and feet. An echocardiogram shows a dilated, poorly contracting heart with a left ventricular ejection fraction of about 20% (normal: 60%). The presumptive diagnosis is dilated cardiomyopathy secondary to a viral infection with stage C, class III heart failure. What treatment is indicated?
Heart failure occurs when cardiac output is inadequate to provide the oxygen needed by the body. It is a highly lethal condition, with a 5-year mortality rate conventionally said to be about 50%. The most common cause of heart failure in the USA is coronary artery disease, with hypertension also an important factor. Two major types of failure may be distinguished. Approximately 50% of younger patients have systolic failure, with reduced mechanical pumping action (contractility) and reduced ejection fraction. The remaining group has diastolic failure, with stiffening and loss of adequate relaxation playing a major role in reducing filling and cardiac output. Ejection fraction may be normal (preserved) in diastolic failure even though stroke volume is significantly reduced. The proportion of patients with diastolic failure increases with age. Because other cardiovascular conditions (especially myocardial infarction) are now being treated more effectively, more patients are surviving long enough for heart failure to develop, making heart failure one of the cardiovascular conditions that is actually increasing in prevalence.
Heart failure is a progressive disease that is characterized by a gradual reduction in cardiac performance, punctuated in many cases by episodes of acute decompensation, often requiring hospitalization. Treatment is therefore directed at two somewhat different goals: (1) reducing symptoms and slowing progression as much as possible during relatively stable periods and (2) managing acute episodes of decompensated failure. These factors are discussed in Clinical Pharmacology of Drugs Used in Heart Failure.
Although it is believed that the primary defect in early systolic heart failure resides in the excitation-contraction coupling machinery of the myocardium, the clinical condition also involves many other processes and organs, including the baroreceptor reflex, the sympathetic nervous system, the kidneys, angiotensin II and other peptides, aldosterone, and apoptosis of cardiac cells. Recognition of these factors has resulted in evolution of a variety of drug treatment strategies (Table 13–1).
TABLE 13–1Therapies used in heart failure. |Favorite Table|Download (.pdf) TABLE 13–1Therapies used in heart failure.
|Chronic Systolic Heart Failure ||Acute Heart Failure |
|Diuretics ||Diuretics |