A 65-year-old man has developed shortness of
breath with exertion several weeks after experiencing a viral illness. This is
accompanied by swelling of the feet and ankles and increasing fatigue. On physical
examination he is found to be mildly short of breath lying down, but feels better
sitting upright. Pulse is 105 and regular, and blood pressure is 90/60 mm Hg. His lungs
show crackles at both 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 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
Although it is believed that the primary defect
in early systolic heart failure resides in the
excitation-contraction coupling machinery of the heart, 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 13–1 Drug Groups Used in Heart Failure. |Favorite Table|Download (.pdf)
Table 13–1 Drug Groups Used in Heart Failure.
|Chronic heart failure||Acute heart failure|
|Aldosterone receptor antagonists||Vasodilators|
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