Chronic Pump Failure

Chronic pump failure, a late stage of coronary-artery disease, results from the destruction of myocardial cells by the recurrent ischemia. In many cases ischemic chest pain is no longer present. Four mechanisms may produce chronic pump failure. (1) A large, transmural myocardial infarction (often leading to left ventricular aneurysm) may affect cardiac function despite survival and recovery from cardiac arrest, so that heart failure persists. (2) Multiple attacks of myocardial infarction can gradually destroy enough heart

muscle to cause chronic cardiac failure. (3) Small areas of ischemic damage to the heart muscle, regardless of the presence of myocardial infarction or angina pectoris, may cause heart failure imitating cardiomyopathy (see chap. 10). (4) Mitral insufficiency produced during myocardial infarction may overload the circulation and cause chronic heart failure.

The first two mechanisms account for most cases of chronic pump failure. The actual impairment of cardiac performance does not necessarily determine the amount of disability caused by the heart failure. Despite a low ejection fraction indicative of serious damage, the patient may continue a life free from symptoms, particularly if his or her life-style does not involve strenuous activity. Gradual resumption of activities after myocardial infarction and caution exercised thereafter may prevent the development of dyspnea and other manifestations of heart failure. Nevertheless, significant impairment of cardiac function indicates potential problems even if symptoms are minimal or absent, and the prognosis in such cases is guarded, particularly since patients with impaired left ventricular function are prone to life-threatening ventricular arrhythmias.

Symptomatic patients with chronic pump failure due to coronary-artery disease respond to standard therapy, which may control disability for long periods, especially if the patient is free from angina pectoris. A stable functional impairment of cardiac function without further evidence of ischemia may, with optimal medical management, permit a long life with only a minor effect on its quality. Many other patients, however, suffer from serious disability, developing major complications and even end-stage heart failure, the only remedy for which is cardiac transplantation.