A person is said to be in heart failure when their heart cannot pump blood at the rate needed to maintain normal metabolism.

Symptoms include respiratory distress (dyspnea), especially when it is worsened by lying down (orthopnea), fatigue, weakness, episodes of severe shortness of breath at night (paroxysmal nocturnal dyspnea). Edema, especially of the legs, may occur. Enlargement of the heart (cardiomegaly) is one of the criteria for diagnosis.

In most cases when the term is used, especially when given as a cause of death, congestive heart failure (CHF) is meant.

Treatment can improve the condition by:

  • removing precipitating causes and treating underlying causes
  • increasing the efficiency with which the heart muscle pumps
  • decreasing cardiac work load by increasing pre-load and decreasing after-load
    • see vasodilators, diuretics, ACE inhibitors.

The term heart failure is frequently misused, especially when given as cause of death: it is not synonymous with "cessation of heartbeat".