According to the American Heart Association, heart failure affects about 5 million Americans, with more than half a million new cases diagnosed every year. Interestingly, while the incidence of other cardiac diseases remains stable or varies only slightly, the incidence of heart failure has increased significantly over the last three decades. This is because of the aging population and physicians’ increased ability to treat other cardiac diseases. In the 1970s, high blood pressure was the leading cause of heart failure. Today, coronary artery disease is the leading cause because of the increased survival due to treatments such as bypass surgery and balloon angioplasty. In spite of its name, heart failure does not mean the heart has completely stopped, which is the case when someone has gone into cardiac arrest. Heart failure means the heart is not operating efficiently and therefore must work harder to make up for the shortcoming. For example, the heart may pump more frequently to compensate for its weakened pumping ability, or the size of its chambers may increase, especially the left ventricle.
The longer the heart must overwork to compensate for its shortcomings, the more its pumping ability is damaged and the more likely that serious pumping failure will result. Before a pumping failure occurs, however, various physical changes may take place in the heart and throughout the body as a result of the heart failure. They include:
- Remodeling. This significant physical change occurs with heart failure. Remodeling is most notably characterized by enlargement and thinning of the left ventricle. This results in an increased use of oxygen, a greater degree of mitral valve regurgitation and decreased ejection fraction. The process is a complex one. Contributing factors include the release of hormones in response to inflammation caused by heart failure and certain genetic factors that affect how the heart reacts to disease or injury. Whatever the causes, left ventricular remodeling sets in motion an unhealthy domino effect, as progressive damage to heart cells leads to reduced cardiac output and more severe heart disease. This weakening may be “global,” as in cardiomyopathy, or regional, affecting only part of the left ventricle.
- Hypertrophy of the heart walls. The heart walls may thicken in an attempt to strengthen their pumping ability.
