Causes of Heart Failure

A person who has experienced cardiac conditions that have damaged or weakened the heart may develop heart failure.

Heart failure can develop quickly after damage caused by a heart attack, or it can develop gradually after years of high blood pressure or coronary artery disease. A defective heart valve may cause heart failure. In this case, repair or replacement of the valve can often reverse heart failure.

How Heart Failure Develops

Over time, the heart can no longer keep up with even the normal demands placed on it. The heart muscle weakens, and the ventricles stretch (dilate) to the point that the heart can't pump blood efficiently throughout the body.

The failing pump causes blood and fluid to back up throughout the circulatory system — lungs, legs, feet and ankles — and the kidneys retain excess water and sodium. This buildup of fluid is the congestive part of heart failure. The lung congestion occurs only with left-sided heart failure with fluid backing up into the lungs. The most common cause of right-sided heart failure is left-sided heart failure. The extra pressure in the lungs is eventually passed on to the right side of the heart, which then fails — causing fluid to collect in the abdomen and lower extremities.