This blood, now oxygen-rich, returns through pulmonary veins to the left atrium in the heart where it is pumped back out to the body by the left ventricle. More commonly, the left side fails, causing systolic dysfunction , in which fluid backs up and accumulates in the lungs. Right-sided heart failure causes diastolic dysfunction , in which fluid entering the heart backs up, causing the veins in the body and tissues surrounding them to swell. Given the interconnected nature between the chambers of the heart, left-sided failure, which is the most common site for initial problems, may ultimately precipitate failure in the right side of the heart. When both sides are affected the condition is known as congestive heart failure.
Heart failure can occur in several ways.
The ventricle muscles of the heart may become thin and weakened so they cannot pump the blood with enough force to reach all the body's tissues. Mechanisms that the body uses to compensate for inefficient pumping action can, over time, change the architecture of the heart and finally lead to irreversible problems. Damage to the mechanisms that control the input to and output of blood from the heart is usually the last stage of one of several heart diseases. Heart failure can occur directly from one of these diseases or it can occur over time as the heart tries to compensate for the abnormalities caused by these conditions. The major cause of congestive heart failure is heart muscle damage done by coronary artery disease, which is the result of atherosclerosis, a buildup of cholesterol deposits on the walls of the arteries supplying the heart muscle with oxygen.