Heart failure is the common result of several different clinical conditions. Below, we highlight some of the more common causes.
Coronary artery disease/dead or dying heart tissue. Approximately two out of three cases of heart failure can be traced to coronary artery disease, the narrowing of the arteries that feed the heart muscle cells. When cholesterol-laden deposits form on the inside walls of the coronary arteries, thereís less space available for blood flow. The lack of adequate oxygen leaves the heart muscle starved for blood. Coronary artery disease also sets the stage for heart muscle damage from a heart attack, another cause of heart failure.
When one of the fatty deposits on the inside of the artery wall bursts open, the blood forms a clot, much the way the body would respond if you cut your finger. If a clot forms in one of the arteries that feed the heart muscle, it can cut off the flow of oxygen to the tissue that lies beyond the clot. This sudden stopping of blood flow to part of the heart muscle is called a myocardial infarction, or heart attack. In the aftermath of a nonfatal heart attack, heart tissue may be seriously damaged or dead, depending on how long blood flow was interrupted. The patches of compromised tissue may not be able to beat with the force needed to push blood through the body. Approximately a quarter of people who survive a heart attack develop heart failure within the next year.
High blood pressure (hypertension). Blood pressure is a measure of the force it takes to move blood through the vessels. The higher the pressure, the harder the heart must work. Just as the muscles in your arms build up when you lift weights, the heart muscle thickens in response to pumping against extra resistance. Instead of strengthening the heart, however, this bulking up does just the opposite. The thickened muscle consumes more oxygen. It also canít fully relax between contractions. The net effect is that the heart muscle gradually stops beating as forcefully as it should. High blood pressure precedes heart failure in 75% of cases. The risk of developing heart failure is considerably reduced if blood pressure is appropriately controlled, and this is one of the major reasons your doctor monitors your blood pressure closely over time.
Cardiomyopathy. This is a broad term used to describe a number of primary diseases of the heart muscle.
- Dilated cardiomyopathy. This type of cardiomyopathy is characterized by progressive heart enlargement and thinning of the ventricle walls. It can be brought on by an infection (typically a virus) or develop from long-term exposure to excessive alcohol use, cocaine, methamphetamines, or other toxins. Dilated cardiomyopathy may also evolve as the consequence of a familial (genetic) tendency or as a result of exposure to certain types of chemotherapy given for cancer treatment.
- Hypertrophic cardiomyopathy. This is an inherited disorder that results in abnormal thickening and scarring of the ventricle walls In some cases, the heart thickens sufficiently to obstruct the flow of blood out of the heart, creating risk for lightheadedness or passing out with exercise. The condition results in increased risk for serious heart rhythm problems and heart failure and is a major cause of sudden death in young people.
- Restrictive cardiomyopathy. In this condition, the heart muscle becomes extremely stiff, which prevents it from filling with blood properly. Sometimes, restrictive cardiomyopathy stems from inflammatory conditions that cause scarring of the heart muscle or the excessive deposition of iron or certain proteins (e.g. amyloid) in the heart.
- Pregnancy/ peripartum disease. Cardiomyopathy may also develop in the mother soon after childbirth, causing the heart to enlarge and its walls to weaken.
Heart valve damage. Faulty heart valves that donít open or close efficiently put additional strain on the heart. Disease, infection, heart attack, and wear-and-tear from aging can all cause damage to the valves. When a valve is narrowed, or stenotic, it doesnít open completely to let blood pass from the chamber. This causes pressure to build up in the heart. A leaky valve allows blood to travel backward between beats, forcing the heart to do double duty to keep blood moving forward.
Heart rhythm disturbances. An abnormally fast heartbeat can produce structural changes in the heartís left ventricle. One rhythm in particular, atrial fibrillation, is known to increase the risk of heart failure. However, treating this condition can slow or prevent the onset of heart failure symptoms.