Causes of Heart Failure
Heart failure results from progressive process of degeneration. Many heart diseases can contribute to the development of heart failure: coronary artery disease, cardiomyopathy (disease of heart muscle), hypertension (high blood pressure) and heart valve disease. Generally speaking, each condition can be a cause of heart failure by:
- Limiting the heart's ability to pump blood.
- Reducing the quantity of blood that fills the chambers of the heart.
- Over-filling the heart's ventricles (pumping chambers) with blood.
Coronary artery disease, cardiomyopathy, hypertension and heart valve disease are the leading causes of heart failure.
Coronary Artery Disease
In the U.S., the most common cause of heart failure is coronary artery disease (also called coronary heart disease, or atherosclerosis). The disease is found in approximately two out of every three heart failure patients.
With coronary artery disease, the inner lining of an artery develops a buildup of plaque, fats, cholesterol, calcium and other artery-blocking substances.
As plaque narrows and hardens an artery, it interferes with blood flow to the heart. This weakens the heart, simply because it's used less frequently.
Cardiomyopathy denotes any form of heart muscle weakness, where the heart cannot pump properly. The walls of the heart can become rigid or inflamed — and therefore unable to pump enough blood out of the heart's ventricles.
Cardiomyopathy can be:
- Dilated (congestive): This is the most common form of cardiomyopathy. The heart cavity becomes enlarged and stretched. It may result from an unknown cause, an inflammatory process (such as myocarditis) or alcohol abuse.
- Hypertrophic: The muscle mass of the left ventricle enlarges. In one form of the disease, the septum (wall) between the two ventricles (pumping chambers) becomes enlarged and obstructs the blood flow from the left ventricle. In the other form of the disease, the enlarged muscle doesn't obstruct blood flow.
- Restrictive: The myocardium (muscle tissue of the ventricles) becomes excessively rigid, and ventricles are less able to fill with blood between heartbeats. Restrictive cardiomyopathy typically affects the elderly.
Also known as high blood pressure, hypertension adds to the heart's workload. Because the heart must work harder to circulate blood throughout the body, the muscle fibers of the heart enlarge (hypertrophy), which may impair the ability of the heart to fill up at diastole (when the heart is at rest, between heartbeats).
Sodium intake is a primary contributor to hypertension, as it can cause water to build up in your blood vessels.
Heart Valve Disease
Heart valves ensure that blood flows in one direction. When a heart valve fails, blood has a harder time moving forward. Pressure within the heart increases as the heart works harder.
Contributors to heart valve disease are:
- Aortic stenosis: The aortic valve does not open completely.
- Aortic regurgitation (or aortic insufficiency): The aortic valve weakens or balloons, and cannot close completely, and blood flows back into the heart.
- Mitral regurgitation: The mitral valve cannot close completely, and blood flows back into the heart.
Other Risk Factors of Heart Failure
Other factors can increase the risk of heart failure. They include:
- Past heart attack.
- Abnormal heart rhythms.
- Congenital heart disease (heart defect present at birth).
- Thyroid problems, leading to an increased metabolic rate.
- Iron overload.
- Severe anemia.
- Hypoxia (when the blood fails to deliver enough oxygen to heart tissue).
- Electrolyte abnormalities (low sodium, potassium or magnesium in the blood, possibly due to use of a diuretic).
- Being overweight.
- Alcohol or drug abuse.
- Certain types of chemotherapy.