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Heart Failure Overview

Benjamin McDonald, MD, edited by Ann Witt, MD

The term "Heart Failure" is used to describe a condition where someone's heart is unable to pump enough blood to support all of his or her body's organs, muscles and other tissues. The heart continues to work during heart failure, but not efficiently enough to adequately support the body's needs. Heart Failure is a major cause of hospitalization for people older than 65 years.

upset older manHeart failure can affect one or both sides of the heart. Recall that the heart is divided into four chambers, with each side of the heart containing an atrium and a ventricle. Blood collects in the atria, and is then pumped out by the ventricles. Ventricles can become defective in two different ways; they can either lose their ability to contract, or lose their ability to relax. When the ventricle loses its ability to contract it can no longer generate enough force to push the blood through the body effectively. When the ventricle loses its ability to relax, it can not open enough to fill completely, and the volume of blood available for pumping is drastically reduced. Either condition results in a decreasing rate of blood flow throughout the body's circulatory system which often leads to fluids backing up in various tissues (e.g, "edema").

Causes of Heart Failure

A variety of factors influence whether someone will develop heart failure. Some individuals who develop heart failure may have simply been born with a structural defect in a portion of their heart. Others develop the disease as a result of medical conditions (such as diabetes or high blood pressure) that have not been controlled. The major causes of heart failure include:

  • Coronary Artery Disease (atherosclerosis): This disease is caused by fatty plaque buildups that disrupt blood flow in the coronary arteries that supply blood to the heart itself. When the blood flow becomes blocked a heart attack occurs.
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  • Diabetes: Diabetes is a condition that occurs when your body cannot control your blood sugar levels and maintain them at a normal level. High blood sugar levels can cause damage to many organs such as the heart and kidneys. Individuals with diabetes are more likely to develop heart failure, and this risk is greater if blood sugar levels are not treated and controlled.
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  • Hypertension (high blood pressure): When pressure in the vessels of the circulatory system increases the heart must work harder to maintain adequate blood flow. Uncontrolled high blood pressure causes the heart muscle to become thicker and stiff, decreasing the heart's ability to relax and adequately collect blood for pumping.
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  • Heart Valve Dysfunction: When the valves separating the heart's chambers cannot open and close properly for any reason it causes the heart to need to pump harder so as to keep up with the body's demand for oxygen. The elevated strain this process places on the heart can lead to heart failure.
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  • Cardiomyopathy: Damage and weakening of the heart muscle can lead to reduced efficiency and heart failure. Cardiomyopathy has many causes including viral infections, alcoholism, autoimmune diseases (e.g., rheumatoid arthritis, lupus), high blood pressure, and heart attacks.
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  • Heart birth defects: Congenital (i.e., something that someone is born with) abnormalities in heart structures such as faulty valves or a deformity in the heart muscle can create heart failure.
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  • Lung Disease: When the lungs are damaged and they do not provide adequate oxygen for exhausted blood to pick up, the heart pumps faster so as to compensate, placing strain on the heart which can lead to heart failure.
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  • Thyroid disease: Thyroid hormone regulates the body's metabolic rate (the rate at which your body burns calories for energy). As thyroid hormone levels increase, a person's metabolic rate also increases. People with hyperthyroidism (too much thyroid hormone) have an increased metabolism, which will necessitate the heart pumping faster to supply enough oxygen to the body. Both too much and too little thyroid medicine can result in heart failure that usually is reversible with treatment.
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  • Arrhythmia (dysrhythmia): Arrhythmia is a condition in which the heart beats irregularly rather than rhythmically. This can mean that it either beats too fast, too slow, at a fluctuating pace, or it may skip regular beats. Arrhythmias interfere with normal blood flow. For example, if the ventricle is beating too quickly it will not have enough time to fill up with blood to pump to the rest of the body.