Medline Plus states that coronary artery disease, high blood pressure and diabetes are the leading causes of heart failure. Heart failure occurs when the heart is unable to pump enough blood to supply the rest of body. It is a chronic, or long-term, disease that an estimated 5.7 million Americans are living with, states the American Heart Association. Heart failure can be described related to the function of both sides of the heart or on its underlying cause.
Systolic Heart Failure
The condition in which the heart becomes too weakened to pump enough blood to the body is called systolic heart failure. Carol Porth, in "Essentials of Pathophysiology: Concepts of Altered Health States," notes that systolic heart failure occurs as a result of the decreased strength of the heart's contractions. The heart also does not pump an adequate amount of blood, called the ejection fraction, out of the heart in this condition. Ejection fraction refers to the amount of blood being pumped out of the heart with each heart beat or contraction. The normal heart pumps out 65 percent of the blood in the ventricles. This amount is lower in systolic heart failure.
Diastolic Heart failure
The Cleveland Clinic suggests that in diastolic heart failure, the ejection fraction is normal but the heart does not fill up with adequate amounts of blood owing to an inability to stretch. When the heart does not stretch, blood backs up into various parts of the body, such as the lungs and the limbs. Diastolic heart failure is caused by any condition that restricts blood flow into the heart---for example, narrow heart valves, a delay in the heart's ability to relax and fill with blood as seen in aging and a decrease in the size of the heart chambers related to an increase in muscle thickness, a condition called myocardial hypertrophy.
Left-Sided Heart Failure
The left side of the heart receives blood from the lungs and then ejects it to the body through the aorta. Blood flows from the lungs to the left atrium---a top chamber of the heart---which in turn supplies blood to the left ventricle, which is a lower chamber of the heart. The left ventricle supplies blood to the rest of the body through the aorta. In left-sided heart failure, the ability of the left ventricle to eject blood into the aorta is impaired. Therefore, the heart pumps less blood out to the body, and more blood remains in the left ventricle. This blood then backflows into the lungs resulting in pulmonary congestion, an accumulation of fluid in the lungs.
Right-Sided Heart Failure
Blood returning to the heart from the body is low in oxygen, or deoxygenated. This blood flows from the rest of the body to the right atrium. From there, it goes to the right ventricle and then into the lungs for oxygenation. In right-sided heart failure, the right side of the heart is unable to transfer enough blood to the lungs. Consequently, the blood flows back to the rest of the body and causes swelling in places like the legs and ankles.
References
- American Heart Association: Heart failure
- Medline Plus: Heart Failure
- "Essentials of Pathophysiology: Concepts of Altered Health States"; Carol Porth; 2007
- Heart Healthy Women: Types of Heart Failure
