What are the different forms of heart failure?
Doctors usually classify heart failure based on which heart function or which side of the heart is most affected by the condition, regardless of the specific disease processes that may have caused it. Heart failure may involve problems with the chambers contracting to pump out blood ( systolic heart failure) or problems with the chambers expanding to fill with blood ( diastolic heart failure). It may affect only the right ventricle ( right-sided heart failure) or the left ( left-sided heart failure), or both.
Every beat of the heart consists of two actions: contraction ( systole) and relaxation ( diastole). When the heart contracts, the lower chambers of the heart (ventricles) pump out blood into the lungs and the rest of the body. When the heart relaxes and expands, the ventricles fill completely with blood.
Adapted from The Merck Manual of Diagnosis and Therapy, Edition 18, edited by Mark H. Beers. Copyright 2006 by Merck & Co., Inc., Whitehouse Station, NJ. Available at: http://www.merck.com/mmpe. Accessed (12/08).
Systolic heart failure is the result of a pumping problem (systolic dysfunction), caused by the ventricle losing its ability to contract normally because the heart muscle has become weak. When this happens, the heart can't pump with enough force and not enough blood is pushed into the circulation. Click here for more info about the diagnosis, treatment, and prognosis of systolic heart failure.
Diastolic heart failure is the result of a filling problem (diastolic dysfunction), caused by the ventricle losing its ability to relax normally because the heart muscle has become stiff. When this happens, the heart can't fill with enough blood, resulting in too little blood being pumped back out into the circulation. Diastolic heart failure is more common in women than men.20-23 Click here for more info about the diagnosis, treatment, and prognosis of diastolic heart failure.
Most people with heart failure experience some degree of both blood-pumping and blood-filling problems.1, 25 Doctors usually classify heart failure based on which problem is worse.24
Left-sided and Right-sided Heart Failure
Left-sided heart failure is the most common type of heart failure.1 The left ventricle on the lower left side of the heart is the main pumping chamber. When it fails, oxygen-rich blood is not pumped to the rest of the body; instead, it can back up into the left atrium and into the lungs, where it builds up. Left-sided heart failure causes fatigue because the body is not receiving enough blood and shortness of breath because of the buildup of fluid (congestion) in the lungs.
Right-sided heart failure usually happens as a result of left-sided heart failure. As the failing left ventricle causes blood to build up in the lungs, the right ventricle finds it harder and harder to pump blood to the lungs to pick up oxygen. Less commonly, right-sided heart failure can also occur on its own, for example, when caused by lung disease (such as emphysema) or heart valve problems. Right-sided heart failure can cause blood to back up in the veins, resulting in swelling in the legs, ankles or belly, and can lead to shortness of breath when the belly is enlarged. Right-sided heart failure can also cause fatigue when the left ventricle doesn't fill with enough blood and can't supply the body with enough oxygen-rich blood.
For more information on heart anatomy and how the heart works, see The Heart & Circulation.