Learning About Heart Failure

Learning to live with heart failure may be easier if you understand what's happening inside the body. This section explains what happens when someone develops heart failure.

Heart failure can involve the heart's left side, right side or both sides. However, it usually affects the left side first. Each side is made up of two chambers: the atrium, or upper chamber; and the ventricle, or lower chamber. The atrium receives blood into the heart, and the ventricle pumps it where it needs to go. Heart failure occurs when any of these chambers lose their ability to keep up with the amount of blood flow.

What is left-sided heart failure?

Left-sided or left ventricular (LV) heart failure involves the heart's left ventricle (lower chamber). Oxygen-rich blood travels from the lungs to the left atrium, then on to the left ventricle, which pumps it to the rest of the body. Because this chamber supplies most of the heart's pumping power, it's larger than the others and essential for normal function.

If the left ventricle loses its ability to contract normally (called systolic failure), the heart can't pump with enough force to push enough blood into circulation. If the ventricle loses its ability to relax normally (diastolic failure) because the muscle has become stiff, the heart can't properly fill with blood during the resting period between each beat. This is an important distinction because the drug treatments for each type of failure are different.

In either case, blood coming into the left chamber from the lungs may "back up," causing fluid to leak into the lungs. (The technical term for this is pulmonary edema.) Also, as the heart's ability to pump decreases, blood flow slows down, causing fluid to build up in tissues throughout the body (edema). This excess fluid or congestion explains the term congestive heart failure, which you've probably heard before.

What is right-sided heart failure?

The right atrium receives the "used" blood that returns to the heart through the veins; then the right ventricle pumps it into the lungs to be replenished with oxygen. Right-sided or right ventricular (RV) heart failure usually occurs as a result of left-sided failure. When the left ventricle fails, increased fluid pressure is, in effect, transferred back through the lungs, ultimately damaging the heart's right side. When the right side loses pumping power, blood backs up in the body's veins. This usually causes swelling in the legs and ankles.

How quickly does heart failure develop?

Heart failure is usually a chronic disease. That means it's a long-term condition that tends to gradually become worse. By the time someone is diagnosed, chances are that the heart has been losing pumping capacity little by little for quite a while. At first the heart tries to make up for this by:

• Enlarging. When the heart chamber enlarges, it stretches more and can contract more strongly, so it pumps more blood.
• Developing more muscle mass. The increase in muscle mass occurs because the contracting cells of the heart get bigger. This lets the heart pump more strongly, at least initially.
• Pumping faster. This helps to increase the heart's output.

The body also tries to compensate in other ways. The blood vessels narrow to keep blood pressure up, trying to make up for the heart's loss of power. The body diverts blood away from less important tissues and organs to maintain flow to the most vital organs, the heart and brain. These temporary measures mask the problem of heart failure, but they don't solve it. This helps explain why some people may not become aware of their condition until years after their heart begins its decline. (It's also a good reason to have a regular checkup with your doctor.) Eventually the heart and body just can't keep up, and the person experiences the fatigue, breathing problems or other symptoms that usually prompt a trip to the doctor.