Chronic obstructive pulmonary disease (COPD) eventually takes a toll on the heart because the heart and lungs function as a unit. Lungs that don't work well stress the heart. As a result, people with COPD can develop heart failure.

After blood becomes oxygenated in the lungs during breathing, it travels to the heart. The heart's left ventricle pumps oxygenated blood into the arteries, which distribute oxygen to the tissues and organs of the body. The heart's right ventricle, on the other hand, pumps returning, deoxygenated blood from the veins into the lungs so it can become oxygenated again.

In COPD, airway obstruction and damage to the lung's air sacs lower oxygen levels. The lung's blood vessels react by getting smaller, making it harder for the right ventricle to pump blood into them. This overworks the right ventricle, and over time the heart muscle walls thicken. In the heart, unlike in the rest of the body, thicker muscle isn't a good thing. Instead, the right ventricle doesn't pump very effectively, and blood gets backed up in the veins. This is called right heart failure. It is not the same type of heart failure caused by a heart attack or high blood pressure, but it can cause similar symptoms, including swelling in the legs and abdomen.

If you already have heart disease, such as coronary artery disease, and you develop COPD, your heart will be very sensitive to low blood oxygen levels. It is therefore very important to treat and monitor your COPD. Also, people with COPD are prone to abnormal heart rhythms, such as atrial fibrillation.