What is heart failure?
It does not mean your heart stops working. It means your heart is no longer as effective as it once was at pumping blood to meet the metabolic needs of your body.2
Does COPD cause heart failure?
COPD may cause right heart failure, left heart failure, or both. There are three theories that attempt to explain how this might happen.
To better understand these, you may want to read my post, “Your Lungs and the Cardiovascular System.”
- Right Heart Failure (RHF) is caused by diseased lungs. The right side of your heart receives unoxygenated blood from the body and pumps it through your lungs. COPD creates areas of your lungs that do not receive much oxygen. Supplemental oxygen will not remedy this problem because the extra oxygen molecules cannot get beyond the obstructed airways. Your body cannot solve the problem either, although it thinks it can by sending in more blood to the diseased areas. It does this by constricting blood vessels leading to them. As these diseased areas increase in number, your heart is forced to work extra hard to pump blood through diseased lungs, increasing your pulmonary blood pressure. Your heart is a muscle, so when it works extra hard, it becomes enlarged (hypertrophy). Hypertrophied arm and leg muscles are good, and make you strong and healthy. Hypertrophied heart muscle is bad, making it a poor pump. 1,2,3
- Left Heart Failure caused by Systemic Inflammation. The left side of your heart receives freshly oxygenated blood from your lungs and pumps it through your entire body. COPD is the result of an abnormal immune response causing an increase of inflammatory markers such as leukotrienes, cytokines and chemokines. They cause inflammation that damages airways (chronic bronchitis) and destroys lung tissue (emphysema). This theory accuses them of also causing inflammation of the lining of blood vessels, thereby causing systemic inflammation. This is thought to increase the development of coronary artery disease (CAD), which narrows blood vessels. Your left heart now has to work extra hard to pump blood through these diseased vessels, thereby increasing your blood pressure. After years of doing this, your left heart becomes hypertrophied. This makes your left heart a poor pump.2,3
- Left Heart Failure caused by COPD Overlap Syndrome. About 10-15% of people with COPD have Obstructive Sleep Apnea (OSA), a combination often referred to as “Overlap Syndrome.” OSA may cause hypoxemia, pulmonary hypertension, and right heart failure.(Egan) Chronic hypoxemia caused by OSA has also been linked to an abundance of inflammatory markers that in turn are thought to speed up the development of CAD, hypertension, and left heart failure.3,4
- Left heart failure may cause right heart failure. When right heart failure occurs by itself, it’s usually caused by a chronic lung disease like COPD, and is defined as cor pulmonale. Still, the most common cause of right heart failure is left heart failure. However, right heart failure may also lead to left heart failure. So, the symptoms are often overlapping. (2, 7)
Can heart failure be prevented?
Quitting smoking, and working with your doctor on creating a good COPD treatment regimen can help prevent the progression of COPD. Wearing CPAP at night if you have OSA has been shown to reduce your risk for developing heart failure.4
These are some of the basic theories of how COPD might cause heart failure. In my next post, I will describe the signs and symptoms of heart failure, when to seek help, and what some treatment options are.