Why is it sometimes called congestive heart failure?
The main problem with heart failure is usually that the pumping function of the heart is diminished. To compensate, the heart can increase the amount of blood pumped with each beat by increasing the blood pressure in the heart. This increased blood pressure in the heart can cause blood to back up into the lungs and other parts of the body, causing watery fluid from the bloodstream to leak out into the airspace of the lungs. Over time, your lungs and other parts of your body may become congested with this leaking fluid.
In addition, your body also tries to compensate for your heart failure by retaining salt and water, with the goal of increasing the amount of blood in your circulatory system. This extra fluid adds to the congestion inside your body.
The congestion that results from heart failure is what causes the classic symptoms of heart failure, including shortness of breath and swelling in your abdomen and legs. For many people with heart failure, when their conditions get worse, symptoms get worse as well.
What causes the congestive aspects of heart failure?
Several factors contribute to worsening of heart failure:
- The heart cannot adequately pump the blood forward, and blood in the circulatory system begins to back up.
- Your kidneys retain salt and water and increase the blood volume.
- Increased pressure inside your blood vessels (particularly the veins) causes blood to leak out in the tissues of your body.
How does heart failure lead to congestion in my lungs? To compensate for your left ventricle's inability to pump blood efficiently, your heart increases the pressure of blood flowing into the ventricle to increase the filling of the ventricle. This increase in pressure inside your ventricle causes pressure to increase inside your left atrium, which in turn can cause an increase in pressure inside your pulmonary veins (vessels that carry blood from your lungs to your left atrium).
Increased pressure inside your pulmonary veins can cause increased pressure inside the tiny blood vessels (capillaries) inside your lungs, where your blood picks up fresh oxygen in exchange for carbon dioxide. These blood vessels have very thin walls that allow this exchange to take place. If too much pressure builds up inside the capillaries, it will force blood out of the vessels and into the breathing space of the lungs, resulting in lung congestion. Doctors refer to the buildup of fluid in your lungs as pulmonary edema.
How does heart failure lead to congestion in the rest of my body? Over time, the pressure buildup that results from heart failure will work its way back through your circulatory system. Pressure buildup in the lungs will lead next to pressure buildup in the pulmonary artery, which carries blood from the right side of the heart to the lungs. Pressure buildup in this artery can cause the right side of the heart to fail, which is the same reason that high blood pressure can cause the left side of the heart to fail. The failing right side will compensate in the same way as the failing left side: by increasing the pressure inside the heart.
As a result, pressure builds up inside the right ventricle, then in the right atrium, and then inside the veins that carry blood from the body back to the heart. This pressure buildup continues through your entire circulatory system, causing fluid to leak into many parts of your body, such as your ankles and feet. The fluid actually leaks from your capillaries, the same type of tiny blood vessels as the ones in your lungs. Your larger blood vessels branch into capillaries throughout your body. Edema from this fluid leakage can also affect your stomach, intestines, and liver. The resulting edema can be very uncomfortable because it can cause swelling of the legs and ankles, abdominal distension, and a feeling of early filling of the stomach, in addition to shortness of breath.
How does fluid retention add to the congestion? To make matters worse, even as blood is leaking out of your blood vessels, your kidneys are retaining extra fluid because they sense low blood pressure, which they interpret to mean that your heart is not pumping out enough blood. Since the heart is unable to efficiently pump the blood that is already in the circulatory system, this extra retained fluid makes congestion worse because most of the retained fluid also ends up backing up from the heart and leaking into the lungs or other organs.
| Author: | Robin Parks, MS | Last Updated: September 1, 2006 |
| Medical Review: | Caroline S. Rhoads, MD - Internal Medicine Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology | |
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