The normal heart
Every part of your body needs oxygen. Your lungs take in oxygen when you breathe. It is the heart’s job to pump blood to the lungs to pick up oxygen, and then to pump this blood to every part of your body.
The heart has two independent pumping systems, one on the right side and one on the left side. Each of these systems has 2 chambers:
- An atrium (pronounced AY-tree-um). Atria is the word used to speak of more than one atrium.
- A ventricle (pronounced VEN-trick-ul)
The ventricles are the major pumps of the heart. The left ventricle is generally the strongest pumping part of the heart.
The heart’s atria and ventricles are connected by the heart valves. The valves are flaps that open and close to allow blood to flow from the atrium to the ventricle.
The atria are the upper chambers, and the ventricles are the lower chambers. The correct direction for blood flow is from the atrium into the ventricle.
The right side
The right side of the heart receives blood from the veins of the body. This blood already has done its work, delivering oxygen to the far sites of the body before returning to the heart.
The blood returns to the right atrium. This chamber expands to hold the blood. When there is enough blood, the tricuspid (try-CUSS-pid) heart valve allows the blood to flow into the right ventricle (the bottom part of the right side of the heart).
The right ventricle pumps the blood to the lungs. The blood needs to return to the lungs to pick up oxygen. When the pumping action triggers the pulmonary valve, it opens. This allows the blood to flow into the lungs.
In the lungs, the blood picks up oxygen and leaves carbon dioxide behind (which you breathe out). The blood, now rich in oxygen, is sent to the left side of the heart.
The left side
The left side of the heart receives blood from the lungs. This blood is now oxygen-rich. The blood enters the left heart from special veins coming directly from the lungs (pulmonary
veins).
The first chamber to receive the blood is the left atrium. As the atrium fills, the valve connecting the atrium and ventricle opens, and blood flows into the left ventricle.
The valve in this case is the mitral (MY-trul) valve. The left ventricle is the strongest pump of the heart. Once blood collects in the left ventricle, it contracts and the aortic valve opens. This allows blood to pass into the ascending aorta (ay-OR-ta), the major artery that supplies blood to the body. After the blood is used by the body, it returns to the right side of the heart, and the whole process begins again.
Blood flow with heart failure
In CHF (congestive heart failure), the heart muscle becomes weaker. When the heart muscle is weakened, it is less forceful in pumping blood throughout the body. Less blood moves out of the heart.
The body has several ways to try to keep the same amount of blood flow moving.
First, the heart’s chambers (the atria and ventricles) stretch to hold more blood. This does help keep blood moving, but only for a while.
Just like a balloon that is stretched again and again, the heart eventually loses its ability to return to its normal shape. Over time, the heart walls become thickened, and the chambers remain enlarged. They become unable to return to their normal size. With thickened heart muscle walls, not enough blood can enter the chamber.
Over time, your weakened heart moves less blood with each pump. Eventually the nice, rhythmic flow of blood from one chamber to the next through the valves no longer exists. Fluid begins to build up throughout the cycle.
Effects on the lungs
One area where blood flow begins to back up is the lungs. The word “congestion” refers to the build-up of fluid in the lungs. This build-up occurs because the heart cannot pump the normal amount of blood through the normal cycle.
Effects on the kidneys
To make up for the changes in blood flow, your body delivers oxygen-rich blood only to the most important organs. These organs are your brain and heart. This means that the kidneys do not receive enough oxygen rich blood. The kidneys help your body get rid of extra water. Over time, without enough blood flow, they cannot perform normally. Then water in your body is no longer regulated well.
When your kidneys are not working right, excess water may settle in different parts of your body. Your ankles, feet, and legs may collect excess water. You may have swelling (sometimes called edema, pronounced eh- DEE-muh).
Effects on the heart valves
Valves open and close to control the blood flow within the heart. If these valves become narrow (stenosis), a back-up of blood occurs at the valve.
If the valve cannot close right, a back-flow of blood could occur. This is called regurgitation (pronounced re-gur-ji-TAY-shun).
The mitral valve between the left atrium and ventricle often becomes broken during heart failure. Then it leaks blood back into the left atrium. This is known as mitral regurgitation.
Differences between left- and right-sided heart failure
Many symptoms of CHF are linked to the congestion that develops as fluid backs up into the lungs and leaks into the tissues. Other symptoms occur because not enough oxygen-rich blood gets to the body. The effects of heart failure on the body depend on which side of the heart is affected.
Right-sided failure
With this type of failure, the heart muscles on the right side thicken, so that the muscle becomes very relaxed (floppy).
Blood that normally enters the right side from the body begins to back up.
This blood backs up into the body and causes the veins in the body and tissues surrounding
the heart to swell.
Symptoms of right-side heart failure include:
- Tiredness (fatigue)
- Fluid build-up, first in the feet, next in the ankles and legs, and finally in the lower belly (abdomen)
- Liver enlargement
- Weight gain, despite having less appetite
- Shortness of breath
Left-sided failure
Failure on the left side is linked to a general weakening of the heart muscle. This is the more common type of heart failure.
The weakened heart muscle no longer can keep up with the demands of the body for oxygen-rich blood. Back-up into the lungs occurs. Symptoms of left-side heart failure include:
- Tiredness (fatigue)
- Shortness of breath
- Asthma-like wheezing
- Dry, hacking cough, which occurs a few hours after lying down, but stops after sitting upright
- Sleep apnea
- Pink-tinged froth in the mouth and pale, clammy skin (these suggest fluid in the lungs)
Classification of severity
To help doctors label severity of symptoms and decide on treatment options, the New York Heart Association came up with a classification system to grade CHF patients by symptom severity.
Class I
- No limitation of physical activity
- No shortness of breath, fatigue, or heart palpitations with ordinary physical activity
Class II
- Slight limitation of physical activity
- Shortness of breath, fatigue, or heart palpitations with ordinary physical activity
- Comfortable at rest
Class III
- Marked limitation of activity
- Shortness of breath, fatigue, or heart palpitations with less than ordinary physical activity
- Comfortable at rest
Class IV
- Severe to complete limitation of activity
- Shortness of breath, fatigue, or heart palpitations with any physical exertion
- Symptoms appear even at rest
