What Can Go Wrong With The Heart

A healthy heart gives the body a good blood supply so that all parts get enough food and oxygen. However, several things can go wrong with the heart. For example, a few people are born with a faulty heart. Many more people start their lives with a healthy heart, but later it becomes diseased. Some heart disease is caused by infections which may be treated with modern drugs and recovery can be quick. An example is rheumatic heart disease.

By far the most common type of heart disease occurs when one (or more) of the coronary arteries becomes partly or almost completely blocked. This is called coronary heart disease. A good way to treat coronary heart disease is to by-pass the blocked bit of coronary artery. Usually, pieces of one of the veins in the leg are used to make the by-pass. The leg does not suffer, because there are plenty of other veins there to share the job of carrying the blood.

For this operation to be successful, the heart must be stopped and by-passed completely. However, the heart is really two pumps. One delivers blood to the lungs. The other delivers blood to the rest of the body. Therefore, in order to make the operation simpler, the lungs are by-passed as well. This means that only one artificial pump is needed and an artificial oxygenator is used instead of the lungs.

The circulation diagram can be modified to show what is needed. Normal body temperature is 37 °C. Cooling the body to about 30 °C reduces the activity in all parts. Therefore less oxygen is needed. The heart is kept much cooler and treated with various chemicals which stop its muscular activity. Therefore it is not damaged when its blood supply is cut off. There is no great leakage of blood when the coronary artery is cut, because there is very little blood in it. Also, the heart has stopped beating and is perfectly still. This enables the surgeon to put the stitches in exactly the right places.

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