Heart transplant: How is it performed?

There are two types of procedures that can be performed in a heart transplant. The first and most common is called an orthotopic transplant. The second and more rare is called a heterotopic heart transplant. The surgery is much the same in both procedures but varies according to the portion of your own heart the surgeon actually removes.

Orthotopic transplant. In an orthotopic heart transplantation, most of your failing heart is removed. The donor heart is then attached to the remaining part of your heart. This complicated operation is described below in 10 basic steps:

1. You are prepared for surgery and given medicines to make you unconscious. An incision is made in the middle of your chest, revealing the breastbone. Your surgeon cuts through your breastbone and separates your rib cage.
2. The sac around your heart (pericardium) is cut open to reveal your heart. Once your heart is visible, you are connected to a heart-lung bypass machine. Your coronary blood vessels are clamped off to stop the blood flow to your heart.
3. Blood flow is diverted from your heart to the heart-lung bypass machine. This machine does the work of your heart and lungs so that your surgeon can perform the surgery. Your heart is then stopped using a chemical solution.
4. Your surgeon cuts away the front part of your heart. The back walls of the left and right atria will stay in your body.
5. The donor heart (minus its back walls) is attached (grafted) into place on the remaining part of your heart.
6. The coronary arteries and veins are stitched to your new heart.
7. The clamp on the main blood vessel leaving your heart (aorta) is removed, which causes your heart to start beating normally. If it starts beating abnormally (fibrillating), your heart is given an electrical shock to correct the rhythm.
8. The clamps are removed from your other blood vessels, allowing blood to flow normally to your new heart.
9. The heart-lung machine is turned off, leaving your new heart to work by itself.
10. Your breastbone is fastened together using heavy steel wire. Your chest incision is closed with stitches.

This operation takes up to 7 hours to perform. You will be unconscious and free of pain under general anesthesia. Talk to your surgeon about the serious risks involved during and after surgery if you are considering this procedure.

Heterotopic transplant. In a heterotopic transplant, your own heart is not removed. The donor heart is positioned so that the chambers and blood vessels of both hearts can be joined. You can think of it as adding a "backup battery" to your heart to cut down on the amount of work it has to do. This procedure follows the same basic steps as the orthotopic operation.

This type of transplant is very rarely used. It is used in cases where the donor heart will need some extra help to function normally in your body. Your surgeon would consider heterotopic transplant for three reasons:

• Your body is somewhat larger than the donor's body.
• The donor's heart functions poorly.
• You have pulmonary hypertension (high blood pressure in your lungs).