After the patient is asleep, a device called the Swan-Ganz catheter may be inserted into the jugular vein in the neck. It is then threaded to the pulmonary artery, which transports blood from the heart to the lungs. The catheter measures heart function, pressures within the heart and lungs and oxygen levels within the blood. Medication is also delivered through the Swan-Ganz catheter. A breathing tube (endotracheal tube) will be inserted into the mouth and down the windpipe (trachea) to maintain an airway. 

An incision is made through the chest and breastbone (sternum), and the ribs are separated. A heart-lung machine takes over the functions of the heart and lungs, freeing the heart from its normal function so that it can be removed. Some heart muscle is reserved during extraction to act as a support for the new heart as it is sewn into place.

When the new heart is positioned and the blood vessels are reattached, the heart incision is closed, the heart is restarted and blood circulation and oxygen are restored. The warmth of the blood should “wake up” the heart and stimulate it to start beating. If this does not occur, it may be necessary to start the heart using an electric shock (defibrillation). Once the blood is flowing through the new heart normally and without any leaks, the heart-lung machine is disconnected and the chest incision is closed.