After the patient is asleep, a device called the Swan-Ganz catheter is often inserted into the jugular vein (in the neck) and threaded to the pulmonary artery (which goes from the heart to the lungs). The catheter can be used to give medication, to measure the oxygen levels in the blood and to measure pressures in the heart. A breathing tube (endotracheal tube) will also be inserted into the mouth and down the windpipe (trachea) to maintain an airway.

The surgeon will then make an incision about 4 to 6 inches long on the left side of the chest. Through this incision, the surgeon can identify the mammary artery (also known as the internal thoracic artery), which will be used for the graft. The artery is located and part of it is retrieved for use (harvested). If the surgeon finds the mammary artery to be unusable for this purpose, or if other complications are revealed (e.g., the LAD shows severe calcification), then the surgeon may proceed with a standard bypass surgery from that point.

Whether the heart is stopped or not depends on the particular patient and the surgeon. If the heart is stopped, a cardioplegia solution is administered and special incisions (ports) are made to accommodate the port access system. The ports are held open during surgery with 1.5-centimeter (1-inch) tubes that provide a workspace for tools and scopes to access the heart and coronary arteries. A catheter is inserted through the groin and fed through the femoral vein and/or femoral artery to assist with the diversion of the blood flow to the heart-lung machine. During the surgery, the heart is still and empty of blood. This enables the surgeon to reach more of the heart than during a “beating heart” surgery.

If the heart is not stopped, specialized clamps and stabilizers are used to hold the heart in place. To prevent ischemia, or lack of blood flow to the heart, a temporary shunt is put in place. Once this has been accomplished, blood flow to the left anterior descending artery (LAD) is temporarily clamped off. The mammary artery is then attached directly to the LAD beyond the blockage.

Once the procedure is finished, blood can flow freely through the LAD beyond the blockage, restoring blood flow to the heart muscle. When the surgeon is satisfied that complete blood circulation has been restored to the heart, the chest incisions are closed (sutured). The procedure takes approximately two hours.