The first incision is made by the cardiac surgeon with the help of saws through the sternum (breastbone) right down the middle of the chest. This surgical procedure is referred to as a median sternotomy or the cutting of the sternum.
Now the heart must be cooled with iced saltwater. A preservative solution is injected into the heart arteries to ensure the least damage caused due to reduced blood flow while the surgery is being performed and this is called cardioplegia.
A cardiopulmonary bypass has to be fixed before the surgery is started and this device is also called a heart-lung bypass machine. This machine is responsible for taking over the function of the heart throughout the surgery.
For the correct channelization of venous blood out of the body, a plastic tube is placed in the right atrium of the heart. This arrangement is made through a plastic sheeting or a membrane oxygenator associated in the machine. The oxygenated blood produced, will now be returned to the body.
In order to permit the bypasses from being connected to the aorta, the main aorta is knocked off or cross clamped during the surgery. This also ensures a bloodless field.
The saphenous vein from the leg is the most commonly selected blood vessel for bypass surgery. The bypass graft is sewn through the narrowing or blocked coronary artery section. The saphenous vein's other terminus is connected to the aorta.
Now, the arteries of the chest wall, as specifically the left internal mammary artery, are chosen for the bypass graft. This artery is connected to the left anterior descending artery or one of its branches after being disconnected from the chest wall. The advantage of these arteries is that it has the nature of remaining open for a longer period of time compared to venous grafts.
It has been observed that after 10 years 66% of vein grafts are found to be opened while for internal mammary arteries almost 90% were found to be open. But the disadvantage with internal mammary arteries is that the length is small and can only be utilized when the disease is located at the beginning of the coronary arteries and not too far away. Usage of the internal mammary artery can prolong the time taken to conduct the total surgery since it takes some time to segregate it from the chest wall. Hence in case of emergency CABG surgeries, these kinds of arteries may not be employed to restore coronary artery blood flow.
The normal time to finish a CABG surgery is around 4 hours in which the aorta is clamped off for about an hour and the body is assisted via the heart-lung bypass machine for 1.5 hours. It is now a routine to make use of triple, quadruple and quintuple bypasses.
After the surgery is completed the sternum with the help of stainless steel is wired together and the incision in the chest is sewn closed. Plastic tubes or chest tubes are kept in place to permit the drainage of blood that has remained in the space (mediastinum) around the heart.
5% of the patients require some exploration within the first day in order to check for continued bleeding post-surgery. Chest tubes can be removed after one-day post-surgery. While the breathing tube can be removed immediately after the surgery.
Right after the day of surgery patients are shifted from the intensive care unit. 25% of patients have been observed to have developed heart rhythm disturbances within 3 to 4 days post-surgery. These irregularities are temporary atrial fibrillation and can be associated with surgical trauma suffered by the heart during surgery.
Patients are now discharged 3 to 4 days after surgery and one can expect a faster recovery. Another advance that has been made in the process is that surgery can be performed without cardiopulmonary bypass, and this can actually reduce the frequent memory defects and other related complications that have occurred in patients who have undergone surgery.