Coronary Artery Bypass Surgery

Surgical techniques in coronary artery bypass surgery

Coronary artery disease in India as compared to the west is totally a different cup of tea. It is characterized by:

• Younger age patients
• Diffuse disease
• High incidence of associated Diabetes

Why Coronary Artery Bypass Grafting (Surgery)?

The purpose of CABG is to improve blood flow to the heart. More blood flow should eliminate chest pain or angina that comes with exercise and in some patients, even at rest.

• It improves quality of life by relieving angina and exercise capacity in the vast majority of cases.
• It not only improves the patient's symptoms like chest pain or occasional difficulty in breathing but also protects the heart against potential risk of a massive heart attack.
• Reduces need of medication.
• Restores a sense of well being.

Will my heart disease be cured once I have had bypass surgery?

Bypass surgery is not a cure for heart disease. It is a form of treatment that relieves symptoms and improves the quality of life for many patients. Coronary artery disease is a steadily progressive disease and may eventually clog remaining arteries of the heart as well as bypasses.

How to get good long term results?

It is essential that you reduce your risk of heart disease by controlling your heart risk factors. This will ensure that you get the best long-term result from your bypass surgery.

What is Coronary Artery Bypass Grafting?

CABG is an open heart operation in which arteries or veins are taken from another part of the body to channel the needed blood flow to the coronary arteries.

Surgical Treatment of Coronary artery disease: Types of CABG

• Conventional CABG under Cardiopulmonary Bypass
• Off Pump CABG
• Minimally Invasive Off Pump CABG
• Total Robotic CABG

Conventional CABG

Preparing for surgery: It is natural to feel anxious and nervous, once the decision is made to have CABG. Various blood tests are conducted. The surgical procedure is explained to you to mentally prepare you by a highly skilled team of doctors and nurses before surgery. It is this teamwork, with your help, that ensures you get the most benefit from your surgery.

Operation: You will be given a general anaesthetic to put you to sleep during the operation. A breathing tube, called an endotracheal tube, is inserted through the mouth. The surgeon makes an incision and opens the chest. Bypass conduits like the internal mammary artery and saphenous vein and others are harvested and prepared for anastomosis.

Heart-lung machine: Now the heart-lung machine is connected to your heart. It performs the functions of your heart and lungs during the operation, allowing the surgeon to make the necessary repairs while your heart remains motionless.

Coronary bypass: During surgery these arteries or veins are connected directly to the coronary arteries. One end of the vein or artery is attached to the aorta and the other end is connected to the coronary artery, beyond the blockage, bypassing the narrow or obstructed area.

For a bypass operation, the surgeon reroutes blood flow around the site of your coronary blockage in one of these ways:

• The internal mammary artery (IMA) arises from the branches of the aorta. It is lying on the inside of the chest alongside the breastbone on both sides, i.e. Left IMA and Right IMA. This procedure allows the blood to flow through the aorta and through the internal mammary artery as it normally would, but it ends up in the coronary artery instead of the inner surface of the chest wall.
• A saphenous vein is taken from your leg and is used as a bypass tube or conduit. One end of the vein is connected to the aorta and the other end is connected to the coronary artery downstream from the blockage. This allows blood to flow around the blockage from the aorta to the coronary artery.

The arteries and vein used in the operation are expendable. Removing them does not affect the flow from where they are taken. Other conduits include:

• Radial artery, which supplies the arm
• Gastroepiploic artery, which supplies the stomach
• The inferior epigastric artery from the abdominal wall

Technique: The patient is given a general anesthesia. The surgeon makes an incision and opens the chest. Bypass conduits like the internal mammary artery and saphenous vein and others are harvested and prepared for anastomosis. Now the heart-lung machine is connected to the heart. It performs the functions of the heart and lungs during the operation, allowing the surgeon to make the necessary repairs while the heart remains motionless. During surgery these arteries or veins are connected directly to the coronary arteries. One end of the vein or artery is attached to the aorta and the other end is connected to the coronary artery, beyond the blockage, bypassing the narrow or obstructed area. Only the internal mammary artery, which arises from the branch of the aorta, is connected directly to the coronary artery of the heart.

Conduits used are: 1. The internal mammary artery (IMA), arising from the branches of the aorta, lying on the inside of the chest alongside the breastbone on both sides, i.e. Left IMA and Right IMA. 2. Radial artery, which supplies the arm. 3. Saphenous vein, taken from the legs. 4. Gastroepiploic artery.

Off Pump Coronary Artery Bypass Surgery

A new era of cardiac surgery began with techniques like the minimally invasive approach, endoscopic interventions, Heartport, and off pump CABG. These changes were extremely significant because they not only presented linear progress but uprooted some of our basic concepts we have learned, practiced, taught and regarded as sacrosanct.

We got something important in return: 1. Less surgical trauma. 2. Elimination of cardiopulmonary bypass. 3. Decreased post-op complications. 4. Shorter hospitalization. 5. Reduced procedural cost.

Technique: The patient is given a general anaesthesia. The surgeon makes an incision and opens the chest, and bypass conduits are prepared for anastomosis, just like conventional CABG. The major difference is that the heart-lung machine is NOT connected to the heart and the heart is not stopped. Hence the heart is beating during surgery.

Stabilisers: Various mechanical stabilisers (from manufacturers like Medtronic, Guidant, Chase Medical) which can stabilize the part of the heart are used. This stabilises the local area containing the coronary artery. Now the coronary artery is cut open and a shunt is inserted into the coronary artery so that blood supply to that part of the heart continues. Then an end-to-side anastomosis between the bypass graft and the coronary artery is carried out using the various available conduits.

Minimally Invasive Off Pump CABG (MIDCAB)

Classically this technique is designed for single vessel grafting, LIMA to LAD. Even a right minithoracotomy can be done for the RCA. A left anterior minithoracotomy of 6-10 cm is performed. The LIMA is harvested. The LIMA is anastomosed to the LAD and Diagonal sequentially. Indications are complex LAD lesion, stent restenosis, LV dysfunction, and hybrid procedures.

Robotic Surgery: Robotic Assisted Total Endoscopic CABG

In a short period of time, endoscopic CABG has gone from the realm of speculation to a clinical reality. This has been enabled by the use of sophisticated robotic microsurgical systems and robotic manipulators. The surgeon sits at the console and grasps specially designed instrument handles. The surgeon's motions are relayed to a computer processor, which digitizes his or her hand motions. The digitized information from the computer control system is relayed to robotic manipulators. These manipulators hold the endoscopic instrument tips which are inserted into the patient through small ports. The unique power is the digital interface between both surgeon and instrument tips. Robotic assisted total endoscopic CABG is still developing.

Other Advances

• Endoscopic harvesting of the bypass grafts (EVH)
• Role of anastomotic devices in CABG

Endoscopic harvesting of the bypass grafts is now a well established technique.

First generation anastomotic devices are available and evolving rapidly for proximal and distal anastomosis. In 2-3 years, when these devices mature, multivessel CABG will be done in half the operating time: proximal anastomosis in 5-10 seconds and distal anastomosis in 1-2 minutes.

Disadvantages: It lacks the bite to bite adjustments that the surgeon makes, especially in local variation in wall thickness and plaques.