Coronary Artery Bypass Surgery

Article contributed by Dr Tan Yong Seng, the Vice Chairman of the Singapore Heart Foundation’s Board of Directors. He is also a Cardiothoracic Surgeon in private practice.

Coronary heart disease is the most common type of heart disease affecting adult Singaporeans. It results from a condition known as atherosclerosis, a process where a waxy material is formed inside the wall of the arteries. This material, known as plaque, is made up of a mixture of cholesterol, fatty compounds, calcium and a blood-clotting material called fibrin.

Types of Plaque

Hard Soft/Vulnerable
Builds up in the arteries that supply blood to our heart, resulting in reduced blood flow to the heart. An inflamed part of an artery that can burst, causing the formation of a blood clot, which can lead to a heart attack.
If the blood flow stops due to 100% blockage of the blood vessel, this will lead to a heart attack. Most heart attacks are caused by soft/vulnerable plaque

Below are three established modalities of treatment for coronary heart disease. For this article, we will explain more about coronary artery bypass surgery.

Medicine Percutaneous Coronary Intervention Surgery
  • Anti-platelets
  • Beta-blockers
  • Calcium channel blockers
  • Nitrates
  • Statins
  • Balloon Angioplasty
  • Stenting
  • Coronary artery bypass surgery

Coronary Artery Bypass Surgery
Bypass surgery is the most common type of heart surgery performed by a heart surgeon. This surgery aims to improve the blood flow to the heart with a new route or “bypass” a section of clogged or diseased artery, by using a section of blood vessel from the leg, chest, or another part of the body to graft onto the affected coronary artery.

During the surgery, the breastbone (sternum) is divided and the heart is stopped, while blood is sent through a heart-lung machine. Unlike other heart surgeries, the chambers of the heart are not opened during the operation. Some bypass procedures can also be done as a limited-access surgery, described as a minimally invasive bypass.

Things to Note

  1. Prior to your operation, it is important to inform your surgeon and cardiologist of any changes in your health, including symptoms of a cold or flu, as a chest infection may affect your post-operative recovery.
  2. Next, you will be asked to stop all your anti-platelet medications, such as Aspirin or Plavix, usually 7-10 days prior to the date of surgery. This is to minimise bleeding and blood loss during surgery.
  3. Before surgery, baseline screening tests which include an electrocardiogram (ECG), blood tests, urine tests and a chest x-ray, will be conducted to provide your surgeon with the latest information about your health.
  4. If you smoke, it is best to stop smoking at least 2 weeks prior to the surgery, because it can lead to blood clotting and breathing problems.
  5. You will be asked to bathe the night before the surgery, to reduce the amount of germs on your skin.
  6. Lastly, the surgery is usually done under general anesthesia and you will need to have an empty stomach. Thus, you are required to fast from food and drink overnight. Should you need to eat or drink after midnight, it is important that you inform your anesthesiologist and surgeon.

On the Day of Surgery
Most patients are admitted to the hospital the day before surgery, or in some cases, on the morning of the surgery. Small plastic disks called electrodes will be attached to your chest to monitor your heart’s rhythm and electrical activity via an electrocardiogram machine. After which, you will receive a local anesthetic to numb the area where a plastic tube (called a line) will be inserted into an artery in your wrist. An intravenous (IV) line, which will provide anesthesia during the operation, will be inserted into your vein. To help you relax, a mild tranquiliser will be administered, before entering the operating room.

Once inside the operating room and when you are completely asleep, a tube will be inserted down your windpipe and connected to a respirator, to take over your breathing. A blood-thinning medicine called an anticoagulant, will also be administered to prevent your blood from clotting. You will then be connected to the heart-lung machine (a machine that performs the same functions of your heart and lungs temporarily), where your heart is stopped and your body is cooled.

The surgery may begin by grafting a long piece of vein from your leg (the saphenous vein). One end of the graft will be attached to the ascending aorta, the large artery that carries oxygen-rich blood from the heart to the body, while the other end will be attached to the affected coronary artery below the blocked area. However, the surgeon may choose to use an artery from the inside of your chest wall (the internal mammary artery) or he may use both for grafts. The procedure can take between 2 to 6 hours, depending on the number of bypasses needed.

Recovery Time
You can expect to stay in the hospital for about a week, including at least 1 to 2 days in the Intensive Care Unit (ICU).

Life after Bypass Surgery
After a bypass surgery, your doctor will recommend that you join a cardiac rehabilitation programme. These programmes can help to motivate you to make informed lifestyle changes, such as modifying your diet, exercising to get your strength back, quit smoking, maintaining a healthy weight and dealing with stress. You and your spouse may discuss freely with your doctor regarding resumption of sexual activity and the effects of some medications that can affect your sexual life (e.g. betablocker, erectile dysfunction medication and nitrates, etc). Generally, sexual activity can be slowly resumed 6-8 weeks after your surgery, when your breast bone has healed. In addition, you should also be free from heart failure or certain abnormal heart rhythm before you can safely resume your normal sexual activity. If in doubt, please discuss with your doctor.

As bypass surgery does not cure the underlying heart disease (atherosclerosis or coronary artery disease), medicines will be an important part of your treatment after the surgery. It is likely that you will need to take a statin or blood lipid lowering agent and begin an antiplatelet therapy.

About 20% to 30% of bypass patients will require a second procedure within 10 years. These late events, which are often associated with recurrence of symptoms, usually require a second revascularisation procedure, most often done with angioplasty or stent placement and less often with a repeat surgical bypass.

Summary
Coronary artery bypass surgery is usually carried out for/when:

  • Patients with debilitating angina that has failed to be controlled by medication.
  • Patients with multiple diseased coronary arteries where the heart’s main pump (left ventricle) is functioning poorly.
  • The left main coronary artery is severely narrowed or blocked.
  • Patients who are not suitable for balloon angioplasty.
  • Patients whose coronary arteries have re-narrowed after angioplasty.

The benefits of a coronary artery bypass surgery include:

  • Prolonged survival
  • Relief of symptoms, such as chest pain or shortness of breath
  • Improved exercise tolerance
  • Reduction of the need for angina medications
  • Prevention of potential fatal heart attacks

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