Coronary Artery Bypass (CABG)

Coronary artery bypass grafting (CABG) restores blood flow to heart muscle that is being starved by narrowed coronary arteries. Rather than opening the blockage itself, the operation routes blood around it using a healthy blood vessel taken from elsewhere in the body — creating a new path, or graft, from the aorta to the artery beyond the narrowing.

Why bypass rather than a stent

Both bypass surgery and stenting relieve angina, and the right choice depends on the pattern of disease. Bypass is generally favoured when several arteries are involved, when the left main artery is significantly narrowed, when disease is diffuse rather than confined to one short segment, and in many patients with diabetes or reduced pumping function. Stenting is often preferable for disease limited to one or two discrete lesions. This decision is usually made jointly by a cardiologist and a surgeon after reviewing the angiogram.

The grafts used

• Internal mammary (thoracic) artery — taken from the inside of the chest wall. It is the most durable graft available and is usually used for the left anterior descending artery, the most important vessel.
• Radial artery — taken from the forearm, used as an additional arterial graft in suitable patients.
• Saphenous vein — taken from the leg, used to reach several targets in one operation.

Removing these vessels does not deprive the arm, chest wall, or leg of its blood supply, because other vessels take over.

How it is performed

The operation is most often carried out through the breastbone, with the heart supported by a heart–lung machine so that fine sutures can be placed on still arteries. In selected patients the grafts can be constructed on the beating heart (off-pump surgery). The number of grafts depends on how many arteries are significantly narrowed and suitable for grafting; three or four is common, and the term "triple bypass" simply refers to that number rather than to complexity.

What surgery achieves

Bypass reliably relieves angina and improves exercise tolerance. In defined groups of patients — particularly those with left main disease, three-vessel disease, or impaired heart function — it also improves survival compared with medical treatment alone. It does not cure the underlying disease process, which is why secondary prevention afterwards matters enormously.

After the operation

Grafts stay open far longer when the process that narrowed the original arteries is controlled. That means continuing prescribed antiplatelet and cholesterol-lowering medication, complete avoidance of smoking, control of blood pressure and diabetes, regular activity, and attending cardiac rehabilitation. Stopping medication because symptoms have improved is one of the commonest avoidable causes of graft failure.

This page explains bypass surgery in general terms and is not advice about your own case. Whether bypass, stenting, or medical treatment is right for you depends on your angiogram and your overall condition.