The coronary by-pass
Heart bypass - or coronary artery bypass graft (CABG) - is a radical procedure that has become the most frequently performed of all surgical operations, with around 500,000 carried out every year in the US alone. Around 10 per cent of all heart patients will undergo a cardiac bypass, especially if they have one or more coronary arteries that are either blocked or severely narrowed.
In an operation that can last from two to six hours, the surgeon removes (or 'harvests') veins from the patient's leg, forearm or chest. These are then attached or grafted to a part of the artery that is not blocked, so bypassing the blocked section. Three or more bypasses may be created, depending on the number of blocked arteries.
The traditional approach is known as 'on-pump', where the heart is stopped for several hours to allow the surgeon to perform the graft. The patient is attached to a heart-lung machine, or pump, so that the blood supply can be diverted from the heart and sent through the pump, where it is oxygenated and then pumped back to the vital organs.
But a newer technique, which some surgeons believe is safer and less traumatic, is known as 'off-pump' or 'beating-heart bypass surgery'. While the grafting procedure for both approaches is the same, 'off-pump' is performed with a heart that continues to beat, stabilised by special equipment.
This procedure is for patients whose arteries are either not entirely blocked, or who have just one main artery blocked. It is a relatively simple procedure that involves threading a 'balloon' type device through the artery, so unblocking it, and pushing the plaque back against the artery walls. A stent is also used to keep open the artery while the procedure takes place.
While it was once considered to be a safer technique than a full by-pass, newer evidence recognizes that angioplasty has its own problems. The most common is that the artery will slowly close up again, and the patient has to have a full by-pass.