The aim of coronary artery surgery is to increase the blood flow to heart muscle by bypassing the narrowings in the coronary arteries. In the same way that a road through a village may be bypassed by a dual carriageway around the outside, the heart bypass increases flow around the problem area, but the native coronary artery with its associated narrowing is left in place once the bypass is completed. The key to successful coronary artery surgery is to manufacture sufficient satisfactory bypasses whilst minimising  the complications which can be associated with surgery.

Bypass vs. off bypass surgery

There are two techniques which are in common use. The first utilises a heart lung bypass machine to temporarily undertake the work of the heart and lungs allowing  the coronary artery bypasses to be constructed on a still and bloodless coronary artery. This is the commonest technique used in the UK at present. Whilst it allows accurate construction of the small anastamoses required for this type of surgery, there are some small risks attached to using a heart lung bypass machine. The alternative technique is to use a coronary stabilising device to keep the coronary arteries relatively motionless  during the operation, whilst the heart continues to pump the blood around the body on its own. Whilst this may avoid some of the potential complications associated with the heart lung bypass machine, the technique itself may create other problems. It is not yet known which of the two techniques is superior.

Available conduits

There are a variety of arteries and veins around the body which can be used to manufacture the bypasses. They include arteries from the inside of the chest wall and the arm, and vein from the leg.

1.     The internal mammary artery - this is a small artery which runs down the inside of the chest wall on either side of the midline. The left internal mammary artery is commonly used, the right less so. It usually dissected down but the top end is left in place where it arises from the branch of the large artery which runs over to supply the left arm. The bottom end of the artery can then be sewn onto the coronary artery. The left internal mammary artery is usually attached to the artery which runs down the front of the heart - the left anterior descending coronary artery.

2.     The radial arteries - the blood supply to the hand is usually derived from two arteries, one of which is called the radial artery. This can often, but not always, be removed whilst still allowing sufficient blood flow to the hand from the other artery in the forearm.

3.     The long saphenous vein - this is a long vein which runs up the inside of the leg from just above the foot to the groin. It is usually responsible for transporting blood back from parts of the foot and leg towards the heart. It can usually be removed, and the blood will then flow back by alternative routes. The long saphenous vein can be used to manufacture up to 3 or 4 bypass grafts

The decision about which of the conduits to use in each different patient is based on a number of factors. In general the left internal mammary stays patent for longer than the long saphenous vein and the radial artery has a patency rate somewhere between the two. The exact choice and combination of conduits for a particular operation will be explained by your surgeon.