Thursday, March 23, 2006

Coronary Artery Bypass Graft Surgery Part 3

This is part 3. Part 1 and part 2 are here.

The risk of CABG

There is obviously a risk with CABG. It use to be as high as 7-10% risk of death or other complications, including kidney failure, risk of strokes, risk of heart attacks, risk of heart failures, risk of GA, etc.. Nowadays, the average open heart center who does more then 10 bypasses a month, should have a risk element of 1-3%. Some risk are so slow and insidious, like long-term memory impairment that it is difficult to quantify.

The other issue with bypass surgery was the use of the leg veins as a channel for the bypass. The veins were not very lasting and tends to re-block after 7-10 years. This has to do with surgical techniques, the quality of veins and also the patient factor. This problem has largely been overcome by the use of arteries as channels for the bypass. God has given us two chest cage arteries (right and left internal thoracic arteries), lying just next to the heart, that can be use as channels of bypass, without any important consequence to the chest wall. These chest wall artery channels have proven to be very durable and the re-blockage rate in them were very low, probably less then 5% in ten years. Almost all bypasses nowadays are done using either one or both of these arteries as bypass channels.

Post-op complications of CABG were mainly attributable to the patient factors and the use the heart-lung machine. The good news is that there has been much improvement in this field. Cardiac anesthesia is much better now. The modern heart-lung machines are better. Cardiac surgeons have learnt to do bypasses on a beating heart, to avoid the use of the heart-lung machines. Surgical wounds, which use to be about 6-8 inches over the breast bone is now 3-4 inches, and some of them are over the ribs (cosmetically better). Beating heart surgery also allows for faster post-op recovery. For the conventional CABG, the patient gets discharged after about 1 week and may take 2-3 months to recover. With beating heart surgery, they may stay in hospital for 4-5 days and take 1-2 months to recover. Overall, things are getting better, especially with keen competition from balloon angioplasty.

Balloon angioplasty versus CABG

There are certain types of patients who will definitely do better with CABG, eg, certain types of blockages in the left main artery of the heart, blockages in two or more arteries that were so hard that it was not possible to balloon, or combinations of these in the context of poor heart function. In the past, before the era of the drug-eluting stents, this list used to be longer, as the bare metal stents were re-blocking more often. Nowadays, with drug-eluting stents, in most types of blockages, angioplasty can be done with minimal risk and minimal re-blockage rates. In this era of drug eluting stents, angioplasty does rival CABG as a good and effective means of treating CAD, except in certain specific categories.

The future

We await further development of the beatings heart surgery technique, especially large, long term studies to show it’s longterm effectiveness. Also, it may be that in future, the cardiac surgeon will team up with the cardiologist. The cardiac surgeon bypassing the left front heart artery and maybe the right artery (which they can do well on a beating heart) and the cardiologist will balloon the left back artery (which the cardiac surgeon may have trouble getting to easily, on a beating heart), allowing the patient to have a smaller scar, and quicker recovery. As always, it is important to remember that the best surgery is no surgery. Prevention of heart disease is the best strategy.

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