Medicine: Second Opinions on the Bypass

Doctors re-evaluate surgery designed to prevent strokes

When it was first attempted nearly 20 years ago, the operation was hailed as a marvel of technical virtuosity and medical logic. Cerebral bypass surgery was designed to circumvent one of the most common causes of strokes: a blockage in one of the arteries that carry blood to the brain. To reroute blood around a blocked vessel, the surgeon uses a nearby, less vital artery to build a bypass road. Taking this detour, blood continues to flow to the brain, and the risk of a stroke's occurring is presumably lessened.

The operation involves advanced microsurgical techniques, the joining of arterial walls...