Carotid Artery Bypass Is Getting a Second Look

Investigators anticipate that the stroke rate in COSS will turn out to be 40% in the medically treated group and 24% in the surgically treated group, even taking into account a 12% perioperative stroke and mortality rate, as reported in the original EC/IC trial, said Dr. Powers, codirector of the Stroke Center at Barnes-Jewish Hospital and the Washington University School of Medicine.

Even if these reduced stroke rates are borne out by the study, EC/IC bypass surgery is unlikely to become as common as coronary artery bypass; elevated OEF occurs in only 30% of patients with carotid occlusion. The study's $21-million price tag over the next 5–7 years may prove to be money well spent if it settles the question of patient selection once and for all. A similar trial, the Japanese EC/IC Trial (JET), is also working on the question of patient selection. A third trial, the Randomized Evaluation of Carotid Occlusion and Neurocognition (RECON) study, was recently funded by NIH to examine the hotly debated question of whether carotid bypass surgery affects cognitive function.

EC/IC Bypass In a Nutshell

The 4-hour EC/IC procedure involves surgical anastomosis of the superficial temporal artery to the middle cerebral artery.

While the patient is under general anesthesia, an incision of several centimeters is made in the scalp on the side of the head where the diseased artery is located. A branch of the superficial temporal artery, generally the anterior division, is then identified and dissected using a surgical microscope.

A small craniotomy is then made beneath the temporalis muscle. A frontal branch of the middle cerebral artery is identified and isolated.

Once a suitable location for the anastomosis is determined, temporary clips are placed above and below the site. A slit is cut into this branch, and the previously dissected and prepared superficial temporal artery is sewn directly onto this middle cerebral artery branch for an end-to-side anastomosis.

The clips are then removed and blood flow restored.

Risks of the surgery include subsequent stroke as a result of temporary occlusion of the middle cerebral artery branch, thrombosis of the bypass graft, myocardial infarction during surgery, bleeding, and infection.

A retrospective analysis of EC/IC bypass surgery performed on 67 patients from 1986 to 2000 reported a perioperative morbidity rate of 3%, with no mortality (Acta Neurochir. [Wien] 2004;146:95–101).