In type A aortic dissection, the intimal disruption is located on or extends to the transverse arch in about 20% of patients. Replacement of the arch may then be necessary to avoid leaving an unresected, acutely dissected aorta and to prevent bleeding, progression of aneurysm, rupture, and ultimately reoperation or death. From 1970 to September 1987, 119 patients were operated on for type A acute dissection. Starting in January 1977, gelatin-resorcin-formaldehyde biologic glue was used in 91 patients to reinforce the dissected tissues at the suture sites. Among these 119 patients, 26 (ages 32 to 76 years) underwent replacement of the transverse aortic arch in addition to replacement of the ascending aorta. In 20 patients cerebral protection was achieved by profound hypothermia (16 degrees to 20 degrees C) associated with circulatory arrest (15 to 40 minutes, mean 27 minutes) during the distal anastomosis. In six patients the carotid arteries were selectively perfused with cold blood (6 degrees C) during moderate core hypothermia (28 degrees C) while cardiopulmonary bypass was discontinued (19 to 34 minutes, mean 25 minutes) to allow the prosthesis to be sutured without the distal aorta being cross-clamped. Moderate hypothermia avoided the long rewarming time necessitated by profound hypothermia. The hospital mortality rate was 34% (9/26). Two of the 20 patients subjected to profound hypothermia and circulatory arrest died during the operation and seven patients died of postoperative complications. No deaths or major complication were observed in the other six patients. Follow-up of the 17 survivors ranges from 3 to 90 months (mean 39). One patient died 6 months after the operation of cerebral hemorrhage. One patient is disabled by neurologic sequelae. Fifteen patients are in good clinical condition (New York Heart Association class I or II). Postoperative aortograms in 12 patients, and computed tomographic scans in all, have shown a stable repair of the transverse arch in all survivors but a persisting dissection of the descending aorta in 11 (70%). Growing experience and improving results in emergency operations for type A aortic dissection have led us to extend the replacement of the aorta to the transverse arch whenever necessary. The gelatin-resorcin-formaldehyde glue has proved to be an efficient adjunct. The best cerebral protection was obtained in our experience by carotid perfusion with cold blood during circulatory arrest at moderate core hypothermia.