Subtypes of acute aortic dissection

Background. This series consists of a 12-year experience with a policy of i dentifying and replacing the aortic segment containing the primary intimal tear for repair of acute aortic dissection. Methods. Patients with type A dissection underwent urgent surgery. Patients with type B dissection were referred for surgery based on selective criter ia, including aortic dilatation greater than 5 cm. A classification system for acute dissection is described that specifies the site of intimal tear w hile retaining the clinical relevance of the Stanford system. Results. Of 168 acute dissections, 139 were type A and 29 were type B. The site of intimal tear was as follows: ascending aorta, 83 cases; arch, 32 ca ses; descending aorta, 29 cases; multiple tears, 11 cases (10 included arch tears); no tear (intramural hematoma), 6 cases; not noted, 7 cases. Only 6 0% of acute type A dissections arose from solitary intimal tears in the asc ending aorta, whereas 30% had arch tears. Hospital mortality for type A dis section was 13.7"/0 (18.8% for arch tears, NS) and 0% for type B. False lum en patency was 57.1% for type A dissection and 18.8% for type B dissection (p = 0.002), yet survival was similar for these groups. Ten-year survival f or type A dissection with arch tear (0.51 +/- 0.12) was lower than 10-year survival for type A dissection with ascending tear (0.74 +/- 0.05; p 0.77), and significantly lower than for type A dissection with descending tear (0 .88 +/- 0.12; p = 0.029). Conclusions. Systematic resection of the primary tear yielded similar hospi tal mortality, 5-year survival, and aorta-related event-free survival rates for subtypes of acute type A dissection. Excellent results were obtained w ith a selective approach to type B dissection. (C) 1999 by The Society of T horacic Surgeons.