Acute aortic disease

Seminar

Acute aortic dissection
Jonathan Golledge, Kim A Eagle

We summarise advances in the epidemiology, presentation, pathogenesis, diagnosis, and management of acute aortic dissection. Improved understanding of this problem has been assisted not only by establishment of an international registry but also by progress in molecular biology and genetics of connective-tissue diseases.Advances in endovascular products and techniques have provided new treatment options. Open surgical repair remains the main treatment for dissection in the ascending aorta, whereas endovascular treatment is increasingly being used in dissection that is limited to other parts of the aorta.

Lancet 2008; 372: 55–66 Vascular Biology Unit, School of Medicine, James Cook University, Townsville, Australia(Prof J Golledge FRCS); and Cardiovascular Center, University of Michigan Health System, Ann Arbor, MI, USA (Prof K A Eagle MD) Correspondence to: Prof Jonathan Golledge, Vascular Biology Unit, Department of Surgery, School of Medicine, James Cook University, Townsville, QLD 4811, Australia jonathan.golledge@jcu.edu.au

Introduction
Aortic dissection is a potentially critical break in the liningof the main arterial outflow from the heart. The emergency nature of this problem does not easily lend itself to study by randomised controlled trials. The establishment of an international registry and improved understanding of molecular biology and genetics of aortic disease have, however, led to substantial advances in the understanding of this disease (panel 1). The aim of this Seminar is toprovide a comprehensive review of acute aortic dissection, concentrating on developments since the last Seminar on this topic in The Lancet.1

during the winter months.5 A similar morning peak has been noted in other acute cardiovascular presentation and has been linked to circadian variation in blood pressure.7

Pathophysiology
Information about the mechanisms that underlie acute dissectioncomes from many sources, and we will discuss findings from case series, imaging studies, post-mortem studies, and pathological examinations of surgical biopsy samples, genetic studies, animal models, and in-vitro studies.8–36 We have focused on investigations reported since 2003 (22 of the 29 studies). The relation between aortic aneurysm and dissection has caused substantial confusion. Sincepre-existing medial degeneration is an important risk factor for acute aortic dissection, patients could have a thoracic aneurysm before dissection. However, in most cases, (more than 80%) acute dissection develops in the absence of a pre-existing aneurysm. After the development of acute dissection, the false lumen might expand later to form an aneurysm as a complication of the dissection. TheInternational Registry of Acute Aortic Dissection (IRAD) has obtained contemporary

Epidemiology
Population-based studies suggest an incidence of acute aortic dissection of about three cases per 100 000 people per year.2–4 Clouse and colleagues2 studied presentation of acute aortic dissection during 14 years in Olmsted County, MN, USA. They estimated that the incidence of acute aortic dissection in theCounty was 3·5 cases per 100 000 people per year between 1980 and 1994.2 In a community-based study of three small towns in western Hungary (Sümeg, Tapolca, and Keszthely) between 1971 and 1998, Mészáros and colleagues3 reported that 84 patients had acute aortic dissection, with an incidence of about 2·9 cases per 100 000 people per year.3 A population-based study reported the combined incidenceof aortic dissection and aneurysm.4 This study is of interest since it was done in Sweden, where excellent maintenance of databases and registries combined with a high rate of post-mortem examination in unexplained deaths suggests improved ascertainment of cases.4 Between 1987 and 2002, 4425 cases of aortic dissection were identified within a population of about 8·7 million, which equates to 3·4...