Open repair in chronic type B dissection with connective tissue disorders.

Aneurysms associated with inherited connective tissue disorders (CTD) constitute a specific but important issue in thoracoabdominal aortic aneurysm (TAAA) surgery. In this respect, Marfan syndrome and Ehlers-Danlos syndrome (EDS) type IV represent the most significant disorders causing aneurysmal dilatation of the thoracic aorta. Marfan syndrome typically causes aortic root dilatation, aortic valve insufficiency and dissection, whereas EDS can generate dissection or aneurysm formation in almost every major artery, including the thoracoabdominal aorta. The majority of patients with Marfan syndrome first suffer from ascending thoracic aortic aneurysm, which requires surgical repair. Marfan patients are significantly younger than patients with degenerative aneurysms (1). Therefore, the physical condition of younger Marfan patients is much better than the non-Marfan group (2). Despite this, there is a higher incidence of dissection and rupture during TAAA surgery in Marfan patients and the recommended threshold for repair is thus an aneurysm diameter of 5.0-5.5 cm (3). The second most common cause of TAAA formation is chronic type B dissection. In patients having surgery for TAAA, up to 24% suffer from chronic dissections (4). Conversely, 20-40% of all patients with aortic dissections will require subsequent aortic replacement for aneurysmal degeneration, irrespective of initial medical or surgical treatment at the time of acute presentation (5). The presence of blood flow in the false lumen is the most significant risk factor for increased aortic diameter, with a mean growth rate of 3.3 mm/year (as compared to 1.4 mm/year diameter shrinkage in patients with a thrombosed false lumen). Position along the aorta also influences growth rate with thoracic aortic aneurysms expanding significantly faster than AAAs (4.1 and 1.2 mm/year, respectively) (6). The growth rate of post-dissection aneurysms can be comparable to that of degenerative thoracic aneurysms or faster. Taking these considerations into account, the combination of chronic dissection, aneurysm formation and connective tissue disease poses major challenges regarding indication for treatment, choice of treatment, and clinical outcome.