Dissection of the Descending Thoracic Aorta

Abstract

In this issue of the Journal, Song et al.(1) report a retrospective analysis of the midterm outcomes of 100 patients with an acute aortic dissection involving the descending thoracic aorta. Of the 100, 51 had a DeBakey type I (involvement of both the ascending and descending thoracic aorta) aortic dissection and underwent early repair of the ascending thoracic aorta, and 49 had a DeBakey type III (no involvement of the ascending aorta) aortic dissection. The subjects were followed longitudinally with serial computed tomography (CT) scans for a mean of 31 months, and were followed clinically for a mean of 53 months. Among a subset of 53 subjects who had aortic imaging repeated beyond 2 years, an aortic aneurysm developed in 28%, with the majority of aneurysms involving the proximal segment of the descending thoracic aorta. The proximal segment also grew most rapidly, at rate of 3.4 Ϯ 3.6 mm/year. There was a trend toward slightly faster rates of aortic growth among those with type I versus type III dissection, at 3.8 Ϯ 3.5 mm/year versus 3.1 Ϯ 3.1 mm/year, respectively. See page 799The authors measured both total aortic diameter and the diameter of the false lumen alone at multiple levels in the aorta. Although overall aortic diameter was a predictor of aortic aneurysm formation, it was not found to be an independent predictor on multivariate analysis. Instead, they found that Marfan syndrome and large false lumen diameters at the upper and mid-descending thoracic aorta were independent predictors of late aneurysm formation. Dividing their populations into those with a small false lumen diameter (Ͻ21 mm) and those with a large false lumen diameter (Ն22 mm) in the upper descending thoracic aorta, they demonstrated that those with a large false lumen had a markedly greater risk of late aneurysm formation (42% vs. 5%, p Ͻ 0.001), with a trend toward increased mortality (17% vs. 5%, p ϭ 0.09) as well.So why are these findings so important? To put these findings into clinical perspective, it is best to step back and consider our current understanding of the management and outcome of distal aortic dissection.It is well established that those with aortic dissection involving the ascending thoracic aorta (DeBakey types I and II, or Stanford type A) are at high risk of early death, as the dissected ascending aorta has a propensity to rupture into the pericardial space. Consequently, such patients are managed with early surgical repair of the ascending thoracic aorta, as decades of data have validated the advantage of surgery over medical therapy for this group.Conversely, those with aortic dissections involving the descending aorta but not the ascending aorta (DeBakey type III, Stanford type B) have a relatively low risk of aortic rupture and, thus, have a significantly lower early mortality. Moreover, surgery to repair the descending thoracic aorta in this setting is associated with substantial mortality and morbidity, including the dreaded complication of paraplegia. Therefore, since surgery was shown to confer no surviv...

A study of aortic dissection screening method based on multiple machine learning models

“…Aortic dissection (AD) is a very rare clinical emergency, the pathogenesis of which is that the blood of the aorta enters the aortic wall under the pressure of the aorta, then a dissecting hematoma is formed in the wall of the aorta, and the longitudinal axis of the aorta is extended to form a "double lumenal aorta" (1). This is a very dangerous cardiovascular disease of which the death rate is 1-2% per hour in the first 24 hours of the onset of the disease and…”