1/6/2024 0 Comments 3d coat 4.7 serialHowever, whereas the aortic root is easily visualized in most transthoracic echocardiograms, in many cases the midportion of the ascending aorta is not. In many cases, this can be accomplished with echocardiography. This suggests that the walls of aneurysms associated with bicuspid aortic valves may be weaker than more “typical” aneurysms.īecause half of those with a bicuspid valve have aortic dilatation, cardiologists should routinely image the ascending aorta in all bicuspid aortic valve patients. Additionally, in a recent study of patients with ascending thoracic aortic aneurysms, Schmid et al 12 found that compared with tricuspid aortic valve controls, the aortic aneurysm tissue of those with a bicuspid aortic valve demonstrated more lymphocyte infiltration and smooth muscle cell apoptosis. This might account for why some patients with a bicuspid valve having undergone the Ross procedure develop late dilatation of the pulmonary autograft (see later sections). Interestingly, samples of the pulmonary arteries of the same subjects showed a similar reduction in fibrillin-1 content among those with bicuspid aortic valves. They found that patients with bicuspid aortic valves had significantly less fibrillin-1 than did patients with tricuspid aortic valves, and the reduction in fibrillin-1 was independent of patient age or aortic valve function. 10 Fedak et al 11 examined ascending aortic specimens from those with bicuspid aortic valves and tricuspid aortic valves undergoing cardiac surgery. 9 Inadequate production of fibrillin-1 during embryogenesis may result in both the bicuspid aortic valve and a weakened aortic wall. In one study, 75% of those with a bicuspid aortic valve undergoing aortic valve replacement surgery had biopsy-proven cystic medial necrosis of the ascending aorta, compared with only 14% of those with tricuspid aortic valves undergoing similar surgery. 8Ĭystic medial degeneration has been found to be the underlying cause of the aortic dilatation associated with a bicuspid aortic valve. Indeed, other studies have demonstrated that a bicuspid aortic valve is associated with a dilated aorta, regardless of the presence or absence of hemodynamically significant valve dysfunction. Nistri et al 7 used echocardiography to evaluate young people with normally functioning bicuspid aortic valves and found that 52% had aortic dilatation (44% at the level of the tubular portion of the ascending aorta and 20% at the level of the sinuses ). It was once thought that such aneurysms were due to “poststenotic dilatation” of the ascending aorta, but the data suggest otherwise. Many cases of ascending thoracic aortic aneurysms are associated with an underlying bicuspid aortic valve. Consequently, at present, it is not possible to perform routine genetic screening for this syndrome. It is also possible that this is actually a polygenic condition, thus explaining the variable expression and penetrance. 1,6 The extent of genetic heterogeneity is likely to become more evident as more families with thoracic aortic aneurysms are studied. 4,5 Mutations have also been mapped to 2 other chromosomal loci (5q13–14 and 11q23.2-q24). A mutation on 3p24.2–25 can cause both isolated and familial thoracic aortic aneurysms, with histological evidence of cystic medial degeneration. Most pedigrees suggest an autosomal-dominant mode of inheritance, but there is marked variability in the expression and penetrance of the disorder, such that some inherit and pass on the gene but show no manifestation of the disease. In an analysis of their large database of thoracic aortic aneurysm patients, Coady and colleagues 3 found that at least 19% of patients had a family history of a thoracic aortic aneurysm, and they presented at significantly younger ages than did those with sporadic aneurysms. Moreover, it is now recognized that although cases of thoracic aortic aneurysms in the absence of overt connective-tissue disorders may be sporadic, they are often familial and are now referred to as the familial thoracic aortic aneurysm syndrome. Customer Service and Ordering Informationįamilial Thoracic Aortic Aneurysm SyndromeĬystic medial degeneration is also seen in patients with ascending thoracic aortic aneurysms who do not have overt connective-tissue disorders.Stroke: Vascular and Interventional Neurology.Journal of the American Heart Association (JAHA).Circ: Cardiovascular Quality & Outcomes.Arteriosclerosis, Thrombosis, and Vascular Biology (ATVB).
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