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Aortic Dilatation and Dissection in Turner Syndrome« Back to Volume 24, Issue 1, May 2008 - Table of Contents The cardiovascular phenotype in Turner syndrome (TS) is largely defined on clinical signs such as aortic valve abnormalities and aortic coarctation. Investigation in asymptomatic patients has revealed a far more complex phenotype. Combined echocardiography and MRI have shown that up to 75% of adult women with TS have significant cardiovascular abnormalities. In parallel there have been reports of a high rate of aortic dissection in TS and dilation of ascending aorta could be among predisposing factors. It is still unknown whether aortic dilatation precedes dissection in these patients and what specific diameter predicts impending deterioration. The purpose of this study by Matura et al was to reliably identify girls and women at risk for such acute aortic events. This study included 166 adult volunteers with TS, aged more than 18 years, who were not selected for cardiovascular disease and a group of healthy females. Ascending and descending aorta diameters were measured by MRI at the right pulmonary artery. Average diameters were identical in both groups; however results needed to take into account a mean 20 cm difference in height between both groups. When normalized to body surface area (aortic size index) the ascending aortic diameters were significantly greater in the TS group, and close to 32% of the TS women had values >95th percentile of 2.0 cm/m2. Ascending/descending aorta diameters ratios were significantly greater in the TS group. During 3 years of follow-up aortic dissection occurred in 3 women with TS. Their ascending aortic diameters ranged from 3.7 to 4.8 cm and the aortic size indices were >2.5 cm/m2. This rate is almost 100 fold higher than that of normal women who are usually affected at a much later age. Unfortunately there are no prospective data to know whether dilatation of the ascending aorta preceded dissection or elongation of the transverse aortic arch—a feature more recently described in TS. The risk for aortic dissection is greatly increased in young women with TS. Because of their small stature, ascending aorta diameters of >5 cm may represent significant dilatation. The use of an aortic size index is therefore recommended. Individuals with a dilated ascending aorta defined as aortic size index >2.0 cm/m2 require close cardiovascular surveillance, and values >2.5 cm/m2 indicate a high risk for aortic dissection. The authors suggested that haploinsufficiency for a pseudoautosomal gene is responsible for the linked cardiovascular and lymphatic defects in TS. In addition, it is acknowledged that this study did not provide evidence-based recommendations for the follow-up of these patients with aortic dilatation. Further studies are also needed, like those in Marfan syndrome, to determine whether beta-blocker or rennin-angiotensin system blockade may prevent or retard aortic dilatation and if prophylactic surgery is appropriate. Editor’s CommentRecently published clinical guidelines1 for care of girls and women with TS recommended that magnetic resonance angiography be used, in addition to echocardiography to evaluate the cardiovascular system. It was suggested that patients with defined defects be cautioned in regard to pregnancy. The present study of Matura et al provided an interesting addition of a new tool with appropriate reference data, which should help to evaluate the vital risk of aortic dissection in TS. However, prospective studies are needed which should include adolescent girls as well. The handling of the infertility issues is critical. The patients with spontaneous puberty and apparent ovarian activity should be evaluated for additional risk factors, such as systemic hypertension. The large group of infertile TS patients who have been told that assisted pregnancy can be considered in adulthood should keep in mind there is a risk of fatal aortic dissection during pregnancy. The aortic diameter should be monitored and be part of the follow-up and be taken into account in the reproductive life during adulthood. Raphaël Rappaport, MD Reference - (linked to
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Volume 25 Number 1
June 2009
www.GGHjournal.com
ISSN 1932-9032
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