Bicuspid aortic valve leaflet morphology in relation to aortic root morphology: a study of 300 patients undergoing open-heart surgery.

OBJECTIVE: There is an ongoing discussion regarding the mechanism of aortic dilatation in bicuspid aortic valve (BAV) disease, that is, is this a hemodynamic effect or related to an inborn weakness of the aortic wall? This study evaluated the possibility of BAV morphology being related to ascending aorta morphology as such a correlation would strengthen the idea that hemodynamic alterations cause the dilatation of the aorta.

METHODS: The morphology of the ascending aorta of 300 patients admitted for aortic valve and/or ascending aorta disease was evaluated by echocardiography and related to the surgeon's inspection of the aortic valve.

RESULTS: A tricuspid aortic valve (TAV), BAV, or unicuspid aortic valve (UAV) was present in 130, 160, and 10 patients, respectively. Ascending aortic aneurysm was more common in patients with BAV compared with TAV (36% and 12%, respectively; p < 0.001), while ectasia of the aorta was similarly common (8% in both groups). Aortic stenosis or regurgitation was equally distributed in TAV and BAV patients with normal aortas (p=0.82). When the aorta was dilated, aortic stenosis was predominantly associated with BAV (BAV 56%, TAV 4%; p < 0.001), while aortic regurgitation was more common in TAV (TAV 81%, BAV 29%; p<0.001). In BAV patients, fusion of the right- and left coronary cusp was predominant (74%) followed by right- and non-coronary cusp fusion (14%) and true BAV (fusion of the right- and left coronary cusp without remnant raphe; 11%) (p < 0.001). The relative distribution of ascending aortic aneurysm or ectasia was similar in all morphologically different BAV (p = 0.95).

CONCLUSIONS: In our study population, >50% of the patients admitted for surgery had a bicuspid valve. Aortic aneurysm was more common in BAV than in TAV patients. Aortic stenosis and aortic regurgitation were equally common in TAV and BAV with normal aortic dimensions, while aortic regurgitation was predominant in TAV with dilated aortas and aortic stenosis in BAV with dilated aortas. Dilatation of the aorta was similarly distributed regardless of BAV leaflet morphology. These findings support the idea of an intrinsic mechanisms underlying dilatation of the aorta in BAV patients.