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Disease summary:
Bicuspid aortic valve (BAV) disease is the commonest congenital heart lesion, affecting approximately 1% to 2% of the population and is approximately three times more common in men.
BAV is typically nonsyndromic, but is seen with increased frequency in the Turner and potentially Loeys-Dietz syndromes.
BAV is usually an isolated cardiac lesion but is often seen in conjunction with coarctation of the aorta and other obstructive left-sided lesions (Shone complex, hypoplastic left heart syndrome).
Aortic stenosis (AS) develops in most patients with BAV. The incidence of AS increases with age and BAV is the commonest indication for aortic valve replacement in patients under 70 years old.
Aortic regurgitation (AI) and infective endocarditis are also more prevalent in BAV.
BAV is associated with an elevated risk of developing thoracic aortic dilation and aneurysms (TADA) and subsequent aortic dissection and rupture. In children, the risk of aortic aneurysm increases with age, indicating the progressive nature of aortic dilation.
Longitudinal echocardiographic monitoring is recommended for patients with BAV, both for development or progression of valvular stenosis or regurgitation, and also for ascending aortic dilation. If the ascending aorta cannot be well visualized with transthoracic echocardiography (TTE), either computed tomography (CT) or magnetic resonance angiography (MRA) should be performed.
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Family history:
Familial involvement has been reported in 37% of patients with BAV. When familial disease is present, inheritance is autosomal dominant with variable penetrance.
There is an increased risk of aortic dilation in individuals with apparently normal tricuspid aortic valve who are first-degree relatives of patients with BAV.
Screening of first-degree relatives of probands with BAV is recommended and this is most commonly accomplished by transthoracic echocardiography.
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Genetic factors:
Mutations in NOTCH1 have been identified in limited kindreds with BAV and aortic calcification.
Mutations in ACTA2 have been identified in kindreds with TADA, livedo reticularis, and BAV.
In the vast majority of cases, the genetic etiology of BAV has not been identified.
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Diagnostic Criteria and Clinical Characteristics
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The cusps or leaflets of the normally tricuspid aortic valve are named after the adjacent coronary ostia, right coronary cusp, left coronary cusp, and noncoronary cusp. Fusion of two cusps causes BAV. The most common BAV morphology involves fusion of the right and left coronary cusps (R-L fusion), followed by right and noncoronary cusp fusion (R-N fusion), whereas fusion of the left and noncoronary cusps is exceedingly rare.
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Physical examination provides clues to the diagnosis, but BAV is usually diagnosed by TTE. Notably, a prominent raphe, or ridge, at the site of leaflet fusion may provide the false impression of three distinct leaflets when the aortic valve is visualized during diastole. Accordingly diagnosis rests on visualizing two, instead of three aortic leaflets during systole. Supporting features are systolic doming or diastolic prolapse of the aortic valve and an abnormal leaflet ...