Bicuspid Aortic Valve Disease

Bicuspid aortic valve disease (BAV) is the most common congenital heart abnormality, affecting 0.5–2% of the total population with a male predominance [1]. Although the majority of cases are sporadic, BAV can be familial and is commonly associated with other congenital heart abnormalities and genetic syndromes [1,2]. In addition to the obvious valvular sequelae to which BAV patients are predisposed, BAV disease is associated with an aortopathy and an associated predisposition to aneurysm formation and dissection of the thoracic aorta [1–3]. Patients with BAV therefore require lifelong evaluation and surveillance at various intervals, depending upon their specific condition. Advances in imaging and in molecular characterization of the underlying aortopathy hold promise to improve both evaluation and treatment of patients with BAV.
The defining feature of BAV is abnormal aortic valvular morphology, with the valve having two leaflets and two commissures instead of three. Most commonly, the two leaflets are asymmetric, and the larger has a central raphe or fibrous ridge in the area where a commissure that would otherwise be present has fused [1]. The leaflets may be of roughly equivalent size, and the raphe may be absent in certain cases [1]. Fusion may occur between any of the three valve leaflets, most commonly between the right- and left-coronary leaflets (70–86%), although also between the right- and non-coronary leaflets (12%) or between the left- and non-coronary leaflets (3%) [1]. Leaflet orientation may play a role in BAV disease progression and aortic dilatation [2,4]. Right- coronary and non-coronary leaflet fusion has been associated with more rapid progression of valvular pathology including stenosis and re- gurgitation [4]. The abnormal hemodynamic stress imposed by the atyp- ical valve anatomy on both the valve tissue and the aorta by BAV may contribute significantly to the ultimate development of valvular dysfunction and to aortopathy [2,5,6].

BAV patients may have many fates. Some patients with BAV are highly symptomatic in childhood with congenital AS or severe AR or have associated lesions such as coarctation of the aorta, which bring them to medical attention. However, many young people with BAV are completely asymptomatic and have “normally” functioning BAVs. It is nevertheless estimated that at least one third and perhaps a majority of patients with BAV will develop a complication during their lifetime. This implies that the vast majority of BAV patients will remain asymptomatic until adulthood, at which time they begin to experience progressive degeneration of valvular function and sequelae of aortopathy including aortic dilatation, aneurysm formation and risk of dissection. Early surgical and autopsy data indicate that progression of valvular dysfunction, particularly aortic stenosis, occurs at a significantly earlier age in BAV patients than in those with a trileaflet aortic valve.

The abnormal hemodynamic stress imposed by the atypical valve anatomy on both the valve tissue and the aorta by BAV may contribute significantly to the ultimate development of valvular dys- function and to aortopathy

References

[1] BravermanAC,GuvenH,BeardsleeMA,MakanM,KatesAM,MoonMR. The bicus-pid aortic valve. Curr Probl Cardiol 2005;30(9):470-522.

[2] Braverman AC. Beardslee. The bicuspid aortic valve. In: Otto C, Bonow R, editors. Valvular heart disease: a companion to Braunwald’s Heart Disease. Philadelphia: Saunders/Elsevier; 2009. p. 169-86.

[3] Braverman AC. Aortic involvement in patients with a bicuspid aortic valve. Heart 2011;97(6):506-13.

[4] Fernandes SM, Khairy P, Sanders SP, Colan SD. Bicuspid aortic valve morphology and interventions in the young. J Am Coll Cardiol 2007;49(22):2211-4.

[5] Wallby L, Janerot-Sjoberg B, Steffensen T, Broqvist M. T lymphocyte infiltration in non-rheumatic aortic stenosis: a comparative descriptive study between tricuspid and bicuspid aortic valves. Heart 2002;88(4):348-51.

[6] Robicsek F, Thubrikar MJ, Cook JW, Fowler B. The congenitally bicuspid aortic valve: how does it function? Why does it fail? Ann Thorac Surg 2004;77(1):177-85.