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Bicuspid Aortic valve

Clinical and genetic features of bicuspid aortic valve

The aortic valve is located at the transition from the left ventricle to the aorta, and usually consists of three pocket-shaped cusps (tricuspid). The bicuspid aortic valve (BAV) represents a deviation from this. In this congenital malformation, the aortic valve comprises only two cusps. BAV is the most common type of congenital cardiac anomaly. It has a frequency of around 1-2% in the general population, with a 3-5 fold greater prevalence being observed among males. BAV may occur as an isolated anomaly. However, it is often associated with genetic syndromes or other cardiovascular malformations.

In BAV, the opening and closing of the aortic valve are typically disturbed secondary to an asymmetry of the two cusps. Valve malfunction requiring treatment occurs in up to 25% of cases. The most common complication of BAV is aortic valve stenosis. In some patients, this is apparent at birth. In others, the stenosis first becomes manifest in adulthood.

Isolated BAV is often first detected in early adulthood. In the compensated stage of aortic valve stenosis, patients complain of fainting episodes, loss of consciousness (syncope), and dizziness. The dizziness is attributable to an insufficient flow of blood to the brain, and is particularly evident in response to exertion. With increasing cardiac muscle thickening, the oxygen requirement increases. Consequently, pain in the heart area (angina pectoris) may occur, even in the presence of healthy arteries. As the left ventricle enlarges (dilates), the symptoms of cardiac insufficiency increase. Severe aortic valve stenosis can also lead to cardiac arrhythmias (e.g., atrial fibrillation).

When clinical symptoms or high-grade aortic valve stenosis occur, surgical therapy is the gold standard (surgical aortic valve replacement). For elderly patients or those with extensive comorbid disease, a catheter-based aortic valve replacement may be the treatment of choice. Without aortic valve replacement, the prognosis of patients with aortic valve stenosis or BAV is poor.

In the vast majority of isolated BAV cases, the etiology is multifactorial, i.e., the disease is attributable to a combination of environmental factors and multiple genetic risk factors. In recent years, genome-wide association studies (GWAS) have identified genetic risk variants for numerous multifactorial diseases. A GWAS of aortic stenosis identified the first genetic risk variants for the disorder in the genes PALMD, TEX41, LPA, and MYH6 (Helgadottir et al. (2018) Nat Commun). However, the study included both BAV nd tricuspid aortic valve. cases. The aim of the present research project is to identify genetic risk variants for isolated BAV. Together with cooperation partners in Bonn, a GWAS of a large BAV case-control collective is planned.

Contact person

Prof. Dr. Johannes Schumacher

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