08 Bicuspid aortic valve

Date: 1937
Size (H x W x D cm): 19 x 15 x 8

The opened left ventricle shows two aortic valve leaflets (one cut in two (A, short arrows) during prosection). The free edge of each leaflet measures approximately 3 cm in length. Each is deformed by nodular deposits of calcified debris (A, long arrows). The resulting rigidity led to stenosis, manifested as hypertrophy of the ventricular muscle (approximately 2 cm thickness) and dilatation of the ventricular cavity.

A. Click on image to enlarge.

History: Fifty-four year-old man. History unknown.

Comment: The semilunar (pulmonary and aortic) valves develop as swellings of the endocardial cushions on the inner aspect of the truncus arteriosus. When the four cushions fuse in the midline to divide the ventricular chambers, two additional swellings appear centrally. Continued growth is accompanied by excavation on the truncal side, resulting in the formation of sinuses between the presumptive leaflets and aorta/pulmonary artery wall. The precise mechanisms by which additional leaflets are formed or leaflets fail to develop are unclear. However, some cases of bicuspid aortic valve have a genetic basis (autosomal dominant with incomplete penetrance).

Bicuspid aortic valve occurs in about 1 - 2% of the population. Its presence may be detected in childhood as a murmur. However, it usually does not cause symptoms until adulthood, when sufficient calcium deposition on damaged valve connective tissue can cause stenosis and decreased cardiac output. Complications include heart failure, ascending aorta aneurysm and sudden death (the last named secondary to transient reduction in coronary artery blood flow followed by arrhythmia).

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