Bicuspid aortic valve type: it takes two

Not all patients with bicuspid aortic valves behave similarly. Some patients have early valve dysfunction and require intervention in infancy or childhood. More commonly, bicuspid valves degenerate gradually throughout adulthood and valve failure does not occur until the fifth decade or later. Some patients have primarily aortic stenosis while others have aortic regurgitation. Others have mixed valve dysfunction. The aorta dilates in some, but not all patients with bicuspid aortic valves. Furthermore, dilation can occur at the sinuses, in the mid-ascending aorta, or in both regions. Numerous authors have attempted to explain this heterogeneity in valve dysfunction and aortic morphology. However, to date, the reason for the variability in presentation remains incompletely explained. The most common way to categorise bicuspid aortic valves is according to the morphology of leaflet fusion, since most valves are trileaflet with a fused commissure. Fusion of the right and left coronary cusps (RL fusion) is most common, followed by fusion of the right and non-coronary cusps (RN fusion). Fusion of the left and non-coronary cusps is quite rare. Some valves have no identifiable raphe and are described as ‘true’ or ‘pure’ bicuspid aortic valves. Because the morphology of bicuspid aortic valves is usually easy to define by echocardiography, it is tempting to ascribe …