Schematic of the BAV anatomical spectrum using the most common right–left cusp fusion as the example. From left to right, note the partial-fusion BAV resembling a tricuspid aortic valve, likely associated with a mild embryological defect, then spanning a continuum of increasing non-fused cusp commissural angles and increasing cusp size/shape similarity, ending with the 2-sinus BAV phenotypes that represent almost perfect ‘bicuspidity’ and are likely associated with the most severe embryological defects. Modified from Michelena et al. [10] with permission from Elsevier. BAV: bicuspid aortic valve.