Superiority of two-dimensional echocardiography in the diagnosis of congenitally bicuspid aortic valve.

This study compares the role of M-mode and two-dimensional echocardiography in the evaluation of the nonstenotic, congenitally bicuspid aortic valve. Ten asymptomatic healthy subjects (age 20-35 years) with a systolic ejection click and short systolic murmur were evaluated. M-mode echocardiograms were entirely normal. The aortic root, diastolic closure line, eccentricity index of the aortic valve, and left ventricular size and function were normal in every subject. The two-dimensional parasternal long axis view of the aortic root was also normal in all patients with bicuspid aortic valves; there were no abnormalities of systolic excursion of the aortic cusps and doming of the aortic valve was absent. Images obtained in the two-dimensional parasternal short axis view of the aortic root at the level of the aortic valve revealed only two cusps, anterior and posterior, in all patients. The classic closure pattern of the normal tricuspid aortic valve forming a "Y" was absent in every subject. Instead, a horizontal closure line along the "X" axis was demonstrated in all patients; changing the angulation of the transducer in various positions did not alter this pattern. All subjects had increased reflectance of echoes along the line of diastolic closure, probably resulting from redundancy of the aortic cusp tissue. We conclude that because of the inability of the M-mode echocardiographic technique to accurately diagnose this condition in the study group, two-dimensional echocardiography should be the technique of choice in the evaluation of patients with a suspected bicuspid aortic valve. Recognition of this condition is important in view of its susceptibility to subacute bacterial endocarditis, aortic stenosis, and regurgitation.