Echocardiographic differentiation of atrioventricular septal defects from inlet ventricular septal defects and mitral valve clefts.

Left ventricular inlet/outlet ratio and percent left atrioventricular valve (AVV) guarded by the posterior leaflet are valuable for characterizing atrioventricular septal defect (AVSD). We performed these measurements echocardiographically in normal patients (n = 101), patients who had AVSD (n = 37), those who had isolated perimembranous inlet ventricular septal defect (VSD; n = 12), and those who had "isolated" mitral valve clefts (n = 5). Surgical findings of 38 patients were reviewed. The normal inlet/outlet ratio was 1.03 +/- 0.07. For patients who had AVSD, the ratio was 0.82 +/- 0.06 (95% confidence interval [CI] 0.180 to 0.237, p = 0.001). For patients who had an isolated inlet VSD, this ratio was lower than that in normal patients (0.93 +/- 0.08, 95% CI 034 to 0.116, p = 0.001) but higher than that in patients who had AVSD (95% CI -0.175 to 0.091, p = 0.001). The percent left AVV guarded by the posterior leaflet was 56 +/- 1.4 in normal patients. For patients who had AVSD, it was significantly lower (43 +/- 1.1). For patients who had an isolated VSD and those who had an isolated mitral cleft, it was normal (57 +/- 1.9 and 55 +/- 2.2, respectively). The 2 measurements are valuable in differentiating AVSD from inlet VSD and isolated mitral cleft, but percent left AVV guarded by the posterior leaflet is more specific.