Usefulness of Left Ventricular Inflow Index to Predict Successful Biventricular Repair in Right-Dominant Unbalanced Atrioventricular Canal

The outcome of biventricular (BV) repair for right-dominant unbalanced atrioventricular canal has remained poor, because it is difficult to predict left ventricular (LV) adequacy before surgery. Our aim was to determine whether preoperative echocardiographic parameters, specifically analysis of color inflow into the LV, would predict survival after BV repair in patients with right-dominant unbalanced atrioventricular canal. Subjects with right-dominant unbalanced atrioventricular canal diagnosed from 1994 to 2007 were included. The echocardiographic parameters were analyzed blinded to the palliation strategy and survival. The LV inflow index (LVII) was calculated as the secondary color inflow diameter indexed to the left atrioventricular valve (AVV) annulus diameter. Univariate analysis, survival analysis, and multivariate modeling with stepwise logistic regression were performed. Of the 45 subjects, 23 (51%) underwent single ventricle (SV) palliation and 22 (49%) underwent BV repair. Of the 23 who underwent SV palliation, 15 (65%) survived compared to 18 (82%) of 22 who underwent BV repair (p = 0.34). In the BV group, a greater LVII predicted survival (R2 = 0.46, p = 0.03). No subjects with a LVII <0.5 survived BV repair. Mortality in the BV group was associated with younger age at initial surgery (p <0.01) and abnormal left AVV morphology (p = 0.02). Of the BV subjects with a patent ductus arteriosus at the initial operation (n = 11), the nonsurvivors were more likely to have retrograde flow in the transverse arch (p <0.01). In the BV group, reoperation within 30 days of the initial repair was strongly associated with mortality (p <0.01). In conclusion, in cases of mild or moderate LV hypoplasia, a greater LVII predicted survival after BV repair in patients with right-dominant unbalanced atrioventricular canal. We propose incorporation of the LVII into the echocardiographic assessment of these patients.