Atrioventricular Inflow Size Correlates with Ventricular Growth After Staged Recruitment for Unbalanced Atrioventricular Canal Defect

Y. Kobayashi¹, G. Marx², S. Emani^3
1Boston Children's Hospital, Boston, Massachusetts ²Boston Children’s Hospital, Boston, Massachusetts ³Boston Childrens Hospital, Boston, Massachusetts

Purpose: Staged ventricular recruitment (SVR) for unbalanced atrioventricular canal defect (uAVCD) consists of atrial and atrioventricular valve (AVV) septation without ventricular septal defect closure. However, ventricular growth occurs to varying degrees following SVR. We hypothesize that size of AVV inflow to the recruited ventricle is associated with subsequent growth.

Methods: This single-institution retrospective review included 46 patients who underwent SVR for uAVCD between 2011 and 2023. The size of AVV inflow jet to the hypoplastic ventricle after SVR was assessed by intraoperative echocardiography and classified as 91–100% (N = 25), 61–90% (N = 7), 41–60% (N = 8), and 0–40% (N = 6) of the inflow across the AVV of the hypoplastic ventricle. End-diastolic volume index (EDVI) was measured by magnetic resonance imaging before and after SVR, and EDVI change (post-pre) was calculated. Pre- and post-SVR EDVI were compared using the Wilcoxon matched-pairs signed rank test.

Results: Forty-two patients (91%) had right dominant uAVCD. Heterotaxy syndrome was present in 21 patients (46%). Single papillary muscle was present in 20 patients (43%), all of whom underwent papillary muscle splitting. In the total cohort, EDVI of the hypoplastic ventricle increased after SVR (median; pre, 30 [20–38] vs. post, 47 [36–64] ml/m2, P < 0.001). Pre-SVR EDVI was not different among the four inflow categories (P = 0.216). However, the median EDVI change varied (AVV inflow category; 91–100%, 25.5 vs, 61–90%, 14.4 vs. 41–60%, 8.0 vs. 0–40%, 6.0 ml/m2, P < 0.001, Figure). One patient (17%) with half inflow and four patients (50%) with poor inflow required additional recruitment procedures, including ventricular septal defect closure, cleft closure, or both. Eventually, 36 patients (78%) underwent biventricular repair. There was a trend that patients with less AVV inflow to the hypoplastic ventricle did not achieve biventricular repair, but the proportion of patients achieving biventricular repair did not differ among the four categories (AVV inflow category; 91–100%, 21 [84%]; 61–90%, 6 [100%]; 41–60%, 4 [67%]; 0–40%, 5 [63%]). No mortality occurred.

Conclusion: Intraoperative AVV inflow pattern after SVR for uAVCD may correlate with growth of the hypoplastic ventricle. This may impact ability to successfully undergo subsequent biventricular repair. Further studies are needed to confirm this relationship and its impact on SVR procedure.

Identify the source of the funding for this research project: None