The Role of Echocardiography and Intracardiac Exploration in the Evaluation of Candidacy for Biventricular Repair in Patients With Borderline Left Heart Structures.

Background: Predictors for single ventricle palliation (SVP) or successful biventricular repair (BVR) in patients with borderline left-side heart structures are not well defined. The goal was to evaluate the role of echocardiography and intracardiac exploration in determining feasibility of BVR.

Methods: All neonates surgically treated from 1995 to 2015 with mitral valve (MV), aortic valve, or left ventricle end-diastolic dimension z score of -2 or less for whom management was controversial were included. Data were analyzed using Fisher's exact test, Kruskal-Wallis test, and Kaplan-Meier analysis.

Results: The cohort consisted of 42 patients: 7 SVP (17%) and 35 BVR (83%). Median follow-up was 7 years (range, 6 months to 18 years). Intracardiac exploration was performed in 29 patients (69%). There was poor correlation between echocardiographic and intraoperative MV measurements (intraclass correlation coefficient 0.14). Preoperative echocardiography significantly underestimated MV size in 14 patients (54%). Two BVR patients were converted to SVP, and 4 (including 1 converted patient) had cardiac-related deaths. All patients with MV greater than 8 mm on preoperative echocardiography had successful BVR. An intraoperative MV less than 8 mm and an abnormal subvalvar apparatus was present in 5 of 6 SVP (83%) and 3 of 3 (100%) failed BVR patients who had intracardiac exploration, and in only 1 of 20 successful BVR patients (5%) who had an intracardiac exploration.

Conclusions: The decision to proceed to BVR in patients with borderline left-side heart structures should not rely strictly on echocardiographic measurements. Intracardiac exploration of the MV and subvalvar apparatus is useful before committing a patient to SVP. Patients with low MV z scores, especially those with a normal subvalvar apparatus, may undergo BVR with good outcomes.