Low preoperative superior vena cava blood flow predicts bidirectional cavopulmonary shunt failure.

BACKGROUND

In this study we sought to determine whether preoperative superior vena cava (SVC) blood flow measured using cardiac magnetic resonance (CMR) predicts physiology and clinical outcome after bidirectional cavopulmonary shunt (BCPS).

METHODS

The retrospective single-center study included 65 (2012-2017) patients who underwent BCPS. Preoperative CMR imaging, echocardiography, catheterization, and clinical outcomes were reviewed. SVC flow was measured using phase contrast CMR. The Kaplan-Meier method and Cox regression was used for BCPS takedown-free survival and predictor analyses.

RESULTS

The absolute and indexed SVC flow was 0.5 (interquartile range [IQR], 0.4-0.7) L/min and 1.7 (IQR, 1.4-2.0) L/min/mm respectively, which was comparable with the SVC blood flow volume previously measured. The median age and body weight at BCPS was 6.5 (IQR, 5.5-8.5) months and 6.9 (IQR, 6.0-7.7) kg. After follow-up, at a median of 17.1 (IQR, 7.9-41.3) months, 14 patients (21.5%) underwent the Fontan completion and 40 (61.5%) with BCPS physiology were waiting for the Fontan completion. The 11 remaining patients (16.9%), included those who underwent takedown (n = 7; 10.8%) or died with a BCPS (n = 4; 6.2%). Severe hypoxia was the leading cause of mortality, directly accounting for two-thirds of deaths (66.6%; 6/9). The BCPS takedown-free survival was 96.8% at 6 months, and 79.9% at 3 years. Preoperative SVC blood flow was significantly positively correlated with early post-BCPS arterial saturation (P = .00). The multivariable analysis showed SVC flow was the only factor associated with BCPS failure (hazard ratio, 0.186; P = .04) among the predictors related to the pre-BCPS anatomy and physiology.

CONCLUSIONS

SVC blood flow might be as critically important as pulmonary artery anatomic and physiologic parameters in the evaluation of BCPS candidacy in the single-ventricle population.