Objective Systemic to pulmonary arterial collateral flow (CollF) is common in single ventricle patients with superior cavopulmonary connections (SCPC), although associations with CollF are not well understood. We previously described a method to quantify CollF by cardiac MRI (CMR). We sought to identify factors associated with CollF in a large cross section of patients with SCPC.

Methods A retrospective observational cohort study of events from birth to study CMR was performed for all patients with SCPC who had CollF quantified by CMR.

Results CollF was quantified in 96 patients at a median age of 2.6 (IQR 1.9–3.1) years and 2.1 (1.4–2.7) years after SCPC and measured 1.6±0.7 L/min/m² (33±11% of aortic flow and 48±16% of pulmonary venous flow). Significantly higher amounts of indices of CollF were associated with: duration of chest tubes (p≤0.05 for all), intensive care unit and hospital length of stay (p≤0.04 for all), higher O₂ saturation at Stage 2 discharge (p=0.04 for CollF/aortic), female sex (p≤0.007 for CollF/aortic and CollF/pulmonary venous), and history of a Blalock-Taussig shunt (p<0.04 for CollF and CollF/aortic). Multivariable models were constructed to identify factors independently associated with CollF measures and included: female sex (p≤0.006 for all), O₂ saturation at Stage 2 discharge (p=0.013 for CollF/aortic) and total chest tube days (p=0.001 for all). These models explained 20–22% of the variance in the outcomes.

Conclusions These data support hypotheses that perioperative morbidity and pleural inflammation play a role in CollF development and that CollF affects pulmonary blood flow.