Systemic-to-pulmonary collateral flow is a well-recognised phenomenon in patients with single ventricle physiology, but remains difficult to quantify. The aim was to compare the reported formula’s that have been used for calculation of systemic-to-pulmonary-collateral flow to assess their consistency and to quantify systemic-to-pulmonary collateral flow in patients with a Glenn and/or Fontan circulation using four-dimensional flow MRI (4D flow MR).

Retrospective case–control study of Glenn and Fontan patients who had a 4D flow MR study. Flows were measured at the ascending aorta, left and right pulmonary arteries, left and right pulmonary veins, and both caval veins. Systemic-to-pulmonary collateral flow was calculated using two formulas: 1) pulmonary veins – pulmonary arteries and 2) ascending aorta – caval veins. Anatomical identification of collaterals was performed using the 4D MR image set.

Fourteen patients (n = 11 Fontan, n = 3 Glenn) were included (age 26 [22–30] years). Systemic-to-pulmonary collateral flow was significantly higher in the patients than the controls (n = 10, age 31.2 [15.1–38.4] years) with both formulas: 0.28 [0.09–0.5] versus 0.04 [−0.66–0.21] l/min/m2 (p = 0.036, formula 1) and 0.67 [0.24–0.88] versus -0.07 [−0.16–0.08] l/min/m2 (p < 0.001, formula 2). In patients, systemic-to-pulmonary collateral flow differed significantly between formulas 1 and 2 (13% versus 26% of aortic flow, p = 0.038). In seven patients, veno-venous collaterals were detected and no aortopulmonary collaterals were visualised.

4D flow MR is able to detect increased systemic-to-pulmonary collateral flow and visualise collaterals vessels in Glenn and Fontan patients. However, the amount of systemic-to-pulmonary collateral flow varies with the formula employed. Therefore, further research is necessary before it could be applied in clinical care.

it was the purpose of this retrospective study to assess the efficacy and the rate of complications of transcatheter embolization of abnormal intrathoracic vessels using coils in children with complex congenital heart disease.

in 17 children (mean age 9.2±5.9 years) with complex congenital heart disease, occlusion by catheter intervention was attempted in 29 abnormal intrathoracic vessels: 13 aorto-pulmonary collaterals, 12 arterio-pulmonary collaterals, 2 systemic arteries supplying pulmonary sequestrations, one central venous connection and a Blalock-Taussig shunt. The mean diameter of the vessels was 4.7 ± 1.6 mm (range 2–8 mm). Steel coils with a helical diameter of three, five or eight mm were used. After selective catheterization of the vessel, they were delivered through a 5 F endhole catheter. The helical diameter of the coils was chosen in order to exceed the inner diameter of the vessel by 10–30%.

as assessed by selective angiography performed 10 minutes or more after release of the coil, 27 of the 29 vessels (93%) were successfully occluded. A mean of 2.6 coils (range 1–11) were necessary for successful occlusion. Complications were encountered during 4 attempts of occlusion (14%). Of a total of 76 coils delivered, 4 coils (5%) secondarily migrated after release from the catheter, mostly to branches of the pulmonary arteries. This complication was seen predominantly in those vessels with the largest diameters. Three of the dislocated coils were left in place as they did not significantly obstruct flow of blood. One coil was retrieved by a basket catheter.

transcatheter embolization of abnormal intrathoracic vessels using coils in children with congenital heart disease is an effective therapy. Potential complications warrant careful evaluation of the indications for these procedures.