1351694 - 4D Flow Diagnosis of a Coronary Cameral Fistula in Pre-Fontan Patient with Tricuspid Atresia and Absent Pulmonary Valve

A 3.5-year-old male with a single ventricle physiology consisting of tricuspid atresia, absent pulmonary valve and severely hypoplastic right ventricle who was post his second stage of surgical palliation (with a bidirectional Glenn circulation), underwent a CMR study in preparation for Fontan surgical palliation. His course had been notable for pulmonary artery stenosis (post- stent plasty), and significant aorto-pulmonary and veno-venous collateral burden. The main pulmonary artery was tightly banded and thought to end in a blind pouch with to-and-fro flow.

Diagnostic Techniques and Their Most Important Findings: Using a 1.5T Siemens Aera scanner (Siemens, Erlangen, Germany), a ferumoxytol enhanced CMR was performed including a respiratory navigated, diastolic gated 3D b-SSFP sequence and 4D Flow (84 x 160 matrix, Flip Angle 15°, TE/TR= 2.4/39.6, 2 segments, and 1.3mm voxel size) was obtained.

Clinically significant findings included a moderately dilated left ventricle with a mildly diminished systolic function (LVEF 46%). The Glenn connection and the right pulmonary artery were widely patent and the neo-left pulmonary artery stent was in place with a good-sized distal vessel. The main pulmonary artery was noted with to-and-fro flow and importantly, noted to be in continuity with the branch pulmonary arteries (Fig 1). The 4D flow also showed a fistulous connection between the branches of the left main coronary artery the coronary sinus concerning for a coronary cameral fistula (Fig 2, 3). Additionally, significant systemic vein to pulmonary venous collaterals were noted bilaterally along with decompressing systemic venous collaterals along the pre-vertebral and azygous venous systems. T1 weighted lymphatic imaging suggested a grade 3 classification of lymphatic abnormalities (1).

Learning Points from this Case: Cardiac MRI evaluation in combination with catheterization prior to Fontan palliation has become standard practice at our center as well as many others. We present a patient with unique single ventricle disease of tricuspid atresia and absent pulmonary valve. His findings of a coronary cameral fistula prompted pre-operative discussion where the concern was raised that a low right ventricular pressure could lead to increased flow through this fistulous connection. This discussion resulted in pre-operative decision to suture close the pulmonary artery connection to the ventricle to eliminate antegrade flow thus hopefully leading to an increased right ventricular pressure and less potential for coronary fistula flow or clot formation.