In a single ventricle palliated with a Fontan (total cavopulmonary connection), follow-up looks for conduit and pulmonary artery obstruction or thrombus, collateral flow, ventricular function, and the liver (Fontan-associated liver disease).
Orient first
- Systemic venous blood flows passively to the lungs; any obstruction or high pulmonary resistance fails the circuit.
- Contrast mixing in the conduit on CT can mimic thrombus — dual injection or delayed imaging helps.
- The liver becomes congested and fibrotic; hyperenhancing nodules are common and HCC must be watched for.
Acquire the study
- Cine, 3D contrast-enhanced MRA, phase-contrast flow in each vessel.
The manoeuvre
- 3D MRA: conduit and branch pulmonary artery calibre in mm; thrombus.
- Phase-contrast: SVC + IVC flow vs branch PA flow; aortopulmonary collateral flow (Qs vs Qp difference).
- Single ventricle volumes and EF; AV valve regurgitation.
- Liver: size, heterogeneity, nodules.
What confirms it
- Anatomy and flows documented; complications named.
What licenses you to exclude it
- Homogeneous opacification on a correctly timed study excludes conduit thrombus.
The classic misread
- Missing venovenous collaterals causing cyanosis.