Novel Lung Perfusion Technique Quantifying Preferential Pulmonary Blood Flow in Fontan Patient With Scimitar Syndrome

Patients with Fontan physiology have increased pulmonary perfusion heterogeneity compared with patients with normal hearts.

A 9-year-old girl with hypoplastic left heart syndrome, Scimitar syndrome, and unilateral right pulmonary vein stenosis underwent stent placement to relieve compression of the reimplanted right pulmonary vein after Fontan completion. Serial upper extremity lung perfusion scans demonstrated decreased right lung pulmonary blood flow despite cardiac catheterization demonstrating no in-stent stenosis and normal Fontan pressures. Pulmonary blood flow quantification was performed via separate upper (superior vena cava) and lower extremity (inferior vena cava) radioisotope injections staggered 2 days apart. The total differential pulmonary perfusion determined via this technique was 69.5% to the left lung and 30.5% to the right lung with significant contribution of right lung perfusion via the inferior vena cava.

This case highlights the strengths and limitations of radioisotope imaging and provides a unique approach to more accurately evaluate pulmonary perfusion patterns in these complex patients.