Improved Lung Perfusion After Left Pulmonary Artery Patch Enlargement During the Norwood Operation

Optimal pulmonary perfusion is crucial for a well-functioning Fontan circulation in patients with hypoplastic left heart syndrome (HLHS). To obtain an adequate size of the left pulmonary artery (LPA), patch enlargement is a routine part of the hemi-Fontan procedure in our center. However, LPA patch enlargement at the time of the modified Norwood procedure may have surgical advantages. Therefore, the aim of this study was to evaluate whether anatomic and functional effects of the new approach are superior.

A total of 51 consecutive HLHS patients underwent a cardiovascular magnetic resonance imaging study including assessment of LPA anatomy and lung perfusion. The LPA of 20 patients was enlarged during the modified Norwood procedure (group N) and of 31 patients during the hemi-Fontan procedure (group HF).

The median indexed cross-sectional area of the LPA in group N was significantly higher than in group HF (49.5 versus 27.9 mm²/m², p < 0.0001). The regional pulmonary perfusion as measured by first-pass, contrast-enhanced signal intensity upslope was significantly improved in group N (left side 0.67 s^-1 versus 0.40 s^-1, p = 0.002; right side 0.84 s^-1 versus 0.52 s^-1, p = 0.01). The total hemi-Fontan bypass and procedure times were significantly shorter in group N (both p < 0.001).

These first magnetic resonance imaging data show that HLHS patients after LPA patch enlargement during the modified Norwood procedure have significantly higher LPA cross-sectional areas and show improved lung perfusion and shorter overall procedure time as compared with LPA patching during second stage (hemi-Fontan). Therefore, this promising surgical technique may improve blood flow dynamics of the Fontan circulation in the long run.