Growth of the pulmonary arteries after systemic-pulmonary shunt.

Pulmonary artery growth after a systemic-pulmonary shunt was angiographically evaluated in 19 out of 35 patients. The mean age of the subjects at the time of the initial operation was 18+/-18 months including 12 patients under a year old. The preoperative diagnosis was tetralogy of Fallot (TOF) in 10 patients, TOF plus pulmonary atresia in five and transposition of great arteries in four. A Blalock-Taussig shunt (BTS) operation was performed in 16 patients (15 classical and 1 modified) and a central shunt was performed in three patients as an initial operation. The preoperative pulmonary artery index (PAI) was 129+/-42 in all patients and there were no significant differences between patients under or over a year old (139+/-42 vs. 115+/-49). Postoperative angiography was performed 32+/-13 months after the surgery. Room air arterial O2 pressure increased significantly from 29+/-5 mmHg to 42+/-5 mmHg just after an initial palliative shunt operation. PAI change in patients under a year old was 214+/-73%, which was higher than 145+/-27% in patients over a year old after a palliative shunt operation. On the ipsilateral side, PAI change was almost the same between patients under and over a year old. On the contralateral side, PAI change in patients under a year old was 216+/-68%, which was significantly higher than the 116+/-21% in patients over one year old. There was a significant negative correlation (r=-0.65, p<0.05) between PAI change and arterial O2 pressure as measured just after a palliative shunt operation. In conclusion, a palliative shunt operation prior to a year old is desirable in order to produce sufficient and bilateral pulmonary artery growth.