ObjectiveTo explore the midterm therapeutic effect of modified Blalock-Taussing shunts (MBTs) in the treatment of tetralogy of Fallot. MethodsWe retrospectively analyzed the clinical data of 69 children with tetralogy of Fallot undergoing MBTs in Shanghai Xinhua Hospital between July 2006 and January 2013. There were 44 males and 25 females with mean age of 17.97±24.73 months (ranged from 2 months to 10 years). The patients weighted from 4 to 24 (9.00±4.03) kg. All the MBTs between subclavian artery and pulmonary artery were performed through right or left posterior lateral incision. ResultsThe patients were followed up for 6-36 months including 57 patients with 6 months following-up, 33 patients with 6 months and 12 months following-up, 16 patients with 12 months and 24 months following-up, and 11 patients with 24 months and 36 months following-up. There was significant growth in McGoon ratio during the first 12 months follow-up (preoperative vs. 6 months:1.09 ±0.33 vs. 1.40 ±0.40, P=0.00; 6 months vs. 12 months:1.29±0.31 vs. 1.36±0.33, P=0.00). There was no obvious growth in McGoon ratio after 12 months (12 months vs. 24 month:1.22±0.31 vs. 1.19±0.32, P=0.14; 24 months vs. 36 months:1.22±0.23 vs. 1.23±0.20, P=0.45). The left ventricular end diastolic volume index (LVEDVI) increased significantly in 6 months after MBTs (preoperative vs. 6 months:29.60±10.12 ml/m2 vs. 49.18±11.57 ml/m2, P=0.00), but there was no significant growth after 6 months. There was no significant decline in left ventricular ejection fraction (LVEF) after MBTs. ConclusionThe MBTs can significantly promote the growth of McGoon ratio in 12 months of patients with tetralogy of Fallot, but there is no obvious growth of McGoon ratio after 12 months. MBTs can significantly improve left ventricular development within 6 months, and it won't lead to excessive expansion of the left ventricle when we extend follow-up time. The MBTs affects little on cardiac function of patients with tetralogy of Fallot.