[Reconstruction of pulmonary blood flow in the Norwood procedure; Blalock-Taussig shunt; from bench to surgery].

Although the right-ventricle to pulmonary artery( RV-PA) shunt as a source of pulmonary blood supply of Norwood procedure has improved early outcomes, disadvantages including right ventricular dysfunction or arrhythmias have been reported. So it has been still remained controversial whether BT shunt or RV-PA conduit should be selected. We examined the influence of Blalock-Taussig( BT) shunt size on regulation of the pulmonary blood flow in experimental model of a univentricular heart to determine the specific guidelines regarding suitable shunt size in the Norwood procedure. The canine univentricular heart model with the ratio of shunt size to body weight (SS/BW) of 0.8 to 1.1 showed significant negative correlation between the pulmonary/systemic blood flow ratio( Qp/Qs)and arterial PCo2, but those with SS/BW of 1.1 to 1.4 did not. Similar phenomena were shown with the grouped data on relationship between the Qp/Qs and inspired oxygen fraction. These findings imply that when SS/BW is 0.8 to 1.1, the Qp/Qs is controllable by physiologic respiratory manipulations. In the context of our clinical experiences, SS/BW of 0.9 to 1.0 is considered a useful index for suitable BT shunt in the Norwood procedure.