Objective : To assess the effect of Fontan modification on systemic venous and pulmonary artery flow and on respiratory dependance of flow.
Method: We performed intravascular Doppler echocardiography in the systemic veins and pulmonary artery in 9 patients with atriopulmonary connection (APC group), 12 patients with total cavopulmonary connection (TCPC)by lateral tunnel(LT group), and 13 patients with TCPC by extracardiac conduit(ECC group). We obtained intravascular Doppler spectrals under simultaneous respirometer recording and compared flow characteristics in each group, according to the cardiac and respiratory cycles.
Result : In APC group, velocity-time integrals (VTI) at systole (VTIS) of caval and hepatic veins were greater than VTI at diastole (VTID) in contrast to LT and ECC groups. VTI of retrograde flow (VTIR) of caval and hepatic veins were significantly greater in APC group than the other two groups. Net antegrade flow integrals (NAFIs) of hepatic vein and pulmonary artery were significantly greater in LT and ECC groups. The respiratory variation index (RVI) of NAFI at superior vena cava and RVI of VTID at pulmonary artery were significantly greater in ECC group than the other two groups.
Conclusion : In LT and ECC groups, the retrograde flows in systemic veins are decreased and the antegrade flows in hepatic vein and pulmonary artery are increased. In ECC group, the flows of superior vena cava and pulmonary artery are more dependent on the respiration than the other two groups. These physiologic differences should be taken into account in respiratory care for patients after Fontan-type repair.