The experimental study of vena cava and pulmonary artery flow dynamics and energy dissipation in different total cavopulmonary connection

Objective To study the vena cava and pulmonary artery flow dynamics and energy dissipation in different total cavapulmonary connection (TCPC).Methods Three different kinds of total cavapulmonary connection (TCPC) according to inferior vena cava (IVC) anastomosis site was used to establish the experimental animal model of TCPC:Group (1) was that the anastomosis site of IVC and superior vena cava (SVC) with right pulmonary artery (RPA) directly opposed each other;Group (2) was the offset of the IVC anastomosis site toward the right side of the SVC anastomosis site with RPA;Group (3) was that IVC directly anastomosed to main pulmonary artery.Using electromagnetic flow meter and echocardiography the flow and velocity of pulmonary artery blood and vena cava blood were measured.The fluid energy loss was calculated by Bernoulli's equation.Results The return of SVC and IVC had been changed after TCPC.The ratio of SVC to IVC was 1.0 or so.In group (2) the flow of IVC went dominantly into RPA and in group (3) the flow of IVC went dominantly into LPA.The postoperative flow quantity ratio of RPA to LPA was significantly less than that of the preoperative (P0.01).The energy loss in group (3) was significantly less than that of the type (1) (P0.01).Conclusion The caval return had been changed after TCPC.The anastomosis site of IVC determined the flow direction and the postoperative flow quantity ratio of RPA to LPA was lower than that of the preoperative.The energy loss was determined by the anastomosis site.When the anastomosis site of SVC and IVC with RPA directly opposed each other,the energy dissipation was larger than any other kinds of anastonosis form.The more offset was the anastomosis site,the less energy was lost.