Patient-specific modeling of cavopulmonary connections.

Surgery for the treatment of congenital heart diseases has been improving very rapidly in recent years. The developed surgical repairs often impose major reconstructive procedures, creating a totally new circulation. The so-called ‘Fontan circulation’ refers to a cardiovascular configuration resulting from a group of operations used to by-pass the non-functional right heart (Fontan and Baudet, 1971). In such a univentricular circulation, the blood returning from the body reaches the lungs via direct blood vessel connections without a pumping chamber. Different surgical procedures have been developed to create the Fontan circulation. One of these procedures is the Total CavoPulmonary Connection (TCPC) (de Leval et al., 1988). In the TCPC the superior and the inferior venae cavae (SVC and IVC, respectively) are directly connected to the right pulmonary artery, the latter by means of an intra-atrial or an extra cardiac tunnel. This final configuration is often obtained through an intermediate stage, the Bidirectional CavoPulmonary Anastomosis (BCPA), where only the SVC is connected to the right pulmonary artery. With particular reference to patient-specific modeling of cavopulmonary connections, the prescription of realistic outlet boundary conditions is required as they control blood flow split into each pulmonary artery. Helping pediatric cardiac surgeons in designing the most effective TCPC by means of a patient-specific ‘virtual surgery’ simulation is quite a tough challenge for bioengineers. Local abnormal flows, as may occur in patients with surgical corrections of congenital heart diseases, might selectively cause mid/long-term adaptation processes in the different pulmonary branches, thus varying local and global pulmonary resistances. In the present study, left and right pulmonary resistances were estimated in a BCPA clinical case on the basis of measured pressures and flow data and patient-specific fluid dynamic simulations. The aim of the study is to assess possible unbalanced lung resistances and verify whether pulmonary resistances change after the TCPC surgical creation.