Virtual surgical modification for planning tetralogy of Fallot repair

Goals for treating congenital heart defects are becoming increasingly focused on the long-term, targeting solutions that last into adulthood. Although this shift has motivated the modification of many current surgical procedures, there remains a great deal of room for improvement. We present a new methodological component for tetralogy of Fallot (TOF) repair that aims to improve long-term outcomes. The current gold standard for TOF repair involves the use of echocardiography (ECHO) for measuring the pulmonary valve (PV) diameter. This is then used, along with other factors, to formulate a Z-score that drives surgical preparation. Unfortunately this process can be inaccurate and requires a mid-operative confirmation that the pressure gradient across the PV is not excessive. Ideally, surgeons prefer not to manipulate the PV as this can lead to valve insufficiency. However, an excessive pressure gradient across the valve necessitates surgical action. We propose the use of computational fluid dynamics (CFD) to improve preparation for TOF repair. In our study, pre-operative CT data were segmented and reconstructed, and a virtual surgical operation was then performed to simulate post-operative conditions. The modified anatomy was used to drive CFD simulation. The pressure gradient across the pulmonary valve was calculated to be 9.24mmHg, which is within the normal range. This finding indicates that CFD may be a viable tool for predicting post-operative pressure gradients for TOF repair. Our proposed methodology would remove the need for mid-operative measurements that can be both unreliable and detrimental to the patient.