A novel pressure phase plane analysis technique identified pulmonary artery wave reflection in 26% of patients with surgically repaired tetralogy of Fallot, with the highest rates (42%) occurring after complex Rastelli procedures compared to simpler valve-sparing repairs (0%). The study of 87 patients revealed that augmentation pressure during late systole correlated significantly with right ventricular dysfunction markers, suggesting wave reflection increases cardiac workload and may predict long-term outcomes. This finding addresses a critical gap in congenital heart disease monitoring, where right ventricular function determines survival but has been difficult to assess non-invasively. The pressure phase plane method could revolutionize follow-up care by identifying patients at risk for heart failure before symptoms appear. However, this preprint awaits peer review, and the relatively small subgroups limit definitive conclusions about surgical technique superiority. The technique's clinical validation in larger cohorts will determine whether it becomes a standard tool for optimizing surgical approaches and timing interventions in this vulnerable population, potentially improving decades-long outcomes for children born with this complex heart defect.