Computed tomography for evaluating right ventricle and pulmonary artery in pediatric tetralogy of Fallot: correlation with post-operative pulmonary regurgitation

The Nakata index and McGoon ratio: correlation with the severity of pulmonary regurgitation after the repair of paediatric tetralogy of Fallot

BACKGROUND

Pulmonary regurgitation is the most common complication after the complete repair of tetralogy of Fallot, and severe pulmonary regurgitation after surgery requires pulmonary valve replacement. In this retrospective observational, cross-sectional study, we included a total of 56 children aged 6 years or younger who underwent complete repair of TOF at Shahid Rajaei Cardiovascular Medical and Research Center in Tehran, Iran. Preoperative dual-source computed tomography was used to measure the McGoon ratio and Nakata index. The patients were divided into two groups based on the severity of postoperative pulmonary regurgitation, as estimated by trans-thoracic echocardiography: the severe pulmonary regurgitation group and the non-severe pulmonary regurgitation group. The McGoon ratio and Nakata index were then compared between the two groups.

RESULTS

When comparing the two groups, we found that the corrected right pulmonary artery diameter, main pulmonary artery diameter, and McGoon ratio in the non-severe pulmonary regurgitation group were higher than in the severe pulmonary regurgitation group. However, none of these differences were statistically significant. Additionally, other variables, including the corrected left pulmonary artery diameter and Nakata index, showed higher measurements in children with severe pulmonary regurgitation, but again, the differences were not statistically significant.

CONCLUSIONS

This study indicates that pulmonary arteries diameter, Nakata index, and McGoon ratio were not significantly correlated with the severity of pulmonary regurgitation after the complete repair of tetralogy of Fallot.

Acute Change in Ventricular Contractility-Load Coupling After Corrective Surgery for Congenital Heart Defect: A Retrospective Cohort Study

Ventricular performance and its loading condition change drastically after surgical correction of congenital heart defect. Pressure-volume loops analysis can provide quantitative information about ventriculo-arterial coupling (VAC) indicating the interaction between ventricular contractility and loading condition. Therefore, we investigated changes in VAC after corrective surgery for ventricular septal defect (VSD)/tetralogy of Fallot (TOF), and implication of ventriculo-arterial decoupling as a prognostic factor of post-operative outcomes. In children with VSD/TOF, pre- and post-operative arterial elastance (Ea), end-systolic ventricular elastance (Ees) and VAC (Ea/Ees) were non-invasively estimated using echocardiographic parameters. Post-operative outcomes included maximum vasoactive-inotropic score, the duration of mechanical ventilation and hospital stay. Preoperatively, patients with VSD had significantly lower Ea and Ees than patients with TOF; however, VAC were preserved in both. In patients with VSD, post-operative Ea increased disproportionately to change in Ees, resulting in increased VAC. Post-operative higher VAC in patients with VSD was independently associated with maximum vasoactive-inotropic score (odds ratio [OR] 63.9; 95% Confidence Interval [CI] 4.0-553.0; P = 0.003), prolonged mechanical ventilation (OR 6.3; 95% CI 1.1-37.8; P = 0.044) and longer hospitalization (OR 17.6; 95% CI 1.6-187.0; P = 0.018). In patients with TOF, Ea and Ees reduced post-operatively; however, VAC remained unchanged and was not associated with post-operative outcomes. Despite of different loading condition, preoperative VAC maintained in both of VSD and TOF. However, particularly in VSD patients, abrupt increase in post-operative loading state induces contractility-load decoupling, which leads to worse post-operative outcomes.