Journal of Pediatric Cardiology and Cardiac Surgery

Background: The tetralogy of Fallot (TOF) is comprised of an anterior deviation of the septal insertion of the cardiac infundibular septum that leads to four detrimental morphological features which include a narrowing of the right ventricular outflow tract. A precise morphology of the frontal architecture of the affected right ventricular outflow tract has not yet been described even though its reconstruction is a critical part of TOF repair. We hypothesized that blood flow through this tract narrowed from behind by an anteriorly deviated infundibular septum causes an anterior prominence compared to the normal heart.

Methods: 51 cases of TOF versus 34 control cases of isolated ventricular septal defect (VSD) without pulmonary hypertension were reviewed by applying a geometric method to clarify cardiac morphology. We analyzed each triangle (AOP) and compared the data between the TOF and control groups, but our hypothesis was disproven as the TOF anterior faces were not anteriorly prominent.

Results: Several angles were shortened on analysis. However, after geometric comparison of triangle AOP between groups, we found only very small visible differences in the overall shapes of the triangles. The relative heights of anterior prominence of the right ventricular outflow tract were nearly the same in both groups.

Conclusions: An anteriorly deviated infundibular septum has no relationship with the anterior wall of the right ventricular outflow tract and that surgeons should expand the anterior wall of the right ventricular outflow tract forward to conform to the deviated infundibular septum during TOF repair to restore normal blood flow.