Histopathologic changes in the infundibular septum after balloon pulmonary valvuloplasty in tetralogy of Fallot.

Abstract

Balloon pulmonary valvuloplasty (BPV) has been applied to tetralogy of Fallot (TOF) as a palliative procedure. To investigate the histopathologic changes by BPV in the infundibular septum of TOF, we performed histopathologic examinations of the infundibular septum resected at corrective surgery. The subjects were 5 patients with TOF, who underwent BPV at the median age of 2.2 months and the corrective surgery at the median age of 15.0 months (BPV group), and 4 patients with TOF who had no prior BPV and who underwent the corrective surgery at the median age of 14.5 months (control group). There was no significant difference between the two groups in the endocardial thickness, myocardial vacuole degeneration, or fraction of fibrous and interstitial space. However, the specimens from 3 patients in the BPV group had localized dense fibrous lesions in the myocardium. The findings in this limited sample suggest that BPV for TOF does not produce overall histopathologic alterations such as fibrosis, thick endocardium, and myocardial vacuole degeneration, but may sometimes damage the myocardium of the infundibular septum resulting in the formation of localized dense fibrous lesions. The clinical significance of this damage is still unknown, and further cases should be investigated.