Morphometric Analysis of the Infundibulum in Tetralogy of Fallot

Kwak, Su Hee; Hyun, Myung Chul; Lee, Sang Bum

Abstract

PURPOSE: The morphogenic mechanism of tetralogy of Fallot is known to be an antero-superior deviation and hypertrophy of the subpulmonary infundibulum. We performed this study to measure the subpulmonary infundibulum in patients with tetralogy of Fallot and compare those with normal control.
METHODS
Echocardiographic data and medical reports of 12 patients, with classical tetralogy of Fa11ot who were diagnosed echocardiographically from Dec. 1996 to Jan. 1999 in Kyungpook National University Hospital, were retrospectively reviewed. A control group consisted of 11 children who underwent a complete echocardiographic examination for a heart murmur and were found to be structually norrnal. Measurements of the subpulmonary infundibulum were performed in systolic still frames with the subxiphoid short axis view.
RESULTS
Compared with the normal control children, the following indexed infundibular dimensions in patients with tetralogy of Fallot were significantly smaller' volume, length, cross-sectional area, diameters of pulmonary valve annulus, main, left and right pulmonary arteries, PA index and McGoon ratio. The following measurements were increased in tetralogy patients ' the angle between infundibular septum and ventricular septum, and infundibular free wall thickness.
CONCLUSION
We confirmed both antero-superior deviation of infundibular septum and infundibular hypoplasia as morphologic abnormalities in tetralogy of Fallot. We also revealed relatively equal contributions of shortening of infundibular length, and increased infundibular septal and free wall thickness to infundibular hypoplasia.