Foramen ovale atrial septal ratio in-utero is directly proportional to transatrial blood flow. We now studied FO:AS in defects with VSD or intact ventricular septum (IVS) to ascertain patterns of intracardiac blood flow. Included were 11 normal hearts, 12 isolated perimembranous VSD, 8 coarctation of the aorta (COA) IVS, 10 COA with VSD, 6 type B interrupted aortic arch (IAA), 4 pulmonary atresia IVS, 7 pulmonary atresia VSD, and 10 tetralogy of Fallot. From planimeter measurements of atrial septal and foramen ovale area, we calculated FO:AS. These data presented as x±SD were analyzed by ANOVA.
The area of the atrial septum was similar among the groups. FO:AS ratio were: normal heart .24±.07; isolated VSD, .40±.06; COA IVS, .15±.07; COA VSD, .34±.07; IAA, .36±.12; pulmonary atresia IVS, .38±.10; pulmonary atresia VSD, .11±.08; tetralogy of Fallot .19±.06.
Thus, defects with intact ventricular septum are associated with a predictable variation in FO:AS ratio suggesting that hemodynamics are an important pathogenetic mechanism in these defects. Conversely, defects with VSD have a discordant FO:AS ratio suggesting that other mechanisms such abnormal conotruncal septation maybe the primary abnoramlity. These results emphasize the defects classified by anatomic similarities may have different pathogenic mechanisms.
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Hawkins, J., Clark, E., Marvin, W. et al. 1293 FORAMEN OVALE ATRIAL SEPTAL RATIO: EVIDENCE FOR DIFFERENT PATHOGENIC MECHANISMS IN CONGENITAL HEART DEFECTS. Pediatr Res 19, 326 (1985). https://doi.org/10.1203/00006450-198504000-01317