To investigate the echocardiographic characteristics of fetuses with isolated restrictive foramen ovale flapor redundant foramen ovale flap, to explore the application value of atrial septal excursion index (ASEI) in the evaluation of redundant foramen ovale flap and restrictive foramen ovale flap fetuses, and to follow the postnatal situation of fetuses.

Fifty-two fetuses with a diagnosis of restrictive foramen ovale flap (n=30) or redundant foramen ovale flap (n=22) by fetal echocardiography from January 2012 to January 2020 were selected retrospectively, and their initial and follow-up echocardiograms as well as pregnancy outcomes were reviewed. As controls, 108 normal fetuses with matched gestational age were randomly selected. Echocardiographic measurements included right atrial diameter to left atrial diameter ratio (RA/LA), right ventricular width to left ventricular width ratio (RV/LV), and pulmonary artery diameter to aortic diameter ratio (PA/AO). ASEIs in the three groups were calculated. All parameters were compared among the fetuses with restrictive foramen ovale flap, those with redundant foramen ovale flap, and controls.

The ratios of RA/LA, RV/LV, and PA/AO in restrictive foramen ovale flap fetuses and redundant foramen ovale flap fetuses increased compared with those of the controls (P＜0.01). ASEI of the 108 fetuses in the control group was 0.53±0.08 (range: 0.38-0.70). ASEI of the 30 fetuses in the restrictive foramen ovale flap group was 0.27±0.04 (range: 0.14-0.33). ASEI of the 22 fetuses in the redundant foramen ovale flap group was 0.73±0.04 (range: 0.68-0.81). ASEIs among the three groups differed significantly (F=296.95, P＜0.001). ASEI in fetuses with restrictive foramen ovale flap significantly decreased compared with those of the controls and redundant foramen ovale flap fetuses (P＜0.001), and ASEI in fetuses with redundant foramen ovale flap significantly increased compared with those of the controls and restrictive foramen ovale flap fetuses (P＜0.001). Postnatal fellow-up by postnatal echocardiography demonstrated that 46 out of 52 cases (88.5%) had a structurally normal heart, one had aortic valvular stenosis and underwent aortic balloon dilatation, one had coarctation of the aortic arch, one had secondary atrial septal defects, and three had moderate tricuspid regurgitation with normal pulmonary artery systolic pressure (right ventricular systolic pressure was 21, 26, and 24 mmHg, respectively).

ASEI is a novel parameter that can quantitatively evaluate the features of the foramen ovale in fetuses with isolated restrictive foramen ovale flap or redundant foramen ovale flap. Most of the fetuses with isolated restrictive foramen ovale flap or redundant foramen ovale flap have no associated structural heart malformations and therefore have a good prognosis.