Prenatal diagnosis of redundant foramen ovale flap aneurysm prolapsing into mitral valve mimicking coarctation of aorta
Balaganesh Karmegaraj
Abstract
A 28-year-old primigravida was referred to our unit for fetal echocardiography at 31 weeks' gestation due to suspicion of coarctation of the aorta. The axial four-chamber view showed significant ventricular disproportion with smaller left-heart structures, but the left ventricle was apex forming (Figure 1a,b; Videoclip S1). The foramen ovale flap (FOF) was redundant, aneurysmal and appeared to prolapse into the mitral valve resulting in dynamic obstruction of the mitral valve inflow and obstruction of the blood flow from the ductus venosus and right atrium to the left atrium, leading to reversal of blood flow to the right atrium (Figure 1c,d; Videoclip S2). The ratio of FOF diameter to left atrial diameter was high (0.78), suggesting the presence of Category III redundancy of FOF (Figure S1)1. The three-vessel view revealed significant great-vessel disproportion with smaller ascending aorta (Z-score of −2.53) (Figure 2). Color Doppler evaluation of the aortic arch in the sagittal view showed significant flow reversal (Figure 3). Using HDlive surface rendering mode, the redundancy of the FOF in relation to the mitral valve was visualized (Figure 4a; Videoclip S3). HDlive color rendering with silhouette mode demonstrated the flow reversal into the aortic arch and disproportion of the great vessels (Figure 4b). A male neonate weighing 2500 g was delivered at 36 weeks of gestation after preterm prelabor rupture of the membranes. Echocardiography performed immediately after birth showed a large ductus arteriosus with bidirectional shunting and a narrow aortic isthmus (Figure S2a,b). The carotid-subclavian artery index was 0.53 (Figure S2c). However follow-up echocardiography performed after complete occlusion of the ductus arteriosus showed no coarctation of the aorta (Figure S2d). At the 3-month follow-up, the infant remained asymptomatic with normal aortic arch. This case demonstrates that redundant FOF aneurysm can present with features identical to those of coarctation of the aorta. The impediment of blood flow to the left-heart structures can be severe, resembling the picture of left ventricular hypoplasia with retrograde aortic flow1, 2. Hence, it is important to recognize this benign cardiac finding, thereby facilitating peripartum care and potentially improving postnatal outcome3. Data sharing not applicable to this article as no datasets were generated or analysed during the current study. Videoclip S1 Axial four-chamber view on grayscale imaging showing significant ventricular disproportion with smaller left-heart structures and a redundant, aneurysmal foramen ovale flap (FOF) prolapsing into the mitral valve. Videoclip S2 Axial four-chamber view on color Doppler imaging showing dynamic obstruction by the foramen ovale flap of the mitral valve inflow and obstruction of the blood flow from the ductus venosus and right atrium to the left atrium which resulted in reversal of blood flow in the right atrium. Videoclip S3 HDlive surface rendering showing the redundant, aneurysmal foramen ovale flap (FOF) prolapsing into the mitral valve (MV). LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; TV, tricuspid valve. Figure S1 (a) Apical four-chamber view showing ventricular disproportion with a small mitral valve (MV). (b) The ratio of foramen ovale flap (FOF) diameter to the left atrial diameter was 0.78, suggesting Category-III redundancy of FOF. 1 D, line drawn across the foramen ovale; 2 D, maximum FOF diameter; 3 D, maximum left atrial diameter; DA, descending aorta; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. Figure S2 (a–c) Echocardiographic images (ductal view) obtained immediately after birth, showing a large ductus arteriosus and a narrow aortic isthmus (a,b) and carotid–subclavian arterial index of 0.53 (c). (d) Echocardiographic images obtained after complete occlusion of the ductus arteriosus, showing absence of coarctation of the aorta. I, isthmus; LPA, left pulmonary artery; MPA, pulmonary trunk; PDA, patent ductus arteriosus. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.