High velocity flows within the region of the coronary sinus may be sometimes observed during early examination of fetal heart (14-17 weeks). Following cases demonstrate a fistula between the right ventricle and coronary sinus that was observed at 15 weeks (case 1) and similar fistula combined with tricuspid regurgitation (case 2).
We had several similar findings in our practice - six of them presented as an abnormal high velocity flow at the level of the right ventriculo-atrial junction, two of them were seen at the level of the left ventriculo-atrial junction. In all cases the finding had disappeared within 1 to 7 days and all newborns had normal cardiac morphology.
We think that coronary sinus fistula in the early pregnancy represents a benign transient phenomenon.
Images 1, 2, and videos 1, 2: 15 weeks of pregnancy; the images and video show a fistula between the right ventricle and right atrium (red flow marked by arrow on the image 2).