Prenatal ultrasound findings, genetic testing, and literature review of Isolated left subclavian artery.

ABSTRACT

BACKGROUND: The occurrence of Isolated left subclavian artery (ILSA) is relatively rare, ILSA is caused by the persistence of the dorsal segment of the sixth left arch, with regression of the fourth arch artery and interruption of the left dorsal aorta at the distal end of the seventh intersegmental artery on the left side during embryonic development. The left subclavian artery is connected to the pulmonary artery through an arterial duct, which can be closed or unobstructed. This abnormality can lead to congenital subclavian steal syndrome and vertebrobasilar artery insufficiency. CASE PRESENTATION We reported three fetuses with ILSA and intracardiac malformation. Among them, one case was suspected to be diagnosed with ILSA by echocardiography, while the other two cases were not diagnosed, but were accidentally discovered during autopsy. We have also conducted a literature review of its prenatal screening, diagnosis, management, and outcomes. Our three cases were tested by WES-Trio (whole exome sequencing). Worldwide, the ILSA cases reported in English literature have not been detected by WES. And likely pathogenic results were found in our two cases. Although it could not explain the intracardiac malformation we found, it will help to explore the etiology in the future. CONCLUSIONS: Prenatal echocardiography detection and diagnosis of ILSA is a new challenge, which has different effects on the prognosis of the fetus. When finding intracardiac malformation with right aortic arch, we need to perform an unconventional view of ultrasound scanning and combine with CDFI to find the origin of the left subclavian artery. Although we cannot find the cause of the disease temporarily, but our genetic results can help prenatal genetic counseling.