EP09.76: HLHS spectrum at first trimester 11–14 week scan: ultrasound appearance, associations and diagnostic pitfalls

Hypoplastic left heart syndrome is routinely diagnosed at mid-trimester anomaly scan. Recent literature quotes a very good detection rate of this entity at 11-14 week scan. The aim of the study is to review the ultrasound appearance, associations and the dilemmas in diagnosis of HLHS at the 11-14 week scan. 26 cases of HLHS diagnosed at 11-14 weeks scan were retrospectively reviewed for left ventricular size and filling in 4 chamber colour and B mode. The 3VT colour view was evaluated for the presence of flow reversal in the transverse aortic arch. Associated extracardiac structural malformations were also assessed. Outcomes were obtained either from autopsy or after anomaly scan. Of the 26 cases, 19 presented with a single inflow tract in 4CH colour and reversal of flow in the aortic arch in 3VT colour view. 8/19 (42.1%) presented with non-visualisation of the left ventricle, 10/19 (52.6%) with small left ventricle and 1/19 (5.26%) with normal sized hypokinetic left ventricle. In 4 cases with initial presentation of single inflow, subsequent transvaginal high-resolution sonography showed filling in the small LV and forward flow in aortic arch favouring the diagnosis of aortic coarctation. 3 cases showed small LV inflow with single vessel in 3VT view, flow reversal in aortic arch could not be demonstrated and needed subsequent follow up. 69.2% of cases were associated with cystic hygroma, 30.7% associated with absent ductus venosus, 34.6% with other system malformations and notably 30.7% were isolated. In 8% of cases there was a previous sibling affected with HLHS. The presence of single inflow tract in 4CH colour view gives the first clue to suspect HLHS. The 4CH grey scale findings presents with the same spectrum as seen in mid-trimester, either absent or small left ventricle or normal sized hypokinetic left ventricle. Documentation of flow reversal in transverse aortic arch is the confirmatory finding for diagnosis of HLHS.