Introduction: The prenatal diagnosis of conotruncal defects (CTDs) has improved over the past decade, particularly with inclusion of outflow tract imaging at routine ultrasound. Appropriate prenatal counseling for CTDs demands an accurate diagnosis, as even more subtle cardiac pathology could complicate clinical outcomes. We sought to determine the anatomical accuracy of fetal echocardiography in evaluating common CTDs and factors that contribute to accuracy. Methods: All cases of tetralogy of Fallot(TOF), double outlet right ventricle(DORV) and truncus arteriosus(TA) encountered in our institution from 2007-2018 were reviewed. Discrepancies in anatomical findings between prenatal (most accurate exam) and postnatal (echo/surgery) or autopsy exams were categorized as: C1) no difference C2) minor difference with no impact on outcome (e.g.aberrant right subclavian artery), C3) minor difference that could make a minor difference to the delivery plan or surgery (e.g.branch pulmonary artery stenosis), C4) major difference that changes the course of the pregnancy, delivery or surgical planning (e.g.ductal dependency). Results: Of the 255 CTD cases, 162 had prenatal and postnatal and/or autopsy data available. Of the 162, 107(65.6%) fit C1, 35(21.5%) C2, 12(7.4%) C3, and 8(5.5%) C4. The greatest accuracy was observed in TOF, with 69/71(97.2%) in C1 and C2 versus 56/69(81.2%) in DORV and 16/22(72.7%) in TA(p=0.003). Excluding 5 cases at 10-16weeks, there was a tendency towards a greater proportion in C1 and C2 when examined at 17-23 weeks (60/64, 93.4%) versus 24-32 weeks (50/57, 87.7%) and >32 weeks (28/36, 77.8%) (p=0.06). Era of assessment also revealed a difference with 43/55(78.2%) of studies performed from 2007-2011 in C1 and C2 versus 99/107(92.5%) from 2012-2018 (p=0.01).When we compared pregnancies with one versus serial exams, we observed a lower proportion of C4 cases from 9.6% to 2.7%, respectively. In those with serial exams, 20% had achieved C1 or C2 only at serial exam. Conclusions: The diagnostic accuracy of fetal echocardiography in CTDs is generally high, especially for TOF and when performed at 17-24weeks. There has been significant improvement in accuracy since 2011. Serial exams potentially improve diagnostic accuracy.

Introduction: Congenital heart disease (CHD) requiring surgical intervention in infancy is associated with impaired neurodevelopmental (ND) outcomes which may be due in part to prenatal insults. Supporting this, we recently found an inverse relationship between 3 rd trimester umbilical artery Doppler-based (UA) pulsatility index (PI=systolic velocity-diastolic velocity/mean velocity) and growth and ND outcomes at 2 years in hypoplastic left heart syndrome and d-transposition of great arteries. In the present study we explore associations between 2 nd and 3 rd trimester UA-PI in all major fetal CHD and 2-year ND outcomes. Methods: We identified all patients with major structural CHD and fetal echocardiography who underwent cardiac surgery and 2-year ND and biometric assessments (Western Canadian Complex Pediatric Therapies Follow-up Program) from 2007-2017 in our program. Eligible surgeries were: bypass < 6 weeks, shunts at < 6 months or isomerisms with surgery at < 12 months. Patients with genetic syndromes were excluded. 2 nd and 3 rd trimester UA-PI z scores were examined for relationships with 2 year Bayley III ND scales. Data is presented as mean (SD). Results: Data from 147 children was analysed (see Table). 2 nd and 3 rd trimester fetal echo was performed at 22.4(3.7) and 34.7(2.9) weeks, with UA-PI z scores of 0.18 (0.3), and 0.51(1.4) and respectively. The Bayley III cognitive, language and motor scores were 93(13), 89(15) and 89(14) for the entire group. Multivariable regression analysis of the entire group and specific subgroups showed an inverse relationship between 3 rd trimester UA-PI and ND domains (see Table). No association was found for 2 nd trimester UA-PI and ND for the whole group and subgroups. Conclusions: Increased 3 rd trimester UA-PI, which could reflect an altered late gestation placental circulation, inversely relates to abnormal 2 year ND. These relationships are most notably observed in SVs and in CHD associated with AOTO.

Background: Children with congenital heart disease are at increased risk of adverse long-term neurodevelopmental outcomes believed in part secondary to a prenatal insult. Altered fetal middle cerebral arterial (MCA) Dopplers suggestive of brain sparing (low Pulsatility Index, PI) as well as