SlowflowHD to Evaluate Fetal Heart at 11–13+6 Weeks of Gestation

of detecting five fetal cardiac views: 4CV, PVs, 3VV, right ventricular outflow tract (RVOT), and left ventricular outflow IntroductIonThe cardiac four-chamber view (4CV) and three-vessel view (3VV) are performed as standard during fetal cardiac anatomical scans at 11-13 +6 weeks of gestation.1 Rates of detecting 4CV and 3VV using conventional power Doppler were reportedly 86 and 79%, respectively, at 11-13 +6 weeks. 2 Conversely, those rates with Superb Microvascular Imaging (SMI) were 95 and 83%, respectively, at 11-13 +6 weeks.3 Detection of pulmonary veins (PV) using two-dimensional echocardiography was very difficult in the first trimester of pregnancy, with detection rates being 0, 0, 3.1, and 25.3% at 10, 11, 12, and 13 weeks, respectively.4 The rate of detecting PVs with conventional high-definition flow (84.8%) was significantly higher than that with conventional color Doppler (28.9%) at 11-13 +6 weeks of gestation.5 Therefore, highresolution ultrasound devices offering better visualization of low-velocity blood flow should be mandatory for firsttrimester screening of fetal cardiac structures.SlowflowHD is the latest power Doppler technology with a high frame rate, high resolution, and good sensitivity that can detect very slow blood flow in small peripheral fetal vessels.[6][7][8][9] This modality can document human embryonic and fetal heart development in the first trimester of pregnancy.10,11 In the present study, we compared the rates