Standardized fetal cardiac biometry using HeartAssist™: multicenter prospective reference ranges in the Korean population

초록

Objectives: To establish comprehensive fetal cardiac reference ranges using an automated measurement system, across 12 major referral centers in the Republic of Korea. Methods: A prospective multicenter study was conducted to establish normative data for fetal cardiac biometry. Normal singleton pregnancies between 16.0 and 36.6 weeks of gestation were recruited from October 2022 to December 2025. Standardized video clips of fetal hearts were obtained from study centers, and a total of 34 cardiac parameters were measured using six standard views. In the four-chamber view, the cardiac axis, thoracic and heart dimensions, atrial and ventricular sizes, and annular diameters of the mitral and tricuspid valves were assessed. In the outflow tract view, the annular diameters of the aortic and pulmonary valves in both states, along with the diameter of the ascending aorta, were measured. The three-vessel view included measurements of the pulmonary artery, aorta, superior vena cava, and thymus. In the three-vessel tracheal view, the diameters of the aortic isthmus and ductus arteriosus were measured. In the aortic arch view, the diameters of the ascending aorta, proximal and distal transverse aortic arches, aortic isthmus, and descending aorta were measured. All measurements were performed using HeartAssist™ (Samsung Medison Co., Ltd., Seoul, Republic of Korea) and further adjusted manually by two specialists in fetal echocardiography. Results: A total of 1376 video clips were analyzed. Each parameter was measured according to precisely defined cardiac cycles, and scatterplots were generated by fetal biometry and gestational age. The cardiac axis remained stable, averaging 36.6◦ throughout gestation. Other parameters showed a progressive increase with advancing gestation. Notably, the annular diameters of the aortic and pulmonary valves tended to be larger at end-diastole than after valve opening. Conclusions: This study establishes gestational age and size-specific reference ranges for fetal cardiac parameters measured at precisely defined cardiac cycle using HeartAssist™.