Foetal Cardiac Dimensions in 18-40 Weeks of Gestation from Tamil Nadu, India: A Cross-sectional Study

Introduction: Foetal echocardiography helps in the identification of congenital anomalies of the heart and arrhythmias. It is usually done from 18 to 22 weeks of gestation but it can also be done as early as 12-13 weeks of gestation through transvaginal ultrasound. Measurement of cardiac dimensions in the foetus plays a major role in the early detection of cardiac defects including hypoplastic right and left heart. In addition, the measurement of foetal cardiac dimensions is useful in the evaluation of foetuses with heart failure due to foetal anaemia, which is secondary to Rh alloimmunisation or Bart’s disease.

Aim: To construct a reference centile curve for foetal cardiac dimensions from 18 to 40 weeks of gestation for the Indian population residing in Tamil Nadu state.

Materials and Methods: This was a cross-sectional study performed between January 2020 and July 2021. A total of 345 antenatal mothers, who came to the Department of Radiology, SRM Medical College and Research Centre, Chennai, India, for for routine anomaly and growth scans were included in the study. Cardiac longitudinal and transverse diameters were measured on 2D images, when the heart was maximally distended in a four-chamber view at the end of the diastole. Left atrial longitudinal and transverse diameters, right atrial longitudinal and transverse diameters, left ventricular longitudinal and transverse diameters, right ventricular longitudinal and transverse diameters interatrial septum thickness interventricular septum thickness cardiac longitudinal and transverse diameters were measured.

Results: The mean values at 18 and 40 weeks of gestation for left atrial longitudinal and transverse diameters, right atrial longitudinal and transverse diameters, left ventricular longitudinal and transverse diameters, right ventricular longitudinal and transverse diameters, interatrial septum thickness, interventricular septum thickness, cardiac longitudinal, and transverse diameters were 0.73,0.65,0.72,0.66,0.83,0.62,0.75,0.62,0.1,0.1,1.71,1.72 cm and 2.22,1.71,2.31,1.9,3.21,1.71,3.3,1.84,0.3,0.3,5.02,3.84 cm, respectively.

Conclusion: The normal reference ranges for foetal cardiac dimensions can be a useful tool in the early identification of cardiac remodeling in congenital heart disease.