Real time cross sectional echocardiographic imaging and colour mapping in the human fetus

ABSTRACT

New high-resolution real-time ultrasound cross-sectional imaging systems have enabled us to demonstrate detailed fetal cardiac anatomy in the second half of pregnancy. We studied fetal cardiac anatomy qualitatively and quantitatively by echocardiography in the second half of the pregnancy in 23 normal pregnancies in healthy mothers. The estimated gestational ages were 20-41 weeks of pregnancy. Nine new horns were also examined within 24 hours of birth. To evaluate fetal cardiac anatomy, we reproduced commonly used cross-sectional views of the heart. The four chamber and short axis great artery views have been most successful for cardiac evaluation in the fetus. Measurements of the right and left ventricle [RV, LV] at the atrioventricular valve level were taken from four chamber plane images of the heart before and after birth and measurements of the aorta and left atrium were taken in the long axis view. Physiologic changes in the circulation at birth affected RV size considerably compared with measurements before birth. The RV/LV dimensional ratio was 1.28 +/- 0.17 before birth and decreased to 0.70 +/- 0.17 within 24 hours of birth. The aorta to left atrial dimensional ratio did not change significantly after birth. Our findings about cardiac growth and the major adjustments of the circulatory system for extrauterine life are similar to those previously reported in humans and animals. One case of single ventricle, atrioventricular canal and transposition of the great arteries was present in the cases examined. It appears from our study that the diagnosis of major congenital heart defects should be possible before birth