FETAL ECHOCARDIOGRAPHY - THE NORMAL HEART

At 20 weeks amenorrhoea, it is currently possible to determine with echocardiography whether a fetal heart, which then weighs approximately 400g with a diameter of 15 mm, is normal or not. The incidence of cardiac malformations has been estimated at 8 per 1000 fetuses. Fetal factors including retarded growth, hydramnios and arrhythmia and maternal factors including rubeola, diabetes, systemic lupus erythematosus, Rhesus incompatibility and drugs increase fetal risk. In certain cardiopathies such as aortic stenosis, coartation, malformation of the mitral valve or left ventricle hypoplasia, the risk of recurrence in a second fetus is greatly increased. With 2D echocardiography, the apical section of the four heart cavities orients the heart in the thorax, identifies the atria and ventricles and visualizes valve movement. The origin of the aorta and the kinetics of the mitral and aortic valves are studied on the para-sternal section. TM mode reproduces the P-QRS sequence thus allowing a measurement of heart rate, the thicknesses of heart walls and septa and identifies conduction disorders. The transvalvular systolic pressures can be measured with Doppler echocardiography and pulsed Doppler quantifies blood flow through the different heart structures. Precision can be increased with colour coding. A complete echocardiography of the fetal heart should be an integral part of all examinations of fetal morphology. Usually performed between 22 and 32 weeks of amenorrhoea, echocardiography of the fetal heart requires a perfect understanding of two-dimensional Doppler modes and of three dimensional representation of heart anatomy.