Advances in fetal cardiology

Abstract

The prevalence of congenital heart malformations as a whole (including diseases of little clinical significance) is 0.8% (8 of 1000 live births). The most frequent pathologies are malformations that prevent blood from reaching the lungs to take oxygen or block the normal supply of oxygenated blood to the body. The transposition of the great vessels (the aorta and pulmonary artery originate from the ‘wrong’ ventricles) is important as it represents the most severe neonatal heart disease. A separate issue, instead, is that of arrhythmias. The diagnosis is made around the 20th–21st week of gestation through a targeted ultrasound examination of fetal heart. This enables the recognition of the vast majority (around 85%) of clinically important congenital heart diseases (CHD) at birth. Nevertheless, targeted examinations are not possible for all pregnancies: the costs would not allow it. They are still available for patients who have recognized risk factors (they had children with previous CHD, they took teratogenic drugs, or they have diabetes), whereas pregnant women who have a very low risk are subjected to basic ultrasound examinations. An ultrasound examination allows at least suspicion of a significant proportion (30–40%) of important heart diseases. Progresses in the diagnostic field are continuous and the development of visualization techniques provides great opportunities. Four-dimensional (4-D) ultrasound that allows volumetrical viewing of the fetus, moving, to the most detailed facial expressions, appears to be promising in the diagnosis of CHD, which often escape the traditional ultrasound examination. Enabling better visualization of the heart, thanks to the ability to view it from different points and angles, volumetric ultrasound could aid the diagnosis of more heart diseases. Recognition of fetuses with heart disease may be useful for planning targeted interventions. The purpose of prenatal diagnosis is, first, to improve the prognosis without serious damages in the neonatal period. If necessary, there is the possibility of interventions on the fetus (which mainly consists of aortic or pulmonary valve and foramen ovale dilation), but they are still experimental cardiac procedures. In general, the first interventions take place on the newborn baby; therefore, the birth can be arranged at a cardiology and cardiac surgery unit, thus avoiding delays and dangerous transfers. Thanks to the timely diagnosis, today, 90% of operated babies survive and reach adulthood with a normal life expectancy (only for patients with univentricular heart, we impose limits on physical and working activity). Today, complex operations are possible even in low-birth-weight babies, with very good results, attempting to prioritize corrective radical rather than palliative solutions, which until recently were often the only options. As medical therapies play a marginal role in heart malformations, they are instead essential in the treatment of fetal tachyarrhythmias: these are quite rare diseases, which are also detectable by echocardiography, often isolated (i.e. not associated with cardiac malformations). These arrhythmias in the fetus are rapidly fatal if not effectively controlled and treated with specific drugs administered to the mother, so that in most cases, they resolve easily, without future problems.