Aspects of the aetiology of congenital heart disease.

A concise overview of current knowledge on the aetiology of congenital heart disease is provided. At present, only 10 to 20% of the cases occurring in neonates can be attributed to known risk factors. Recurrence within relatives, chromosomal anomalies, genetic disorders, maternal disease and teratogen exposure are addressed briefly; contemporary research models and methods, e.g. embryology and genetics and molecular biology, are referred to. A major innovation has been the introduction of the concept of common pathogenetic pathways. Thus, different teratogenic factors or risk-factors may affect normal development at an identical stage and cause similar malformations. Also, the importance of timing of an event is stressed. If the time frame of exposure does not coincide with embryogenesis any teratogenic effect may be missed. Large-scale epidemiological studies on fetuses and neonates with congenital heart disease are introduced as a third mode of research on the aetiology, although this approach is not used efficiently at present; cases of intra-uterine death can be considered a valuable source of information that needs further attention. Combined, the above three lines of research may prove productive, but the design of a comprehensive research project would need to be handled carefully. Possibilities for prevention of the occurrence of cardiovascular malformations are reported. Through lack of knowledge of causality, at present, only secondary prevention may be possible and hence deserves attention. However, there appears to be no provision for thorough pre-natal screening tests for congenital heart disease in an unselected population.