A Study of Congenital Heart Defects

Mongolism has aroused widespread interest since the days of Langdon Down's pioneer work in 1866. Numerous hypotheses relating to its aetiology and mechanism have appeared, but none can be regarded as conclusive or final, further observations and research being necessary before a full understanding is possible. Of the many anomalies found in mongolism, affecting nearly every system, that of congenital heart disease is the most remarkableand least understood, certainly, as Abbott (1936) stated, 'calling for an explanation'. The life span of mongol children has already been extended by chemotherapy and antibiotics, and a further prolongation will follow the recent advances in cardiac surgery. For this reason congenital heart disease in mongols has ceased to be of mere postmortem interest and has become a stimulus to further understanding. The cause of the cardiac abnormality, the stage of foetal life at which it occurs and the pathological processes involved are problems of considerable interest which are difficult to solve. Among the early observations were those of Abbott, who has stressed the frequent combination of mongolism and persistent ostium primum. Taussig (1947) emphasized the high correlation between mongolism and persistent atrioventriclaris communis. Esen (1957) found a similar high correlation, but Evans (1950), in his study of cardiac anomalies in mongolism, showed a preponderance of ventricular and atrial septal defects. Benda (1946) stated that about 750% of mongoloid infants who die in the first two years of life have congenital heart disease, and 35% of the survivors thereafter. In Evans' series 50%0 died before 5 years of age. Keith, Rowe and Vlad (1958), in their study of 18 mongoloid infants who died at the Hospital for Sick Children, Toronto, mentioned that few die in the first month of life, and two-thirds die between 4 weeks and 1 year. On clinical evidence, those with the most severe cardiac anomalies die young, and so, as the age group progresses, the incidence of severe cardiac anomaly becomes less. This largely accounts for the comparatively low incidence found by other observers. This point is well illustrated in the two different age groups studied at the Fountain Hospital, the percentage of cardiac anomalies in the 3-year age group being much higher than that in the 10-year group. Southwick (1939) and Ingalls (1947) were interested in the causation and time of origin of the cardiac anomalies. Ingalls postulated that the latter was between the sixth and ninth week of foetal life. This hypothesis has been well supported by many pathologists from necropsy material as well as from embryological evidence. The higher incidence, about to be discussed, of maternal illness in the early part of pregnancy in the congenital heart defect group than in the control group, suggests that the time of development of the anomalies must be early. The frequent combination of congenital heart defect and mongolism suggests that the cause and time of development of congenital heart defect are similar to, if not identical with, that of mongolism as a whole. Among the many factors involved in the aetiology of mongolism advanced maternal age (Davenport and Allen, 1925; Penrose, 1934; Bleyer, 1938), and maternal illness (Ingalls, Babbott and Philbrook, 1957) are considered here. Engler (1949) stressed the influence ofan unfavourable intrauterine environment. Maternal rubella as a cause of congenital heart defect was mentioned by Gregg (1941) and Swan, Tostevin, Moore, Mayo and Black (1943). So far rubella has not been recorded in the literature as a cause of congenital heart defect in mongolism.