Pediatric clinics of North America
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Congenital heart disease occurs in approximately 1 per cent of liveborn children, but in a much higher percentage of those aborted spontaneously or stillborn. To detect as many as possible with CHD, including those with mild lesions, very intensive studies are needed. Studies that are not so intensive, especially those done before modern diagnostic techniques were in general use, considerably underestimated the incidence of CHD in liveborn children. ⋯ The popular explanation for their inheritance has been the interaction of polygenic effects and the environment, but recent studies of the recurrence and transmission risks of various forms of CHD do not fit this model well. The alternative model is a single gene defect modulated by random events. The recurrence risks for future siblings are 2 to 6 per cent, and for offspring are 1 to 10 per cent, but in a few families the recurrence and transmission risks may be much higher.
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In this article, the determinants of hypoxemia and cyanosis are analyzed and discussed. The pathophysiology, clinical presentation, diagnostic evaluation, and treatment of major cyanotic forms of congenital heart disease also are reviewed.