++
Congenital heart diseases occur in at least 10 per 1000 live-born
children; the incidence is much higher in stillborn infants and
in spontaneous abortuses. This figure excludes bicuspid aortic valves,
patent ductus arteriosus in premature infants, and tiny muscular ventricular
septal defects with respective incidences of 10 to 20, 4 to 5, and
30 to 40 per 1000 live-born children. The distributions of various common types
of congenital heart diseases at birth are given in Table
484-1.
++
++
Congenital heart diseases result from interaction between genetic and
environmental factors.
++
Single classic mendelian mutant genes account for 3% of
congenital heart diseases; 5% are caused by gross chromosomal
aberrations, 3% by known environmental factors (eg, rubella,
fetal alcohol syndrome), and the rest by multifactorial gene effects
or single gene effects modulated by random events. The genetics
of congenital heart disease are discussed in detail in Chapter 481.
+++
Environmental
Factors
++
Women taking lithium salts during pregnancy may have children
with congenital heart diseases, with a high incidence of mitral
and tricuspid valve lesions, especially Ebstein syndrome. Diabetic
women or those taking progesterone in pregnancy have an increased
risk of having children with congenital heart diseases. About half
the children of alcoholic mothers have congenital heart diseases
(usually left-to-right shunts). Retinoic acid used to ...