Over a hundred years ago, Sir William Osler, in his classic textbook The Principles and Practice of Medicine (New York, Appleton & Co, 1892, pp 659–663), devoted only five pages to “Congenital Affections of the Heart,” with the first sentence declaring that “[t]hese [disorders] have only limited clinical interest, as in a large proportion of cases the anomaly is not compatible with life, and in others nothing can be done to remedy the defect or even to relieve symptoms.” Fortunately, in the intervening century, considerable progress has been made in understanding the basis for these disorders and their effective treatment.
The most common birth defects are cardiovascular in origin. These malformations are due to complex multifactorial genetic and environmental causes. Recognized chromosomal aberrations and mutations of single genes account for <10% of all cardiac malformations. Congenital heart disease (CHD) complicates ~1% of all live births in the general population—about 40,000 births/year—but occurs more frequently in the offspring (about 4–10%, depending on maternal CHD type) of women with CHD. Owing to the remarkable surgical advances over the last 60 years, >90% of afflicted neonates and children now reach adulthood; women with CHD may now frequently successfully bear children after competent repairs. As such, the population with CHD is steadily increasing. Women with CHD are at increased risk for peri- and postpartum complications, but maternal CHD is generally not considered an absolute contraindication to pregnancy unless the mother has certain high-risk features (e.g., cyanosis, pulmonary hypertension, decompensated heart failure, arrhythmias, aortic aneurysm, among others). Consultation with an adult CHD expert is warranted for all females with CHD who desire to become pregnant.
Nearly one and a half million adults with operated or unoperated CHD live in the United States today; there are now more adults than children with CHD in the United States. Because true surgical cures are rare, and all repairs—be they palliative or corrective—may leave residua, sequelae, or complications, most require some degree of lifetime expert surveillance. The anatomic and physiologic changes in the heart and circulation due to any specific CHD lesion are not static but, rather, progress from prenatal life to adulthood. Malformations that are benign or escape detection in childhood may become clinically significant in the adult. Unfortunately, the growing number of adults with CHD has not been paralleled by an adequate increase in the number of specialists and specialty centers that are trained and equipped to manage this challenging population. Ongoing efforts to increase awareness, resources, and advocacy are essential for the necessary growth of this specialty.
(See also Chap. 265e) CHD is generally the result of aberrant embryonic development of a normal structure or failure of such a structure to progress beyond an early stage of embryonic or fetal development. This brief section serves to introduce the reader to normal development so that defects may be better understood; by necessity, it is not exhaustive. Cardiogenesis is a finely tuned process with transcriptional control of a complex group of regulatory proteins that activate or inhibit their gene targets in a location- and time-dependent manner. At about 3 weeks of embryonic development, two cardiac cords form and become canalized; at that point, ...