Congenital heart disease (CHD) is one of the most common major birth defect in live births, occurring in approximately .8-1% of live births. In approximately 30% of cases the CHDs occur in association with other defects such as central nervous system, gastrointestinal, or genitourinary system defects. It is possible that these babies have an underlying chromosome abnormality or prenatal exposure. Otherwise most CHD are caused by multifactorial conditions or basic inheritance. The recurrence risk for a couple that has one child with an isolated heart defect is dependent on the type of defect and can range from 1-3%.
The most common cardiac defect, accounting for approximately 30% of all CHD, is a ventricular septal defect (VSD).This defect results in an opening or hole between the two lower chambers of the heart (ventricles) and usually occures approximately at 7 weeks gestation. This defect may be isolated or may be a component of a complex heart defect. The prognosis depends on the presence and severity of associated anomalies. If an isolated VSD is small, the prognosis is good. Many such holes can close spontaneously.
Atrial septal defects (ASDs) result in an opening or hole between the two upper chanmbers of the heart (atria) and may also be referredt o as endocardial cushion defects. ADS are also frequently this defect is associated with other cardiac and extracardiac abnormalities, and there has been an association between ASDs and chromosome abnormalities, especially trisomy 21. Because of the high incidenc of asociated anomalies and chromosome abnormalities, the prognosis may be poor though some such defects close spontaneously.
Hypoplastic left heart syndrome (HLHS), also known as aortic atresia, is characterized by hypoplastic left ventricle with aortic and mitral atresia. Diagnosis is made by diminished left ventricle size in comparison to right ventricle size. Also, aortic atresia and hypoplasia of the ascending aorta may be visualized. The etiology of HLHS is not known, but the recurrence risk is approximately 4% after the birth of one affected infant.
Hypoplastic right ventricle (HRV), also known as pulmonary atresia, is a condition where the ventricles are normally formed, but the pulmonary artery and tricuspid valve are atretic, resulting in obstruction of pulmonary outflow. Hypoplasia of the right ventricle is secondary to this obstruction. Sonographic findings of this condition are diminished right ventricle volume in comparison to the left ventricle and atresia or hypoplasia of the pulmonary artery.
REFERENCES
Nyberg, D.A., Mahony, B.S., and Pretorius, D.H. Cardiac Malformations
in Diagnostic Ultrasound of Fetal Anomalies. Mosby-Year Book, Inc:
St Louis, 1990. pp 300-341.
Romero, R., Pilu, G., Jeanty, P., Ghidini, A., and Hobbins, J.C. The Heart in Prenatal Diagnosis of Congenital Anomalies. Appleton & Lange: Connecticut, 1988, pp 125-194.
Sadler, T.W. Cardiovascular System in Langman’s Medical Embryology, Sixth Edition. Williams & Wilkins: Baltimore, 1990. pp 179-227.
