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What is Congenital Anomalies of the Heart and Great Vessels

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The congenital cardiovascular defects make up the largest category of the human congenital malformations, accounting for about 20% of all con­genital anomalies observed in liveborn infants. The percentage in stillborns is much higher. The incidence of congeni­tal heart defects (CHD) has been esti­mated to be 6 to 8 per 1000 births.
The cause of most cardiovascu­lar malformations is not well under­stood. However, a few can be attrib­uted to specific genetic or environ­mental factors. It has been estimated that about 4% of cardiovascular defects can be ascribed to single gene muta­tions, another 6% to chromosomal ab­errations such as monosomies and trisomies, and 5% to exposure to spe­cific .teratogens. The remaining 85% of the cardiovascular defects are caused by multifactorial inheritance, ie, by a
complex interplay between genetic and environmental factors.
The teratogens known to cause CHD are rubella virus, thalidomide, vi­tamin A, and alcohol, etc. There is evi­dence that maternal diabetes and hy­pertension also cause congenital car­diac defects.
Most of the congenital cardio­vascular defects are well tolerated dur­ing intrauterine life because gaseous exchange is occurring in placenta and pulmonary circulation has not begun. After birth, however, the pulmonary circulation starts and the impact of con­genital heart defects become evident. Some of these defects produce very little disability, others are incapacitat­ing, while still others are incompatible with extrauterine life. The cyanosed child is also called a blue baby.
Those cardiovascular anomalies which cause shunting of oxygenated blood into the deoxygenated blood produce a clinical condition called cya­nosis, which consists of a dark bluish or purplish discolouration of the skin and mucous membranes. The Cyonosis results from excessive concentra­tion of reduced hemoglobin in the blood. A considerable number of con­genital cardiovascular defects can be corrected surgically.
The number of reported con­genital cardiac defects is very large. The cardiac anomalies of clinical sig­nificance can be grouped as under:
1) Anomalies of position.
2) Atrial septal defects (ASD).
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