CONGENITAL HEART DEFECTS
Congenital heart disease refers to defects of the heart that are present at birth. Among the terms you may hear are congenital heart defect, congenital heart disease and congenital cardiovascular disease. About 6 to 8 babies out of every 1,000 who are born alive have a congenital heart defect.
If you consider that 3 weeks after conception the embryo's heart consists of a tiny tube that folds, fuses, excavates, and moulds itself so that all of its basic structures are present by the eighth week of development, it is more amazing that things turn out right as often as they do!
What causes congenital cardiovascular defects?
In most cases scientists don't know why they occur. Sometimes a viral infection causes serious problems. German measles (also called rubella) is an example. If a mother contracts German measles during pregnancy, it can interfere with the development of the baby's heart or produce other malformations. Other viral diseases also may produce congenital defects.
Heredity sometimes plays a role in congenital cardiovascular disease. More than one child in a family may have a congenital cardiovascular defect, but this rarely occurs. Certain conditions affecting multiple organs, such as Down's syndrome, can involve the heart, too. Some prescription drugs and over-the-counter medicines, as well as alcohol and "street" drugs, may increase the risk of having a baby with a heart defect.
Other factors that affect the heart's development are under study. The fact is that we don't know what causes most congenital cardiovascular defects.
Any part of the cardiovascular system can be affected by congenital problems, and more than one defect can occur in the same heart. Some defects are mild enough to go unnoticed at birth. Others cause major
problems shortly after the baby is born.
Common defects include the following:
- Abnormally formed blood vessels that impede the flow of blood
- Valves that obstruct blood flow, allow backward leakage, or are missing
- Incorrect or reversed connections between the main arteries and the heart or between the main veins and the heart
- Defects in the partition between the atria or the ventricles that allow blood to flow from the right side to the left side of the heart without going through the lungs, or from the left side to the right side without going through the rest of the body.
Doctors often think of congenital defects in terms of whether they cause blueness of the skin (cyanosis). You have probably heard of "blue babies." Some of their blood circulates through their body without passing through the lungs to pics up more oxygen, and as a result their skin has a bluish tint.
ęCopyright TQ Team 25896, 1999. The Circulatory System- Online Learning.