A common name for a congenital heart defect in which the two sides of the heart are not properly separated.

The term “hole in the heart” is an accurate description of the condition, which may occur on its own or with other congenital deformities in the cardiovascular system. The hole may be between the two upper chambers (an atrial septal defect) or between the two lower chambers (ventricular septal defect). In either case, the hole allows blood to pass directly from one side of the heart to the other without going to the lungs, so that unoxygenated blood circulates. Consequently the person may have a blue appearance due to the high proportion of unoxygenated blood in the circulation.

Congenital heart defects of this kind affect about one child in every thousand in America. The diagnosis usually is made when the pediatrician detects a heart murmur. It must be stressed, however, that there are many different types of heart murmurs and that many of them are not dangerous.

If surgical treatment is planned, the diagnosis will be confirmed and the severity of the defect measured by cardiac catheterization--the passing of a thin, flexible tube through a large vein into the chambers of the heart. The movement of blood within the heart is charted by the pressure in the chambers and by X-ray examination. Many septal defects are isolated defects, but in a minority of cases there are other problems in the heart, making surgical repair more difficult.

With advances in heart surgery, such as the use of the heart-lung bypass that allows the surgeon to work on a resting heart, most cases of septal defect can now be corrected. If the hole is large it is covered either by tissue taken from elsewhere in the person’s body or by an artificial knitted Dacron patch. Usually correction of the defect allows the child to return to a normal or near normal life.