Atrioventricular Septal Defects
However, it should be mentioned that there is sometimes the particular problem of a bi-directional flow of blood across the VSD when an AVSD is present. This means that poorly oxygenated blood mixes in with the oxygenated blood destined to be pumped throughout the body in addition to the standard left-to-right shunt inherent to all septal defects, in which blood that has already been oxygenated returns to the lungs unecessarily.
This additional circulatory problem can result in cyanosis, a bluish tinge of the skin which occurs when the body is not sustained by a sufficient amount of oxygen-rich blood. Needless to say, this problem can be very serious if the degree of cyanosis is severe. For this reason, complex congenital anomalies such as an AVSD require prompt surgical correction so as to decrease the incidence of patient morbidity.
Another problem posed by this defect is that the common valve between the upper and lower chambers of the heart fails to close properly. Blood hence leaks backward from the ventricular chambers to the atrial chambers, a phenomenon referred to as valvular regurgitation or insufficiency. When the valve leaks, the heart has to pump more blood. This can lead to enlargement of the heart and hence precipitate congestive heart failure. The inadequate function of this single valve may also result in certain disturbances to the heart's normal rythm.
Incidence:
Fortunately, AVSDs are rare, accounting for only 4% of congenital heart defects and occurring in 0.19 out of every thousand live births. However, children with Down's Syndrome are frequently the victims of CHD, and many such infants are affected by this particular condition. (40% of children with Down's Syndrome have CHD, and of those 40% have an atrioventricular septal defect). Treatment: When the affected infant reaches the age of 6 to 9 months, surgery will be performed to correct the defect, providing that he or she is strong enough to withstand the rigours of an open-heart procedure. Treatment consists of sealing both the ASD and the VSD with patches made of teflon of dacron. In addition, the surgeon will construct two valves out of the common valve in order to promote normal circulation. The outcome is generally very good, but there are instances in which residual valvular insufficiency results in the continued regurgtation of blood from the ventricles to the atria. This may result in congestive heart failure due to the added strain placed upon the heart. A
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