Why is atrioventricular canal a concern?If not treated, this heart defect can cause lung disease. When blood passes through both the ASD and VSD from the left side of the heart to the right side, then a larger volume of blood than normal must be handled by the right side of the heart. This extra blood then passes through the pulmonary artery into the lungs, causing higher pressure than normal in the blood vessels in the lungs.
The larger the volume of blood that goes to the lungs, the higher the pressure. The lungs are able to cope with this extra pressure for a while, depending on exactly how high the pressure is. After a while, however, the blood vessels in the lungs become damaged by the extra pressure.
As pressure builds up in the lungs, the flow of blood from the left side of the heart to the right side and on to the lungs will diminish. This helps preserve the function of the lungs, but causes yet another problem. Blood flow within the heart goes from areas where the pressure is high to areas where the pressure is low. If the septal defects are not repaired, and lung disease begins to occur, pressure in the right side of the heart will eventually exceed pressure in the left. In this instance, it will be easier for oxygen-poor (blue) blood to flow from the right side of the heart, through the ASD and VSD, into the left ventricle, and on to the body. When this happens, the body does not receive enough oxygen in the bloodstream to meet its needs, and children may become cyanotic, or exhibit a blue coloring in their skin, lips, and nailbeds.
Because blood is pumped at high pressure through the septal openings, the lining of the right and left ventricles will become irritated and inflamed. Bacteria in the bloodstream can easily infect this injured area, causing a serious illness known as bacterial endocarditis.
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