Atrial Septal Defect
Inferior Vena Cava Fig. 7.4
Right Atrium are somewhat higher. Children with Down's syndrome have a higher chance of having atrioventricular canal defect.
Any surgical repair of atrial septal defect requires a heart-lung machine, and afterwards most patients can look forward to a normal life expectancy.
In coarctation of the aorta, there is an abnormal narrowing of a short segment of the aorta, usually less than an inch long (Fig. 7.5). The aorta can be narrowed up to 90 percent in this area. Over time, it can become totally occluded. If the aorta is narrowed, blood to the lower body bypasses the narrowing by using collaterals, or tiny channels. In a healthy person, these collaterals are barely functioning, but in patients with coarctation they can become very large.
This defect can be diagnosed at birth or shortly afterwards. Typical signs include high blood pressure in the arms and abnormally low blood pressure in the legs, and strong pulses in the arms and minimal or absent pulses in the legs. Some infants may develop severe heart failure, and an emergency operation may be required. In less severe cases, coarc-tation of the aorta is not diagnosed until a child is older and sometimes not until he or she is a teenager or an adult.
The life span of people with coarcta-tion of the aorta can be severely shortened if they do not have surgical correction. This is partially because of the high blood pressure in the upper body, which can result in strokes or heart failure. Also, infection is prone to occur at the point of the coarctation, or the aorta can rupture near the coarctation.
In surgery, doctors can remove the narrowed area and suture the normal ends of the aorta back together. Or they can widen the narrowed area with a patch, or replace the narrowed area with a tube made of Dacron. This is a curative
operation. The chance of surviving repair of isolated coarctation of the aorta is greater than 99 percent. The arteries that supply blood to the spinal cord sometimes originate from the aorta in the area of the coarctation. Because of this, about one in two hundred patients undergoing surgical repair develops some degree of paralysis of the lower half of the body. Occasionally the defect can recur and has to be reoper-ated on. If it does recur, the narrowed segment can sometimes be dilated with a balloon catheter.
In transposition of the great arteries, the two main arteries coming out of the heart, the aorta and the pulmonary artery, are switched (Fig. 7.6). As a result, when the unoxygenated blood returns from the veins into the heart, it is pumped directly back into the aorta, making the infant very cyanotic. The oxygenated blood that returns from the lungs is pumped back into the lungs through the pulmonary artery, which branches off the left ventricle. When children have any congenital heart defect in which the child is cyanotic or the
Fig. 7.5: Coarctation of the Aorta:
An abnormal narrowing of the aorta after it leaves the heart.
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