Congenital heart disease (the presence of a structural heart defect at birth) occurs in 40 - 50% of children with Down syndrome and cardiac abnormalities are probably the most common malformations seen in trisomy 21. The most common heart defect (about 2/3) is called an endocardial cushion defect or atrioventricular canal defect. In its complete form there is a hole (defect) in the wall (septum) between the pumping chambers (ventricles)and a hole in the wall between the receiving chambers (atria) of the heart. In addition, rather than two valves inside the heart between the receiving and pumping chambers, there is a large single valve. This defect requires surgical repair, which involves closing both holes and creating two valves out of the one large valve.
This surgery is usually done in the first few months of life. Less common defects are the presence of a hole between just the ventricles (VSD) or between just the atria (ASD) and depending on the size of the hole, these defects may or may not require surgery. The holes do not get bigger with growth of the child and can spontaneously get smaller thus not requiring surgery. Children with Down syndrome may also be born with cyanotic congenital heart disease of be a "blue baby". Most commonly this is a defect called Tretralogy of Fallot, which is a complex structural problem that requires surgical repair and does not spontaneously fix itself. Timing of the surgery is dependent on how cyanotic (blue) the baby is.
Because congenital heart disease is so common, it is recommended that all children with Down syndrome have a full Pediatric Cardiology evaluation by 2 months of age. Also, it is well recognized that children with Down syndrome are at risk for developing damage in their lung arteries at an early age if they have a heart defect. There appears to be a number of reasons for this increased risk but it is critical to recognize the defect and do the repair early since the severe damage can be irreversible and progressive even after surgery. The timing of surgery is dependent on how the child is doing, however, as a rule it is done by 6 months of age and virtually always by one year of age.
Children with Down syndrome without anatomic heart disease also are at risk for the development of pulmonary hypertension, which is high blood pressure in the lung arteries. Usually when we think of blood pressure it is the pressure in the systemic arteries and is measured most commonly with a blood pressure cuff on your arm. The pulmonary artery pressure can sometimes be estimated by echocardiography but the only way to measure it directly is by placing a catheter into the lung artery during a heart catherization. If there is significant pulmonary hypertension, it places an increased work on the right ventricle, which can be detected on an electrocardiogram or echocardiogram. Again, thee appear to be a number of reasons for pulmonary hypertension in these children but one of the most significant is upper airway obstruction, especially during sleep.
Adapted with permission from the Tidewater Down Syndrome Association newsletter.
This article first appeared in issue #8 of Down Syndrome Amongst Us