Abnormalities of the cardiovascular system are common in Down syndrome. Approximately half of all infants born with Down syndrome have a heart defect. Many of these defects have serious implications and it is important to understand them and how they may affect the child so that appropriate medical treatment may be provided.
What Are the Most Common Heart Defects in Children With Down Syndrome?
The most common defects are Atrioventricular Septal Defect (formally called Endocardial Cushion Defect), Ventricular Septal Defect, Persistent Ductus Arteriosus and Tetralogy of Fallot.
What Is an Atrioventricular Septal Defect?
An Atrioventricular Septal Defect is caused by a failure of tissue to come together in the heart during embryonic life. This results in a large opening in the center of the heart, with usually a hole between the two pumping chambers (a Ventricular Septal Defect) and between the two collecting chambers (an Atrial Septal Defect) as well as abnormalities of the two atrioventricular valves, the mitral and tricuspid valves. Of those children with Down syndrome who are born with congenital heart disease, an antrioventricular septal defect is the most common. In less severe cases, Ventricular Septal Defects and Atrial Septal Defects can also occur separately.
What Is Persistent Ductus Arteriosus?
The ductus arteriosus is a channel between the pulmonary artery and the aorta. During fetal life it diverts blood away from the lungs because prenatal blood is already oxygenated from the mother. After birth this channel usually closes on the first day of life. If it does not close, it is termed “persistent” and results in an increased flow of blood into the lungs.
What Is Tetralogy of Fallot?
This is a term given to a heart condition composed of four abnormalities:
- Ventricular septal defect
- A narrowing of the passage from the right ventrical to the lungs
- An overenlarged right ventrical because of the backup of blood
- An overenlarged aorta, which carries blood from the left ventrical to the body
What Is the Relationship of Heart Defects to the Respiratory System?
The lungs of children with Down syndrome do not develop as fully as in the general population. Consequently, the growth of blood vessels throughout the lungs is limited. The narrowed arteries of the lungs hold potential for lasting consequences due to the increased pressure and flow of blood through the lungs.
How Are the Defects Diagnosed?
Some children with Down syndrome and major heart defects will present with heart failure, difficulty breathing and failure to thrive in the newborn period; however, because in some children the defect may not be at first apparent, it is important that all children born with Down syndrome, even those who have no symptoms of heart disease, should have an echocardiogram in the first two or three months of life. Some heart conditions are also identified during prenatal ultrasounds.
What Is the Recommended Treatment?
Heart surgery to correct the defects is recommended and it must be done before age five or six months in order to prevent lung damage. Although the complexity of the defects raises the risk of surgery slightly above that of surgery on children without Down syndrome, successful surgery will allow many children with heart conditions to thrive as well as any child with Down syndrome who is born with a normal heart. There may be residual defects (such as imperfect valves in cases of Atrioventricular Septal Defect), but their effect on health is often minimal.
What Are the Guidelines for Choosing a Hospital?
Look for a medical center in a major metropolitan area which has experience in open heart surgery on infants, and experience in operating on infants with Down syndrome in particular. A hospital which conducts at least 10 such operations a year and has a good survival rate would be considered an experienced hospital.
What Should Be Considered in Selecting a Surgical Team?
Again, experience, together with the parents’ rapport with the physician, should be the determining factor in the choice. It is important that an experienced anesthesiologist be selected, as children with Down syndrome often have airway problems.