Early Childhood: Down Syndrome and Congenital Heart Defects
Ralf J. Holzer, MD MSc FACC FSCAI
David Wallace – Starr Foundation
Professor of Pediatric Cardiology
Chief, Division of Pediatric Cardiology
Weill Cornell Medicine
Director, Pediatric Cardiac Catheterization
NewYork-Presbyterian Komansky Children’s Hospital
How common is congenital heart disease in children with Down syndrome?
About 0.7% of infants are born with some form of congenital heart disease, ranging from minor defects to complex, life-threatening cardiac malformations. This prevalence is increased to about 40-60% in infants born with Down syndrome.
Why is congenital heart disease so common in children with Down syndrome?
There is a clear genetic basis to heart disease seen in children with Down syndrome. While not all genetic mechanisms have been completely identified, a variety of potential genes have been found to be associated with associated cardiac (and non-cardiac) problems.
How is congenital heart disease usually diagnosed?
Echocardiography, which is an ultrasound of the heart, is used to delineate the structure and function of the heart. It is the ideal imaging modality to identify cardiac defects.
Are there other (cardiac) test that may be needed in children with Down syndrome who have congenital heart disease?
All patients will usually have a standard 12-lead electrocardiogram. On occasions, a cardiac CT or MRI scan may be needed. Very rarely, a diagnostic heart catheterization procedure has to be performed.
When is the diagnosis of congenital heart disease usually made?
If the diagnosis of Down syndrome was made during pregnancy, then usually a fetal heart scan (echocardiography) is being performed, which is able to identify the vast majority of the more significant cardiac abnormalities. However, even a specialized fetal scan may not be able to detect all forms of congenital heart disease, in particular smaller septal defects (ASD, VSD) or abnormalities of the aortic arch (e.g. coarctation). As such, a postnatal scan is usually recommended, in particular if someone identifies a heart murmur, or any abnormalities on EKG, or abnormalities of blood pressure and/or oxygen content after birth. If the diagnosis of Down syndrome is made after birth, then every child will require a cardiac echocardiography to rule out any cardiac defect.
What are the most common heart defects in Children born with Down syndrome?
- Atrioventricular Septal Defect (AVSD): ~25-30% of CHD in Children with Down syndrome
- Ventricular Septal Defect (VSD): ~20-25% of CHD in Children with Down syndrome
- Atrial Septal Defect (ASD): ~20% of CHD in Children with Down syndrome
- Tetralogy of Fallot (TOF): ~4-5% of CHD in Children with Down syndrome
- Persistent Ductus Arteriosus (PDA): ~15% of CHD in Children with Down syndrome
- Other Congenital Heart Disease (including complex CHD): ~5-10% of CHD in Children with Down syndrome
If a heart defect is identified, does my child require any treatment?
This depends on the type of heart defect (more details below) and its size. As a general rule, about 50% of children with Down syndrome who were born with a congenital heart defect require heart surgery early in life. Some defects can be just watched and monitored with regular follow-up visits in clinic, while other defects can get smaller with time, or may even correct themselves completely. The latter applies to small ASDs, small VSDs (in particular those surrounded by thick muscle), as well as PDAs. However, certain forms of congenital heart disease, such as an atrioventricular septal defect or Tetralogy of Fallot, do not have any propensity to correct themselves completely.
My child requires heart surgery: is the outcome any worse in patients with Down syndrome?
Studies have looked at important outcome parameters after heart surgery in children with Down syndrome. With current management, there is no significant difference in terms of survival after open heart surgery, and there is no difference in the frequency of tracheostomy (a special form of airway management). There is however a difference in the length of hospital stay with patients with Down syndrome staying longer in hospital. This is mainly due to the time it takes to start feeding, and some children with Down syndrome may require a temporary gastrostomy/feeding tube after surgery.
My child requires open heart surgery: how long can I expect to stay in hospital?
A lot depends how early surgery needs to be performed and what type of underlying heart defect is present. If a child with Down syndrome requires surgery in the neonatal period, then the length of stay may be as much as 3 weeks, often related to feeding problems after surgery and the need for the infant to “learn” how to feed. Later during infancy, recovery may be quicker, and the time to discharge in some infants with VSDs where the child was feeding well before the procedure could be as little as 4-5 days from the time of surgery.
Can you tell me more about the most common cardiac defects associated with Down syndrome?
Atrioventricular Septal Defect (AVSD)
Definition: This is a malformation of the central portion of the heart, where there is one instead of two separate AV valves, and defects of the atrial and/or ventricular septum above and below the AV valves.
Symptoms: Symptoms depend on the size of the holes and the functioning of the AV valves (such as presence of leakiness). Some patients with Down syndrome may not have any symptoms, while in others symptoms are present early and worst around 4-6 weeks of age. Symptoms are non-specific and can also occur with other unrelated medical problems, but in general include heavy and fast breathing, breathlessness and tiring with feeds, sweating with feeds, and poor weight gain (failure to thrive). The lack of or improvement of symptoms does not always mean that defects are getting smaller, and in fact can sometimes be a warning sign with the need to perform surgery earlier.
Management: Surgery is required in the vast majority of patients. Large defects are usually corrected between 3-6 months of age, while smaller ones occasionally are deferred until 4-5 years of age. Some patients may require diuretics (water medicine) and other medication until the time of surgery.
Surgical mortality: The surgical mortality is about 1-2%
Long-term outcome: The long-term outcome is generally good. While surgery can improve valve function, it does not make the valves normal. Some patients have leakiness or narrowing of the AV valves even after surgery, and very few may require further valve surgery or even valve replacement in the future.
Ventricular Septal Defect (VSD)
Definition: This is a defect of the wall between the two pumping chambers. Some defects are surrounded by muscle (muscular VSDs), while others are located closer to the aortic valve within the membranous portion of the ventricular septum (peri-membranous VSDs).
Symptoms: Symptoms depend on the size of the defect. Similar to AVSDs, some patients with Down syndrome may not have any symptoms, while in others symptoms are present early and worst around 4-6 weeks of age. Symptoms are non-specific and can also occur with other unrelated medical problems, but in general include heavy and fast breathing, breathlessness and tiring with feeds, sweating with feeds, and poor weight gain (failure to thrive). As mentioned for AVSDs, the lack of or improvement of symptoms does not always mean that defects are getting smaller, and in fact can be a warning sign to perform surgery earlier.
Management: Management options depend on the size of the defect. Large (non-restrictive) defects need to be closed surgically within the first 3-6 months of life. If the defect is small enough to protect pulmonary artery pressures (pressures in the lungs), then surgery can often be deferred and patients can initially be managed medically. Some defects, in particular smaller muscular VSDs, can close completely over time, while others can become so small, that no medical or surgical therapy may be needed. Similar to AVSDs, some patients may require diuretics and other medication until the time of surgery.
Surgical mortality: The surgical mortality is about 0.6%
Long-term outcome: The long-term outcome is excellent. Patients who had successful closure of their defects, may not require any cardiac procedure for the rest of their lives. Patients with small (residual) defects should be followed loosely once a year, in particular if the defect is closely related to the aortic valve. Very rarely, a small defect may over time make the aortic valve leaky, in which case such a defect would then need to be closed surgically.
Tetralogy of Fallot (TOF)
Definition: This is a combination of a ventricular septal defect (defect between the two pumping chambers), the aorta being pushed anterior (to the front) and thereby being located right on top of the VSD (overriding the VSD). This then creates a narrowing of the blood flow to the lungs either at the valve, or more commonly below the valve, combined with thickening of the right heart muscle that tries to overcome the narrowing towards the lungs.
Symptoms: Symptoms depend on the degree of narrowing towards the artery going to the lungs. In severe forms, patients are very blue as there is not enough blood reaching the lungs to carry the oxygen needed in the body. This can present as sudden “blue spells” where the lips and tongue/face of the child become very dusky (which is an emergency and requires to see a doctor immediately). At the other end of the spectrum, if the narrowing to the lungs is extremely mild, then symptoms may resemble those of an isolated ventricular septal defect.
Management: Surgery is required in all of these patients. In the absence of “blue spells”, surgery is usually performed between 3-9months of age, and involves the closure of the VSD, as well as enlargement of the pathway to the lungs using a patch. If blue spells are present early in life, the child may need an additional form of blood supply to the lungs, which can be delivered through a shunt (a connection created surgically between a systemic artery and a vessel to the lung, usually using a small Gore Tex tube). Some patients may undergo heart catheterization under X-ray guidance and have either a stent placed towards the lungs, or through a small persistent arterial duct (if still present). If patients are “blue” early after birth, they may be started on a special medication (called prostaglandin) directly after delivery to allow extra blood flow going to the lungs via an arterial duct, until a more permanent source can be created through either surgery or cardiac catheterization. Patients who underwent a shunt procedure, usually undergo full surgical correction closer to the end of the first year of life.
Surgical mortality: The surgical mortality of the “full” correction is about 1-2%
Long-term outcome: The long-term outcome is good. However, it is important to emphasize that “full surgical correction” does not mean that the heart is now normal. Patients will always need follow up and usually require additional surgical and/or transcatheter procedures later in life. The need for additional procedures is due to often residual or recurrent narrowing of the blood vessels going to the lungs, as well as the need for a competent pulmonary valve later in life (which in many patients can be implanted using a transcatheter approach, thereby avoiding open heart surgery).
Atrial Septal Defect (ASD)
Definition: This is a defect of the wall between the two collecting chambers.
Symptoms: Most patients do not have any symptoms the first 1-2 decades of life. However, changes within the heart such as right heart dilation are present much earlier, and are the reason to proceed with transcatheter or surgical closure. A few patients with Down syndrome may have non-specific symptoms that are difficult to attribute to other causes, which may or may not disappear after closure of the defect.
Management: These defects will require closure, usually performed sometime between 1-5 years of age. 90% of defects can be closed using a minimally invasive heart catheterization procedure (suture-less, just through a small puncture in the groin), where patients have no scars and are discharged the day after the procedure. 10% of patient will require open heart surgery.
Surgical/Cath mortality: The surgical mortality is about 0.29%. Mortality associated with a minimally invasive transcatheter approach is less than 0.1%.
Long-term outcome: The long-term outcome is excellent for both, surgery and heart catheterization, and patients are expected to live a completely normal life (in relation to the heart).
Persistent Ductus Arteriosus (PDA)
Definition: A PDA is present in all babies in the womb to allow blood to bypass the lungs. It usually closes after birth. When it does not close, then it is called a persistent ductus arteriosus.
Symptoms: Most patients do not have any symptoms whatsoever. Very few infants can present with symptoms that resemble those of a VSD, such as heavy and fast breathing, breathlessness and tiring with feeds, sweating with feeds, and poor weight gain (failure to thrive).
Management: As many PDA close spontaneously, most patients are observed conservatively for the first year of life, unless symptoms require to have the PDA closed earlier. If a PDA has not closed by 1 year of age, it is unlikely to close on its own, and then usually the duct can be closed using a minimally invasive cardiac catheterization procedure.
Cath mortality: The mortality associated with a minimally invasive transcatheter approach is less than 0.1%.
Long-term outcome: The long-term outcome is excellent and patients are usually discharged from follow up one year after the transcatheter procedure.