Hypoplastic right heart syndrome is a congenital heart defect in which the right ventricle of the heart fails to grow and develop appropriately. The underdeveloped ventricle cannot contain the proper amount of blood pumped from the right atrium, and because the muscle's structure is poor, additional problems are encountered as the heart attempts to pump blood to the pulmonary valve for transfer to the lungs. This condition needs immediate and emergency treatment, as the heart begins to fail almost immediately after birth. An inadequate blood supply to the lungs means a poor return of oxygenated blood to the body, and the muscle in the ventricle will exhaust easily.
Babies born with hypoplastic right heart syndrome tend to be cyanotic, turning blue shortly after birth. If the condition has not been diagnosed earlier, the obstetrician or pediatrician will hear a discernible murmur with a stethoscope. An echocardiogram can then confirm diagnosis. Some radiologists notice a significant size difference in the ventricles during routine prenatal ultrasounds. Unfortunately, not all do, and fetal echocardiograms are not routine, though they are significantly less invasive than other routine procedures, like amniocenteses.
If this heart defect is diagnosed in a fetus, the parents are referred to a hospital with a pediatric cardiology and pediatric cardiothoracic surgical team. It is best if the baby is born at this Level 3 hospital, so cardiologists are on hand to assess and immediately treat the newborn. If the mother does not live close to a Level 3 hospital, early arrangements can be made for either an induced delivery or a Caesarian, if the mother cannot have a vaginal birth.
As with most heart problems, a hypoplastic ventricle does not pose problems to the fetus, but after birth, when the baby’s body must provide its own oxygen, problems begin almost immediately. If the baby is born in a hospital that cannot support immediate care, the infant is transferred immediately to a Level 3 hospital. Pregnant women who do not live close to a Level 3 hospital, especially those who plan a home birth, should request a fetal echocardiogram, particularly if there is any family history of heart defects.
There is no way to repair a small right ventricle, though its effects can be addressed. Surgeons rely on the Fontan procedure to bypass the right ventricle. The Fontan is split into two procedures, the Glenn shunt and the Fontan completion; early Fontans were performed in one step, but splitting the procedure is more successful. In the first few days of life, the baby will also be given a temporary shunt, called a Blalock-Taussig shunt, that provides a temporary way for blood to get to the lungs.
In about three months, the child undergoes the Glenn shunt, in which the superior vena cava is attached to the pulmonary arteries. Sometime in the next three to five years, the surgeons will complete the Fontan, which connects the inferior vena cava to the superior vena cava through an intra-cardiac baffle or tunnel, or through an extra-cardiac shunt. The result is complete bypass of the right ventricle, so blood flows back from the body directly into the lungs.
Many surgeons now prefer the extra-cardiac shunt because the Fontan completion can thereby be performed on a warm, beating heart. It does not require heart lung bypass and has a lower risk of inducing arrhythmias. Some surgeons still prefer the older intra-cardiac baffle, however, and parents should ask which type of Fontan surgeons tend to employ.
Most surgeons now predict a survival rate of 15 to 30 years post-Fontan. This does not mean that the child will die at this time, however, and when heart function begins to deteriorate, the individual will be listed for transplant. Some parents opt immediately for transplantation after birth instead of the Fontan. Other parents feel that transplantation technology still needs work, and prefer to buy time for this technology to improve by choosing the Fontan route.
The outlook for children with hypoplastic right heart syndrome is better now than it has ever been, and the improvements in care and surgeries have made an enormous change. This birth defect used to be considered almost certainly fatal, but now many children survive the initial surgeries and are able to pursue active and purposeful lives.
Frequently Asked Questions
What is Hypoplastic Right Heart Syndrome?
Hypoplastic Right Heart Syndrome (HRHS) is a congenital heart condition that impedes normal development of the right side of the heart, causing insufficient oxygenated blood flow in the body due to underdeveloped right ventricle, right atrium, and pulmonary valve.
What are the causes of Hypoplastic Right Heart Syndrome?
It is usually caused by a combination of genetic and environmental factors and may be more prevalent in infants with family history of congenital heart issues or exposure to certain medications or toxins during pregnancy.
What are the symptoms of Hypoplastic Right Heart Syndrome?
Common signs and symptoms of HRHS include shortness of breath, fatigue, slow growth, increased heart rate, cyanosis (bluish skin and nail discoloration due to lack of oxygen), heart murmur, and swelling in the legs and abdomen.
How is Hypoplastic Right Heart Syndrome diagnosed?
Diagnosis of HRHS is usually conducted prenatally or shortly after birth using physical exams, chest X-rays, echocardiograms, cardiac MRI scans, and other tests.
How is Hypoplastic Right Heart Syndrome treated?
Treatment for HRHS is dependent on the severity of the condition and its associated symptoms. Medications may be used to manage symptoms, surgery may be used to repair or reconstruct the affected heart structures, and lifestyle changes such as a low-salt diet and oxygen therapy may also be implemented. In severe cases, heart transplant may be necessary.