Hypoplastic Right Heart Syndrome (HRHS)

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What is hypoplastic right heart syndrome (HRHS)?

Hypoplastic Right Heart Syndrome (HRHS) is a condition that is even more rare than Hypoplastic Left Heart Syndrome (HLHS). HRHS refers to the underdevelopment of the right side structures of the heart, which means that the chambers, valves and related blood vessels on the right side of the heart are malformed. This malformation involves the pulmonary valve atresia which has not formed, a very small right ventricle, a small tricuspid valve and a small hypoplastic pulmonary artery. As the ventricle has failed to grow and develop the ventricles muscle structure is poor, so additional problems are encountered as the heart attempts to pump blood to the pulmonary valve for transfer to the lungs. The proper amount of blood pumped from the right atrium is not sufficient and this causes the blood to be not pumped efficiently to the lungs.

Main Problem:

  • Pulmonary valve atresia which is absent is a valve that normally opens and closes to let blood flow to the pulmonary artery.

Secondary Problems

  • A very small (hypoplastic) right ventricle is the lower chamber which normally pumps blood to the lungs,
  • A small tricuspid valve which is the valve that allows blood to flow into the right ventricle
  • A small (hypoplastic) pulmonary artery.
  • The blood flow into the coronary arteries may be abnormal causing damage to the heart muscle.

Foramen ovale is a hole between the atria and the infant is born with this connection which helps the blood flow. The second connection is the Patent ductus arteriosus (PDA) a blood vessel between the aorta and pulmonary artery. As these connections begin to close, the infant becomes critically ill.

However, due to the right ventricle failing to grown and developing properly, the babies born with HRHS need to be operated on within the first days of their life.

What are the Symptoms of hypoplastic right heart syndrome?

The problems with a hypoplastic right ventricle begin almost immediately after the baby is born, this is because the baby’s body must provide its own oxygen and the heart is not capable of doing this, whilst in the womb the baby does not need to provide his/her own oxygen. The oxygen-rich bloody supply is severely reduced through out the body and this is when the symptoms appear, the symptoms is a bluish tint (cyanosis) to the:

  • skin
  • lips
  • fingernails
  • and other parts of the body.

Basically, an inadquate bloody supply to the lungs means a poor return of oxygenated blood to the body, and the muscle in the ventricle will exhaust easily.

How is hypoplastic right heart syndrome diagnosed?

Your child’s physician may have heard a heart murmur during a physical examination and referred your child to a paediatric cardiologist for a diagnosis. A heart murmur is simply a noise caused by the turbulence of blood flowing through a narrow region. Symptoms your child experiences also will help with the diagnosis.

A paediatric cardiologist specialises in the diagnosis and medical management of congenital heart defects, as well as heart problems that may develop later in childhood. The cardiologist will perform a physical examination, listening to the heart and lungs, and make other observations that help in the diagnosis.

If the condition has not been diagnosed earlier, the obstetrician or paediatrician will hear a discernible murmur with a stethoscope.
An echocardiogram (a procedure that evaluates the structure and function of the heart by using sound waves, recorded on an electronic sensor, that produces a moving picture of the heart and heart valves) which 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 hypoplastic right heart syndrome is diagnosed in a fetus, the parents are referred to a hospital with a paediatric cardiology and paediatric cardiothoracic surgical team.

If HRHS is diagnosed while fetal, the baby will be born in a hosiptail specialising with in hearts and there will be cardiologists on hand to assess and immediately treat the newborn. However, if a mother is expecting a baby with HRHS and does not live close to Heart Specilised hospital, early arrangements can made for either an induced delivery or a Caesairian, if the mother cannot have a vaginal birth.

When a baby with hypoplastic right heart syndrome is born in a hospital that cannot support immediate care, the infant is transferred immediately to a Heart Specialist hospital. Pregnant women who do not live close to a Heart Specialist hospital, especially those who plan a home birth, should request a fetal echocardiogram, particularly if there is any family history of heart defects.

What are the treatments for hypoplastic right heart syndrome?

As with HLHS, the treatment options include open-heart surgeries, heart transplant surgery or the Norwood procedure.

In the first few days a baby will undergo an operation called Blalock-Taussig Shunt. The Blalock-Taussig Shunt is performed due to the blue blood not being able to pass through the right side of the heart to get to the lungs. The blue blood crosses into the left atrium and mixes with red blood returning from the lungs. This mixed blood is pumped out of the aorta. The only way in which blood gets to the lungs is through the PDA. The PDA must be maintained open with medicine (PGE1). The Blalock-Taussig Shunt Surgery is usually performed shortly after starting PGE1 to create an artificial connection between the aorta and the pulmonary artery, this is a temporary way to deliver blood to the lungs.

However, there is no way to repair a small right ventricle, though its effects can be alleviated but the Fontan procedure is performed 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.

When the child is around 3 months he/she child will undergo the Glenn shunt which is where 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.

Parents should ask which type of Fontan surgeons tend to employ.

What are the outcomes for hypoplastic right heart syndrome?

The survival rate is precited to be 15-30 years post-Fontan but this does NOT mean the child will die at this time. It MEANS that the heart function has started to deteriorate and children will be listed for transplant. However, some parents opt immedidiately for transplantation after birth instead of the Fontan.

Other parents do feel that with the advances of medical techonology and that the tranplantation still needs more work, they prefer to buy time for this technology to improve by choosing the Fontan route.

What is the outlook for hypoplastic right heart syndrome?

The outlook for children with HRHS is better now than it has ever been.

The improvements in the methods and delivery of the Fontan have made an enormous change.

HRHS used to be considered almost certainly fatal, but NOW many children survive the initial surgeries and are able to pursue active and purposeful lives.

Related Links:

If you want to meet other parents whose children have HRHS, then this is a very good forum, that was recommended to me http://www.hypoplasticrighthearts.org/public_html/index.php

I gathered the information for this article from these websites:
yourtotalhealth.ivillage.com - hypoplastic-left-heart-syndrome

Disclaimer: The facts and opinions shown in this article are as accurate and up to date as possible, but are provided as general “information resources”, which may not be relevant to individual persons. This article is not a substitute for individual assessment and always take advice from a doctor who is familiar with the particular person..

Written by: CHD-UK