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by Jones P
(HRHS)

Definition

Hypoplastic right heart syndrome (HRHS) is a problem with how the right side of the heart develops. The lower area called the ventricle is too small or weak. The ventricles push blood out of the heart, to the lungs, and back to the heart. HRHS may also change how other parts of the heart develop such as:

  • Tricuspid valve—Controls flow of blood from upper and lower chambers of the heart. Called tricuspid atresia if valve is not present.
  • Pulmonary valve—Controls flow of blood out of the heart to the lung. Called pulmonary atresia if valve is not present.
  • Pulmonary artery—Carries the blood from the right side of the heart to the lungs.
  • Atrium—The top part of the heart.

HRHS makes it hard for the heart to move blood to the lungs and back to the heart. The blood will have less oxygen for the body.

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Causes

The heart develops in fetus early in the pregnancy. It is unclear why the heart does not develop as it should. It may be a mix of changes in the genes and things in the fetus and mother's environment.

Risk Factors

A family history of similar heart defects will increase the risk of HRHS.

Symptoms

HRHS can cause poor blood flow to the lungs. This can lead to:

  • Blue tint to skins and lips
  • Rapid breathing
  • Feeding problems

Symptoms of HRHS may worsen over the first few weeks of life.

Diagnosis

HRHS may be diagnosed before birth. The doctor may see a difference in the right side of the heart during a prenatal ultrasound. A fetal echocardiogram may be done to confirm HRHS.

After birth, HRHS may be suspected based on the baby’s symptoms. The doctor may also hear a heart murmur. Your baby may be referred to a pediatric cardiologist.

Treatment

Babies with HRHS will need treatment shortly after birth. If HRHS was detected before birth, a team of specialists will help monitor and treat the baby immediately after birth. The full treatment plan will depend on the baby’s overall health and parents' choices.

Medicine may be given shortly after birth to support the baby until surgery can be done. Surgery choices include:

Blalock-Taussig Shunt

A shunt will increase the flow of blood to the lungs. It is often done within the first few days of life.

A shunt is a tube that creates a new path for blood flow. This shunt increase the flow of blood to the lungs by creating a path from the aorta to the main artery to the lungs. The aorta is a major artery that carries blood away from the heart to the rest of the body.

The shunt is a temporary step. It will improve oxygen supply to the body and ease some symptoms.

Glenn and Fontan Procedures

The blalock-taussig shunt will not be as helpful as the child grows. Glenn and Fontan procedures may be done once the child is around age 3 months. The procedures are often split into two separate surgeries.

The Glenn shunt creates a pathway between the superior vena cava and the main artery to the lungs. The superior vena cava is a large vein that collects blood from the body and sends it back to the heart. This shunt sends some of the blood right to the lungs instead of moving it all through the heart.

The Fontan or Fontan completion is done when the child is age 3 to 5 years. This surgery makes a connection between the inferior vena cava and superior vena cava. The inferior vena cava also collects blood from the body. This last connection means more of the blood returning from the body will go straight to the lungs and bypass the right side of the heart.

Heart Transplant

The shunts can increase oxygen in the blood. This should decrease most symptoms. Surgery cannot repair the damaged ventricle. The left side of the heart will at some point have a hard time keeping up. The heart will need to be replaced through a heart transplant.

A heart transplant may be done instead of the Glenn and Fontan procedures or later in adulthood.

Prevention

There are no steps to prevent HRHS because the cause is unknown. Proper prenatal care can decrease the risk of some heart defects.

RESOURCES

American Heart Association  http://www.heart.org 

GARD—Genetic and Rare Diseases Information Center  https://rarediseases.info.nih.gov 

CANADIAN RESOURCES

About Kids Health—The Hospital for Sick Children  http://www.aboutkidshealth.ca 

Canadian Cardiovascular Society  http://www.ccs.ca 

References

Blalock-Taussig (BT) shunts. About Kids Health—The Hospital for Sick Children website. Available at: http://www.aboutkidshealth.ca/En/ResourceCentres/CongenitalHeartConditions/TreatmentofCongenitalHeartConditions/SurgicalCorrectionofCongenitalHeartDefects/Pages/Blalock-Taussig-BT-Shunts.aspx. Accessed September 15, 2019.

Hypoplastic right heart syndrome. GARD—Genetic and Rare Diseases Information Center website. Available at: https://rarediseases.info.nih.gov/diseases/2922/hypoplastic-right-heart-syndrome. Accessed September 15, 2019.

Single ventricle defects. American Heart Association website. Available at: http://www.heart.org/HEARTORG/Conditions/CongenitalHeartDefects/AboutCongenitalHeartDefects/Single-Ventricle-Defects%5FUCM%5F307037%5FArticle.jsp#.WbwA3bKGNxA. Accessed September 15, 2019.

Tricuspid atresia. EBSCO DynaMed website. Available at:  https://www.dynamed.com/condition/tricuspid-atresia . Accessed September 15, 2019.

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