Hypoplastic left heart syndrome (HLHS) is a combination of several abnormalities of the heart and great blood vessels. It is a congenital (present at birth) syndrome, meaning that the heart defects occur due to abnormal underdevelopment of sections of the fetal heart during the first 8 weeks of pregnancy.
In the normal heart, oxygen-poor (blue) blood returns to the right atrium from the body, travels to the right ventricle, then is pumped through the pulmonary artery into the lungs where it receives oxygen. Oxygen-rich (red) blood returns to the left atrium from the lungs, passes into the left ventricle, and then is pumped out to the body through the aorta.
In hypoplastic left heart syndrome, most of the structures on the left side of the heart are small and underdeveloped. The degree of underdevelopment differs from child to child. The structures affected usually include the following:
Perhaps the most critical defect in HLHS is the small, underdeveloped left ventricle. This chamber is normally very strong and muscular so it can pump blood to the body. When the chamber is small and poorly developed, it will not function effectively and cannot provide enough blood flow to meet the body's needs. For this reason, an infant with hypoplastic left heart syndrome will not live long without surgical intervention.
Some congenital heart defects may have a genetic link, either occurring due to a defect in a gene, a chromosome abnormality, or environmental exposure, causing heart problems to occur more often in certain families. In hypoplastic left heart syndrome, there may be abnormalities of other organs, such as diaphragmatic hernia, omphalocele, and hypospadias.
In many children, HLHS occurs sporadically (by chance), with no clear reason evident for their development.
Infants with HLHS usually develop symptoms shortly after birth. The following are the most common symptoms of hypoplastic left heart syndrome. However, each child may experience symptoms differently. Symptoms may include:
The symptoms of hypoplastic left heart syndrome may resemble other medical conditions and heart problems. Always consult your child's physician for a diagnosis.
Your child's physician may have heard a heart murmur during a physical examination, and referred your child to a pediatric cardiologist for a diagnosis. A heart murmur is simply a noise caused by the turbulence of blood flowing through the obstruction from the right ventricle to the pulmonary artery. Symptoms your child exhibits will also help with the diagnosis.
A pediatric cardiologist specializes 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. Diagnostic testing for congenital heart disease varies by the child's age, clinical condition, and institutional preferences. Some tests that may be recommended include the following:
Specific treatment for hypoplastic left heart syndrome will be determined by your child's physician based on:
Your child will most likely be admitted to the intensive care unit (ICU) or special care nursery once symptoms are noted. Initially, your child may be placed on oxygen, and possibly even on a ventilator, to assist his/her breathing. Intravenous (IV) medications may be given to help the heart and lungs function more efficiently.
There are two surgical approaches offered to treat HLHS. Your child's cardiologist and cardiac surgeon will explain the risks and benefits to you. The surgical options include the following:
After surgery, infants will return to the intensive care unit (ICU) to be closely monitored during recovery. The chest is often left open in most patients, but still covered with sterile drapes. The open chest prevents compression of the heart by the rib cage. The chest is then closed several days later, when the heart has had a chance to adjust to the new circulation.
While your child is in the ICU, special equipment will be used to help him/her recover, and may include the following:
Your child may need other equipment not mentioned here to provide support while in the ICU, or afterwards. The hospital staff will explain all of the necessary equipment to you.
Your child will be kept as comfortable as possible with several different medications; some which relieve pain, and some which relieve anxiety. The staff will also be asking for your input as to how best to soothe and comfort your child.
After discharge from the ICU, your child will recuperate on another hospital unit before going home. You will learn how to care for your child at home before your child is discharged. Your child may need to take medications for a while, and these will be explained to you. The staff will give you instructions regarding medications, activity limitations, and follow-up appointments before your child is discharged.
Infants who spent a lot of time on a ventilator, or who were fairly ill while in the ICU, may have trouble feeding initially. These babies may have an oral aversion; they might equate something placed in the mouth, such as a pacifier or bottle, with a less pleasant sensation such as being on the ventilator. Some infants just are tired, and need to build their strength up before they will be able to learn to bottle feed. Strategies used to help infants with nutrition include the following:
Pain medications, such as acetaminophen or ibuprofen, may be recommended to keep your child comfortable at home. Your child's physician will discuss pain control before your child is discharged from the hospital.
If any special treatments are to be given at home, the nursing staff will ensure that you are able to provide them, or a home health agency may assist you.
You may receive additional instructions from your child's physicians and the hospital staff.
Without intervention, most infants with HLHS will not survive longer than a few days to a few weeks. Heart transplantation is an option, but because of the difficulty in obtaining a donor heart for an infant, the series of surgical procedures is most often recommended.
The first-stage procedure poses the highest risk for poor outcomes and death. Some specialized centers where a greater number of procedures are performed have achieved survival rates that are higher than at centers where fewer procedures are performed. Survival rates are higher with later stage procedures.
Infants and children who undergo the staged surgical procedures will require special care and treatment to support growth and nutrition. These children often have diminished physical strength as well as slowed developmental progress and will need support.
There is significant risk for progressive development of complications such as heart failure, dysrhythmias, and protein-losing enteropathy liver congestion resulting in cirrhosis and/or liver congestion.
Some cases will require heart transplantation in order to survive into adulthood.
Regular follow-up care at a center offering highly-specialized congenital cardiac care should continue throughout the individual’s lifespan.
Consult your child's physician regarding the specific outlook for your child.
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