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    SUPPORTING CHILDREN WITH CONGENITAL HEART DISEASE

    June 2012

    hlhs

    Hypoplastic
    Left Heart
    Syndrome

    BY GEMMA PENNEY

     

     

    Hypoplastic left heart syndrome (also known as HLHS), is a rare CHD in which the left ventricle of the heart is severely underdeveloped.

    The heart consists of four chambers: the two upper chambers, called atria, where blood enters the heart; and the two lower chambers, called ventricles, where blood is pumped out of the heart. The flow between the chambers is controlled by a set of valves that act as one-way doors.

    With Hypoplastic Left Heart Syndrome, the left side of the heart (the part that pumps oxygenated blood to the rest of the body) is underdeveloped. The degree of underdevelopment differs from child to child.

    The structures affected usually include:
     
    Mitral valve: The valve that controlsblood flow between the left atrium and left ventricle in the heart.

    Left ventricle: The lower left-hand chamber of the heart. It receives oxygen-rich (red) blood from the left atrium and pumps it into the aorta, which takes the blood to the body. The left ventricle must be strong and muscular in order to pump enough blood to the body to meet its requirements. 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.

    Aortic valve: The valve that regulates blood flow from the heart into the aorta.

    Aorta: The largest artery in the body and the primary blood vessel leading from the heart to the body.

    In many children, HLHS occurs by chance, with no clear reason evident for the underdevelopment.

    Babies with this condition may appear normal at birth. Foetuses are nourished by oxygen-rich blood from their mothers so they don't breathe and don't use their lungs. Babies with HLHS may seem normal at birth because the patent ductus arteriosus (a blood vessel that connects the pulmonary artery to the aorta, thereby bypassing the lungs and the defective left side of the heart.) is still open, allowing blood to continue circulating directly into the aorta and out to the rest of the body. Once the

    ductus closes a few days after birth, blood flows to the lungs and then to the left side of the heart where it is blocked and can't circulate through the rest of the body. It is at this time that these babies show symptoms.

    The following are the most common symptoms of hypoplastic left heart syndrome:

    • cyanosis (blue colour of the skin, lips and nailbeds)
    • pale skin
    • sweaty or clammy skin
    • cool skin
    • heavy and/or rapid breathing
    • fast heart rate
    • difficulty feeding


    Some children are diagnosed with this condition during pregnancy, in which case preparations will be made to provide medical support as soon as the baby is born. However, it is not unusual for a baby to not be diagnosed for hours or sometimes days after birth.

    What are the treatments for hypoplastic left heart syndrome?

    HLHS is fatal unless treated. While there are treatments, HLHS is not correctable and is therefore described as a palliative condition.

    Your child most likely will be admitted to the intensive care unit or special care once symptoms are noted. Initially, your child may be placed on oxygen, or a ventilator to assist his/her breathing. Intravenous medications, (including prostaglandins which prevent the ductus from closing) may be given to help the heart beat stronger and lungs function better.

     

    If a HLHS diagnosis is made after birth then there will be two options available to you but if the condition is discovered during pregnancy, parents will also be offered the option of a termination of pregnancy as well.

    The two options available to families and children with a HLHS diagnosis are:

    Comfort Care - includes the process of relieving pain and suffering, and controlling debilitating symptoms, while not preventing the patient from dying.


    Surgical Repair - consists of 3 open heart surgeries that will result in the body using its right ventricle to do the work normally done by 2 ventricles. The goal is to separate blue and red blood circulation. Because blood vessels of the lungs change over the first year of life, the surgery must be performed in stages. A successful Fontan (final stage) requires sufficient and easy blood flow through the lungs so as not to require the force of the missing ventricle to pump the blood. This is not possible in the first months of life and therefore 2 procedures (stages) must be performed until the lungs are matured and ready to undertake the final stage.

    STAGE1–NORWOOD

    This surgery is normally performed in the first week of life. A repair is made to allow the right ventricle to pump blood to both the lungs and the body. Because blood flow must be forceful for the immature lungs, the surgeon creates a tube from a branch of the aorta to the pulmonary artery known as the modified Blalock-Taussing shunt. The baby will still appear blue (cyanotic) after this surgery.


    STAGE 2 - bi-directional Glenn or Hemi-Fontan


    This surgery is typically performed at about 6 months of life when the blood starts to flow more easily and the ventricular force is not needed. The surgeon creates a direct connection between the superior vena cava and the pulmonary artery thus diverting half of the blood flow without the assistance of ventricular force. This reduces the work on the right ventricle by allowing it to only pump blood to the body and allowing all blood from the upper body to go straight to the lungs. This will hopefully stabilise the hearts function until stage 3 can be completed.


    STAGE 3 - FONTAN

    This surgery is often performed between 18 - 48 months. The surgeon connects the inferior vena cava to the pulmonary artery. This will allow the remaining blood coming back from the body to go directly to the lungs. The final result will be no mixing of blood in the heart with more oxygen rich blood going to the body. This will significantly improve the child's health and growth, and hopefully give them more energy and stamina.


    HEART TRANSPLANT
    – As HLHS surgeries are only a palliative option it is very likely that at some stage in a child’s life the heart will still fail and in this situation it may be that the child needs a heart transplant to stand any chance of survival. After the successful transplant, the recipient will be required to remain on anti-rejection medications for life.


    HLHS requires a life time of follow up care. Most HLHS patients will require heart medications for life. They are at a high risk of heart valve infection (endocarditis) and require antibiotics before dental work and most surgeries. At this time, life expectancy is relatively unknown. 70% of infants who survive the Fontan will survive to the age of 5.

     

    Please click here to read Imogen's Story written by Gemma Penney

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