A single ventricle anomaly is a condition where one of the pumping chambers or ventricles is too small to work correctly. There are many types of single ventricle anomalies and these hearts are among the most complex of heart conditions. These include:
Single ventricle anomalies can cause blood oxygen levels that are lower than normal. Because of this, children are cyanotic (having a blue tinge on the skin, lips and nail beds). Each type of single ventricle condition has its own unique combination of defects that cause different effects and symptoms.
These conditions can be detected on ultrasounds done during pregnancy. If undetected, newborns are cyanotic and a heart defect can be detected by routine screening. An echocardiogram performed shortly after birth will be able to provide details of the heart’s anatomy. Complex heart structure may require a CT scan or an MRI to help in planning and management before surgery.
After a baby is born and a diagnosis is confirmed, depending on the type of defect, medications can be given to ensure that there is enough blood to the lungs and rest of the body before surgery can be done.
In single ventricle anatomy, only one ventricle receives both oxygen-poor blood from the body and oxygen-rich blood from the lungs and effectively pump to the rest of the body. Infants with single ventricle anomalies are cyanotic until complete surgical correction. Typically, a series of operations is done in three stages to rebuild the heart and achieve circulation that can provide enough blood and oxygen to the body.
There are three stages of the surgery to fix a single ventricle anomaly.
The first stage is done within the first few days of life to ensure that there is enough blood circulating in the lungs and enough oxygen is being delivered to the rest of the body for survival. This can be achieved with a surgical procedure or in some instances, a cardiac catheterization intervention, depending on the type and complexity of the heart defect.
The second stage, called the Glenn procedure is done between 4-6 months of age to connect the superior vena cava (SVC), a large vein that drains the upper part of the body, to a pulmonary artery, a vessel that provides blood to the lungs. This partially offloads the blood to the single ventricle by allowing oxygen-poor blood to drain into the lungs directly.
The third and final stage is performed at approximately 4 years of age and is called the Fontan procedure. During this surgery, the inferior vena cava (IVC), a large vein that drains the lower part of the body is connected to the pulmonary artery. This allows all of the oxygen-poor blood to drain directly into the lungs and only oxygen-rich blood is received by the single ventricle to pump to the rest of the body.
The Fontan circulation is a special kind of circulation that affects other organs if it is not functioning well. It can affect many organ systems such as the brain, lungs, liver, gut and kidneys. Abnormal heart rhythms can also develop. Lifelong follow up with a cardiologist is required. Regular monitoring allows the cardiologist to assess the heart's function, identify any potential issues, and provide appropriate care and intervention as needed. This includes bloodwork, ECGs, Holter monitors, echocardiograms, exercise stress tests, cardiac catheterization procedures and imaging such as a CT or MRI.
Children with this heart condition often experience limitations in exercise tolerance compared to individuals with normal hearts. Growth and development may be affected. Neurodevelopmental issues such as intellectual disability or psychiatric conditions such as ADHD have been observed.
Imaging, cardiac catheterization, exercise testing and blood work are done regularly to monitor the Fontan circulation and anticipate complications. The Fontan circulation is a special kind of circulation that affects other organs if it is not functioning well. It can affect many organ systems such as the lungs, gut, liver and kidneys. Abnormal heart rhythms can also develop.
Adolescents and adult females should inform their cardiologist of any plans of pregnancy. The use of contraception should be discussed because some maintenance medications can interact with oral contraceptive pills increasing the risk of stroke. There is also an increased rate of abortion in those with a Fontan circulation. The pregnancy itself puts a lot of strain on the heart, but a healthy pregnancy with a Fontan circulation is possible.
The BC Children's Hospital Heart Hub is a clinically reliable and accurate online resource for patients and families living with congenital and acquired heart disease.
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