Challenges, consequences and complications on the single ventricle treatment pathway
This section explores the sort of challenges that can occur before, during or after heart surgery when a child or young adult has a single ventricle heart.
When doctors discuss a new baby’s diagnosis and the treatment path that they plan for them to travel, they also discuss the risks that go hand in hand with a complex heart problem and the treatments available.
Most parents understand that having only half a heart is never straightforward.
Here we briefly discuss a broad range of problems that can occur. It is very important that parents, and the patients themselves as they get older, talk to their medical team about their personal risks as not all problems are a risk for every child.
Reduced energy levels
When you only have one ventricle doing the job of two it affects the amount of energy you have for day-to-day life. Learning to balance
your activity with the amount of energy available every day is something that children gradually learn to do.
In early life the area most affected by reduced energy is the ability to take in calories and grow.
Feeding
Babies with half a working heart need more calories to run their inefficient heart but their heart condition affects the amount of
energy available to take in any extra calories. To help with their growth, babies will often be offered higher-calorie milk and have a mixture of feeding styles. For example, the baby may breast and bottle feed or bottle and nasogastric tube feed (a small tube passed through the nose into the stomach).
Low oxygen levels
All children with a cyanotic heart condition have lower-than-normal oxygen levels. It is safe for them to be moderately low for short periods of time, especially when there is a treatment plan in place and the children are carefully monitored, but if oxygen levels are left too low for long periods of time, this can affect energy levels and brain function.
There is also a risk of low oxygen levels when a child undergoes cardiac surgery or in the postoperative recovery period, especially if the team uses the heart-lung bypass machine. Low oxygen levels leading to problems with the brain are known as neurological incidents.
Doctors will explain the risk of low oxygen levels but they will also work to reduce that risk as much as they can.
Infection
Postoperatively there is a risk that the chest scar wound both inside the body and on the skin will become infected. The doctors work to prevent this by giving antibiotics but it can still occur after surgery. If the scar is weeping or red, a test will be done to identify the type of infection and treatment will begin.
Necrotising Enterocolitis (NEC)
NEC occurs when part of the gut (intestines) starts to die and becomes infected because of a lack of oxygen. This can occur in babies around the time of the first stages of surgery, causing an intolerance to the absorption of milk in the gut. Treatment will be given for the infections and the gut will be rested; calories will be given via a drip (intravenous line). Babies may require surgery to remove any of the gut that has died.
Bacterial endocarditis
There is also a risk of something called bacterial endocarditis. This is an infection that often starts in the mouth and can travel to the heart. For more information on dental care, visit the information section of our website.
Blood loss
After any operation there is a risk of bleeding. Blood loss will be measured and replacements will be given if the medical staff feel that the loss is compromising blood flow. If the blood pressure remains low for long periods, the kidneys are unable to work properly and ultimately blood containing oxygen is unable to reach the brain.
If bleeding occurs between the heart muscle and the outside skin of the heart, this can cause problems with the pumping of the heart. If this happens, the surgeons may need to remove the blood that has collected there.
Chest drain losses
After chest surgery children and adults have chest drains inserted to ensure that any fluid or blood in the chest can drain away. In some cases the drainage becomes excessive. This could signify increased blood loss or that fluid fat (chyle) is leaking in the chest. If the drainage is excessive, and doctors are unable to keep the fluid in balance, they may require a change in diet or further surgery to look for a bleeding or leak point.
If chyle continues to collect in the chest, the children will be prescribed a change in their diet. The MCT (medium-chain triglyceride) diet reduces the amount of fat a child eats. This helps to reduce the amount of chyle in the chest, allowing for any leaking points to heal. For more information, see the LHM booklet MCT diet.
High blood pressure in the lungs
The need to change the way that blood flows through the heart and around the body can create changes to the blood’s pressure in different parts of the body.
Normally there is a low blood pressure in the lungs but following the second and third stages of surgery, or as the child grows from childhood to adulthood, the pressure can change.
If the blood pressure rises in the lungs, it creates a back-pressure on the liver, gut and other parts of the body normally below the lungs.
Without treatment this can create changes to the way that the liver and gut work. For more information, see the long-term effects of the Fontan within The Fontan procedure booklet.
Clots
The heart is responsible for pumping blood around the body. If the heart is not working efficiently, especially around the time of surgery,
there is a risk that the blood will clot on areas where surgery has been performed or in pockets of the heart where blood moves slowly. There are also changes to liver function in patients who have a Fontan circulation, and these make the risk of clotting greater than normal. There are a number of risks associated with this clotting. The heart’s pumping can be compromised if clots grow within the heart. Small bits of the clot can travel into the lungs, causing problems with breathing, or to the brain where they could cause a stroke. Children and young adults undergoing heart surgery or living with a Fontan circulation are often prescribed anticoagulation medication to reduce the risk of clots. See LHM’s booklet Living with anticoagulation.
Strokes
A stroke is a disruption to the circulation of blood to the brain, either because of a bleed or because of a blockage, usually a clot. This disruption causes damage to the brain tissue, a condition that is called a stroke. Strokes can take different forms. They can affect mobility, sight, speech and memory, and can cause developmental. problems. Medical teams will be working to avoid strokes by making sure that the risk of clots is low, and that the heart is supported to pump well and maintain the oxygen circulating to the brain.
Arrhythmias
An arrhythmia is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slowly, or with an irregular rhythm. Children with single ventricle hearts have a risk of arrhythmias because of the structure of their heart. The risk is increased after surgery when the circulation has been altered. Arrhythmias can be treated with medications or the use of a pacemaker but often a postoperative arrhythmia will disappear once the heart has recovered from the operation.
A number of these complications can occur routinely around the time of surgery or treatment and so the medical and nursing staff will be watching for them and will intervene swiftly with treatment to help resolve the problems