The Fontan circulation
The normal heart has four chambers, two of which are pumps or ventricles. The pump on the right side pumps blue blood to the lungs where it picks up oxygen. The pump on the left has the harder job of pumping oxygen-filled red blood around the body.
A Fontan circulation only has one pump (single ventricle), formed by having two or three stages of surgery. This surgery enables the one pumping chamber to pump oxygen-filled blood around the body. The blood that needs to return to the lungs, to pick up oxygen, will need to flow there without a pump behind it.
Because there is no pump driving the blood to the lungs, it moves slowly. If the resistance to blood flow in the lung blood vessels is too high, it makes it difficult for the blood to flow to the lungs. This creates a ‘back’ pressure throughout the body (like a traffic jam), to the gut and liver. It can also cause back pressure upwards through the chest, head and neck which can affect breathing and cause headaches. In certain cases, people with a Fontan circulation appear cyanosed (blue) at times, although not everyone with a Fontan circulation is cyanosed.
Over time, the pressure in the Fontan circulation can affect the body’s organs, for example, the liver or the gut, so they should be monitored at regular intervals.
Protein losing enteropathy (PLE) – What is it?
Protein-losing enteropathy (PLE) is one of the complications associated with a Fontan circulation. It can also occur in many other unrelated conditions such as cancers, immune disorders, inflammation of the gastrointestinal tract and all intestinal and digestive diseases.
PLE occurs when albumin (protein) and other materials leak into your intestine.
Albumin is the most common protein in your blood. It has many functions, including transporting hormones, retaining water in your bloodstream, controlling the thickness of the blood and helping the immune system.
As well as your blood circulation you have another system in your body called your lymphatic system. This works a bit like a sponge absorbing any extra fluid that contains protein, electrolytes (salts) and cells in your main organs and returning it into your bloodstream so it can be re-used by your body.
People with a Fontan circulation have extra pressure on the lymphatic system and produce more lymphatic fluid. This can lead to a complex reaction in some Fontan patients, particularly in the gut. A combination of inflammation and abnormal lymphatic vessels develops, leading to leakage of protein into the gut where it leaves the body via your poo, or it collects as extra fluid in your abdomen and around your legs and ankles.
It is important to kno0w that PLE only develops in small numbers of Fontan patients.
Signs and symptoms
PLE symptoms can vary: some people will have only mild symptoms, and other people will have all the symptoms and struggle to function day to day. Common symptoms can include:
- Elevated temperature
- Swollen abdomen (bloating) sometimes filled with fluid (ascites)
- Swollen legs (oedema)
- Generally feeling unwell or extreme tiredness (more than normal with a Fontan)
- Low weight, not interested in food, struggle to digest food (unable to gain weight)
- Greater susceptibility to infections
- Low calcium levels (hypocalcaemia)
- Low albumin levels (hypoalbuminaemia)
How is PLE diagnosed?
Your medical team will diagnose PLE based on the signs and symptoms you have.
A blood test will be taken to see what your albumin levels are, people with PLE have low albumin levels as the albumin passes out through the bowel during loose stools/diarrhoea.
A special poo sample is also sent away to be evaluated to confirm if you have PLE: this test is known as ‘faecal alpha 1 antitrypsin’. Not all hospitals are able to assess for this so the samples are often sent to a specialist laboratory for testing and this may take up to 6 weeks.
A special MRI scan may be performed if your doctors think that there may be new lymphatic pathways developing. Dynamic contrast magnetic resonance lymphangiography (DCMRL) is used to see where the extra fluid is leaking from. It may then be possible to consider repairing these ‘leaking’ areas, with a cardiac catheter intervention. This is not a routine procedure and is being studied to see how useful it is.
How is PLE treated?
The sooner you are diagnosed with PLE the sooner you can receive treatment to try and reduce the symptoms you are having. Common therapies include:
- Special dietary information to ensure you eat the right foods to support your Fontan circulation and look after your stomach and bowel.
- Diuretics (water tablets) commonly used to help get rid of the extra fluid in your legs and abdomen.
- Sildenafil, a tablet that is used to try and decrease the pressure in your Fontan circulation, may be used.
- Steroids, tablets that can reduce inflammation in your gut and lymphatic system.
- Heparin, an injection under the skin can be used
- Drainage of the fluid from your abdomen by a specialist liver team, so you feel more comfortable. You may need to have albumin replaced in your body when this is done.
Treatment for your PLE may take place in hospital so your cardiac team can keep a close eye on you. Catheter or surgical interventions can be considered in very severe cases of PLE. These can include blocking off new lymphatic connections that have formed, an operation to ‘take down’ your Fontan connection, or in certain circumstances a heart transplant. PLE can be treated but it rarely disappears completely except after a heart transplant. Doctors will work to reduce the effects of PLE so that it causes minimal interference with how you live your life.
Lorna Carruthers RGN, BSc Practice Development
ACHD Nurse Specialist and SVH Adult Service lead for Little Hearts Matter
Dr Louise Coats
Congenital Heart Disease (ACHD) cardiologist at the Freeman Hospital in Newcastle.
Suzie Hutchinson RGN, RSCN
Chief Executive and Service Lead for Little Hearts Matter
Dr Paul Clift
Consultant ACHD cardiologist at University Hospitals Birmingham