Normally, when the heart pumps, the right side takes in blood from the body and sends it to the lungs to get fresh oxygen. That oxygen-loaded blood then goes to the heart's left side, which pumps it out to the rest of the body.
The main pulmonary artery is the vessel that carries blood from the heart to the lungs. The one that sends it out to the body is the aorta. A valve in each artery controls the flow to make sure the blood follows its regular route.
With truncus arteriosus, those vessels don't become separate channels. The baby has only one large artery that carries blood to the lungs and body.
A baby born with this condition also usually has just one valve instead of two controlling the blood flow out of the heart, and that valve often has problems. It can be too thick or too narrow, which means too little blood can get to the lungs. Or it can leak, and that means blood gets back into the heart.
In most cases, there's also a hole in the wall that separates the lower chambers of the heart from each other. That means oxygen-rich and oxygen-poor blood can mix together.
Truncus arteriosus happens in about 1 of every 10,000 babies born -- roughly 300 times a year in the United States.
Causes and Risk Factors
Like with most birth defects, doctors don't know what causes truncus arteriosus. But some things can raise the odds of a child being born with heart problems. These include things involving the mother, such as:
- They have an illness during pregnancy, such as rubella or diabetes, that's not managed properly.
- They smoke during pregnancy.
- They have a family history of heart defects or genetic disorders, like DiGeorge's syndrome, which can cause several body systems not to develop right in the womb.
- They take medications that aren't recommended during pregnancy.
Symptoms and Diagnosis
A baby with this birth defect has less oxygen in their blood than normal. That can make the skin around their mouth or fingernails look slightly blue. Their breathing is often rapid and they may wheeze. Their pulse pounds and they don't eat well.
These are signs that the baby isn't getting enough oxygen or is developing congestive heart failure, which means the heart can't pump enough blood to meet the body's needs. That can enlarge and weaken their heart.
If the doctor thinks your baby might have truncus arteriosus, a simple test that measures the oxygen in the baby's blood can help confirm it. An echocardiogram, which uses sound waves to draw a picture of the baby's heart, can also help find the problem.
If a problem with the baby's heart is found with an ultrasound before they are born, a fetal echocardiogram may be done to show more detail about the heart's structure. This can help doctors and nurses be ready for any complications when they are born.
To correct the problem, surgery is done on the baby's heart within the first two weeks after birth. Before the procedure, the infant might be given drugs to make their heart stronger and help their body get rid of fluid.
The surgeon will make the single blood vessel into two by putting in a tube, called a conduit, with an artificial heart valve in it. That will connect the right side of the heart to the blood vessel that goes to the lungs. This is known as a Rastelli repair.
The original single blood vessel then becomes the aorta and carries oxygen-rich blood from the heart to the body. A patch made of fabric -- or sometimes tissue from the outside of the heart -- closes the hole between the two sides of the heart.
After the surgery, the baby will spend several days in the hospital and may need pain medication, like acetaminophen (Tylenol) or ibuprofen (Advil or Motrin). It will take a few weeks for them to fully recover, and they'll probably need more rest than usual in that time.
Outlook and Follow-Up Care
Surgery is successful in more than 90% of infants who have it. But a child born with the condition will need follow-up surgeries and regular checkups with a heart doctor (called a cardiologist) for the rest of their life.
As your child gets older, they'll likely outgrow the conduit and it will have to be replaced two or three times. Over time, the conduit might become narrow or blocked and need to be opened up or cleared out. Sometimes the valve leading to the rebuilt aorta can leak and need to be replaced.
Some children born with truncus arteriosus aren't able to take part in intense physical activities or play competitive sports. And they'll have to take antibiotics before future surgery or dental work to prevent an infection known as endocarditis that attacks the lining of the heart.
Some people also experience problems later in life such as leaking heart valves, irregular heartbeats, or high blood pressure in the lungs. A person born with truncus arteriosus will need regular checkups for the rest of their life to watch for these things or other heart issues.