A heart shunt is an atypical pattern of blood flow through your heart. Left-to-right cardiac shunts don’t affect whether your blood gets oxygen. In right-to-left cardiac shunts, some of your blood doesn’t get oxygen. Some left-to-right shunts go away without treatment. Right-to-left shunts usually require surgery.
A cardiac shunt is an irregular pattern of blood flow in your heart. You may have a cardiac shunt along with typical blood flow patterns. Or you may have a cardiac shunt in place of a typical blood flow pattern. A shunt is a passage by which blood moves from one area (blood vessel or heart chamber) to another in a pattern that isn't normal.
A cardiac shunt is a congenital heart defect, meaning it’s present at birth. Cardiac shunt symptoms can vary widely. Some people have no signs of a cardiac shunt, while other shunts can be fatal. When babies are born with a severe cardiac shunt, healthcare providers usually treat it in the first few months of life.
Usually, blood flows through your heart in a series of steps:
With a cardiac shunt, blood doesn’t flow through these steps. Oxygenated blood may leak back into your lungs. Or oxygen-poor blood may not reach your lungs.
Cardiac shunts may be:
In left-to-right shunts, blood that’s already oxygenated leaks backward to your lungs. Examples of left-to-right cardiac shunts include:
In right-to-left shunts, oxygen-poor blood doesn’t always go to your lungs. Instead, it may flow directly back to the rest of your body. Examples of right-to-left cardiac shunts include:
Circular shunts are severe, life-threatening conditions. In a circular shunt, blood circulates through your heart without sending enough blood to the rest of your body. Circular shunts most commonly appear in severe forms of Ebstein’s anomaly (EA).
Cardiac shunts are the most common type of congenital heart defect. About 1 in every 100 babies are born with a congenital heart defect.
Sometimes, cardiac shunts have a genetic component. You may have a cardiac shunt due to a change (mutation) in a specific gene. For example, up to half of people born with Down syndrome also have a type of cardiac shunt.
Some factors during pregnancy can also affect the chances of having a baby with a cardiac shunt. Babies have a higher risk of a cardiac shunt if their birthing parent had:
Cardiac shunt symptoms can vary significantly. Left-to-right shunts often don’t cause any symptoms until you’re a teenager or adult. When symptoms develop, they may include:
In right-to-left shunts, babies usually have symptoms that start early. One of the most common symptoms of a right-to-left shunt is a baby that looks blue (cyanosis). Other symptoms include:
To diagnose a cardiac shunt, your healthcare provider may use tests such as a:
Cardiac shunt treatment varies depending on symptoms and severity. Small shunts may clear up (resolve) without treatment. Your healthcare provider may operate on a larger shunt to redirect blood flow. Common heart shunt surgeries include:
There’s no guaranteed way to prevent a cardiac shunt. If you're pregnant, you can increase your overall chances of having a healthy baby by practicing healthy habits. You may:
Cardiac shunts vary widely, and so does the outlook. Larger or more severe cardiac shunts need treatment to avoid complications. Some types require surgical treatment within the first few weeks of birth. If you develop severe pulmonary hypertension, you're more likely to need heart shunt surgery or experience complications.
Many times, shunts that don’t affect the process of blood oxygenation don't cause severe complications. They may not cause symptoms at all or require any treatment.
You may also want to ask your healthcare provider:
A note from Cleveland Clinic
Cardiac shunts are irregular patterns of blood flow in your heart. They’re often genetic, although some are linked to pregnancy factors. Shunt symptoms vary widely. Some types of shunts cause few to no symptoms. Others are severe and can be life-threatening without treatment. If a cardiac shunt is severe, your healthcare provider may operate to create a new path for blood flow.
Last reviewed by a Cleveland Clinic medical professional on 05/16/2022.
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