Shone's Complex

What is Shone’s complex?

Shone’s complex is a congenital (present at birth) heart disease. It affects how blood flows both into and out of the left side of the heart. The multiple sites of blockage in the blood flow through the left side of the heart differentiates Shone’s syndrome from other isolated heart defects. Shone’s syndrome is another name for Shone’s complex.

How does your heart typically pump blood?

A healthy heart pumps blood throughout your heart, lungs and the rest of your body. A network of blood vessels called the circulatory system carries blood through your body.

In this process:

1. Oxygen-poor blood collects in the right side of your heart.
2. Your pulmonary arteries carry the blood to your lungs.
3. Your lungs oxygenate (put oxygen into) the blood.
4. Pulmonary veins carry the oxygen-rich blood to the left side of your heart.
5. From the left side of your heart, aortic valves carry blood to your aorta, the largest artery in your body.
6. Your aorta pumps out blood to the rest of your body.

What conditions are associated with Shone’s complex?

Shone’s complex is named for the person who discovered it. Originally, Shone’s was associated with four types of heart problems. Now, experts have identified up to eight components of congenital heart defects related to Shone’s syndrome.

Babies born with Shone’s complex have at least three of these heart conditions:

• Bicuspid aortic valve and small aortic valve annulus: These two valve conditions usually occur together. Typically, the aortic valve has three moving parts. A bicuspid valve has only two parts, resulting in a smaller valve opening and less blood flow.
• Coarctation of aorta: Narrowing of the aorta restricts blood flow.
• Cor triatriatum: The pulmonary veins don’t connect to the heart as they should. As a result, babies have a blockage in the heart's left side that restricts blood flow.
• Hypoplastic left heart ventricle: The left heart ventricle is stiff, reducing blood flow.
• Parachute mitral valve: Instead of multiple mitral valve muscles, you only have one muscle to help your mitral valves open and close. Mitral valves are the tubes that connect the top and bottom portions of the left side of your heart. A parachute mitral valve does not usually cause severe symptoms.
• Small aortic arch: A small or stiffened aortic arch can restrict blood flow and lead to high blood pressure.
• Subaortic stenosis: The muscles thicken around your aortic valve. The left side of your heart then has to work harder to pump blood to your aorta.
• Supramitral ring: Thick tissue forms around the opening of your mitral valves. This tissue narrows the valve’s opening and blocks blood flow.

How common is Shone’s complex?

Shone’s complex is very rare. It accounts for less than 1% of all congenital heart diseases.

What are the symptoms of Shone’s complex?

Shone’s complex is variable. Some patients are diagnosed before birth, while others are diagnosed as a result of heart murmurs or other findings including:

• Poor weight gain.
• Rapid breathing.
• Shortness of breath (dyspnea), especially around feeding time.

Babies born with Shone’s complex may also have symptoms of congestive heart failure, such as:

• Cough and congestion in the lungs.
• Difficulty breathing.
• Fatigue or extreme sleepiness, such as becoming too tired to eat.
• Sweating.

What causes Shone’s complex?

Healthcare providers don’t always know exactly what causes Shone’s complex. Some factors can increase the chances that a baby will be born with a congenital heart defect. Some of these risks include genetic and environmental factors.

How is Shone’s complex diagnosed?

Healthcare providers may use a range of tests to diagnose Shone’s complex. These tests tell providers about the heart’s blood flow and size:

• Transthoracic echocardiograms (TTE) take ultrasounds to evaluate the chest wall and the heart.
• CT scans take X-rays from many angles and create detailed images of the inside of your body.
• MR angiography uses magnets, radio waves and a computer to assess the blood vessels.

How is Shone’s complex treated?

Most babies who have Shone’s complex require surgery soon after birth. The surgery type and technique depend on which of the eight possible defects the baby has.

The surgery type also depends on how severe the baby’s symptoms are. Often, babies need multiple surgeries to treat all the heart defects of Shone’s complex.

How can I take care of myself if I have Shone’s complex?

Adults who have Shone’s complex need to visit a cardiologist (heart doctor) at least once a year. During this visit, your cardiologist uses a few tests to check your heart’s function:

• Echocardiograms.
• Exercise tests.
• CT scans.
• Cardiac MRI stress tests.

How can I prevent Shone’s complex?

There is no guaranteed way to prevent having a child with Shone’s complex. You can increase the chances that your baby will be healthy by:

• Avoiding harmful substances, such as nicotine, illegal drugs and alcohol, during pregnancy.
• Discussing the benefits and risks of all medications with your healthcare provider.
• Getting a rubella vaccine, as rubella infection can affect heart development.
• Managing chronic conditions, such as diabetes.
• Taking prenatal vitamins and any other supplements as directed.

What is the outlook for people with Shone’s complex?

Babies who receive treatment for Shone’s complex often grow into adults who experience a high quality of life. In general, babies who have surgery tend to have good outcomes. A baby’s chances of a positive outlook also depend on how complex or severe the congenital heart defects are.

What else should I ask my doctor?

You may also want to ask your healthcare provider:

• What is the most likely cause of a congenital heart defect?
• What will happen during my baby’s surgery?
• What follow-up care does my baby need after surgery?
• How does Shone’s complex affect my child’s quality of life?
• What are the chances that I will have another child with Shone’s complex?

A note from Cleveland Clinic

Shone’s complex is a congenital heart disease. It involves multiple heart defects that affect blood flow. Babies born with the condition may show signs of congestive heart failure. Most babies need surgery shortly after birth to treat Shone’s complex. Babies who have surgery usually grow up to live healthy and full lives. Adults who were born with Shone’s complex need regular follow-up with a cardiologist for the rest of their life.