Shone's Complex

Also known as: Shone syndrome, Shone's disease, Shone's anomaly.

What is Shone's complex?

Shone’s syndrome is a rare condition, even among congenital heart defects. Of all the cases of congenital heart diseases, it makes up only 0.6%. For those who do get the disease, about 24% to 27% ultimately do not survive the condition. These two factors mean there are very few adults with Shone’s syndrome.

Shone’s syndrome is characterized by eight specific heart lesions. These include:

• Cor triatriatum. This occurs when the pulmonary veins from the lungs do not connect normally to the left atrium of the heart. This obstructs blood flow.
• Supramitral ring. The mitral valve connects and allows blood flow from the left atrium to the left ventricle of the heart. This ring narrows the opening of the valve and obstructs blood flow.
• Parachute mitral valve. This occurs when the strands that allow the mitral valve to open and close are comprised of a single, solid muscle, like a parachute. This often does not cause problems, but it may further narrow the opening of the mitral valve and obstruct blood flow.
• Subaortic stenosis. This is a thickening that forms under the aortic valve. It obstructs blood flow from the left ventricle to the aorta.
• Bicuspid aortic valve and small aortic valve annulus. These two defects frequently occur together with Shone’s syndrome. A typical aortic valve is tricuspid (three flaps), so a bicuspid valve further restricts blood flow.
• Coarctation of the aorta. With this defect, a blood vessel found in fetuses known as the ductus arteriosus closes improperly and cuts off blood flow through the aorta.
• Hypoplastic (stiff) left ventricle. This defect causes the left ventricles of the heart to be stiff, which can cause fluid to back up into the lungs or arrhythmia as the heart beats.
• Small aortic arch. The aorta can also be stiff and inflexible with Shone’s syndrome, which leads to an arch developing in it.

What causes Shone’s syndrome? 

Shone’s syndrome develops very early on in the fetus and occurs in both sexes, and all races, or ethnic groups. The cause is unknown.

What are the symptoms of Shone's syndrome? 

Symptoms of congestive heart failure (which can occur in the first week of life) include fatigue, rapid breathing and wheezing, faster than normal heart rate, poor oral intake, poor weight gain, fluid retention (edema) in the legs, pallor (anemia), and frequent pneumonias.

Health care providers can use several imaging tests to diagnose Shone’s syndrome. Sometimes, these occur before the baby is born. These tests include:

• Transthoracic echocardiograms: these are ultrasounds to evaluate the heart and chest wall.
• CT scans: these are X-rays to get a detailed look inside the body.
• MR angiography: this imaging test assesses the blood vessels

What are Shone’s syndrome care options?

Depending on when the diagnosis is made, (sometimes the diagnosis is made when the baby is still in the mother's uterus), early delivery, medications and a number of surgeries or catheter-based techniques are required to treat the individual problems related to Shone’s syndrome.

Several procedures are needed to fix all the problems. Some of the procedures that may be required to repair the defects related to Shone’s syndrome include:

• Surgical treatment, such as excision with end-to-end anastomosis or subclavian flap angioplasty, to repair coarctation of the aorta.
• A surgery known as septal myectomy to repair subaortic stenosis.
• Corrective surgery for mitral stenosis.
• Other procedures and follow-up care as needed.

Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: February 04, 2025 05:33 PM