Subvalvular aortic stenosis (AS) is a rare congenital heart defect in which the left ventricle is narrowed below the level of the aortic valve resulting in obstruction to blood flow out of the heart. The condition is also known as subaortic stenosis.

Normally, blood passes through the aortic valve en route to the aorta. In subvalvular aortic stenosis, a narrowed area below the aortic valve limits blood flow, increasing the workload for the left ventricle. This can cause the left ventricle to enlarge and fail. If your condition causes moderate to severe symptoms or related valve disease, you may need heart valve surgery to treat the condition.

Subvalvular aortic stenosis causes

Subvalvular aortic stenosis is a congenital heart defect that occurs during fetal development. The precise cause is unknown, but genetics may play a role. Subaortic stenosis has also been associated with several congenital syndromes.

Symptoms of subvalvular aortic stenosis

Children who have subvalvular aortic stenosis may not have symptoms, but the condition can worsen with age. In more severe cases in babies, symptoms include:

  • Rapid breathing
  • Rapid heart rate
  • Inability to eat
  • Heart failure

In more severe cases in older children, symptoms include:

  • Fatigue
  • Fainting
  • Chest pain

Diagnosis of subvalvular aortic stenosis

At Ohio State, we ensure that each patient receives individualized care for their congenital heart defect. By creating a care team to diagnose and treat each case, we can better understand what steps will help patients get back to living their lives.

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Subaortic stenosis treatment


Currently, there are no medications used to treat subvalvular aortic stenosis. In cases where patients develop heart failure, medications such as beta-blockers or angiotensin receptor blockers (ACE-inhibitors) may be used, but these should be used cautiously under the direct supervision of a cardiologist.


For patients with moderate or severe obstruction that has a significant impact on the heart function, surgery is required to relieve the obstruction. This most often involves removal of the excess muscle or tissue. In severe cases that also affect the function of the aortic valve, valve repair or replacement may be necessary.

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