What Is Aortic Stenosis?

Human Heart Anatomy
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Aortic stenosis is a type of heart valve disease caused by partial obstruction of the aortic valve. With aortic stenosis, it becomes relatively difficult for the heart to pump blood out to the body’s organs. Aortic stenosis can significantly impact cardiac function, producing significant symptoms, and may ultimately lead to death unless it is treated.

What Is Aortic Stenosis?

The aortic valve guards the opening between the left ventricle and the aorta.

As the left ventricle begins to contract, the aortic valve opens in order to allow the blood in the left ventricle to eject out of the heart, into the aorta, and out to the rest of the body. As soon as the left ventricle is finished contracting, the aortic valve closes to keep blood from washing back into the ventricle.

When a person develops aortic stenosis, their aortic valve fails to open up completely when the ventricle begins to beat, so the heart has to work much harder in order to eject blood against the partially closed valve. This extra stress on the heart can lead to heart failure and other significant cardiac problems.

What Are the Causes of Aortic Stenosis?

There are several disorders that can produce aortic stenosis, including:

  • Degeneration and calcification: In people over 70 years of age, the most common cause of aortic stenosis is "wear and tear." With the passage of time, the aortic valve can begin to degenerate, causing calcium deposits to accumulate on the valve. These calcium deposits infringe on the valvular opening, causing aortic stenosis.
  • Bicuspid aortic valve: The most common cause of aortic stenosis in younger people is a congenital bicuspid valve. In this condition a person is born with an aortic valve consisting of two "cusps" (i.e., flaps) instead of the normal three. Bicuspid aortic valves are especially prone to the formation of calcium deposits—and thus, to aortic stenosis. People with bicuspid aortic stenosis usually develop symptoms in their 40s and 50s.
  • Rheumatic heart disease: Not that many decades ago, rheumatic heart disease was the leading cause of aortic stenosis in the developed world. But with the development of antibiotics effective against streptococcus bacteria, and the subsequent reduction in cases of rheumatic fever, rheumatic heart disease has become relatively uncommon.
  • Congenital aortic stenosis: Several congenital problems in addition to a bicuspid valve can produce aortic stenosis. These include various malformations of the aortic valve itself, as well abnormal formations of obstructing cardiac muscle above or below the actual aortic valve. These more unusual forms of congenital aortic stenosis are usually seen in children.

What Problems Are Caused by Aortic Stenosis?

With aortic stenosis, the outflow of blood from the left ventricle becomes partially obstructed, so it becomes more difficult for the heart to eject blood. This extra cardiac work places significant stress on the left ventricular muscle, which causes it to thicken, or "hypertrophy."

This left ventricular hypertrophy can lead to diastolic dysfunction and diastolic heart failure, in which the thickened muscle “stiffens” the ventricle, and makes it more difficult for the ventricles to fill with blood in between heart beats.

Symptoms eventually result. These symptoms commonly include dyspnea (shortness of breath), easy fatigue and reduced exercise tolerance, and an increased risk of developing atrial fibrillation.

As the aortic stenosis worsens, angina can occur, as well as episodes of lightheadedness and even syncope (loss of consciousness) during exertion.

With very severe aortic stenosis, the muscle of the left ventricle can convert from being too thick and stiff to becoming weak and dilated—a condition called dilated cardiomyopathy. Once aortic stenosis produces dilated cardiomyopathy, heart failure may be irreversible.

Sudden death is common with severe aortic stenosis.

How Is Aortic Stenosis Diagnosed?

Because untreated aortic stenosis is often fatal, making the correct diagnosis is critical. Fortunately, diagnosing aortic stenosis today is usually not difficult.

Doctors become suspicious of aortic stenosis when their patients complain of "typical" symptoms (shortness of breath, reduced exercise tolerance, chest pain, dizziness, or syncope). More preferably, a doctor will become suspicious of aortic stenosis before symptoms develop when they hear the heart murmur that is typical of this condition. The diagnosis can be easily confirmed or ruled out by an echocardiogram.

Treating Aortic Stenosis

The treatment of aortic stenosis is surgical valve replacement. Drug therapy can improve symptoms for a while, but ultimately is ineffective because the problem is the mechanical obstruction of the aortic valve. So when a person has aortic stenosis, the question is usually not whether to do surgery, but when.

As a general rule, replacement of the aortic valve should be done soon after a person’s aortic stenosis begins producing symptoms—shortness of breath, chest pain, dizziness, or syncope. Once any of these symptoms results from aortic stenosis, the average life expectancy without valve replacement is 2 or 3 years. Timely valve replacement greatly improves this prognosis. Once a person is diagnosed with aortic stenosis, it is important that they be closely monitored for any sign of developing those symptoms.

Because surgery suddenly relieves the severe obstruction to cardiac blood flow, in most cases cardiac function improves fairly dramatically after valve replacement. So even people who are quite elderly and very symptomatic may do quite well after aortic stenosis surgery.

The prosthetic valves used to replace a diseased aortic valve can either consist entirely of man-made materials (mechanical valves), or they can be made from the heart valve of an animal, generally a pig (bioprosthetic valve). Deciding which type of artificial valve to use depends on a person’s age, and whether they can take a blood thinner like Coumadin.

All artificial heart valves have an increased propensity to form blood clots. However, blood clotting is less of a problem with bioprosthetic valves than it is with mechanical valves, so people with the former may not have to take chronic Coumadin therapy; those with mechanical valves do. On the other hand, mechanical valves generally seem to last longer than bioprosthetic valves.

So for people with aortic stenosis under the age of 65 who can take Coumadin, mechanical heart valves are usually recommended. In people over 65, or who cannot take Coumadin, a bioprosthetic valve is generally recommended.

Less Invasive Approaches to Treating Aortic Stenosis

Treatments that are less invasive than surgical valve replacement are being developed.

In aortic valvulotomy, a balloon catheter is passed across the aortic valve and the balloon is inflated in order to fracture some of the calcium deposits on the valve. This often allows the valve to open more fully, and relieves some of the aortic stenosis. Unfortunately, valvulotomy does not yield uniformly helpful results, and it can cause serious complications.

Another catheter-based procedure for treating aortic stenosis is trans-catheter aortic valve implantation (TAVI). Several TAVI devices are under active development, and a few have been approved for clinical use in patients who are at very high risk for typical valve replacement surgery. However, complications with TAVI at this point are a limiting factor. Both TAVI and valvulotomy at this time are reserved for people with critical aortic stenosis who are unlikely to survive surgical valve replacement.

A Word From Verywell

Aortic stenosis is a type of valvular heart disease that obstructs the flow of blood out of the heart. Advanced aortic stenosis causes significant symptoms, and greatly reduces life expectancy. Fortunately, with well-timed surgical treatment, people with aortic stenosis can do quite well.

Sources:

Eveborn GW, Schirmer H, Heggelund G, et al. The Evolving Epidemiology of Valvular Aortic Stenosis. the Tromsø study. Heart 2013; 99:396.

Leon MB, Smith CR, Mack M, et al. Transcatheter Aortic-valve Implantation for Aortic sSenosis in Patients Who Cannot Undergo Surgery. N Engl J Med 2010; 363:1597.

Nishimura RA, Otto CM, Bonow RO, et al. 2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease: a Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2014; 63:e57.

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