Aortic Valve Stenosis

What are the  causes of aortic valve stenosis or narrowing?

Acquired (Degenerative) Aortic Stenosis: Most common cause of aortic valve stenosis in adults. This problem happens as a part of the aging process in some individuals. Calcium starts to deposit on the valve leaflets. As a rslt the valve is hardened and will not open properly resulting in aortic stenosis. Sometimes the valve becomes very hard as a stone.

Congenital Aortic Stenosis: The aortic valve is normally formed of three leaflets. In this condition, you are born with an aortic that has 2 leaflets only (Bicuspid Aortic Valve). The abnormal structure of the aortic valve induces abnormal and turbulent flow, which traumatizes the leaflets and leads to fibrosis and calcification. Calcifications progress to produce clinically evident aortic stenosis by the age of 50 or 60.

Rheumatic Aortic Stenosis: This is caused by rheumatic fever and represents the least common form of aortic stenosis in the adult population. Rheumatic aortic valve stenosis is rarely an isolated disease, and usually occurs in conjunction with mitral valve stenosis.

What happens as a result of this Aortic Stenosis?

Stenotic aortic valves cause stress on the left ventricle, which is forced to work harder to push blood through the narrowed opening. As a result, the ventricular heart muscle will thicken, or hypertrophy, until it actually outgrows its blood supply. Finally, the left ventricle will no longer be able to force enough blood past the valve. In this case, the heart itself may begin to fail, and patients usually start to develop symptoms. Severe left ventricular hypertrophy causes significant associated changes in coronary blood flow. Abnormalities in coronary blood flow will lead to chest pain or angina.

Symptoms and signs

1. No symptoms for a prolonged period of time.
2. Syncope or blackouts.
3. Chest pain or Angina: Occurs in about two thirds of patients with severe aortic stenosis. Approximately one half of these patients have underlying coronary artery disease. Angina in patients who do not have coronary artery disease is due to increased need of the thickened ventricle to blood.
4. Easy fatiguability and exercise intolerance
5. Shortness of breath and finally heart failure
6. Infective endocarditis can occur in younger patients with aortic stenosis; it is less common in elderly patients with severely calcified valves.
7. Irregular heartbeats
8. On rare occasions, a stenotic valve can be a source of calcium emboli to any organ. This might happen in the brain causing stroke.
9. On examination, your doctor will listen to a heart murmur over your chest.

Diagnostic tests

1. Electrocardiogram: can detect abnormal patterns of the thickened left ventricle

2. Chest X-Ray: Normal in most patients with aortic stenosis. Can show the increased thickness of the left ventricle

3. Echocardiography:  

• Most commonly used noninvasive diagnostic method for assessing the significance of aortic stenosis.
• Identifies the cause and severity of aortic stenosis.
• Evaluates heart chamber size and function.

4. Cardiac Catheterization: Coronary angiography  is indicated in patients undergoing aortic valve replacement who are suspected to have coronary artery disease.

Grading The Degree Of Aortic Stenosis: The normal area of the adult aortic valve measures on average 3.0 to 4.0 cm². Currently accepted criteria for the grading of aortic stenosis are:

1. Mild aortic stenosis: area >1.5 cm²
2. Moderate aortic stenosis: area 1 to 1.5 cm²
3. Severe aortic stenosis: area <1.0 cm²

Treatment decisions are largely based on the absence or presence of the symptoms, rather than on the size of the aortic valve area.

Treatment

Antibiotic prophylaxis against infective enodocarditis will be advised before you have any surgical or dental procedure.

If you develop Heart failure, you will be prescribed a diuretic.

Percutaneous aortic balloon valvuloplasty: in which your valve can be widened using cardiac catheterization. This is usually useful in patients in whom surgery can be life threatening.

Surgical Treatment in the form of aortic valve replacement:

There are three main classifications of artificial valves:

Bioprosthetic valves are from animals (for example, the Hancock and Carpentier Edwards valves) specially treated with chemicals to avoid rejection.

Mechanical valves are made of metal, carbon and/or synthetics (for example, the St. Jude valve). Anticoagulation is required to prevent blood clots.

Biologic valves are human heart valves obtained from donors after death and frozen for later use (homograft). In the Ross procedure, the patient’s own pulmonary valve replaces the diseased aortic valve and in turn is replaced by a homograft valve.