Aortic Stenosis - Treatment Strategies

Dateline: 06/01/97

A few weeks back, we saw how mitral stenosis (narrowing of the mitral valve) could be treated surgically. In the next few weeks, the topic of discussion will be treatment of the narrow aortic valve - or Aortic Stenosis. Here, in a sequence of articles, I will explain what the treatment options for aortic stenosis are, and describe in greater detail the operations of valve repair, replacement and the Homograft and Ross operations for this disease.

What is Aortic Stenosis ?

The aortic valve, as we have discussed before, is located between the left ventricle and the aorta. It may be narrowed by a variety of disease processes, until it's orifice becomes too small to allow blood to flow freely out of the left ventricle. This condition is called aortic stenosis.

What causes Aortic Stenosis ?

While Mitral Stenosis is most often caused by rheumatic fever, Aortic Stenosis has a variety of causes. It may be a birth defect, due to a maldevelopment of the valve during fetal life. It may also be a sequel of an attack of rheumatic fever. In elderly people, calcium may get deposited on to the leaflets causing the valve to become stiff and narrow. So, aortic stenosis may be a disease of childhood, young adults or even the elderly.

When should Aortic Stenosis be treated ?

The presence of symptoms of aortic stenosis - angina (chest pain), syncope (sudden loss of consciousness, or "blackouts") and breathlessness on exercise due to heart failure - are all indications for early treatment in aortic stenosis. On evaluation by cardiac catheterization or echocardiography, if the pressure gradient across the narrow valve exceeds 40 mm. of Hg (normally there should be no gradient), the stenosis is severe enough to require intervention. Additionally, if there is worsening of the ill-effects of aortic stenosis, like progressive hypertrophy (thickening of the wall) of the left ventricle, heart failure or increasing severity of stenosis, surgery may be required. Finally, in calcific aortic stenosis in the elderly, repeated embolic episodes may be caused by specks of calcium breaking off from the valve and entering the blood stream and reaching the brain, blocking blood supply to a part of the brain. This may be sufficient reason to intervene and treat aortic stenosis by surgical means.

What are the options available ?

The narrowed aortic valve can be opened up without surgery, in some cases, by trans-catheter methods. Alternatively, an operation can relieve the obstruction. In earlier days, before open heart surgery was possible, many innovative methods were used to open up the stenosed aortic valve while the heart was beating. These operations, collectively called closed aortic valvotomy, are still used in certain circumstances. Today, the procedure most often employed is open-heart surgery. At surgery, the valve is assessed, and if possible, a valve repair is performed. Alternatively, the valve may need to be replaced. The choices available are:

• Mechanical artificial prosthesis
• Homograft valve (taken from human cadavers)
• Autograft Pulmonary valve (using the patient's own pulmonary valve in the aortic position)

In some cases of severe aortic stenosis, it may be necessary to widen the very connection of the aorta with the left ventricle, a procedure called a Aortic Root Enlargement.

Over the next few weeks, I will describe each of these options in detail, with special attention to their advantages and drawbacks, and when each of these procedures is best indicated.