Aortic valve stenosis is one of the most common types of valvular heart diseases. Characterised by the narrowing of the aortic valve opening, the condition restricts blood flow from the left ventricle to the aorta, resulting in reduced supply of oxygenated blood to the brain and other major organs.
Aortic valve stenosis can be either mild or severe. When it is mild, it is usually asymptomatic because the heart’s pumping efficiency is not severely affected. In many cases, the condition is diagnosed when a heart murmur is detected during a routine physical exam or diagnostic tests are performed for another unrelated condition.
If the condition progresses and is left untreated, its symptoms will include reduced physical performance, arrhythmia, shortness of breath, and eventually, heart failure. Depending on its severity, an open-heart surgery may be necessary to repair or replace the aortic valve.
Aortic stenosis affects about 2% of people over 65 years of age and is more common in men than women.
Aortic valve stenosis can be congenital (present from birth) but it usually develops later in life due to calcium build-up. Calcium is a mineral found in the blood. When blood flows through the aortic valve, small amounts of calcium may be left behind and accumulate over time. Patients who have congenitally abnormal aortic valve are more prone to developing aortic valve calcification than those who do not. Abnormal aortic valve means that instead of having three cusps, the aortic valve has one (unicuspid), two (bicuspid) or four (quadricuspid) cusps. This condition requires close monitoring as it can lead to serious complications, such as heart failure.
Aortic valve stenosis can also develop due to rheumatic fever, which can cause the formation of scar tissue that can prevent the aortic valve from opening fully.
Aortic valve stenosis does not always produce noticeable symptoms unless the narrowing of the valve is severe, in which case the following symptoms develop:
Chest pain that may radiate to the arm, jaw, and neck
Fainting, dizziness or weakness with exertion
Shortness of breath
Fatigue or becoming easily tired
Many patients with aortic valve stenosis are diagnosed through a routine physical exam wherein their heartbeat is checked using a stethoscope. If an abnormal sound is detected, such as a heart murmur, the following tests are usually carried out to determine what causes it:
Exercise tests - Determines how the heart respond to stress.
Echocardiogram - A standard test performed when a heart problem is suspected. Using high-pitched sound waves, this test creates an image of the heart, which allows doctors to easily identify any abnormalities. The procedure can also be performed by inserting a tube with a transducer (transesophageal echocardiogram) down the throat and guiding it to the oesophagus.
Electrocardiogram - A diagnostic test that helps determine if the left ventricle is enlarged or thickened, which is a possible indicator of aortic valve stenosis.
Chest x-ray - This test is also useful in gathering important details needed to make a definitive diagnosis. It reveals the size and shape of the heart, whether or not the left ventricle has enlarged, if there's calcium deposit in the aortic valve, and if fluid and blood are backing up in the lungs.
Computerised tomography (CT) and magnetic resonance imaging (MRI) scans
Treatment of aortic valve stenosis depends on many factors, including the patient’s age, the severity of the condition, and whether or not it is causing symptoms.
In mild and moderate cases, watchful waiting and medications are often combined to manage the condition. Drugs that lower blood pressure and control arrhythmia may be prescribed to provide symptoms relief. Patients are also monitored and are required to undergo tests every three to five years to ensure that the condition is not progressing. During their follow-up visits, their doctor will decide whether or not they will require additional treatment.
Severe aortic valve stenosis is often treated with surgical procedures, which can be performed immediately after diagnosis if there are signs of impending heart failure. Stenotic aortic valves can be replaced with either a tissue or mechanical valve; each has its own pros and cons. Mechanical valves are very durable and do not have to be replaced because they can last for up to 40 years. However, it is possible for blood clots to form near or around them, which can increase the risk of embolic stroke. Thus, patients are required to take anticoagulant medications for the rest of their lives to prevent this complication. Tissue valves, on the other hand, do not require the use of any maintenance drugs but they can eventually narrow and may need to be replaced. The average life expectancy of an aortic valve bioprostheses is ten to fifteen years. They are not usually recommended for young patients because they easily calcify and degenerate. They are primarily used in adult patients whose general health condition prevents them from taking blood thinners.
The aortic valve can be replaced through a procedure called transcatheter aortic valve replacement or TAVI, a minimally invasive method that wedges a replacement valve into the aortic valve’s place using a catheter. Because it does not require an incision in the chest, patients get to enjoy shorter recovery time and minimal risk of infection and scarring.
Balloon valvuloplasty is also one of the treatment options and is often recommended for young patients including infants and children. It is also a catheter-based procedure that involves guiding a small balloon to the aortic valve where it is inflated and deflated several times until the valve opens up. The procedure can also be a short-term measure for adult patients who do not qualify for aortic valve replacement surgery.
Nishimura. RA, Otto CM, Bownow 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 Thorac
Cardiovasc Surg. 2014;148(1):e1-e132. PMID: 24939033 www.ncbi.nlm.nih.gov/pubmed/24939033.