Understanding aortic stenosis
As it is known, a heart murmur is a sound produced when blood flows across one of the heart valves, and is loud enough to be heard with a stethoscope.
While a heart murmur could be inconsequential or “innocent”, especially in young people, it may reflect in older adults a problem with cardiac valves performance.
These problems could be related to tight or leaky valves generating the murmur(s).
We'll discuss tight or “stenotic” valves in this column; next week we'll look at leaky valves.
The heart has two right and two left valves. Tight right heart valves are quite rare, so is mitral valve stenosis (a left valve tightening), especially in the Western hemisphere where rheumatic fever is, nowadays, very unusual to occur. With that, we would spend the rest of this review focusing on the most commonly encountered valve stenosis: aortic stenosis.
What is aortic stenosis?
Aortic stenosis occurs when the aortic valve, or the valve between the left heart (or left “ventricle”) and the main vessel that supplies blood to the body (called “aorta”), doesn't fully open. When this happens, two sets of consequences develop:
• The body and brain do not get sufficient blood, resulting in the below-described symptoms
• The heart has to work much harder than usual to pump out blood against a tight valve leading, in the long run, to cardiac problems, mainly enlarged and weakened heart muscle.
What are the symptoms of aortic stenosis?
Early on, most people have no symptoms.
They usually find out they have AS after their doctor hears a heart murmur on a routine exam. As the valve gets gradually tighter, people can start experiencing:
• Shortness of breath
• Dizziness or fainting
• Chest pain
These symptoms usually happen with physical activity and not at rest.
What are the causes of aortic valve stenosis?
Most people who have aortic valve stenosis are born with a normal valve that has three gates (or “leaflets”) but develop aortic stenosis late in life. Ageing and calcium build-up can cause the leaflets of the valve to thicken and harden, preventing them from opening properly.
Typically, stenosis develops slowly over many years.
On the other hand, most young people who have aortic valve stenosis developed it from a congenital heart defect called “bicuspid aortic valve”; here the valve has two leaflets and after a few decades of life, those leaflets get overused and stiff, leading to early stenosis.
Some people may develop aortic stenosis after having rheumatic fever, which again is quite rare in developed countries.
What are the tests needed to diagnose aortic stenosis?
An echocardiogram (or “echo”) is usually done to check for aortic stenosis and see how severe it is. This test uses sound waves to create a picture of your heart as it beats. Usually, aortic stenosis is graded as mild, moderate or severe.
To get more information about AS, but also about the rest of your heart condition including the coronary vessels, another test called cardiac catheterisation (or cardiac “cath”) can be done. During this procedure, a thin, flexible tube is advanced from the arm or leg, up to the heart cavities, where pressure measurements and pictures of the different heart parts are taken, including coronary vessels.
How is aortic stenosis treated?
Treatment depends on symptoms and how severe aortic stenosis is. If AS is mild or moderate with little or no symptoms, you might not need any treatment but it will be followed by serial “echos” every six to 12 months. When aortic stenosis gets to be severe or you have symptoms, you will likely need a treatment.
Treatment can include:
• Surgery to replace the aortic valve: the narrowed valve is removed and replaced with a new and normally functioning valve. This new valve can be made from metal or from tissue derived from a pig, cow or horse. While a mechanical valve can last a lifetime but requires the permanent use of a blood thinner (warfarin), tissue valves do not need such a treatment but they typically last about 15 years. In some cases, a new valve could come from another person or from using one's own pulmonary valve, a right side heart valve of “lesser importance”.
• TAVR: if a chest surgery is deemed high risk or the patient is quite old or does not want an open heart surgery, a new procedure is now available where a prosthetic valve can be deployed through a small groin or chest wall incision.
• Valvuloplasty: here, and again through a groin access and via the use of special catheters, a balloon is inflated in the narrowed aortic valve to try to open it. It is usually used in children and young adults. It is rarely done in older adults, where it is of limited help, except as a palliative approach.
Can I exercise if I have aortic stenosis?
If your aortic stenosis is mild or moderate with little or no symptoms, you can likely exercise with no major limitations. But if your aortic stenosis or symptoms are more serious, your doctor might recommend that you limit your physical activity.
Read next week's column for more on diseases of the heart valves.
• Joe Yammine is a cardiologist at Bermuda Hospitals Board. He trained at the State University of New York, Brown University and Brigham and Women's Hospital. He holds five American Board certifications. He was in academic practice between 2007 and 2014, when he joined BHB. During his career in the US, he was awarded multiple teaching and patients' care recognition awards. The information herein is not intended as medical advice nor as a substitute for professional medical opinion. Always seek the advice of your physician. You should never delay seeking medical advice, disregard medical advice or discontinue treatment because of any information in this article.
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