Aortic Stenosis

What is aortic stenosis?

Aortic Stenosis, otherwise known as Aortic Valve Stenosis or sometimes just “AS”, is the narrowing of the heart’s aortic valve. The aortic valve controls the blood flow as it moves from the heart’s main pumping chamber (the left ventricle) to the aorta (the body’s main artery). The aortic valve opens to allow blood to move forward from the main pumping chamber into the aorta as the heart contracts, and then the aortic valve closes while the heart is relaxing. When aortic stenosis occurs, the aortic valve cannot open fully. Blood flow from the heart into the aorta is reduced or blocked, preventing blood from flowing on to the rest of the body properly.

This places extra stress on the heart, as it works harder and harder to pump blood through the narrowed aortic valve to the rest of your body. The heart can only keep this up for so long and in time this can reduce the amount of blood your heart can effectively pump. Eventually this can damage the heart muscle and lead to heart failure.

What are the symptoms of aortic stenosis?

You may or may not experience symptoms for aortic stenosis, as the severity of this condition ranges between mild and severe. Symptoms may only occur when the condition has reached a more severe level, it can take years for it to become apparent that something could be wrong.

The most common symptoms can include:

• Shortness of breath – this is the most common symptom and occurs in most people with moderate and severe aortic stenosis. This begins at first as just shortness of breath with exercise, but in severe aortic stenosis this occurs at rest and when lying flat
• Pain in your chest (angina)
• Tightness in your chest when exercising
• Feeling faint or dizzy when active, and even blacking out or collapsing
• Fatigue
• Irregular heartbeat- a rapid or fluttering feeling in your chest

As well as this, your doctor or cardiologist may discover certain features of the disease on examination, particularly a heart murmur, which is when your heart makes abnormal sounds when listened to with a stethoscope.

What causes aortic stenosis?

Aortic stenosis can be caused by age and by calcium building up on the aortic valve. Over time, valves can accumulate calcium deposits. These deposits are common and for some, may never cause any heart problems. For some however, it can cause hardening around the valves, which in turn can cause the valve to narrow. In aortic stenosis this would restrict the aortic valves’ ability to open and close properly, which is how your blood is pumped from the heart through the aortic valve, to the aorta and then to the rest of your body. Symptoms for aortic stenosis caused by calcium deposits may not present themselves until a patient is 70 or older.

Aortic stenosis can also be caused by a congenital heart defect, meaning some are born with a defect in their aortic valve. A fully developed aortic valve will have three flaps of tissue known as the valve leaflets. These leaflets open and close each time your heart beats to keep your blood flowing in the right direction, through the valve and around your body.

An aortic valve that has not developed properly may only have two of these leaflets, and more rarely only one. This defect can go unnoticed into adult life as the valve may be able to function for some time with the incorrect number of leaflets. However, eventually the valve can narrow. In this case the valve will usually need to be repaired or even replaced.

Another cause for aortic stenosis can be rheumatic fever, as this can sometimes lead to the aortic valve forming scar tissue. This scar tissue can cause the aortic valve to narrow or the damage to the surface of the valve can make it more susceptible to collecting calcium deposits, eventually leading to aortic stenosis. This is a less common cause for aortic stenosis as rheumatic fever is, for the most part, rare in Australia. However, in certain populations including indigenous Australians and migrants from high-risk countries, rheumatic fever may still be a relevant cause of aortic stenosis and other heart valve diseases.

How is aortic stenosis diagnosed?

Your doctor will need to ascertain if you are experiencing any symptoms and if you have any risk factors that are linked to aortic stenosis. Common risk factors include:

• High blood pressure
• High cholesterol
• Diabetes
• Obesity
• Old age
• Congenital heart disease – a defect in the aortic valve from birth
• Kidney disease

Your doctor will also want to perform a thorough physical examination and listen carefully to your heart with a stethoscope. Next, an echocardiogram is used to confirm if you have aortic stenosis and this will also help to determine treatment.

How is aortic stenosis treated?

Once diagnosed, if your symptoms continue to be mild and the aortic stenosis isn’t severe, regular check-ups are advisable to monitor for any developments.

Depending on the severity of the condition your doctor may prescribe medications, recommend valve repair or valve replacement as treatments for aortic stenosis.

While medications can help to some extent with some of the symptoms, they cannot open a valve once it has become too narrow. In these cases, aortic valve replacement procedures may be required.

In terms of valve replacement, there are two main options. The first is conventional open heart surgery with Surgical Aortic Valve Replacement (SAVR). Although SAVR was previously the most common way of doing aortic valve replacement, since about 2015 there has been a progressive switch to a revolutionary, minimally invasive procedure that is done via small catheters called Trans-catheter Aortic Valve Replacement (TAVR). TAVR has the major advantage that it doesn’t require open heart surgery, and rather than spending 5-7 days in hospital that typically happens after SAVR, most TAVR patients go home the next day. While increasingly more patients are having TAVR, if you need to have aortic valve replacement for aortic stenosis, the decision to perform SAVR or TAVR is usually made by a team of doctors and healthcare professionals to make sure you get the option that is best for you.

Early intervention to improve survival for people with aortic stenosis

Here at the Institute, we are researching novel ways to diagnose and predict risk in patients with aortic stenosis using artificial intelligence applied to medical imaging. This work is being led by cardiologist A/Prof Mayooran Namasivayam, Head of the Heart Valve Disease and Artificial Intelligence Laboratory, who is also Associate Director of Echocardiography at St Vincent’s Hospital Sydney. Leading a team spanning Institute, St Vincent’s Hospital, and UNSW Sydney, A/Prof Namasivayam and his team hope to be able to better identify patients with aortic stenosis earlier in their disease course and also identify which patients are most likely to benefit from early intervention.

How can aortic stenosis be prevented?

In many cases, aortic stenosis is mainly driven by age, and it might be hard to have a major impact on reducing your chances of developing this disease. However, certain lifestyle changes may help to prevent aortic stenosis:

• Maintaining a healthy weight
• Eating a healthy diet

Ask your doctor for a heart health check which looks at the key risk signs. Download our Heart Health Check Guide to take with you to your next doctor's appointment.