The Aging Heart: Understanding Aortic Stenosis

Disclaimer: This article is for informational purposes only and is not intended to diagnose any conditions. LifeDNA does not provide diagnostic services for any conditions mentioned in this or any other article.

Overview

As we age, certain changes inside the heart can quietly affect how well it pumps blood. These changes often go unnoticed until they begin causing symptoms or are discovered during routine checkups. In some cases, they result from health issues that develop in middle age or from rare conditions present at birth.

One common issue that can arise from these hidden changes is the narrowing of one of the heart’s main valves. This narrowing puts extra strain on the heart, making it harder to pump blood to the rest of the body. Over time, this may lead to symptoms like shortness of breath, fatigue, chest pain, or more serious complications. Understanding what causes Aortic Stenosis and how it progresses is key to managing it effectively.

What Is Aortic Stenosis?

Aortic stenosis (AS) is when the aortic valve, one of the main valves in your heart, becomes narrowed or stiff. Normally, this valve opens and closes with every heartbeat, letting blood flow from the left side of the heart (left ventricle) into the aorta, which carries blood to the rest of the body.

In AS, the valve doesn’t open fully. This makes it harder for the heart to pump blood through it. Over time, the heart has to work harder to push blood out, which can lead to heart muscle thickening, fatigue, shortness of breath, and eventually heart failure if not treated. AS can happen for different reasons, including birth defects or age-related wear and tear. That’s why physicians say it can be either congenital (from birth) or acquired (developed later in life).

Types of Aortic Stenosis

Congenital Aortic Stenosis: This type is something people are born with. The most common cause is called a bicuspid aortic valve, where the valve has only two flaps (cusps) instead of three. Because of this unusual shape, the valve can become stiff and narrow earlier in life. There is an even rarer condition having a valve with only one flap, and this usually causes even more serious problems and symptoms at a younger age.

Acquired Aortic Stenosis: This type usually happens as people get older. It occurs when a normal valve with three flaps slowly becomes stiff and narrow because of calcium building up on it. This process is often caused by aging and lifestyle factors like high blood pressure, high cholesterol, and smoking.

Symptoms of Aortic Stenosis

Aortic stenosis (AS) may often go unnoticed for many years because early on, the narrowing valve may not cause any obvious problems. However, as the valve becomes more restricted, symptoms typically start to appear, especially during physical activity. Common signs to watch for include:

Shortness of breath during activity: The narrowed valve limits the amount of oxygen-rich blood reaching the body, making it harder to breathe when moving or exercising.
Chest pain or pressure (angina): The heart must work harder to push blood through the tight valve, which can cause discomfort or pain in the chest.
Fatigue and low energy: With less blood being pumped out, the body receives less oxygen, leading to feelings of tiredness and weakness.
Dizziness or fainting (syncope): Reduced blood flow to the brain during exertion can cause lightheadedness or fainting spells.
Heart palpitations or irregular heartbeat: As the heart tries to compensate for the restricted blood flow, abnormal heart rhythms may develop.

These symptoms often signal that aortic stenosis has progressed to a moderate or severe stage. If left untreated, severe AS can become life-threatening, especially once symptoms appear. Early recognition and medical evaluation are crucial to managing the condition effectively.

What Causes Aortic Stenosis Diagnosed?

Aortic stenosis happens when the valve that controls blood flow from your heart to the rest of your body becomes narrow or stiff. This narrowing makes it harder for your heart to pump blood, which may lead to symptoms and heart problems.

There are several reasons why this valve may become damaged or narrowed over time. Understanding these causes helps explain how aortic stenosis develops and why it affects some people more than others:

Born With Valve Problems: Some people have heart valves that didn’t form normally before birth. For example, instead of having three flaps (cusps), their valve might have only two or even one. This can cause the valve to wear out faster and narrow earlier in life.
Calcium Buildup with Age: As people get older, calcium can slowly build up on the valve, making it stiff and less able to open fully. This is the most common cause in adults over 65.
Damage from Infections: If infections like strep throat or scarlet fever aren’t treated, the bacteria can travel to the heart valves and damage them due to a condition called rheumatic fever . The body’s immune system tries to fight the infection but ends up damaging the valve, causing it to become narrow many years later.
Other Health Conditions: Some rare diseases like Paget’s disease (which affects bones), kidney failure, and inherited conditions that cause high cholesterol can also harm the valve. Autoimmune diseases like lupus and rheumatoid arthritis may cause inflammation that damages the valve too.
Age-Related Calcification: As people age, calcium, a mineral that helps build strong bones and may build up on the aortic valve. This calcium buildup causes the valve to stiffen and lose flexibility. When the valve can’t open fully, less blood passes through, so the heart must work harder. This process is the most common cause of aortic stenosis in older adults.
Rheumatic Fever: This is a rare complication from untreated strep throat or scarlet fever infections. It causes inflammation and scarring in the heart valves, including the aortic valve. The scarring thickens the valve and prevents it from opening properly. While less common today in many countries, rheumatic fever still causes aortic stenosis in some parts of the world.
Lifestyle and Health Risks: High blood pressure, smoking, and high cholesterol can injure your heart valves and blood vessels over time, making the valve wear out faster, especially as you age.

Genetics on Aortic Stenosis

The congenital bicuspid aortic valve (BAV), a common congenital heart valve condition where the valve has two flaps instead of three, is highly genetic, with heritability estimated as high as 89%. However, this condition is not caused by just one gene but likely involves multiple genes and environmental factors.

Research has identified mutations in several important genes linked to BAV, such as NOTCH1, which is involved in valve development and calcification, and the GATA family of genes (GATA4, GATA5, GATA6), which also influence valve formation. Mouse studies show that altering these genes affects valve development and can cause BAV or related heart problems.

BAV changes the blood flow through the valve, creating abnormal stress that causes early calcium buildup and valve stiffening, which can lead to aortic stenosis (AS) and enlargement of the aorta. This calcification is an active process, similar to bone formation, involving cells in the valve turning into bone-like cells. The abnormal blood flow in BAV patients causes increased wall stress in the aorta, which differs based on the specific BAV subtype, leading to variations in how quickly calcification and valve disease develop.

Apart from BAV, acquired AS occurs later in life, mostly due to age-related calcium buildup on a normal valve and other cardiovascular risk factors like smoking, high cholesterol, and high blood pressure. This degenerative calcification is complex and likely requires multiple risk factors to cause significant valve damage.

Simply lowering cholesterol may not be enough to stop or reverse valve damage once it has progressed, highlighting the need for more personalized and combination therapies.

How Is Aortic Stenosis Diagnosed?

Diagnosing aortic stenosis usually starts when a doctor hears a heart murmur during a routine check-up. A murmur is an unusual sound made by blood flowing through a narrowed valve.

To confirm the diagnosis and understand how severe the stenosis is, doctors use several tests, including:

Echocardiogram: This is the most important test. It uses sound waves to create moving images of the heart and valve. It shows how well the valve is opening and how much blood is flowing through it.
Electrocardiogram (ECG or EKG): This test records the electrical activity of the heart and helps check for any irregular heartbeats or signs of heart strain.
Chest X-ray: This can show if the heart is enlarged or if there is fluid buildup in the lungs due to heart problems.
Cardiac catheterization: In some cases, a thin tube is inserted into a blood vessel and guided to the heart to measure blood pressure inside the heart chambers and valves. This gives detailed information about valve function.
CT scan or MRI: These imaging tests can help when more detailed pictures of the heart and valve are needed.

Early diagnosis is important because it helps doctors monitor the condition and decide when treatment may be needed to prevent serious complications.

How is Aortic Stenosis Treated?

Treatment depends on how serious the narrowing is and whether you have symptoms.

Monitoring Without Symptoms: If your aortic stenosis isn’t causing any symptoms, your doctor may just want to keep an eye on it. This means regular checkups and tests to watch for any changes.
Medications: For mild cases or to help with symptoms, doctors might prescribe medicines. These can include blood thinners to prevent clots, diuretics to reduce fluid buildup, or medicines for high blood pressure or irregular heartbeats. However, medications do not fix the valve or stop the narrowing from getting worse, they just help manage symptoms.
Valve Repair: If the valve damage is limited, your doctor might suggest repairing it. This can be done through surgery where the doctor opens your chest to fix the valve directly. Another option is balloon valvuloplasty, where a small balloon is inserted through a blood vessel and inflated to widen the valve opening. This may improve symptoms but is usually a temporary solution until a valve replacement is performed.