Aortic Valve Stenosis: Causes, Diagnosis, and Treatment

Aortic valve (AV) stenosis is a progressive narrowing of the heart's aortic valve opening, which can affect blood flow from the left ventricle (the heart's primary pumping chamber) into the aorta (the major artery that carries oxygenated blood to the body). In the US, it affects approximately 2% of people over 65. If not managed, AV stenosis may contribute to heart function challenges and impact a person's quality of life.

This article reviews the causes, diagnostic procedures, and management options for aortic valve stenosis.

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What is Aortic Valve (AV) Stenosis?

The aortic valve (AV) is one of the heart's four valves. It is the gateway between the left ventricle (the heart's main pumping chamber) and the aorta (the body's largest artery). The AV comprises 3 flaps (leaflets) that open to let blood pass through. It regulates blood flow, ensuring it moves in one direction and preventing backflow.

The thickening and narrowing of the aortic valve characterize aortic valve (AV) stenosis. AV stenosis can affect blood flow from the heart to the rest of the body. Consequently, the left ventricle may face increased resistance when blood is pumped into the aorta. This heightened workload can cause the heart's left ventricle muscle to thicken over time, a condition known as hypertrophy, as the heart tries to adapt to the decreased blood flow.

The valve's narrowing may restrict the amount of blood pumped out of the heart with each contraction. Ultimately, the heart's ability to deliver oxygen-rich blood to the body's organs and tissues might be reduced, resulting in decreased cardiac output. As the heart works to meet the body's demands, pressure can build up in the heart's chambers.

Elevated pressure in the left atrium can cause blood to back up into the lungs, potentially leading to pulmonary congestion and symptoms such as shortness of breath and fatigue. If not addressed, AV stenosis may progress to heart failure. 

What Are the Symptoms of Aortic Valve Stenosis?

AV stenosis can present with a range of symptoms depending on the degree of stenosis. In the early stages, a person may not notice any symptoms, but symptoms tend to appear gradually as the stenosis progresses.

Common symptoms of AV stenosis include:

• Chest pain or discomfort (angina): Often experienced during physical exertion or activity due to the heart's increased demand for oxygen-rich blood and inadequate blood supply to the heart.
• Shortness of breath (dyspnea): May result from reduced cardiac output, causing difficulty in breathing, particularly during exertion or when lying flat. This may also be due to impaired oxygen exchange in the lungs from pulmonary congestion.
• Fatigue: As the heart works harder to overcome the narrowed valve, the individual may experience increased tiredness.
• Heart palpitations: Some may feel irregular or rapid heartbeat.
• Swelling (edema): Swelling of the ankles and feet may result from heart function challenges.
• Syncope (fainting): In severe cases, reduced blood flow to the brain may cause episodes of lightheadedness or fainting, particularly during physical activity.

Severe AV stenosis can lead to serious complications such as heart failure, arrhythmias, and sudden cardiac events if not managed. 

What Are the Causes of Aortic Valve Stenosis?

Various factors can contribute to AV stenosis, each playing a role in valve narrowing. Common causes of AV stenosis include:

Rheumatic Fever

Rheumatic fever, a complication of untreated streptococcal throat infection, can lead to valve damage and its subsequent stenosis. The body's immune response to the streptococcal infection causes inflammation, resulting in scarring of the heart valves. 

Congenital Defects

Some people are born with abnormal valves, which predispose them to stenosis from birth. A common congenital defect is a bicuspid aortic valve. A normal AV has three leaflets, but a bicuspid valve has only two. Bicuspid valves are prone to leakage, stenosis, or dilation.

Calcification and Degeneration

With age, the heart's valves can undergo degenerative changes, including calcification of the valve leaflets. Over time, the valve tissue becomes stiffer and less flexible, which may affect its ability to open fully. Calcification of the valve leaflets further contributes to the narrowing of the valve opening, resulting in stenosis.

Infective Endocarditis 

Infective endocarditis occurs when bacteria invade the bloodstream and infect the heart valves, causing inflammation and tissue damage. Over time, the healing process can result in fibrosis and scarring of the valve, leading to stenosis.

How to Diagnose Aortic Valve Stenosis

Diagnosing AV stenosis involves assessing the severity of valve narrowing. Diagnosis is achieved by:

Clinical Assessment

The diagnostic process often begins with a clinical evaluation by a healthcare provider. They will review the individual's medical history, including any symptoms suggestive of AV stenosis, such as chest pain, shortness of breath, or fatigue. The physical examination can reveal signs like a heart murmur or abnormal heart sounds.

Imaging Studies

1. Electrocardiogram (ECG): This test assesses the heart's electrical activity and detects arrhythmias. 
2. Echocardiography: Echocardiography is the primary imaging test used to diagnose AV stenosis. It provides detailed images of the heart's structures, allowing assessment of valve morphology, function, and blood flow across the valve.  some text
   • Transthoracic echocardiogram (TTE): Cardiac images are obtained using a probe over the skin of the chest.  
   • Transesophageal echocardiogram (TEE): This procedure involves inserting a probe into the esophagus to capture detailed images of the heart's structures. While a TEE is more invasive, it provides a more close-up and clear image than a TTE.
3. Cardiac Catheterization: Cardiac catheterization may be performed to confirm the diagnosis of AV stenosis and assess coronary artery anatomy if surgical intervention is being considered. 

Diagnosing and managing AV stenosis requires a multidisciplinary team, including cardiologists, cardiac surgeons, and other specialists, to develop the most suitable management approach tailored to the patient's needs.

Management Options for Aortic Valve Stenosis

Management options for AV stenosis range from medical management to surgical intervention.

Medication Management

Medications may help manage symptoms and reduce the risk of complications associated with aortic valve stenosis. Commonly used medications include: 

• Diuretics: Diuretics, such as furosemide or hydrochlorothiazide, may help reduce fluid retention and relieve symptoms of pulmonary congestion, such as shortness of breath and swelling.
• Beta-Blockers: Beta-blockers, like metoprolol or carvedilol, are administered to help reduce blood pressure and decrease the heart's workload, which may help alleviate symptoms like chest pain.
• Anticoagulants: These drugs are given to help prevent stroke in patients with atrial fibrillation or other high-risk factors for blood clots. Warfarin or direct oral anticoagulants (DOACs) may be prescribed.

Procedures and Surgeries

Percutaneous balloon valvuloplasty is a minimally invasive procedure that dilates the narrowed valve using a balloon. It can temporarily alleviate symptoms.

Surgical valve repair or replacement is often necessary for severe cases of AV stenosis or when other management options are ineffective.

• Aortic Valve Repair: In some cases, the damaged valve can be surgically repaired to improve function and alleviate symptoms. 
• Aortic Valve Replacement: Valve replacement entails the removal of the diseased valve and replacement with an artificial one.
• Transcatheter Aortic Valve Replacement (TAVR): TAVR is a minimally invasive heart procedure for patients at high risk for complications from traditional valve replacement surgery. During TAVR, a prosthetic valve is delivered using a catheter and implanted within the diseased valve, effectively replacing it and supporting normal blood flow.  

Supportive Lifestyle and Management Strategies

Regular Monitoring

Routine follow-up with a cardiologist is crucial for evaluating the effectiveness of management and monitoring disease progression. Routine echocardiograms and other cardiac tests help assess valve function and guide management decisions.

Lifestyle Adjustments

Adopting heart-healthy habits can significantly improve quality of life and support disease management. Encouraging a diet rich in veggies, fruits, lean proteins, and whole grains while limiting saturated fats and sodium supports cardiovascular health. Regular physical activity enhances cardiovascular fitness and overall well-being. Smoking cessation is essential since tobacco use can affect AV health.

Managing Comorbidities

Effective management of hypertension, diabetes, and other chronic conditions through medication adherence, lifestyle modifications, and regular medical follow-up helps reduce their impact on heart function.

Prognosis and Outcomes

The prognosis of AV stenosis depends on factors such as:

• Severity: Severity and degree of the stenosis.
• Age: Older people may face more challenges due to age-related valve changes and reduced physiological reserve. 
• Comorbidities: Conditions like hypertension, diabetes, chronic kidney disease, and coronary artery disease can impact outcomes by increasing the heart's workload.

Appropriate management, particularly AV replacement, can significantly improve long-term outcomes. After AV replacement, many people experience symptom relief and better daily functioning. AV replacement or repair has been shown to support improved survival.

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Key Takeaways

• Aortic valve stenosis is a progressive narrowing of the aortic valve that can lead to significant challenges and reduction in quality of life if not managed. 
• Common causes of aortic valve stenosis include rheumatic fever, congenital abnormality of the valve (e.g., bicuspid valve), and degenerative changes.
• An echocardiogram is the primary modality used for diagnosing aortic valve stenosis.
• Management for aortic valve stenosis ranges from medication to surgical intervention. In many cases, aortic valve replacement provides a comprehensive management option.
• Individuals are encouraged to seek medical advice if they experience symptoms. Adherence to management plans supports optimal health outcomes.