Aortic Stenosis

Definition

Aortic Stenosis is a condition characterised by narrowing of the aortic valve, which restricts blood flow from the left ventricle into the aorta. This results in increased pressure within the left ventricle, leading to hypertrophy, reduced cardiac output, and heart failure if left untreated.

Aetiology

Aortic stenosis can be caused by several underlying conditions, including:

• Calcific Degeneration: The most common cause in older adults, often due to age-related calcification of the valve leaflets.
• Congenital Bicuspid Aortic Valve: The presence of a bicuspid rather than a tricuspid aortic valve, which is more prone to early degeneration and stenosis.
• Rheumatic Heart Disease: A complication of rheumatic fever, which can lead to fibrosis and calcification of the valve leaflets.
• Radiation Therapy: Previous radiation exposure to the chest can cause long-term damage to the aortic valve, leading to stenosis.

Pathophysiology

Aortic stenosis occurs when the aortic valve narrows, reducing blood flow from the left ventricle to the aorta. This leads to increased afterload, resulting in left ventricular hypertrophy as the myocardium adapts to maintain cardiac output. Over time, left ventricular function deteriorates, leading to heart failure and other complications.

Risk Factors

• Advanced age.
• Male gender.
• Congenital bicuspid aortic valve.
• Rheumatic heart disease.
• Hyperlipidaemia and atherosclerosis.
• Previous chest radiation therapy.

Signs and Symptoms

Symptoms of aortic stenosis typically appear once the condition becomes severe and may include:

• Exertional Dyspnoea: Shortness of breath during physical activity.
• Angina: Chest pain due to increased myocardial oxygen demand and reduced supply.
• Syncope: Fainting or dizziness, particularly during exertion, due to reduced cerebral perfusion.
• Fatigue and Reduced Exercise Tolerance: Due to decreased cardiac output.
• Heart Failure Symptoms: Including orthopnoea, paroxysmal nocturnal dyspnoea, and peripheral oedema.

Investigations

Diagnostic evaluation for aortic stenosis includes:

• Physical Examination: A systolic ejection murmur (crescendo-decrescendo) heard best at the right upper sternal border, radiating to the carotids. Severe aortic stenosis may present with a delayed and weakened carotid pulse (pulsus parvus et tardus).
• Electrocardiogram (ECG): May show left ventricular hypertrophy and other conduction abnormalities.
• Echocardiography: The mainstay for diagnosis, used to assess the severity of stenosis, left ventricular function, and valve anatomy.
• Chest X-ray: May show cardiomegaly or calcification of the aortic valve.
• Cardiac Catheterisation: Performed when non-invasive imaging is inconclusive or to assess coronary anatomy before valve surgery.

Management

Management of aortic stenosis depends on the severity of the condition and the presence of symptoms:

• Medical Management:
  • Monitoring: Regular follow-up with echocardiography for asymptomatic patients with mild to moderate stenosis.
  • Symptomatic Management: Treatment of heart failure symptoms with diuretics, beta-blockers, and angiotensin-converting enzyme inhibitors (ACE inhibitors).
  • Avoiding Overexertion: Advise patients to avoid strenuous physical activity to prevent complications such as syncope or sudden death.
• Surgical Management:
  • Aortic Valve Replacement (AVR): The definitive treatment for severe symptomatic aortic stenosis. It can be performed surgically or through transcatheter aortic valve implantation (TAVI) in high-risk patients.
  • Balloon Aortic Valvuloplasty: A temporary measure, often used in critically ill patients as a bridge to surgery or TAVI.
• Referral: All patients with symptomatic aortic stenosis or severe stenosis on echocardiography should be referred to a cardiologist for further evaluation and management.

References

1. NHS (2024) Aortic Stenosis. Available at: https://www.nhs.uk/conditions/aortic-stenosis/ (Accessed: 24 June 2024).
2. National Institute for Health and Care Excellence (2024) Aortic Valve Disease: Management and Outcomes. Available at: https://www.nice.org.uk/guidance/ng208 (Accessed: 24 June 2024).
3. British Heart Foundation (2024) Aortic Stenosis. Available at: https://www.bhf.org.uk/informationsupport/conditions/aortic-stenosis (Accessed: 24 June 2024).
4. Royal College of Physicians (2024) Management of Aortic Stenosis. Available at: https://www.rcplondon.ac.uk/guidelines-policy/aortic-stenosis (Accessed: 24 June 2024).