Aortic Stenosis: Causes, Symptoms, Diagnosis, Management and Prevention

Aortic Stenosis: Causes, Symptoms, Diagnosis and Management

~Introduction

Aortic stenosis (AS) is a progressive and potentially life-threatening condition characterized by the narrowing of the aortic valve opening, which impedes blood flow from the left ventricle to the aorta and subsequently to the rest of the body. This narrowing increases the workload on the heart, leading to hypertrophy (thickening) of the left ventricular wall and eventually heart failure if left untreated.

Aortic stenosis is one of the most common and serious types of valvular heart disease, particularly in the elderly population. With increasing life expectancy worldwide, its prevalence continues to rise, making it a major public health concern. Early recognition and appropriate management can significantly improve the quality of life and prognosis for affected individuals.

~Anatomy and Physiology of the Aortic Valve

The aortic valve is one of the four valves in the human heart. It is located between the left ventricle and the aorta, the main artery that carries oxygenated blood from the heart to the rest of the body. The valve normally consists of three thin, flexible leaflets (cusps) that open fully during systole (heart contraction) to allow blood to flow forward and close tightly during diastole (heart relaxation) to prevent backflow into the ventricle.

In a healthy heart, the aortic valve area typically measures around 3 to 4 cm². In aortic stenosis, the valve area progressively decreases—sometimes to less than 1 cm²—causing significant obstruction to blood flow. This obstruction leads to increased left ventricular pressure, myocardial hypertrophy, and eventually decreased cardiac output.

~Etiology and Causes of Aortic Stenosis

The causes of aortic stenosis can be broadly classified into congenital, acquired, and degenerative categories.

1. Congenital Aortic Stenosis

Congenital aortic stenosis occurs when the valve is malformed at birth. The most common congenital abnormality is a bicuspid aortic valve (BAV), where the valve has only two leaflets instead of three. This abnormality affects about 1–2% of the population and predisposes the valve to early calcification, fibrosis, and narrowing, often becoming symptomatic by middle age.

2. Rheumatic Aortic Stenosis

Rheumatic fever, a sequela of untreated streptococcal throat infection, can cause inflammation and scarring of the heart valves, including the aortic valve. Although rheumatic heart disease has become rare in developed countries due to better antibiotic use, it remains a significant cause of aortic stenosis in developing regions.

3. Degenerative (Calcific) Aortic Stenosis

The most common cause of aortic stenosis in the elderly is age-related degenerative calcification of the valve leaflets. Over time, calcium deposits build up on the valve, causing stiffness and restricted motion. Risk factors for this form of AS are similar to those for atherosclerosis and include:

• Aging

• Hypertension

• Hyperlipidemia

• Smoking

• Diabetes mellitus

• Chronic kidney disease

4. Other Rare Causes

• Radiation-induced valve disease

• Inflammatory diseases such as systemic lupus erythematosus

• Paget’s disease of bone or chronic renal failure leading to secondary calcification

~Pathophysiology of Aortic Stenosis

The pathophysiological changes in aortic stenosis develop gradually over years or decades. As the valve narrows, the left ventricle must generate higher pressure to overcome the resistance to blood flow. Initially, the myocardium responds by concentric hypertrophy—thickening of the ventricular wall without dilatation—to maintain normal cardiac output.

However, as the disease progresses, this compensatory mechanism becomes inadequate, leading to diastolic dysfunction (impaired relaxation), increased myocardial oxygen demand, and eventually systolic dysfunction (decreased ejection fraction). When this occurs, symptoms such as angina, syncope, and heart failure develop, signaling advanced disease.

~Clinical Presentation

Aortic stenosis may remain asymptomatic for many years, even when the obstruction is severe. However, once symptoms appear, the prognosis worsens dramatically if the condition is left untreated.

Classic Triad of Symptoms

1. Angina (Chest Pain):
   Caused by increased oxygen demand due to left ventricular hypertrophy and reduced coronary perfusion.

2. Syncope (Fainting Spells):
   Occurs due to reduced cerebral perfusion during exertion when the fixed cardiac output cannot meet metabolic demands.

3. Dyspnea (Shortness of Breath):
   Results from elevated left ventricular filling pressures, pulmonary congestion, and eventual heart failure.

Other Possible Symptoms

• Fatigue and weakness

• Palpitations

• Reduced exercise tolerance

• Sudden cardiac death (in severe cases)

~Physical Examination Findings

On physical examination, the following signs are characteristic:

• Pulsus parvus et tardus: Weak and delayed carotid pulse.

• Systolic ejection murmur: A harsh, crescendo-decrescendo murmur best heard at the right upper sternal border and radiating to the carotid arteries.

• Systolic thrill: Palpable vibration over the aortic area in severe cases.

• Soft or absent A2 heart sound: Indicates reduced valve mobility.

• Left ventricular heave: Due to hypertrophy.

~Diagnostic Evaluation

Diagnosis of aortic stenosis is based on a combination of clinical findings, imaging studies, and hemodynamic assessments.

1. Echocardiography

Echocardiography is the gold standard for diagnosing and assessing the severity of aortic stenosis. It provides information about:

• Valve anatomy and calcification

• Aortic valve area (AVA)

• Transvalvular pressure gradient

• Left ventricular size and function

Severity Classification (based on echocardiography):

Severity	Valve Area (cm²)	Mean Gradient (mmHg)	Jet Velocity (m/s)
Mild	>1.5	<20	<3.0
Moderate	1.0–1.5	20–40	3.0–4.0
Severe	<1.0	>40	>4.0

2. Electrocardiogram (ECG)

May show left ventricular hypertrophy, left axis deviation, or strain pattern.

3. Chest X-Ray

Findings may include post-stenotic aortic dilation, left ventricular hypertrophy, or signs of pulmonary congestion.

4. Cardiac Catheterization

Used for direct hemodynamic measurements and to assess coronary artery disease before valve surgery.

5. CT and MRI

Useful in evaluating valve calcification and aortic anatomy, especially for planning transcatheter procedures.

~Natural History and Prognosis

The natural history of aortic stenosis follows a long asymptomatic period. However, once symptoms develop, the prognosis deteriorates rapidly:

• Angina: Average survival ~5 years without treatment

• Syncope: Average survival ~3 years

• Heart failure: Average survival ~2 years

Thus, timely intervention after symptom onset is crucial to prevent sudden death and irreversible cardiac damage.

~Management of Aortic Stenosis

Management depends on disease severity, symptoms, comorbid conditions, and surgical risk.

1. Medical Management

Medical therapy cannot reverse or halt the progression of aortic stenosis but can help alleviate symptoms and manage comorbidities:

• Diuretics for pulmonary congestion (use with caution)

• ACE inhibitors or ARBs for hypertension

• Beta-blockers for rate control (if tolerated)

• Lipid-lowering therapy (statins) to reduce atherosclerotic risk

Patients should avoid strenuous activity if symptomatic or if severe AS is diagnosed.

2. Surgical and Interventional Management

a. Surgical Aortic Valve Replacement (SAVR)

This is the definitive treatment for severe, symptomatic aortic stenosis. The diseased valve is replaced with a mechanical or bioprosthetic valve.

• Mechanical valves: Durable but require lifelong anticoagulation.

• Bioprosthetic valves: Less durable (10–20 years) but do not require long-term anticoagulation.

b. Transcatheter Aortic Valve Replacement (TAVR)

A less invasive alternative suitable for:

• Patients at high or intermediate surgical risk

• Elderly individuals with comorbidities

• Those with contraindications to open-heart surgery

TAVR involves delivering a collapsible valve through a catheter (usually via the femoral artery) and deploying it within the diseased valve. It has become an increasingly popular treatment with excellent outcomes.

c. Balloon Aortic Valvuloplasty (BAV)

Primarily used as a temporary or palliative measure, especially in children or high-risk adults who cannot undergo valve replacement. It provides short-term relief but restenosis often occurs within 6–12 months.

~Postoperative Care and Follow-Up

After valve replacement, lifelong follow-up is necessary to monitor for:

• Prosthetic valve function

• Endocarditis (infection of the valve)

• Thromboembolic events (especially with mechanical valves)

• Heart rhythm abnormalities

Regular echocardiographic monitoring is recommended at 6 months post-surgery, then every 1–2 years.

~Complications of Aortic Stenosis

If left untreated, aortic stenosis can lead to several complications:

• Heart failure

• Arrhythmias (e.g., atrial fibrillation)

• Sudden cardiac death

• Endocarditis

• Bleeding tendencies due to acquired von Willebrand factor deficiency

• Left ventricular dysfunction

~Prevention and Lifestyle Modifications

While congenital and age-related causes cannot be entirely prevented, certain lifestyle measures can slow disease progression and reduce complications:

• Control of blood pressure, cholesterol, and diabetes

• Regular exercise as tolerated

• Avoiding smoking and alcohol abuse

• Prompt treatment of streptococcal infections to prevent rheumatic disease

• Regular cardiac check-ups for individuals with known valve disease

~Aortic Stenosis in Special Populations

1. In Children and Adolescents

Congenital aortic stenosis, often due to a bicuspid valve, may require balloon valvuloplasty or surgical correction early in life.

2. In the Elderly

Degenerative aortic stenosis is common. TAVR has revolutionized treatment in this age group, providing a minimally invasive, life-saving option.

3. In Pregnant Women

Severe aortic stenosis during pregnancy poses significant risks for both mother and fetus. Management requires a multidisciplinary approach, often with percutaneous intervention if symptoms worsen.

~Prognosis After Valve Replacement

Both SAVR and TAVR significantly improve survival and quality of life in symptomatic patients. The prognosis depends on:

• Age and comorbidities

• Left ventricular function prior to surgery

• Type of prosthetic valve used

• Adherence to follow-up and anticoagulation therapy

With modern interventions, 5-year survival rates after valve replacement exceed 70–80%, representing a remarkable improvement compared to untreated disease.

~Conclusion

Aortic stenosis remains a major cause of morbidity and mortality worldwide, particularly among older adults. Although the condition often progresses silently, the onset of symptoms marks a critical turning point that necessitates urgent evaluation and treatment.

Advances in diagnostic imaging, surgical techniques, and transcatheter valve therapies have revolutionized management, offering hope for patients across all age groups. Regular monitoring, early intervention, and comprehensive cardiovascular care remain the keys to improving outcomes in individuals with aortic stenosis.