Thoracic Aortic Aneurysm

Overview

The aorta is the body's largest artery, carrying oxygen-rich blood from the heart to the rest of the body. A thoracic aortic aneurysm occurs when a section of the aorta within the chest cavity weakens and bulges outward, forming a balloon-like expansion. This weakening can occur anywhere along the thoracic aorta, from where it exits the heart to where it passes through the diaphragm.

Most thoracic aortic aneurysms develop slowly over years and often remain asymptomatic until they become large or rupture. The danger lies in their potential for sudden rupture or dissection, which are medical emergencies with high mortality rates. The risk of rupture increases exponentially as the aneurysm grows larger, making early detection and monitoring crucial.

Modern imaging techniques have improved our ability to detect and monitor these aneurysms before they become life-threatening. With appropriate surveillance and timely intervention, many people with thoracic aortic aneurysms can be successfully treated before complications occur. Understanding risk factors and recognizing warning signs are essential for preventing catastrophic outcomes.

Symptoms

Most thoracic aortic aneurysms grow slowly and produce no symptoms until they become large or complications develop:

Common Symptoms (When Present)

• Sharp chest pain - May be sudden and severe
• Shortness of breath - From compression of airways or heart failure
• Chest tightness - Feeling of pressure or fullness
• Back pain - Between shoulder blades
• Hoarseness - From nerve compression
• Difficulty swallowing - From esophageal compression
• Persistent cough - From airway irritation

Associated Symptoms

• Dizziness - From reduced blood flow
• Fatigue - General weakness and tiredness
• Sharp abdominal pain - If aneurysm extends below diaphragm
• Jaundice - Rare, from compression of bile ducts

Symptoms by Location

• Ascending aorta: Chest pain, heart failure symptoms
• Aortic arch: Hoarseness, difficulty swallowing, cough
• Descending aorta: Back pain, spinal symptoms

Causes

Thoracic aortic aneurysms result from weakening of the aortic wall due to various factors:

Degenerative Causes

• Atherosclerosis: Hardening and weakening of arterial walls
• Hypertension: Chronic high blood pressure damages aortic wall
• Aging: Natural degeneration of elastic fibers
• Smoking: Accelerates arterial damage

Genetic and Connective Tissue Disorders

• Marfan syndrome: Affects connective tissue throughout body
• Ehlers-Danlos syndrome: Causes fragile blood vessels
• Loeys-Dietz syndrome: Aggressive arterial disease
• Turner syndrome: Chromosomal disorder affecting women
• Familial thoracic aortic aneurysm: Inherited predisposition

Other Causes

• Bicuspid aortic valve: Congenital heart defect
• Aortic inflammation:
  • Giant cell arteritis
  • Takayasu arteritis
  • Behçet's disease
• Infections: Syphilis, bacterial endocarditis
• Trauma: Blunt chest injury
• Previous aortic surgery: Weakening at surgical sites

Risk Factors

Several factors increase the risk of developing thoracic aortic aneurysms:

Non-Modifiable Risk Factors

• Age: Risk increases after age 60
• Male gender: Men affected 2-4 times more than women
• Family history: 20% have affected family members
• Genetic syndromes: Marfan, Ehlers-Danlos, etc.
• Congenital conditions: Bicuspid aortic valve

Modifiable Risk Factors

• Smoking: Most important modifiable risk factor
• Hypertension: Uncontrolled high blood pressure
• Atherosclerosis: Plaque buildup in arteries
• High cholesterol: Contributes to arterial damage
• Cocaine use: Acute aortic stress
• Weight lifting: Extreme straining

Medical Conditions

• Chronic obstructive pulmonary disease (COPD)
• Previous aortic aneurysm or dissection
• Inflammatory conditions
• Chronic kidney disease

Types and Classification

Thoracic aortic aneurysms are classified by location and extent:

By Location

• Ascending aortic aneurysm (60%):
  • Between aortic valve and brachiocephalic artery
  • Often associated with aortic valve disease
  • May involve aortic root
• Aortic arch aneurysm (10%):
  • Involves curved portion giving rise to head/arm vessels
  • Complex surgical anatomy
• Descending thoracic aneurysm (30%):
  • From left subclavian artery to diaphragm
  • Often extends into abdomen
• Thoracoabdominal aneurysm:
  • Involves both chest and abdominal aorta
  • Crawford classification (Types I-IV)

By Shape

• Fusiform: Circumferential dilation (most common)
• Saccular: Focal outpouching from one wall

By Etiology

• Degenerative: Age and atherosclerosis
• Genetic: Inherited syndromes
• Inflammatory: Vasculitis
• Infectious: Mycotic aneurysm
• Traumatic: Post-injury

Diagnosis

Many thoracic aortic aneurysms are discovered incidentally during imaging for other conditions:

Physical Examination

• Often normal in asymptomatic patients
• Blood pressure differences between arms
• Heart murmur (if aortic valve involved)
• Diminished pulses
• Signs of genetic syndromes

Imaging Studies

• CT Angiography (CTA):
  • Gold standard for diagnosis and monitoring
  • Precise measurements of diameter
  • Evaluates entire aorta
  • Surgical planning tool
• MR Angiography (MRA):
  • No radiation exposure
  • Excellent for young patients
  • Better for soft tissue evaluation
• Echocardiography:
  • Transthoracic (TTE) for ascending aorta
  • Transesophageal (TEE) for better visualization
  • Evaluates aortic valve function
• Chest X-ray:
  • May show widened mediastinum
  • Calcium in aortic wall
  • Not sensitive for diagnosis

Additional Testing

• Genetic testing: For familial syndromes
• Cardiac catheterization: If coronary disease suspected
• Pulmonary function tests: Pre-operative assessment
• Blood tests: Inflammatory markers, infection screen

Size Criteria

• Normal diameter: 2.5-3.5 cm (varies by location)
• Aneurysm: 50% increase over normal
• Surgical threshold: Generally 5.0-5.5 cm
• Lower threshold for: Marfan syndrome, rapid growth

Treatment

Treatment depends on aneurysm size, location, growth rate, and patient factors:

Medical Management

For small aneurysms (<5.0 cm) without symptoms:

• Blood pressure control:
  • Beta-blockers (first-line)
  • ACE inhibitors or ARBs
  • Target BP <130/80 mmHg
• Lifestyle modifications:
  • Smoking cessation (critical)
  • Avoid heavy lifting
  • Moderate exercise only
  • Stress management
• Regular surveillance:
  • CT or MRI every 6-12 months
  • More frequent if growing

Surgical Treatment

Indications for Surgery

• Diameter ≥5.5 cm (5.0 cm for genetic syndromes)
• Growth rate >0.5 cm/year
• Symptomatic aneurysm
• Complications (dissection, rupture)

Open Surgical Repair

• Procedure: Replace diseased aorta with synthetic graft
• Advantages:
  • Durable, long-lasting repair
  • Can address valve problems
  • Complete aneurysm removal
• Risks:
  • Mortality 3-5% in experienced centers
  • Stroke, paralysis, kidney failure
  • Longer recovery time

Endovascular Repair (TEVAR)

• Procedure: Stent graft placed via femoral arteries
• Advantages:
  • Less invasive
  • Shorter hospital stay
  • Lower immediate risk
• Limitations:
  • Not suitable for all anatomies
  • Requires lifelong surveillance
  • Risk of endoleaks
  • May need reintervention

Hybrid Procedures

• Combination of open and endovascular techniques
• For complex anatomy (arch aneurysms)
• Debranching procedures

Emergency Treatment

• Immediate surgery for rupture/dissection
• Blood pressure control
• Pain management
• Intensive care support

Prevention

While genetic factors cannot be changed, many risk factors are modifiable:

Primary Prevention

• Blood pressure control:
  • Regular monitoring
  • Medication compliance
  • Low-sodium diet
• Smoking cessation:
  • Most important modifiable factor
  • Reduces growth rate
  • Improves surgical outcomes
• Cholesterol management:
  • Statins if indicated
  • Heart-healthy diet
  • Regular exercise

Screening Recommendations

• Family history: Screen first-degree relatives
• Genetic syndromes: Regular imaging from young age
• Bicuspid aortic valve: Baseline and periodic imaging
• Previous aneurysm: Lifelong surveillance

Activity Restrictions

• Avoid heavy lifting (>50 lbs)
• No competitive sports
• Avoid straining (Valsalva maneuver)
• Moderate aerobic exercise only
• Avoid stimulants (cocaine, amphetamines)

Medical Optimization

• Control other cardiovascular risk factors
• Manage COPD if present
• Treat infections promptly
• Regular medical follow-up

Complications

Thoracic aortic aneurysms can lead to life-threatening complications:

Aortic Rupture

• Risk factors: Large size, rapid growth, symptoms
• Presentation: Sudden severe pain, shock, collapse
• Mortality: 80-90% die before reaching hospital
• Treatment: Emergency surgery if survives initial event

Aortic Dissection

• Mechanism: Tear in inner layer allows blood between walls
• Types:
  • Type A: Involves ascending aorta (surgical emergency)
  • Type B: Descending aorta only (often medical management)
• Complications: Organ malperfusion, tamponade, rupture

Other Complications

• Aortic regurgitation: From root dilation
• Heart failure: From valve dysfunction
• Thromboembolism: Clots from aneurysm sac
• Compression symptoms:
  • Airway obstruction
  • Esophageal compression
  • Nerve compression
• Infection: Rare but serious

Post-Surgical Complications

• Stroke (2-3%)
• Spinal cord ischemia/paralysis (1-3%)
• Kidney failure
• Respiratory failure
• Bleeding
• Graft infection
• Endoleak (TEVAR)

When to See a Doctor

Schedule Urgent Appointment For:

• New or worsening chest discomfort
• Progressive shortness of breath
• Hoarseness or voice changes
• Difficulty swallowing
• Persistent cough
• Family history of aortic disease

Screening Recommendations

• First-degree relatives of aneurysm patients
• Known genetic syndrome (Marfan, etc.)
• Bicuspid aortic valve
• Previous aortic dissection

Follow-up Schedule

• Small aneurysm (4.0-4.4 cm): Annual imaging
• Medium aneurysm (4.5-4.9 cm): Every 6 months
• Large aneurysm (≥5.0 cm): Every 3-6 months or surgery
• Post-surgical: Lifelong surveillance