Cardiology > Aortic Aneurysm

Background

An aortic aneurysm is a localized, pathological dilation of the aorta to greater than 1.5 times its normal diameter. It results from weakening of the aortic wall and can occur in any segment of the aorta, most commonly in the abdominal portion (abdominal aortic aneurysm, AAA) and less frequently in the thoracic segment (thoracic aortic aneurysm, TAA). Aneurysms are often asymptomatic but carry a high risk of rupture, which is life-threatening.

II) Classification/Types

By Location: 

• • Abdominal Aortic Aneurysm (AAA): Most common; typically infrarenal. 

• • Thoracic Aortic Aneurysm (TAA): Involves ascending aorta, arch, or descending thoracic aorta. 

• • Thoracoabdominal Aneurysm: Spans both thoracic and abdominal segments. 

By Morphology: 

• • Fusiform: Circumferential dilation of the vessel. 

• • Saccular: Outpouching of a portion of the aortic wall. 

By Etiology: 

• • Degenerative (most common): Due to atherosclerosis. 

• • Genetic/Heritable: Marfan syndrome, Ehlers-Danlos syndrome, Loeys-Dietz syndrome. 

• • Inflammatory: Takayasu arteritis, giant cell arteritis. 

• • Infectious (mycotic aneurysms): Rare, associated with endocarditis or septicemia. 

• • Post-traumatic or post-dissection. 

By Size (AAA): 

• • Small: <4.0 cm 

• • Medium: 4.0–5.4 cm 

• • Large: ≥5.5 cm (increased risk of rupture) 

III) Pathophysiology 

Aneurysm formation results from chronic degradation of structural components (elastin, collagen) in the aortic media due to inflammation, proteolytic enzymes, oxidative stress, and mechanical wall stress. Inherited connective tissue disorders or atherosclerosis further compromise the structural integrity of the aortic wall. 

IV) Epidemiology

• • Sex: Male predominance (especially in AAA, 4:1 ratio). 

• • Age: Incidence increases after age 65. 

• • Geography: Higher prevalence in developed countries due to risk factor profiles. 

• • Comorbidities: Associated with smoking, hypertension, and atherosclerosis. 

Etiology

I) Causes

• • Atherosclerosis (major cause of AAA) 

• • Hypertension (particularly in TAA) 

• • Genetic syndromes: Marfan, Ehlers-Danlos, Loeys-Dietz 

• • Bicuspid aortic valve (associated with ascending TAA) 

• • Chronic aortic dissection 

• • Trauma 

• • Vasculitides: Giant cell arteritis, Takayasu arteritis 

• • Infections (e.g., Salmonella, Staphylococcus aureus) 

1. II) Risk Factors

• • Male sex 

• • Age >65 

• • Smoking (strongest modifiable risk factor for AAA) 

• • Hypertension 

• • Family history of aneurysm 

• • Connective tissue disorders 

• • Atherosclerotic disease 

• • History of thoracic radiation (for TAA) 

Clinical Presentation

I) History (Symptoms)

Often Asymptomatic and found incidentally on imaging. When symptomatic:

AAA: 

• • Pulsatile abdominal mass 

• • Abdominal, back, or flank pain 

• • Sudden severe pain may indicate impending rupture 

TAA: 

• • Chest, back, or interscapular pain 

• • Hoarseness (left recurrent laryngeal nerve compression) 

• • Dysphagia (esophageal compression) 

• • Cough or dyspnea (tracheal compression) 

Aneurysm Rupture (AAA or TAA): 

• • Sudden, severe pain 

• • Hypotension or shock 

• • Syncope or collapse 

• • Pulsatile mass (AAA rupture) 

1. II) Physical Exam (Signs)

   Vital Signs:

• • Hypotension and tachycardia in rupture 

• • Hypertension in chronic TAA 

Abdominal Exam (AAA): 

• • Pulsatile mass (typically >5 cm) 

• • Bruit over aorta 

• • Tenderness with expansion or rupture 

Cardiovascular Exam: 

• • Signs of aortic regurgitation (TAA involving the aortic root) 

• • Murmur if dissection is present 

Pulmonary and Neurologic: 

• • Stridor, wheezing, or hoarseness (mass effect from TAA) 

• • Paraplegia (if spinal arteries are involved) 

Differential Diagnosis (DDx)

• • Aortic dissection 

• • Acute coronary syndrome 

• • Mesenteric ischemia 

• • Renal colic 

• • Pancreatitis 

• • Spinal compression fracture 

• • Retroperitoneal hemorrhage 

• • Esophageal rupture (Boerhaave syndrome) 

Diagnostic Tests

Initial Imaging: 

Ultrasound (AAA): 

• • First-line for screening and monitoring 

• • High sensitivity and specificity 

CT Angiography (CTA): 

• • Gold standard for preoperative planning 

• • Determines exact location, size, and anatomy 

MRI Angiography: 

• • Alternative to CTA in renal dysfunction or allergy 

Chest X-ray (TAA): 

• • Widened mediastinum 

• • Displaced trachea or aortic knob 

Electrocardiogram (ECG): 

• • To rule out myocardial infarction 

Laboratory Studies: 

• • CBC (anemia in rupture) 

• • Renal function (pre-contrast imaging) 

• • D-dimer (nonspecific but often elevated in rupture) 

Treatment

I) Medical Management:

Indications: Asymptomatic, small aneurysms or non-surgical candidates

• • Risk factor modification: 

• • • Smoking cessation 

• • • Blood pressure control (target <130/80 mmHg) 

• • • Statins for atherosclerosis 

• • • Glycemic control in diabetics 

• • Surveillance: 

• • • AAA: 

• • • • 3.0–3.9 cm: Ultrasound every 2–3 years 

• • • • 4.0–4.9 cm: Every 12 months 

• • • • 5.0–5.4 cm: Every 6 months 

• • • TAA: 

• • • • Monitor with CT/MRI every 6–12 months depending on size and growth 

1. II) Interventional/Surgical:

Indications for Repair: 

• • AAA: Diameter ≥5.5 cm, rapid growth >0.5 cm in 6 months, or symptomatic 

• • TAA: Diameter ≥5.5 cm (ascending), ≥6.0 cm (descending), or symptomatic 

Surgical Options: 

• • Open Surgical Repair (OSR): Durable but more invasive 

• • Endovascular Aneurysm Repair (EVAR/TEVAR): Minimally invasive; preferred in high-risk patients 

Emergency Surgery: 

• • Required in rupture; mortality remains high despite intervention 

Patient Education, Screening, Vaccines

Education: 

• • Importance of smoking cessation and blood pressure control 

• • Adherence to surveillance imaging 

• • Recognize warning symptoms of rupture (sudden severe back or abdominal pain) 

Screening: 

• • One-time abdominal ultrasound for AAA in: 

• • • Men aged 65–75 years with a history of smoking 

• • • Individuals with a first-degree relative with AAA 

Vaccinations: 

• • Influenza annually 

• • Pneumococcal vaccine 

• • COVID-19 vaccination 

Consults

• • Vascular Surgery: For aneurysm >5.5 cm or symptomatic aneurysm 

• • Cardiothoracic Surgery: For TAA, especially involving the ascending aorta 

• • Cardiology: For aortic valve or coronary disease 

• • Radiology: For CTA/MRA surveillance 

• • Anesthesiology: For preoperative risk assessment 

• • Primary Care/Internal Medicine: For chronic disease optimization 

Follow-Up

• • Regular Imaging Surveillance: 

• • • Based on aneurysm size and location 

• • Blood Pressure Monitoring: 

• • • Target BP <130/80 mmHg 

• • Lifestyle Counseling: 

• • • Smoking cessation support 

• • • Diet and exercise 

• • Post-Repair Monitoring: 

• • • Lifelong imaging after EVAR (endoleak risk) 

• • • Surgical site surveillance after OSR 

• • Educate on warning signs of rupture or complications