Aortic Aneurysm: Evaluation, Classification, and Management
Signs and Symptoms
Most aortic aneurysms are asymptomatic and discovered incidentally on imaging studies. 1, 2
Symptomatic Presentations Requiring Urgent Evaluation:
- Abdominal pain or back pain suggests expansion or impending rupture and requires urgent referral 3, 4
- Pulsatile abdominal mass on physical examination (detected in approximately 30% of asymptomatic AAAs) 1
- Compression symptoms in thoracic aneurysms: dysphagia, dyspnea, or hoarseness 3
- Chest or back pain in thoracic aneurysms indicates potential expansion 4
Critical pitfall: Never delay referral of symptomatic patients, as rupture risk increases dramatically with symptoms 3
Imaging Criteria and Evaluation
Initial Screening and Detection:
- Abdominal ultrasound (DUS) is the screening modality of choice for AAA due to high sensitivity, specificity, safety, and lower cost 1
- CT angiography (CTA) with fine-cut (≤0.25 mm) imaging of the entire aorta is mandatory when EVAR is being considered 5, 6
- Complete vascular evaluation including ascending, arch, and descending aorta is required to determine optimal management strategy 5
Pre-operative Planning Requirements:
- Three-dimensional centerline reconstruction software is recommended for accurate TEVAR case planning 6
- Assessment of femoro-popliteal segment by DUS should be performed prior to AAA repair to detect concomitant aneurysms 5
- Ultrasound-guided percutaneous access is supported for EVAR due to lower complication rates 5
Classification and Surgical Criteria
Abdominal Aortic Aneurysm (AAA):
Elective repair is recommended at the following thresholds: 5
- ≥55 mm diameter in men
- ≥50 mm diameter in women (women have four-fold higher rupture risk at same diameter) 4
Additional surgical indications: 5
- Rapid growth ≥5 mm in 6 months or ≥10 mm per year (regardless of absolute size) 5, 4
- Saccular aneurysm ≥45 mm may be considered for repair 5
- Symptomatic AAA requires urgent surgical evaluation 3, 4
Contraindication to elective repair: 5
- Limited life expectancy <2 years - elective AAA repair is not recommended 5
Thoracic Aortic Aneurysm (TAA):
Ascending aorta/aortic root surgical thresholds: 4
- ≥5.5 cm in patients without genetic disorders 4
- ≥4.5 cm when concomitant aortic valve surgery is planned 4
Genetic syndrome patients require earlier intervention: 3, 4
Growth rate criteria for surgical referral: 4
Descending Thoracic Aorta:
- TEVAR is the preferred approach over open repair for elective descending TAA due to reduced morbidity, mortality, and length of stay 6
Management Options
Endovascular Repair (EVAR/TEVAR):
EVAR should be considered as preferred therapy for AAA when: 5
- Suitable anatomy exists
- Reasonable life expectancy >2 years
- Based on shared decision-making
Anatomic requirements for conventional EVAR: 5
- Proximal neck length >10-15 mm
- Proximal neck diameter <30 mm
- **Mural thrombus/calcification covering <90% of circumference** (>90% increases type I endoleak risk) 5
Advantages of endovascular repair: 5, 6
- Peri-operative mortality <1% for EVAR 5
- Lower CV complications compared to open repair 5
- Reduced morbidity and length of stay 6
Critical limitation: 5
- Lifelong surveillance is mandatory due to higher rate of late complications (endoleaks, migration, rupture) and re-interventions 5
Open Surgical Repair:
Indications for open repair: 5
- Unsuitable anatomy for EVAR (>50% of patients) 5
- Failed EVAR 5
- Patient preference with suitable surgical risk
Open repair considerations: 5
- Peri-operative mortality approximately 5-10% with CV complications 5
- Ruptured AAA has ~48% complication rate with open repair 5
Special Techniques:
For complex anatomy: 5
- Fenestrated or branch stent endografts for juxta- or para-renal AAA 5
- Both open and endovascular approaches can be offered in high-volume centers 5
Ruptured AAA Management:
In ruptured AAA with suitable anatomy, endovascular repair is recommended over open repair to reduce peri-operative morbidity and mortality 5
Surveillance Protocols
AAA Surveillance: 4
- 3.0-3.9 cm: ultrasound every 3 years
- 4.0-4.9 cm: more frequent monitoring (specific intervals not defined in guidelines)
- ≥5.0 cm in women or ≥5.5 cm in men: surgical evaluation
Thoracic Aneurysm Surveillance: 4
- Aortic arch <4.0 cm: imaging every 12 months
- Aortic arch ≥4.0 cm: imaging every 6 months
Post-EVAR/TEVAR Surveillance: 6
- Contrast-enhanced CT at 1 month, 12 months, then yearly for life 6
- More frequent imaging if endoleak or abnormality detected at 1 month 6
Medical Management
Cardiovascular Risk Reduction:
Optimal CV risk management is recommended to reduce major adverse cardiovascular events in all patients with aortic aneurysms 5
- Smoking cessation - critical to slow aneurysm growth 7, 2
- Blood pressure control - particularly with ACE inhibitors (observational data suggest benefit for rupture prevention) 7
- Treatment of dyslipidemia - PCSK9 inhibitors may be beneficial based on Mendelian randomization studies 7
Important caveat: 5
- Fluoroquinolones are generally discouraged but may be considered if compelling indication exists with no alternative 5
Pre-operative Cardiac Evaluation:
Coronary revascularization before elective aortic surgery is NOT recommended in patients with stable cardiac symptoms, as this strategy does not improve outcomes or reduce 30-day MI rate 5
Routine coronary angiography and systematic revascularization is NOT recommended prior to AAA repair 5
Referral Criteria Summary
Urgent Referral Required:
- Any symptomatic aneurysm (pain, compression symptoms) 3, 4
- Rapid growth (≥5 mm/6 months or ≥10 mm/year) 3, 4
- Ruptured aneurysm 5