Overview
Definition:
Endovascular Aneurysm Repair (EVAR) is a minimally invasive surgical procedure used to treat aneurysms, particularly abdominal aortic aneurysms (AAA) and thoracic aortic aneurysms (TAA)
It involves deploying a stent graft within the aneurysm sac, which reinforces the aorta and prevents blood from flowing into the weakened wall of the aneurysm, thereby reducing the risk of rupture.
Epidemiology:
Aneurysms, especially AAAs, are more common in older individuals (over 65 years), men, smokers, and those with a family history
The prevalence of AAA in the general population is estimated to be between 4-8%, with higher rates in specific demographic groups
EVAR has become the preferred treatment for a significant proportion of eligible AAA patients in developed countries.
Clinical Significance:
Aneurysm rupture is a catastrophic event with high mortality rates
EVAR offers a less invasive alternative to open surgical repair, leading to shorter recovery times, reduced morbidity, and mortality for carefully selected patients
Understanding EVAR is crucial for vascular surgeons, general surgeons, and interventional radiologists involved in the management of aortic diseases.
Indications
General Indications:
Symptomatic aneurysms require urgent intervention
Asymptomatic aneurysms are typically repaired when they reach a certain diameter (e.g., >5.5 cm for AAA in men, >5.0 cm in women) or demonstrate rapid expansion (>0.5 cm in 6 months)
Risk of rupture must outweigh the risks of the procedure.
Anatomical Suitability:
The aneurysm must be amenable to EVAR based on imaging
Key factors include the presence of adequate sealing zones (proximal and distal to the aneurysm), the absence of unfavorable angulation, tortuosity, or excessive thrombus that could compromise stent graft deployment and sealing.
Patient Factors:
Patient comorbidities and life expectancy are considered
EVAR is often favored in patients who are poor candidates for open surgery due to advanced age or significant comorbidities such as cardiac, pulmonary, or renal insufficiency.
Preoperative Preparation
Imaging Assessment:
Multidetector-row computed tomography angiography (MDCT) is essential to precisely map the aneurysm, including neck length, diameter, angulation, iliac artery anatomy, and presence of thrombus
Preoperative planning software is often used.
Risk Stratification:
Comprehensive assessment of cardiovascular, pulmonary, renal, and cerebrovascular status
Anesthesia risks are evaluated
Patients undergo thorough medical workup.
Informed Consent:
Detailed discussion with the patient and family about the procedure, benefits, risks (including endoleak, graft migration, rupture, stroke, renal failure, access site complications), alternatives to EVAR, and the need for lifelong surveillance.
Anticoagulation Strategy:
Appropriate preoperative anticoagulation or antiplatelet therapy is determined based on patient factors and institutional protocols
Prophylactic antibiotics are administered.
Procedure Steps
Access And Sheath Placement:
Bilateral femoral arteries are accessed, typically via open arteriotomy or percutaneous techniques
Large-bore sheaths are introduced to facilitate stent graft delivery.
Stent Graft Delivery And Deployment:
The stent graft, a fabric-covered stent, is advanced through the sheaths to the target location within the aorta
It is then deployed, expanding to seal against the aortic wall above and below the aneurysm.
Completion Angiography And Assessment:
Post-deployment angiography confirms proper placement, seal, and absence of significant endoleaks
Intraoperative imaging (fluoroscopy) is critical throughout the procedure
Additional sealing techniques or limb extensions may be used if necessary.
Closure:
Femoral access sites are closed using sutures, vascular staples, or closure devices.
Postoperative Care
Immediate Monitoring:
Close monitoring of vital signs, urine output, and access site for bleeding or hematoma
Pain management and fluid resuscitation are initiated
Serial Doppler ultrasound may be used to assess graft patency.
Imaging Surveillance:
Early postoperative imaging (CT scan or ultrasound) is performed within 30 days to assess graft integrity, sealing, and detect endoleaks
Ongoing surveillance typically involves CT angiography or ultrasound at 6 months, 1 year, and then annually, or as indicated by findings.
Management Of Complications:
Prompt recognition and management of endoleaks (Type I, II, III, IV, V)
Management options for endoleaks include endovascular re-intervention, open surgical conversion, or conservative management depending on the type and clinical significance.
Lifestyle Modifications:
Smoking cessation, blood pressure control, and management of hyperlipidemia are strongly encouraged to reduce further cardiovascular risk and prevent graft complications.
Complications
Early Complications:
Access site complications (hematoma, pseudoaneurysm, infection)
Endoleak (most common immediate complication)
Stroke
Myocardial infarction
Renal dysfunction
Graft limb occlusion
Hypotension.
Late Complications:
Graft migration
Stent fracture
Endoleak (persistent or new onset)
Graft infection
Aortic rupture (rare, but possible if endoleak is untreated)
Endograft-enteric or endograft-venous fistula
Juxtarenal or infrarenal neck dilation.
Prevention Strategies:
Meticulous patient selection based on anatomical suitability
Precise preoperative planning
Experienced procedural team
Use of appropriate stent graft technology
Aggressive management of endoleaks
Lifelong surveillance to detect and treat complications early.
Key Points
Exam Focus:
EVAR is a minimally invasive technique for AAA/TAA repair
Key anatomical requirements are adequate proximal and distal sealing zones
Endoleaks are the most common complication
understanding their types and management is critical.
Clinical Pearls:
Never underestimate the importance of lifelong surveillance after EVAR
A small type II endoleak from a lumbar artery may be monitored if asymptomatic and the sealing zones are intact
Consider hybrid approaches for complex anatomies.
Common Mistakes:
Inadequate preoperative imaging leading to poor anatomical assessment
Failure to identify all potential sources of endoleak
Over-reliance on percutaneous access in unsuitable patients
Insufficient postoperative surveillance leading to delayed diagnosis of complications.