Overview
Definition:
Endovascular repair of common iliac artery aneurysms (CIAs) using stent grafts with integrated or fenestrated branches designed to extend into the iliac or internal iliac arteries
aims to exclude the aneurysm from circulation while preserving flow to pelvic organs and the lower extremities.
Epidemiology:
Common iliac artery aneurysms are found in approximately 1-2% of the population, often associated with abdominal aortic aneurysms (AAAs)
Isolated CIAs account for about 10% of iliac aneurysms
Prevalence increases with age and in males.
Clinical Significance:
Unruptured CIAs are often asymptomatic but carry a significant risk of rupture, leading to high mortality
Rupture can cause massive retroperitoneal hemorrhage
Endovascular repair with branch devices offers a less invasive option, particularly for patients with challenging anatomy or those unsuitable for open repair, preserving internal iliac artery flow which is crucial for pelvic perfusion.
Indications
Indications For Repair:
Indications for repair include aneurysm diameter > 3.5 cm in females or > 4.0 cm in males
rapid expansion (> 0.5 cm in 6 months)
presence of symptoms (pain, rupture, distal embolization)
and specific anatomical considerations such as association with AAA or contralateral iliac artery involvement.
Indications For Branch Device:
Branch devices are indicated for CIAs that extend to or involve the iliac bifurcation, requiring preservation of the internal iliac artery (IIA) to prevent buttock claudication, sexual dysfunction, or visceral ischemia
They are also used in cases where the contralateral limb of an aortic stent graft cannot be easily accommodated in the common iliac artery due to tortuosity or stenosis.
Patient Selection Criteria:
Ideal candidates have adequate iliac artery anatomy for device deployment and sealing (e.g., infrarenal neck for aortic components, iliac artery diameter and length)
Patients must have suitable access vessels (common femoral arteries)
Contraindications include severe aortoiliac tortuosity precluding access, active infection, or prohibitive contrast allergies.
Ct Angiography Requirements:
A detailed CT angiography with thin slices and multiplanar reconstruction is essential to accurately delineate aneurysm dimensions, neck length and diameter, iliac artery anatomy (tortuosity, diameter, landing zones), and the origin of the internal iliac arteries.
Preoperative Preparation
Imaging Assessment:
Preoperative planning includes precise measurement of the aneurysm sac, infrarenal neck (if applicable), common iliac arteries, internal iliac arteries, and external iliac arteries
Assess the contralateral iliac artery for suitability for stent graft limb deployment.
Anesthesia Considerations:
General anesthesia is typically used, allowing for precise hemodynamic control and patient positioning
Regional anesthesia may be an option in select patients
Invasive hemodynamic monitoring (arterial line, central venous line) is often employed.
Pharmacological Management:
Patients are typically pre-medicated with antibiotics and may receive anticoagulation (e.g., heparin) during the procedure
Aspirin and clopidogrel are commonly prescribed for dual antiplatelet therapy post-procedure, along with statin therapy.
Equipment Selection:
Selection of the appropriate stent graft system (e.g., bifurcated aortic stent graft with iliac extensions and iliac branch components) is crucial, based on pre-operative templating and patient anatomy
This includes sizing the main body, iliac limbs, and contralateral components.
Procedure Steps
Access And Delivery:
Bilateral common femoral artery access is obtained under ultrasound guidance
An angiography catheter is used to delineate the anatomy, and guidewires are advanced to position the stent graft components.
Deployment Of Main Body And Limbs:
For bifurcated aortic grafts, the main body is deployed in the infrarenal aorta, followed by contralateral and ipsilateral iliac limbs
For isolated iliac aneurysms, a bifurcated iliac stent graft may be deployed across the iliac bifurcation.
Deployment Of Branch Device:
When using branch devices, the main body or bifurcated iliac graft is deployed, and then the integrated or fenestrated branches are advanced and deployed into the common iliac artery and the internal iliac artery
This may involve a contralateral gate-bridging device or a separate iliac branch prosthesis.
Confirmation Of Seal And Flow:
Post-deployment angiography is performed to confirm adequate sealing proximally and distally, absence of endoleaks, patency of the iliac branches, and satisfactory flow to the external iliac arteries and pelvic circulation
Balloon angioplasty of stent graft junctions may be performed if necessary.
Closure Of Access Sites:
Access sites are closed using percutaneous closure devices or surgical repair to achieve hemostasis.
Postoperative Care
Immediate Monitoring:
Patients are monitored in an intensive care unit or a specialized vascular ward for vital signs, fluid balance, and signs of bleeding or limb ischemia
Serial ankle-brachial indices (ABIs) may be obtained.
Pharmacological Management:
Dual antiplatelet therapy (aspirin and clopidogrel) is continued for a specified period (typically 6 months to 1 year), followed by lifelong aspirin therapy
Statins are continued for secondary prevention of atherosclerosis.
Imaging Surveillance:
Regular duplex ultrasound and CTA scans are performed at 1, 6, and 12 months post-procedure, and annually thereafter, to assess the integrity of the stent graft, monitor aneurysm sac size, and detect any endoleaks or device-related complications.
Patient Education:
Patients are educated on medication adherence, lifestyle modifications (smoking cessation, diet, exercise), and the importance of lifelong surveillance
They are advised to report any new symptoms such as groin pain, abdominal pain, or limb weakness immediately.
Complications
Early Complications:
Early complications include access site hematoma or pseudoaneurysm, endoleak (type I, II, III, IV, V), stent graft migration, limb occlusion, acute kidney injury, myocardial infarction, stroke, and bleeding
Retroperitoneal hemorrhage from rupture during deployment is a critical early complication.
Late Complications:
Late complications include endoleak (especially type II), graft infection, stent graft limb occlusion or kinking, sac enlargement or rupture, iliac artery stenosis or occlusion, and Aenean-related events (AREs)
Atraumatic rupture of the aneurysm sac can occur even after successful endovascular repair.
Prevention Strategies:
Meticulous preoperative planning and patient selection, appropriate device sizing and deployment, adequate sealing zones, and comprehensive post-operative surveillance are key to preventing complications
Careful technique during access and closure also minimizes access-related issues.
Key Points
Exam Focus:
Understanding the indications for endovascular repair, specifically the role of branch devices in preserving internal iliac artery flow
Recognizing common endoleak types and their management
Knowledge of surveillance protocols and potential complications is crucial for DNB/NEET SS exams.
Clinical Pearls:
In complex iliac anatomy, consider staged repair or balloon-assisted deployment of branches
Always obtain contralateral iliac artery roadmap before contralateral limb deployment
Meticulous imaging review is paramount for successful planning.
Common Mistakes:
Inadequate sealing zones leading to type I endoleaks
Failure to adequately revascularize the internal iliac artery when indicated, resulting in buttock claudication or ischemic complications
Over-reliance on a single imaging modality for surveillance
CTA is essential for graft integrity
Underestimating the risk of sac expansion or rupture in the presence of type II endoleaks.