Overview
Definition:
Hypogastric artery preservation in EVAR refers to techniques aimed at maintaining flow through one or both internal iliac arteries during endovascular repair of abdominal aortic aneurysms (AAA) or aortoiliac aneurysms
This is crucial to prevent pelvic ischemia and associated complications.
Epidemiology:
The hypogastric (internal iliac) artery is a major visceral artery supplying the pelvic organs, gluteal region, and perineum
Its occlusion during EVAR can occur in up to 20-40% of cases, depending on the extent of the aneurysm and the anatomy requiring treatment
The incidence of symptomatic pelvic ischemia after bilateral hypogastric artery sacrifice is estimated at 10-20%.
Clinical Significance:
Preserving hypogastric artery flow is vital for preventing potentially debilitating complications such as buttock claudication, erectile dysfunction, rectal dysfunction, and ischemic proctitis
These symptoms can significantly impact a patient's quality of life and are important considerations for exam candidates evaluating management strategies.
Indications For Preservation
Anatomy Related:
Aneurysmal involvement of or extension to the hypogastric arteries
Need for preservation in cases of unfavorable iliac artery anatomy for standard EVAR
Presence of anomalous or dominant hypogastric artery origin.
Patient Factors:
Younger patients with longer life expectancy
Patients with known or suspected pelvic vascular disease
Patients with pre-existing symptoms of pelvic ischemia or claudication
Patients undergoing bilateral hypogastric artery embolization for other reasons prior to EVAR.
Procedural Considerations:
Need for maintaining adequate distal landing zones for stent grafts
Complex EVAR configurations requiring preservation of specific branches
Avoiding retrograde embolization into the hypogastric system.
Techniques For Preservation
Iliac Branch Endoprosthesis:
Use of iliac branch endoprosthesis (IBE) or bifurcated grafts with dedicated iliac extensions that cannulate the hypogastric artery
Requires precise anatomy and skilled cannulation.
Fenestration Techniques:
Custom fenestrations in the main body of the stent graft to allow deployment of a branch stent into the hypogastric artery
Technically demanding and associated with higher reintervention rates.
Chimney Technique:
Placement of a separate stent graft (mini-stent) in the hypogastric artery, "chimneying" alongside the main aortic stent graft
Offers flexibility but can be associated with guttering and endoleaks.
Coil Embolization Strategy:
Selective embolization of the hypogastric artery only if necessary, often as a last resort, with careful consideration of contralateral flow and patient factors
This is an alternative to full sacrifice but needs careful technique.
Diagnostic Approach And Assessment
Preoperative Imaging:
Detailed CT angiography (CTA) is paramount to assess aneurysm morphology, iliac artery diameter, tortuosity, and the origin and branching pattern of the hypogastric arteries
Assess for existing collateralization or occlusion.
Arterial Mapping:
Angiography to precisely map the iliac and hypogastric arteries, identify takeoff angles, and evaluate the potential for access and device deployment.
Assessment Of Pelvic Circulation:
Evaluating collateral supply to the pelvis via the internal pudendal, obturator, and gluteal arteries
Assessing the patency of the contralateral hypogastric artery if unilateral preservation is planned.
Complications Of Hypogastric Artery Sacrifice
Early Complications:
Acute buttock claudication
Erectile dysfunction
Ischemic proctitis or rectosigmoid ischemia
Potential for retrograde embolization to the lower extremities.
Late Complications:
Chronic buttock claudication
Worsening erectile dysfunction
Chronic pelvic pain syndromes
Bowel ischemia with potential for stricture formation
Impaired wound healing in the gluteal region.
Management Of Sacrificed Arteries:
In cases of unavoidable sacrifice, prophylactic embolization of the hypogastric artery is often considered to prevent distal embolization
Postoperative monitoring for symptoms of ischemia is essential
Revascularization may be considered in select symptomatic patients.
Key Points
Exam Focus:
Understand the indications for hypogastric artery preservation in EVAR
Differentiate between techniques like IBE, fenestration, and chimney grafts
Recognize the symptoms and long-term consequences of hypogastric artery sacrifice.
Clinical Pearls:
Always obtain detailed preoperative imaging of the hypogastric arteries
Consider patient factors like age and lifestyle
If bilateral sacrifice is unavoidable, discuss the risks and benefits thoroughly with the patient.
Common Mistakes:
Underestimating the importance of hypogastric artery patency
Inadequate preoperative assessment of pelvic circulation
Aggressive embolization without considering collateral pathways
Failing to counsel patients about potential long-term sequelae.