Complications - EVAR – Endovascular repair of abdominal aortic aneurysm (Y-graft) – Vascular Surgery

1. Access route complications

• Incidence: 9–16% of all patients
• Injury to access vessels with or without acute thrombosis; bleeding complications; later also pseudoaneurysms and arteriovenous fistulae
• In particular in narrow, delicate or highly tortuous, calcified vessels
• Dissection; access vesssel occlusion; vascular rupture → stent implantation
• Bleeding complication at puncture site (5-8%) → mostly nonsurgical; surgical hematoma evacuation and suturing of the vessel required in <3% of cases

Prevention:

• Careful patient selection and preoperative assessment
• Correct selection of introducer set

2. Endograft malposition

• Most often, incorrect placement of the proximal tip of the endograft in relative to the renal arteries

Placement too inferior:

• Inadequate proximal seal → Endoleak type I
• Proximal extension with additional stent graft or bare-metal stent

Prevention:

• Careful pre-operative assessment
• Becoming familiar with the different markings on the endograft

Placement too superior:

• Accidental renal artery occlusion → probing of renal artery with Simmons Sidewinder 1 catheter or alternatively transbrachial approach + stenting of renal artery
• If interventional management is no longer possible ( often) → convert to open surgery 

Endograft torquing

• Results in consecutive kinking of the graft limb with stenosis or occlusion of the limb → remedy by implantation of a self-expanding stent

Prevention:

• If the delivery system must be rotated for some compelling reason before before deploying the graft → retract the delivery system into the iliac vessels and advance it again once the position has been corrected

1. Ischemic complications

Limb ischemia  

• Peripheral embolisms (<2%) → resove by combination of thrombolysis, catheter aspiration, angioplasty/stenting, and Fogarty maneuver

Pelvic ischemia

• Due to embolization or occlusion of the internal iliac artery with the endograft → urinary or fecal incontinence; gluteal claudication; rectal ischemia; erectile dysfunction; skin or muscle necrosis

Prevention:

• Use of endografts with iliac side limbs to maintain pelvic blood flow

Visceral ischemia

• Due to occlusion of the inferior mesenteric artery and/or thromboembolism; occlusion of the inferior mesenteric artery only results in intestinal ischemia if the collateral circulation via the superior mesenteric artery and/or internal iliac artery is inadequate (quite rare with endoluminal procedures despite unfavorable collateral circulation)
• Affects mostly the large intestine, primarily the descending and sigmoid colon
• Clinical signs: bloody stools; diarrhea; abdominal pain; peritonitis.
• Diagnostic work-up: Rectosigmoidoscopy, possibly colonoscopy (Caution: increased risk of perforation!); laboratory panels are non-specific!
• Management: nonsurgical (watchful waiting) only in case of transient mucosal ischemia/grade A, otherwise bowel resection depending on location, possibly Hartmann procedure.

Prevention

• Ruling out preoperatively significant stenosis of the superior mesenteric artery and celiac artery

Spinal ischemia and paraplegia ("ischemic spinal cord injury" - SCI)

• Cause: Reduced blood flow to the spinal cord due to endovascular stenting of arteries relevant to the spinal cord in combination with other risk factors such as perioperative hypotension, major blood loss/anemia; especially in thoracic/thoracoabdominal procedures.

If at least two spinal perfusion territories are compromised, the likelihood of spinal ischemia increases.

• Clinical signs: range from minor transient sensory impairments through functional disorders of the continence organs to complete paraplegia with lifelong bed confinement and need for nursing care.

• Treatment:  Increase spinal perfusion pressure, e.g. ,increase the mean arterial pressure with medication and insert a CSF shunt to reduce the arterial perfusion backpressure in the CSF spaces

Prevention:

• Avoid hypotensive intra-/postoperative phases and maintain mean arterial pressure at 80-90 mmHg for at least 48 h after segmental artery occlusion
• Fashion prophylactic spinal CSF drainage if at least two territories of the spinal circulation (see above) are impaired and cannot be reopened through revascularizing measures
• Adequate perioperative central venous saturation (ScvO2) of ≥70% and intraoperative central venous pressure (CVP) of ≤10 mmHg, hemoglobin level ≥8 mg/dl, and keep intraoperative blood loss as low as possible, cell saver
• Prompt postoperative extubation to assess neurological status, follow-up checks

2. Systemic complications

• Cardiopulmonary and cerebrovascular complications and contrast-media induced nephrotoxicity
• Acute coronary syndrome; myocardial infarction; pneumonia; cerebrovascular events; kidney failure→ adequate multidisciplinary management
• Preoperative assessment: cardiac status, lung function, retention parameters

 3. Post-implantation syndrome

• Incidence: 13–60%
• Cause: inflammatory immune response with release of cytokines due to endothelial activation by the endograft material
• Presentation: transient, acute, flu-like symptoms, fever
• Laboratory panels: Elevated C-reactive protein (CRP), interleukin-6, and TNF-α during the first week post-implantation; typically no leukocytosis and no microbial presence
• Management: symptomatic (antipyretic measures; antibiotics are not indicated).

4. Access vessel pseudoaneurysms

• Percutaneous puncture site pseudoaneurysms more common than following surgical exposure of the access vessel.
• Incidence of pseudoaneurysms requiring treatment: 3–6%
• Management: ultrasound-guided thrombin injection into the aneurysm, possibly surgical repair, esp. in aneurysms >1.5 cm diameter

5. Endograft migration

• Endograft displacment by more than 5–10 mm from its original position, usually in a caudad direction
• Incidence: 1–10% (1-year follow-up after EVAR)
• Main reason for re-intervention in type I endoleaks (see below).

6. Kinking/occlusion of endograft limb

• Incidence:  2–4% of patients after EVAR
• Causes: progressive shrinkage of the excluded aneurysm sac with consecutive deformation of the endograft, marked angulation of the aortic neck, narrower diameter of the distal aortic neck, which may result in compression of the graft limbs
• Presentation: intermittent claudication, also acute leg ischemia
• Treatment: placement of bare-metal stents or additional stent grafts within the original endograft; in acute occlusion, revascularization with thrombolysis and subsequent stenting

7. Material fatigue

• Cause: fractures of the stent struts, tears in the endograft material, loosening of prolene sutures attaching the endograft material to the stent struts
• Sequelae: type I or type III endoleaks (see below)

8. Endograft infection

• Incidence following EVAR: 0,4–3%
• Mortality 20–50%!
• Risk factors: age; diabetes; obesity; malnutrition; gangrene/ulcer; duration of preop. hospitalization; operating time; inguinal access; blood loss; reinterventions; lymphocele; hematoma; seroma; wound healing disorders; wound infections
• Varied clinical signs: rather unremarkable findings (elevated inflammation markers); back pain; febrile infections including dramatic courses with active hemorrhage/perforation; erosion of adjacent organs with fistula formation
• Management: broad-spectrum antibiotics immediately after diagnosis; in the absence of pathogen presence in blood culture → vancomycin + anti-gram-negative preparations (e.g., ceftriaxone, fluroquinolone, or piperacillin-tazobactam), otherwise according to antimicrobial susceptibility testing; in case of persistent or recurrent infection after/or despite antibiotic regimen → open surgical graft explantation.

9. Endoleaks

• Definition: persistent blood flow in aneurysm sac after completed endograft placement
• Most common complication after EVAR
• Classification:

• Type I and type III endoleaks are associated with a higher risk of aneurysm rupture → prompt intervention recommended
• Diagnostic work-up: CT; MRI; contrast-enhanced color-coded duplex ultrasonography
• Management