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EVAR / TEVAR — Endovascular AAA + Spinal Cord Protection in TAAA

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Vascular · 7 min read

Endovascular aortic repair has replaced open AAA for most infrarenal cases — but TEVAR for thoracic + thoracoabdominal disease still carries a 3-10% paraplegia risk. The spinal cord protection bundle is the exam-favorite + the OR reality.

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EVAR — infrarenal AAA repair

KeyBilateral femoral access (often percutaneous) with stent-graft deployment across the aneurysm sac, excluding it from arterial pressure.

Far less invasive than open AAA

no cross-clamp
minimal blood loss
no large laparotomy
1-2 day LOS vs 7-10

MAC with femoral nerve block or low-dose neuraxial is feasible in selected patients; GA more common for breath-hold during graft deployment + imaging.

Major peri-procedural concerns

contrast-induced AKI (CKD patients — pre-hydrate, minimize iodinated contrast, consider CO₂ angiography)
access-site hematoma/pseudoaneurysm
distal embolization

EVAR-1 + DREAM trials: early survival advantage over open vanishes by 2-3 years from re-intervention burden.

AAA repair: EVAR (endovascular) vs open repair - EVAR has lower perioperative morbidity, requires arterial access and contrast; open repair carries higher hemodynamic instability and aortic cross-clamp consequences.

TEVAR — thoracic + thoracoabdominal disease

Indications

descending thoracic aneurysm
complicated type B dissection (malperfusion, rupture, refractory pain)
penetrating ulcer
blunt aortic injury

Left subclavian artery is frequently covered by the graft if dominant vertebral or LIMA-to-LAD, plan carotid-subclavian bypass first.

One-lung ventilation often required for surgical exposure when a hybrid approach is used.

Paraplegia risk 3-10% from intercostal artery + artery of Adamkiewicz coverage — the higher the proximal landing zone + the longer the covered segment, the higher the risk.

Extent II Crawford TAAA repairs carry the highest cord-injury rate.

Spinal cord blood supply and ischemia syndromes: 1 anterior spinal artery (motor, sensory pain/temp), 2 posterior spinal arteries (dorsal columns); artery of Adamkiewicz T9-T12; anterior spinal artery syndrome from cross-clamp or hypotension.

Spinal cord protection bundle

Lumbar CSF drain placed pre-op for high-risk cases (long covered segment, prior AAA repair, hypogastric occlusion): target CSF pressure <10 mmHg, drain 10-15 mL/hr only if pressure climbs — over-drainage causes intracranial hypotension + subdural hematoma.

MAP target >85-90 mmHg intra-op + 24-48 hr post-op (perfusion = MAP minus CSF pressure).

Permissive hemoglobin ≥10 g/dL for O₂ delivery.

Avoid hyperthermia.

Maintain spinal cord perfusion

if delayed paraplegia appears post-op
immediately raise MAP to >100
drain CSF aggressively
transfuse to Hb >10 — the COPS protocol (Coselli) reverses ~half of delayed deficits

Neuromonitoring — SSEPs + MEPs

Somatosensory evoked potentials monitor posterior columns; motor evoked potentials monitor anterior horn cells + corticospinal tracts (the cord region most vulnerable to ischemia).

Combined SSEP + MEP is gold standard for TEVAR/open TAAA.

Anesthetic implications: total IV anesthesia (propofol + remifentanil ± low-dose ketamine) preferred; volatile <0.5 MAC + avoid nitrous + avoid neuromuscular blockade after intubation (MEPs need intact NMJ).

A >50% MEP amplitude drop or >10% latency increase triggers the rescue cascade (raise MAP, drain CSF, transfuse, reassess graft position).

Evoked potentials and raw EEG patterns: SSEP, MEP, BAEP can be affected by volatile anesthetics; minimize agent doses, use TIVA when monitoring evoked potentials.

Endoleaks — types I-V

KeyType I: inadequate seal at proximal (Ia) or distal (Ib) attachment — high pressure leak, urgent re-intervention.

Type II: retrograde flow from collateral branches (lumbar, IMA) into sac — most common, often observed if sac stable.

Type III: graft component separation or fabric defect — urgent.

Type IV: graft fabric porosity (early after deployment, self-resolves).

Type V (endotension): sac expansion without identifiable leak — pressure transmission through graft, controversial.

Surveillance CT angio at 1 mo, 6 mo, 12 mo, then annual.

Ruptured AAA + acute type B dissection

Ruptured AAA: emergent EVAR if anatomy suitable + center capable — IMPROVE trial showed equivalent 30-day mortality vs open but better quality-of-life; permissive hypotension (SBP 70-90) until proximal control, large-bore access, MTP activated, REBOA if available.

Acute type B dissection: initial medical management (esmolol/labetalol then nitroprusside or clevidipine, target SBP 100-120 + HR <60), TEVAR for complicated cases (malperfusion, rupture, rapid expansion, refractory pain) per INSTEAD-XL — TEVAR improved 5-year aorta-specific mortality.

Damage control resuscitation (DCR): permissive hypotension (SBP 80-90), hemostatic resuscitation (1:1:1), and damage control surgery; minimize crystalloid, treat coagulopathy with blood products and TXA.

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