5.5 Endovascular Aortic Repair: EVAR and TEVAR

What Endovascular Aortic Repair Is, and Who Qualifies

EVAR (endovascular aneurysm repair) places a covered stent-graft inside an infrarenal abdominal aortic aneurysm through bilateral femoral access, excluding the aneurysm sac from arterial pressure while blood flows through the fabric lumen. TEVAR (thoracic endovascular aortic repair) does the same in the descending thoracic aorta. Neither operation removes the aneurysm — the sac is still there, and it will still rupture if it becomes repressurized. That single fact explains everything about endoleaks and about lifelong surveillance, and it is the concept the CMC exam is really testing.

Anatomic Criteria — Why Not Every Aneurysm Is a Candidate

The device needs a landing zone of healthy aorta above and below the aneurysm to seal against.

• Proximal neck length — generally at least 10-15 mm of non-aneurysmal infrarenal aorta below the lowest renal artery.
• Neck angulation — severe angulation (roughly beyond 60 degrees) prevents wall apposition and predisposes to type I endoleak and graft migration.
• Neck diameter, thrombus and calcium burden — a wide, thrombus-lined or heavily calcified neck seals poorly.
• Iliofemoral access — the vessels must accept a 14-24 French delivery system without being too small, too calcified or too tortuous. When they will not, a surgical iliac conduit or an iliac branch device is used.

When the aneurysm involves the renal or visceral segment, fenestrated (FEVAR) and branched (BEVAR) devices with custom holes or side branches preserve flow to the renal, superior mesenteric and celiac arteries. These are longer cases with far more contrast, higher renal risk, and higher spinal cord ischemia risk than a standard infrarenal EVAR — an important nursing distinction when the handoff simply says "the patient had a stent graft."

Size Thresholds and Indications

A post-EVAR patient often looks better than a post-cholecystectomy patient: two small groin punctures, out of bed the same day, an ICU stay measured in hours. That deceptive appearance is exactly why the exam tests complication recognition — the catastrophes are silent until they are not.

Endoleaks: The Defining Complication

An endoleak is persistent blood flow into the aneurysm sac outside the graft lumen. Because the sac was never removed, an endoleak means the sac may still be pressurized and can still rupture.

Memory hook: I and III are high-pressure and get fixed. II is watched. IV is a non-event. V is expansion without an explanation.

Surveillance

CT angiography is the surveillance standard — typically at 1 month, at 12 months, and annually thereafter, with duplex or contrast-enhanced ultrasound substituted at some intervals in renal impairment. A non-contrast CT shows sac diameter but will not show the leak. The teaching point the exam rewards: the patient must return for imaging for the rest of their life, even feeling perfectly well. Missed surveillance is how an unrecognized type I endoleak becomes a rupture years later.

Other Graft-Related Complications

• Graft migration — caudal movement out of the proximal seal zone, which then produces a type Ia endoleak.
• Graft limb occlusion or kinking — presents as new unilateral claudication or a cool, pulseless leg in the first days to weeks. Compare limbs at every assessment; a graft limb thromboses silently in a patient who is comfortable in bed.
• Access-site complications — hematoma, pseudoaneurysm, dissection, and limb ischemia from 14-24 French sheaths. Percutaneous closure device failure is more consequential here than after coronary work purely because of sheath caliber.
• Contrast-associated acute kidney injury and renal infarction — from a heavy contrast load plus suprarenal fixation barbs or inadvertent coverage of an accessory renal artery. Trend creatinine and urine output and document the contrast dose.
• Aortoenteric or aortobronchial fistula — late, rare and catastrophic. A "herald" gastrointestinal bleed or hemoptysis in any patient with an aortic graft is a fistula until proven otherwise.
• Stroke and left upper-limb ischemia after TEVAR when the left subclavian artery is covered without revascularization. Assess left arm pulses and blood pressure, left arm claudication, and posterior circulation symptoms such as vertigo, diplopia and ataxia.
• Retrograde type A dissection after TEVAR — new severe chest or interscapular pain with hemodynamic change, a new murmur, or a pulse/blood pressure differential between arms.

Spinal Cord Ischemia and the Competing Blood Pressure Targets

Spinal cord ischemia (SCI) is the complication that makes TEVAR a critical-care nursing problem. The anterior spinal artery is supplied by a collateral network fed by segmental intercostal and lumbar arteries; covering the thoracic aorta with graft fabric occludes those segmental feeders. Incidence after standard TEVAR is low single digits but rises sharply with:

• long coverage length, particularly beyond about 20 cm, and extensive thoracoabdominal coverage;
• coverage of the left subclavian artery without revascularization;
• prior infrarenal aortic repair, because the lumbar collateral supply is already gone;
• any period of hypotension, intraoperative or postoperative;
• fenestrated/branched repair and emergency repair.

SCI may be immediate, apparent on emergence, or delayed — appearing 12 hours to several days later, very often triggered by a hypotensive episode. Delayed onset is precisely why hourly neurologic checks continue long after the patient leaves the hybrid room.

The Governing Equation

Spinal cord perfusion pressure = MAP minus cerebrospinal fluid (intrathecal) pressure.

There are only two levers, and nursing manages both:

1. Raise the MAP. Induced or permissive hypertension to a MAP of roughly 90-100 mmHg using fluids plus norepinephrine or phenylephrine per protocol.
2. Lower the CSF pressure. A lumbar CSF drain is placed prophylactically in high-risk cases or therapeutically as rescue, and drained to an intrathecal pressure target of about 10 mmHg — commonly lowered to 5 mmHg once a deficit appears.

Adjuncts: keep hemoglobin around 10 g/dL or above to maximize oxygen delivery, correct hypoxemia, avoid fever, and lighten sedation enough to obtain a true motor examination.

CSF Drain Nursing Management

• Level and zero the transducer to the ordered reference point at every position change; a drain left open against the wrong reference over-drains silently.
• Drain by protocol, never by feel — typically no more than 10-15 mL per hour with a defined daily maximum. Over-drainage causes intracranial hypotension, positional headache, and the feared complication, subdural hematoma.
• Document CSF character hourly: volume, color and clarity. Bloody or cloudy fluid, fever, nuchal rigidity or a change in mental status suggests hemorrhage or meningitis. Strict sterile technique at every access point, minimal manipulation, closed-system integrity.
• Anticoagulation timing around drain placement and removal follows neuraxial catheter rules; a spinal or epidural hematoma announces itself as new back pain with ascending motor weakness or bladder dysfunction.
• Assess hourly: bilateral lower-extremity motor strength graded 0-5 by muscle group, sensory level, and bowel/bladder function. Use the same scale every time — "moves all extremities" is not an assessment.

A new or worsening lower-extremity motor deficit is a stat page. The immediate bundle is to raise the MAP, open or increase CSF drainage per order, check hemoglobin and oxygenation, and hold every antihypertensive. Reversal is frequently possible when it is caught within minutes to hours.

The Competing Targets — the tension the exam loves

After TEVAR the surgical team wants the pressure low so the fresh seal zone is not stressed, the device does not migrate, and a repaired dissection flap is not propagated — often a systolic of 100-120 mmHg or a MAP of 70-80 mmHg. The spinal cord wants the pressure high. These goals genuinely conflict, and the resolution is not a compromise number but a priority rule: the ordered range is deliberately narrow, the nurse titrates within it and treats the edges promptly, and if a motor deficit appears, spinal cord perfusion wins — MAP goes up and the provider is notified immediately. Never quietly tolerate permissive hypotension after TEVAR on the theory that it protects the graft.

Post-Implantation Syndrome versus Graft Infection

Nursing Priorities Summary

• Bilateral distal pulses or Doppler signals, temperature, capillary refill, and motor/sensory function hourly at first — a graft limb occludes without complaint.
• Blood pressure held inside the ordered narrow window; verify arterial line accuracy and square-wave test before treating any number.
• New or worsening back, flank, abdominal or chest pain means rupture, retrograde dissection or endoleak until proven otherwise, especially combined with tachycardia, hypotension and a falling hemoglobin.
• Access-site assessment: hematoma, pulsatile mass, bruit, oozing. Large-bore sheath sites bleed more and bleed later.
• Urine output, creatinine trend and documented contrast dose.
• Discharge teaching: the lifelong CT angiography surveillance schedule and why appointments are not optional, reporting new back or abdominal pain immediately, activity and lifting restrictions per the surgeon, carrying the device identification card, and aggressive blood pressure control plus smoking cessation to protect the rest of the aorta.