Endovascular Aortic Aneurysm Repair (EVAR)
Kristine Clodfelter Orion
Rachael Nicholson
Indications for aneurysm repair remain the same for both open and endovascular techniques. However, the choice of technique is dependent upon morphologic characteristics of the patient’s aneurysm. When determining whether or not a patient is a candidate for endovascular repair of an abdominal aortic aneurysm (EVAR), anatomic criteria that need to be evaluated include the diameter and length of the normal aortic segment between the lowest renal artery and the proximal extent of the aneurysm (the neck), angulation of the neck, adequacy of the distal landing site, patency and degree of aneurysmal and/or occlusive disease within iliac and femoral arteries. The exact anatomic dimensions vary slightly by device manufacturer. Currently there are several companies producing stent grafts for aneurysm repair with many variations in their individual product design. As devices have evolved, anatomic requirements have changed and will continue to transform as technology advances.
The technique for performing EVAR has also progressed, so that the procedure can now be performed completely percutaneously, in well-chosen patients (as shown here), rather than through the standard exposure of the common femoral arteries through two transverse groin incisions. Detailed analysis of preoperative imaging is essential for the determination of a patient’s EVAR candidacy, choice of stent graft, as well as operative approach. The following is a description of the basic steps of a percutaneous, two-piece endograft placement for an isolated infrarenal abdominal aortic aneurysm with normal iliac and common femoral arteries.
SCORE™, the Surgical Council on Resident Education, classified endovascular repair of aortic aneurysm as a “COMPLEX” procedure.
LIST OF STRUCTURES
Aorta
Common, external, and internal iliac arteries
Common femoral, superficial femoral, profunda arteries
Femoral nerve
Renal arteries
Celiac artery
Superior mesenteric artery
Inferior mesenteric artery
Lumbar arteries
Pubic tubercle
Anterosuperior iliac spine
Inguinal ligament
STEPS IN PROCEDURE
Mark bilateral pedal pulses
Use ultrasound to mark the common femoral artery bifurcation
Prep the patient from nipple to knees
Obtain bilateral common femoral arterial access
Exchange micropuncture sheath and place guidewire
Position two percutaneous closure devices and replace these with 9-Fr sheaths
Systemic heparinization (100 U/kg)
Place guidewire and catheter into the proximal descending thoracic aorta and exchange wire
Mark distal extent of wire on the table to avoid inadvertent advancement of the wire during the remainder of the case
Under fluoroscopy exchange 9-Fr sheaths for large bore sheaths
Obtain lateral fluoroscopic view
Select the main body of endograft.
Advance the main body into the pararenal aorta and pull sheath back
Aortogram through a marking pigtail catheter near the renal arteries under magnified views
Position endograft to deploy just below the lowest renal artery and deploy
Deploy the main body of the stent graft
Inflate coda Balloon
Cannulate the contralateral gate of the main body and perform exchange for stiff wire
Place stiff wire back into the proximal descending thoracic aorta through the pigtail catheter
Pull contralateral sheath to a location distal to the hypogastric artery
Perform an angiogram
Advance contralateral sheath with its dilator into contralateral gate
Advance contralateral limb into the main body
Pull contralateral sheath into the external iliac artery and deploy the limb
Angioplasty area of graft-to-graft overlap (mandatory) as well as the distal landing sites (optional)
Perform completion angiogram to ensure no endoleak
Remove sheaths and close arteriotomies with percutaneous closure devices
Assess distal lower extremities for ischemia and distal embolization
Pitfalls and complications
Endoleak
Vascular injury due to advancing wires/catheters without direct fluoroscopic visualization
Embolization secondary to wire/catheter/graft manipulation
Thrombosis because of inadequate anticoagulation
Groin hematoma/lymphocele
Migration of endograft
Arteriovenous fistula
Renal failure
Bowel ischemia
Spinal cord ischemia
Stroke
Initial Access to the Femoral Artery (Fig. 112.1)
Technical Points
This procedure may be performed under general anesthesia, with a spinal block or with local anesthetic and monitored sedation depending on the surgeon and patient’s preferences and overall surgical risk. It is vital that the patient be comfortable enough to prevent aberrant motion and disruption during fluoroscopy. Mark the pedal pulses bilaterally, and prep the patient from nipples to knees.
If performing the procedure percutaneously, take extreme care to ensure a clean puncture in the common femoral artery (Fig. 112.1A). Use fluoroscopy to mark the middle of the femoral head with a hemostat. In addition, use ultrasound to note the level of the femoral bifurcation (Fig. 112.1B). Ultrasound may be used to guide puncture of the common femoral artery as well. If after employing these measures, concerns remain about the quality and location of the puncture, inject contrast through the small caliber micropuncture sheath, confirming the accuracy of the puncture in the common femoral artery before committing to the large bore sheaths that will eventually be needed for the stent graft. Obtain bilateral common femoral arterial access using a micropuncture kit.
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