1. science
2. medicine
3. surgery

AANA Journal Course
1
Update for Nurse Anesthetists
Anesthesia Case Management for Endovascular
Aortic Aneurysm Repair
Sass Elisha, CRNA, EdD
John Nagelhout, CRNA, PhD, FAAN
Jeremy Heiner, CRNA, EdD
Mark Gabot, CRNA, MSN
The incidence of angiopathology involving the aorta
and microvasculature is expected to become more
prevalent because of increased life expectancy and
incidence of obesity. With the advent of endovascular
aortic repair (EVAR), patients who were not considered surgical candidates for abdominal aortic aneurysmectomy because of their tenuous physical status can
undergo corrective treatment and return to their activities of daily living. Because of the limited invasiveness
of the procedure, it is unnecessary to cross-clamp
the aorta, which minimizes hemodynamic variability
and release of inflammatory mediators. As a result,
the rate of myocardial ischemia, acute kidney injury,
Objectives
mesenteric ischemia, and blood loss is decreased.
However, there are serious complications that can
occur with EVAR, which include cerebral and myocardial ischemia, rapid massive hemorrhage, damage
to access vessels, and endoleak. Presently, the most
common anesthetic technique provided to patients
undergoing EVAR is local anesthesia and monitored
anesthetic care. A thorough understanding of the surgical procedure, perioperative process, and anesthetic
considerations is vital to provide comprehensive care.
Keywords: Endoleak, endovascular aortic repair, endovascular stent graft, EVAR.
At the completion of this course, the reader should be
able to:
1.Discuss strategies that can be employed to decrease
perioperative mortality for patients having endovascular aortic repair (EVAR).
2.Create a comprehensive anesthetic plan for patients
undergoing EVAR.
3.
Describe the surgical advantages and disadvantages comparing EVAR with the traditional open
approach for abdominal aortic aneurysmectomy.
4.
Identify specific complications that can occur
during intraoperative anesthetic management for
patients having EVAR.
5.
Discuss the postoperative anesthetic and surgical
concerns after EVAR.
allow surgeons to perform minimally invasive surgery,
endovascular aortic repair (EVAR) has emerged as the
preferred method for repair of abdominal aortic aneurysm (AAA). Endovascular aortic repair has evolved as
the treatment of choice for AAA repairs. The surgical
technique was initially developed in the late 1990s for patients who had significant comorbidities, which excluded
them as a candidate for open surgical repair. The perioperative surgical and anesthetic management for patients
with an AAA is multifaceted and must be individualized
to the patient’s vascular anatomy and type and severity
of coexisting disease. The occurrence of major perioperative complications such as myocardial infarction, acute
kidney injury, mesenteric ischemia, postoperative pneumonia and inflammatory mediator release is less with
EVAR than with the traditional open approach.1
Introduction
Surgical Procedure
As surgical and technologic advancements continue to
Endovascular aortic aneurysm repair involves deploy-
AANA Journal Course No. 34 (Part 1): AANA Journal course will consist of 6 successive articles, each with objectives for the
reader and sources for additional reading. At the conclusion of the 6-part series, a final examination will be published on the AANA
website and in the AANA Journal. This educational activity is being presented with the understanding that any conflict of interest
on behalf of the planners and presenters has been reported by the author(s). Also, there is no mention of off-label use for drugs
or products.
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•Electrocardiogram
•Echocardiogram (if history of congestive heart failure or
other major risk factors)
• Cardiac stress testing (if history of myocardial ischemia)
• Angioplasty (according to risk factors)
•Aneurysm scanning and ultrasound imaging for surgical planning (per surgeon)
• Pulmonary function tests
• Chest X-ray
• Complete blood count
• Blood chemistry
• Estimated glomerular filtration rate
• Blood urea nitrogen
Figure 1. Comparison of Traditional Open Approach
(A) and Endovascular Aortic Repair (B)
ment of an endovascular stent graft within the aortic
lumen. The graft reinforces the portion of the aorta
where the aneurysm exists. A comparison of the traditional open procedure and EVAR is included in Figure
1. This procedure can be performed for patients who
have descending thoracic aortic aneurysms or AAAs. The
femoral arteries will be cannulated via a percutaneous
approach or by dissection, depending on the size of the
patient. Systemic anticoagulation with heparin, 50 to 100
units/kg, is accomplished before catheter insertion and
manipulation into the femoral arteries.
A sheath that contains the endovascular stent graft
(EVSG) is inserted over a guidewire and positioned at
the aneurysm location using radiographic imaging. The
proximal end of the sheath must extend beyond the aneurysm. Once the EVSG is deployed, radial force or fixation mechanisms such as hooks or barbs become embedded into the aortic wall to prevent migration. The distal
ends of the graft are then deployed and extend into both
iliac arteries. After the EVSG is correctly positioned, the
guidewire and sheath are removed followed by closure of
both femoral artery insertion points.
The procedure can take place in an interventional radiology suite or in the operating room (OR). Compared
with the conventional surgical method, advantages of the
endovascular approach include no aortic cross-clamping;
improved hemodynamic stability; and decreased incidence
of embolic events, blood loss, stress response, incidence
of renal dysfunction, and postoperative discomfort.2
Endovascular graft design and durability continue to
improve. Graft devices are either unibody (1 piece) or
modular (multiple pieces). The endograft fabric is either
woven polyester (Dacron) or polytetrafluoroethylene.
The graft skeleton is constructed of stainless steel, nitinol,
or elgiloy. Nitinol stents are popular because they exhibit
minimal shortening after deployment. Future developments may include the use of drug-eluting endovascular
stents. Drugs being tested are immunomodulators, anti-
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• Serum creatinine
• Coagulation profile
• Arterial blood gases analysis
• Urine analysis
• Hemoglobin A1c (if the patient is diabetic)
• Blood glucose
• Liver function tests
Table 1. Suggested Preoperative Testing
inflammatory, and antiproliferative agents. Initial clinical
trial findings note that the rate of restenosis is improved
with third- and fourth-generation endovascular stents.3
Improvements in surgical techniques, imaging, and graft
devices will allow a greater number of patients to experience the technical and physiologic advantages of EVAR.
Preoperative Evaluation and Preparation
Patients undergoing EVAR are often elderly and have
significant comorbidities. Preexisting cardiac, respiratory, and renal disease may significantly influence surgical outcomes.4 A thorough preoperative evaluation is
required to determine if any essential testing is necessary
to identify interventions to improve outcomes. Suggested
preoperative testing is summarized in Table 1. Extensive
radiographic imaging is performed by the surgical team
to determine whether the patient is a candidate for EVAR
as well as the best operative approach and the optimum
EVSG for the aneurysm repair. The guiding principle for
preoperative evaluation is to identify information that
will alter management to improve postoperative outcomes or provide baseline information that can be used
to guide perioperative care. Preoperative testing most
often involves identifying and characterizing cardiac,
respiratory, renal, endocrine (such as diabetes), atherosclerotic, and peripheral arterial occlusive disease.
Cardiac complications, especially related to coronary
artery disease, remain the most frequent cause of mortality
following either open aortic repair or EVAR.5 Guidelines
have been developed for cardiac evaluation of patients
scheduled for noncardiac vascular surgery.6 Patients are
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Evaluation
Activity level
1. Is there an active
cardiac condition?
Clinical risk factors
Recommendation
Unstable coronary syndrome
Unstable or severe angina
Recent MI (< 1 mo)
Decompensated CHF
Significant arrhythmias
Severe valvular disease
Presence cancels or delays aortic aneurysm repair until condition is treated.
Implement medical management and
consider coronary angiography.
2. Does the patient have good functional
capacity without
symptoms?
MET ≥ 4
Mild angina pectoris
Prior MI
Compensated or prior CHF
Diabetes mellitus
Renal insufficiency
May proceed with aneurysm repair. In
patient with unknown cardiovascular
disease or at least one clinical risk factor,
β-blockade is appropriate.
3. Is functional capacity poor or
unknown?
MET < 4
Mild angina pectoris
Prior MI
Compensated or prior CHF
Diabetes mellitus
Renal insufficiency
In patients with ≥ 3 clinical risk factors,
preoperative noninvasive testing is appropriate if it will change management.
Table 2. Preoperative Cardiac Evaluation for Patients Undergoing Aneurysm Repair
Abbreviations: CHF, congestive heart failure; MET, metabolic equivalent unit; MI, myocardial infarction.
(Adapted from Chaikof et al6 and Fleisher LA, Beckman JA, Brown KA, et al. ACC/AHA 2007 Guidelines on perioperative cardiovascular
evaluation and care for noncardiac surgery: executive summary. Circulation. 2007;116(17): e418-e500. Used with permission.)
ranked according to the number of risk factors present
and their overall functional capacity. Risk factors include
the following: symptomatic heart disease and the presence
of angina, prior history of myocardial infarction, compensated congestive heart failure (CHF), renal disease, diabetes, and cerebrovascular accident. The extent of testing
will depend on the individual patients’ symptoms and the
number of risk factors. Stress testing and myocardial reperfusion scans are helpful in predicting possible adverse
events in higher risk patients.7 Coronary angiography may
be considered for patients with active myocardial ischemia
or disease of the left coronary artery. An electrocardiogram is required in all patients, and an echocardiogram is
included for those with a history of CHF or other major
cardiac risk factors or symptoms. Table 2 summarizes
cardiac evaluation guidelines.6,8 Antihypertensive agents,
statins, β-blockers, aspirin, and other antiplatelet drugs
are widely used in these patients and should be assessed
for proper dosing and efficacy. Statin therapy results in
significant risk reduction in vascular surgery and should
be started in all patients 1 month before surgery and
continued indefinitely. Oral β-blockers should be given
to all patients with intermediate to high cardiac risk.
They should be started as early as possible before surgery,
preferably 1 month, and titrated to a target heart rate of
60 to 70 beats/min. Administration of intravenous (IV)
high-dose β-blockers immediately before surgery may be
detrimental and should be avoided.8 Antiplatelet drugs are
not a contraindication for EVAR, and aspirin is frequently
continued throughout the perioperative period. Warfarin
therapy is discontinued 5 to 7 days before surgery, and
the patient is bridged to treatment with low-molecularweight heparin or unfractionated heparin if kidney injury
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is present.4,8 If regional anesthesia is planned, a detailed
protocol should be in place and followed for managing
perioperative anticoagulation for neuraxial blockade, catheter insertion, and catheter removal.
As smoking is a major risk factor for the development
of AAA, many of these patients have chronic respiratory
disease. A respiratory assessment, including chest radiograph, pulmonary function testing, and blood gas analysis, will help guide anesthesia providers to create a comprehensive plan for perioperative ventilation. Patients
with a history of respiratory disease, especially chronic
obstructive pulmonary disease, should have their therapy
optimized. Smoking cessation 2 weeks before surgery,
along with chest physical therapy, incentive spirometry,
and early ambulation, may all be beneficial in avoiding
postoperative respiratory complications.6 Recent steroid
use should be ascertained and appropriate coverage instituted to avoid the potential for acute adrenal crises.
Preexisting renal disease is the most significant risk
factor for postoperative kidney injury after aortic aneurysm repair. In addition, coexisting renal artery occlusion may be present in up to 38% of patients with an
AAA.5 Renal compromise may result from inadvertent
procedural vascular occlusion and possible radiographic
contrast nephropathy. Renal assessment and protection strategies may improve postoperative outcomes.
Determination of serum creatinine and estimated glomerular filtration rate (eGFR) will help guide potential
renal protection strategies. An analysis of the effect of
renal status on postoperative outcomes in 8,701 patients
in the National Surgical Quality Improvement Program
database was recently reported.9 Patients were assigned
to a chronic kidney disease (CKD) class based on eGFR
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values according to the National Kidney Foundation
clinical guidelines.10 With the CKD classification system,
the eGFR and CKD severity were categorized as normal
to mild (CKD stage 1 or 2), moderate (CKD stage 3), and
severe (CKD stage 4 or 5). This information is presented
in Table 3. The presence of moderate or severe CKD
is associated with significantly increased mortality and
therefore should figure prominently in clinical decision
making. The high mortality in AAA repair in patients
with severe CKD may be a contraindication to an elective
repair except in extenuating clinical circumstances.9 In
a retrospective analysis of 208 patients who underwent
EVAR, acute kidney injury occurred in 15% to 19% of patients.10 Major risk factors for renal injury are preexisting
renal disease (eGFR < 60), advanced age, operative time,
contrast volume, and preoperative use of angiotensinconverting enzyme inhibitors.
Intravenous hydration to maintain an adequate urine
output is effective in reducing renal complications. This
requires careful management in patients with renal
disease. They may benefit from strategies to minimize
the inherent renal risks of EVAR, including the use of alternate diagnostic methods that allow for the administration of reduced volumes or different contrast mediums.
Other strategies that may reduce renal injury include the
administration of N-acetylcysteine, preoperative bicarbonate, and ascorbic acid.4,6 Diabetic patients should be
managed according to standard hospital protocols.
Intraoperative Considerations
Intraoperative objectives for patients undergoing EVAR
should focus on maintaining hemodynamic stability, providing analgesia and anxiolysis, and planning to rapidly
convert to general anesthesia (GA) if an open procedure is
necessary. Anesthetic techniques employed during EVAR
can include GA, neuraxial (spinal and epidural) anesthesia, or local infiltration with sedation. Traditionally,
GA or neuraxial anesthesia (NA) was the preferred anesthetic techniques for EVAR. Currently, there is evidence
to suggest that patients who receive local anesthesia
(LA) with sedation or NA, compared with GA, have
decreased cardiac, respiratory, and renal complications;
fewer postoperative admissions to the intensive care unit
(ICU); and a decreased length of hospitalization.11-15
Researchers evaluated more than 5,500 patients from
the EUROSTAR database in an attempt to determine if
anesthesia influenced patient outcomes: mortality, morbidity, hospital stay, and ICU admission. There were no
significant differences in mortality, but a reduction in
cardiac complications, decreased overall ICU stay, and
length of hospitalization was achieved for those patients
who received LA as the primary anesthetic.16 Results
from studies also indicated that plasma catecholamine
concentrations and mediators of the systemic immune
response were decreased in patients who underwent
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StageDescription
GFR
1
Kidney damage with normal or increased GFR
> 90 (with CKD
risk factors)
2
Kidney damage with mild or decreased GFR
60-89
3
Moderately decreased GFR
30-59
4
Severely decreased GFR
15-29
5
Kidney failure
< 15 (or dialysis)
Table 3. National Kidney Foundation Classification:
Stages of Chronic Kidney Disease
Abbreviations: GFR, glomerular filtration rate; CKD, chronic kidney
disease.
(Adapted from Pisimisis et al.10 Used with permission.)
EVAR compared with conventional open repair.17 Plasma
cortisol release was lower in patients having EVAR than
in traditional open AAA repair. The EVAR group also
experienced a decreased incidence of sepsis and systemic
immune response syndrome.18 Endograft complications
that can arise from EVAR include thrombosis, EVSG
migration or rupture, and infection. Procedural complications include iliac artery rupture and lower extremity
ischemia.19 Fatal cerebral embolism resulting in sudden
respiratory arrest has also occurred during EVAR.20
A consensus regarding the preferred anesthetic technique
for EVAR has yet to be determined. Indications for GA, NA,
and LA for EVAR are listed in Table 4. Research is ongoing
to determine an ideal anesthetic technique that results in a
decreased mortality within 30 days postoperatively.
• General Anesthesia. General anesthesia is most
often reserved for complex vascular anatomy or if the
patient is unable to tolerate NA or LA. The use of GA
has been associated with increased blood loss, volume of
ionized contrast medium administered, and exposure to
radiation compared with LA and NA.11 A review of more
than 6,000 EVAR procedures from the American College
of Surgeons National Surgical Quality Improvement
Program database indicated that increased pulmonary
complications and longer hospitalization are associated
with GA.21 In healthy patients, cerebral and coronary
artery autoregulation is maintained at a mean arterial
pressure between 60 mm Hg and 140 mm Hg.22 When
mean arterial pressures are below this general range,
blood flow becomes largely pressure dependent. For
patients with vascular disease, it must be assumed that
there is some degree of angiopathology in the cerebral
and coronary vasculature. Higher mean arterial pressures may be necessary to adequately perfuse the heart
and brain because of autoregulatory changes. One of the
most important intraoperative goals during GA for EVAR
includes achieving hemodynamic stability and maintaining adequate blood flow to vital organs.
• Neuraxial Anesthesia. Spinal anesthesia can be successfully performed using 0.75% bupivacaine as a single
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General anesthesia
Neuraxial anesthesia
Local anesthesia
• Retroperitoneal approach
•History of difficult airway management
• History of difficult airway management
• Local anesthetic allergy
•Cardiac, respiratory, and renal disease
•Inability to obtain patient
cooperation
• Sleep apnea
•Severe cardiac, respiratory, and renal
disease
• Severe gastroesophageal reflux
• Obstructive sleep apnea
•Inability to lie still for
long periods of time
• Need for an awake patient
• Severe gastroesophageal reflux
• Previous groin surgery
•Currently prescribed antiplatelet or anticoagulant medications
• Surgeon’s preference
• Need for an awake patient
• Severe anxiety
•Challenging aneurysm
morphology
• Obesity (BMI > 35 kg/m²)
•Need for associated abdominal
procedures requiring general
anesthesia
•Need to convert to open aortic
repair
Table 4. Indications for the Use of General, Neuraxial, and Local Anesthesia for Endovascular Aortic Repair
Abbreviation: BMI, body mass index.
injection. Epidural anesthesia using 0.5% bupivacaine
divided into 5-mL bolus doses to achieve a T6-T8 level
provides adequate anesthesia. Additional bolus doses
may be given throughout the intraoperative period. The
use of NA eliminates pain associated with initial cannulation, dilation, and manipulation of the femoral arteries, and it prevents movement of the lower extremities.
Systemic anticoagulation is established before sheath
insertion and EVSG deployment. Because of systemic
anticoagulation, the potential risk of hemorrhage from
neuraxial techniques is increased. If an epidural catheter
has been placed, the return of normal coagulation parameters should be verified before removal.
• Local Anesthesia. The pain associated with EVAR
originates from cannulation of the femoral artery.
Adequate anesthesia can be accomplished by providing both bilateral ilioinguinal and iliohypogastric nerve
blocks and local infiltration at the femoral insertion
sites using local anesthetics combined with epinephrine.
Sedation is titrated for patient comfort while maintaining
adequate spontaneous ventilation. Dexmedetomidine and
remifentanil may be especially useful because of their
short duration of action. Dexmedetomidine can work synergistically with opioids decreasing the transient ischemic
pain associated with femoral artery occlusion during stent
deployment.23 Furthermore, dexmedetomidine has the
potential to cause diuresis by inhibiting vasopressin secretion, inducing sympatholysis and enhancing glomerular
filtration resulting in an increase in urine output, which
may help to clear radiographic contrast dye.
When receiving LA compared with NA and GA, the
patient retains the ability to sense severe discomfort
during insertion of the femoral sheaths. Ischemic pain
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resulting from femoral artery occlusion by the sheath
can be a sign of impending femoral artery rupture.23 In
addition, the use of LA may promote improved hemodynamic stability because fewer cardiac and respiratorydepressant medications are required.
The preferred monitoring for EVAR is outlined in Table
5. Arterial blood pressure monitoring should be considered
before the beginning of the procedure, especially since this
patient population has vascular and cardiac comorbidities
and accurate blood pressure measurements are necessary to guide therapeutic interventions. Venous access
should consist of 1 to 2 large-bore peripheral IV access
and is strongly recommended. Central venous access can
be considered in patients with severe cardiac disease, although many researchers believe it is not required because
prolonged infusions of vasoactive medications and ICU
admissions are rare.24 Lead shielding is required for the
patient and OR personnel because of extensive use of
radiologic imaging during EVAR. Bradycardia can occur
during deployment of the EVSG because of increased pressure transmitted to the aortic baroreceptors. If bradycardia
occurs, it is most often of short duration and can be treated
by anticholinergic medications.
A major complication during the EVAR procedure is
severe hemorrhage. Hemorrhage may occur from damage
to the femoral arteries or aortic rupture. A type and
screen should be ordered and resuscitation equipment
should be readily available, as shown in Table 5.25 The
anesthetist should be prepared to secure the patient’s
airway with an endotracheal tube in the event that surgeons need to convert to an open procedure. If there is
substantial blood loss, rapid transfusion of blood and
blood products should be initiated.
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MonitoringEquipment
• Five-lead electrocardiography
• Intravenous access supplies
• Pulse oximetry
• Forced-air convective warming device
• End-tidal CO2
• Fluid warmers
• Automatic intermittent blood pressure cuff
• Crystalloid and colloid fluids
• Temperature monitor
• Invasive monitoring access supplies and transducers
• Foley catheter
• Medication infusion pumps
• Intra-arterial pressure monitoring
• Level 1 rapid infuser
• Central venous pressure monitoring (as indicated)
• Blood analysis equipment
• Type and screen
• Lead aprons for OR personnel
•Electrolytes
• Complete blood cell count
• Coagulation assays
• Blood glucose
Table 5. Anesthetic Preparation for Endovascular Aortic Repair
Abbreviations: CO2, carbon dioxide; OR, operating room.
Thoracic Endovascular Aortic Repair
•Endoleak
Thoracic aortic aneurysms comprise 25% of aortic aneurysms and affect approximately 15,000 people in the
United States per year.26 In 2010, the American College
of Cardiology Foundation and other organizations proposed evidence-based guidelines for the diagnosis and
treatment of patients with thoracic aortic disease.27 These
experts recommend that thoracic endovascular aortic
repair (TEVAR) be strongly considered for patients with
degenerative or traumatic aneurysms of the descending
thoracic aorta exceeding 5.5 cm, saccular aneurysms, or
postoperative pseudoaneurysms.27 Thoracic endovascular
aortic repair has been used for treatment of aneurysms of
the descending aorta and more proximal aneurysms using
2-staged or hybrid procedures such as combined endovascular and surgical extra-anatomic bypass grafting.26
Intraoperative transesophageal echocardiography has
gained increasing acceptance because of its ability to
assess ventricular function and provide diagnostic information.28 Somatosensory and motor evoked potentials
and electroencephalographic monitoring have also been
used to assess spinal cord and cerebral ischemia, respectively.26,28 Cerebrospinal fluid (CSF) drainage is recommended as a spinal cord protective strategy to promote
spinal cord perfusion in TEVAR and open procedures for
patients at high risk of spinal cord ischemic injury. Spinal
cord ischemia and stroke remain the most devastating
complications associated with TEVAR. The incidence
has been reported to be as high as 8%.26 However, the
incidence of paraplegia has been reported to be as high
as 20% when aortic cross-clamping is used in an open
approach.29 Compromised blood flow as a result of hypotension, graft occlusion, inadequate collateral perfusion, or atheroembolism to the anterior spinal artery or
vertebral arteries has been suggested as possible causes.
Intraoperative neuromonitoring, blood pressure support
• Arterial damage
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o Iatrogenic aneurysm rupture
oIliac artery damage during arterial access, placement of
sheath, or delivery device
o Iliac or aortic dissection
•Embolization (distal embolization of atheromatous material
causing ischemia to the bowel, lower extremities, spinal
cord, kidneys, or other organs; proximal embolization to the
aortic arch causing cerebral ischemia and neurologic deficit)
• Hemorrhage, either overt or covert (eg, retroperitoneal)
• Endograft-related complications
o Failed or delayed displacement of graft
o Migration or malpositioning of graft
o Occlusion of renal, mesenteric, or other major aortic ostia
•Contrast related complications (eg, allergic reaction to
contrast media, contrast nephropathy)
•Postimplantation syndrome (eg, fever, back pain,
leukocytosis, elevated C-reactive protein)
•Infection
Table 6. Surgical-Related Complications Associated
With Endovascular Aortic Repair
(Adapted from Smaka et al24 and Walker et al.30 Used with
permission.)
with volume expansion and vasopressor therapy, and
lumbar CSF drainage have been cited as strategies to decrease the risk of spinal cord ischemia.26,28
Postoperative Considerations
Postoperative considerations related to EVAR can be
divided into patient and surgical-related complications.
These may be attributed to coexisting medical conditions
such as cardiac, renal, respiratory, and other vascular
disease. Subsequent exacerbation of an underlying pathologic process, for example, myocardial ischemia, acute
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Classification
Defining characteristics
Type 1Failure to achieve complete seal between
endograft and aortic or iliac artery wall;
persistent flow into aneurysm sac
through proximal or distal endograft
attachment site
Type 2Retrograde flow into aneurysm sac,
usually from lumbar artery or inferior
mesenteric artery
Type 3Flow into aneurysm sac due to inadequate
overlap at junction of modular graft
components or to defect in graft fabric
Type 4Blood flow through pores in fabric of
stent graft into aneurysm sac
Table 7. Classification of Endoleak (Types 1-4)
(Adapted from Smaka et al24 and Walker et al.30 Used with
permission.)
Figure 2. Schematic Representations of Endoleak
(Types 1-4)a
a Type 1 endoleak = inadequate proximal graft seal resulting in
kidney injury, or respiratory failure, occurs because of
the physiologic stress of surgery and anesthesia. Surgicalrelated complications are found in Table 6.24,30
Endoleak, or continued blood flow outside the EVSG
into the residual aneurysm sac, is the most common
surgical complication following EVAR.30 Endoleak diagnosed with the use of postoperative computed tomography (CT) has been reported to occur in 15% to 52% of
patients.31 Endoleak may cause aortic rupture by exposing the weakened aneurysm wall to continued pressure
from blood flow. Endoleaks are classified according to
the source of continued perfusion of the aneurysm sac.
Characteristics and an illustration of endoleak can
be found in Table 7 and Figure 2.24,30 Type 2 endoleaks
caused by collateral retrograde flow are the most common
type of endoleak. Seventy percent of type 2 endoleaks are
self-limiting and resolve spontaneously in the first month
after implantation.31 Type 1 and type 3 endoleaks may
require secondary reintervention to minimize blood flow
to the aneurysm sac. Treatment of an endoleak varies according to patient symptoms and radiographic findings,
and may involve medical management or surgical intervention. Possible surgical reintervention may include
coil embolization, endograft removal, implantation of a
graft sleeve, or open repair.3,30 If secondary endovascular
reinterventions fail, then an open abdominal aortic aneurysmectomy is required.
Because of the lack of quantitatively established longterm outcomes, postoperative follow-up care for patients
who have undergone EVAR is critical. Physical examination and contrast medium–enhanced CT are recommended at 1, 6, 12, and 18 months postoperatively and then
annually. Abdominal radiographs should be obtained
on a regular basis. Lifelong radiographic evaluation and
surveillance is necessary to monitor aneurysm size, graft
migration, and endoleak. Intensive follow-up care, the
need for reinterventions, and the cost of the endograft
make EVAR more expensive than open repair.32
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perigraft blood flow; type 2 endoleak = retrograde blood flow
from collateral vessels pressurize aneurysm sac; type 3 endoleak
= graft failure and modular disconnection of graft sections; and
type 4 endoleak = blood flow through graft skin over time.
Three prospective randomized trials comparing early
and late morbidity and mortality following open repair
and EVAR have been reported. The results indicate the
following: (1) the 30-day morbidity rates are significantly
lower after EVAR than open repair; (2) 2-, 4-, and 6-year
morbidity rates are similar in both groups; and (3) reintervention rates after EVAR are higher than after open
repair.33 A multicenter, randomized trial by Lederle et
al34 determined that no significant difference existed in
long-term (9-year) all-cause mortality between EVAR
and open repair. This may be due to the fact that the life
expectancy for patients with severe systemic angiopathology is decreased. Endovascular aortic repair was also
associated with improved long-term outcome for patients
less than 70 years of age, but for older patients EVAR
reduced survivability.34
A comprehensive knowledge of all aspects of the surgical procedure and the patient’s physical status is necessary for competent anesthesia care. Despite the minimal
surgical invasiveness of EVAR compared with the traditional open procedure, serious and life-threatening
complications such as massive hemorrhage, myocardial
or cerebral infarction, embolism, acute kidney injury,
and vascular damage are possible. By being informed and
prepared, all members of the surgical team can safely
contribute to high-quality patient care in patients undergoing EVAR.
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AUTHORS
Sass Elisha, CRNA, EdD, is the assistant director of the Kaiser Permanente
School of Anesthesia in Pasadena, California. Email: [email protected].
John Nagelhout, CRNA, PhD, FAAN, is the program director of the
Kaiser Permanente School of Anesthesia in Pasadena, California.
Jeremy Heiner, CRNA, EdD, is an educator at the Kaiser Permanente
School of Anesthesia in Pasadena, California.
Mark Gabot, CRNA, MSN, is an educator at the Kaiser Permanente
School of Anesthesia in Pasadena, California.
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