Endovascular Repair of AAA and TAA

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• Endovascular Repair of AAA and TAA
• A. Berezin, MD, Ph.D
• 2/14/2007

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Endovascular Repair of AAA
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Endovascular Repair of AAA
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Endovascular Repair of AAA

• Current estimates are that more than 20000
  EVAR procedures take place each yeas in the USA,
  which represents 36 of all AAA repair.
• The estimate is that gt12 of all procedures in
  Europe are with EVAR, and expected annual growth
  is 15 at this time.
• The endovascular repair of AAA and TAA has
  became a viable alternative to open repair and is
  often the approach of choice for high risk
  patients because of its
  minimal incisions,
  
  shorter operating time
  reduced blood
  loss.

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Endovascular Repair of AAA

• A ruptured AAA has a mortality rate
  approaching 90.When an AAA is repair
  electively, the mortality drops to less than
  5.AAA affects 4 7 of adult over the age of
  65 years, with a far greater prevalence in male
  than in female, this problem will encounter more
  frequently as population ages.

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Indications for AAA treatment

• Patients with symptomatic aneurysms should
  be offer repair, after careful consideration of
  comorbidities, even if the aneurysm is not of
  usual elective operation size.
  Patients with the aneurysm
  increases in size by 1 cm per year.

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Indications for AAA treatment

• Most asymptomatic AAAs are discovered by
  accident often on imaging examination for other
  complains.
• For the patients with asymptomatic AAAs there
  is guidelines to help plan further surveillance
  or operative repair.
• The size of the AAA is one factor, and the
  operative approach is another.
• In general, the clinical recommendation
  remains to offer treatment for AAA between 5 and
  5.5 cm, depending on the results of clinical
  trials.

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Clinical and Anatomical Selection Factors

• Patient selection has emerged as the most
  important factor related to successful EVAR.
• 3D reconstruction CT scan or angiography with
  a calibrated catheter necessary for assessment
  for EVAR eligibility.
• Proximal neck diameter, length, angel,
  presence or absence of thrombosis
• Distal lending zone diameter and length
• Iliac arteries presence of aneurysm or
  occlusive disease
• Access arteries diameter, presense of
  occlusive disease
• Up to 37 of all patients may NOT be suitable
  candidate for EVAR of their infrarenal AAA.

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Evaluation for EVAR

• Contraindications for EVAR
• Short of proximal neck
• Thrombus present in proximal landing zone
• Conical proximal neck
• Greater than 120º angulations of the proximal
  neck
• Critical inferior mesenteric artery
• Significant iliac occlusion
• Torture of iliac vessels

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EVAR AAA Repair
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Indication for EVAR AAA repair

• Open repair is advocated for younger,
  lower-risk patients.
• Open surgical repair of AAA has proven
  long-term durability.
• EVAR is preferred for older, high risk
  patients.
• EVAR has shown a reduction in 30-day
  mortality relative to that achieved with open
  repair ( 1.2 versus 4.6 )
• EVAR follow up is now 15 years.
• Further study is required to determine whether
  there is a long-term survival advantage.
• Risk stratification determines survival in
  general and shows that both open surgery and EVAR
  decrease the risk of death from AAA rupture

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EVAR complications

• Deployment related
• Failed deployment
• Bleeding
• Hematoma
• Lymphocel
• Infection
• Embolization
• Perforation
• Arterial rupture
• Dissection
• Device related
• Structural failure

• Implant related
• Endoleaks
• Limb occlusion/stent-graft kink
• Sac enlargement/proximal neck dilatation
• Stent migration
• AAA rupture
• Infection
• Buttock/leg claudication

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EVAR complications

• Systemic
• Cardiac
• Pulmonary
• Renal insufficiency, contrast-induced neuropathy
• Deep vein trombosis
• Pulmonary embolism
• Coagulopathy
• Bowel ischemia
• Spinal cord ischemia

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EVAR complications

• Endoleak is the most common complications,
  greater than 20 - 30 in some studies.
• An endoleak is define as persistent blood flow
  outside the wall of the stent into the aneurysmal
  sac.
• The endoleak exposes the weak aneurysm wall to
  continues flow that may lead to rupture.
• Any increase in the aneurysm sac warrants
  immediate repair.

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Classification of Endoleaks

• I Attachment site leaks
• Proximal end of endograft
• Distal end of endograft
• Iliac occluder ( plug )
• II. Branch leaks ( without attachment side
  connection )
• Simple or to-and-fro (from only 1 patient branch)
• Complex or flow-through ( with 2 or more patient
  branches).
• III. Graft defect
• A. Junction leak or modulator disconnect
• Fabric disruption ( midgraft hole )
• IV. Graft wall ( fabric ) porosity ( lt30 days
  after graft placement )

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Intraoperative management, M.M.Mondecai,2004

• The procedure is less invasive.
• Requires minimal anesthesia.
• Less likely to induce homodynamic stress.
• May still be associated with risks and
  complications of any aortic surgery such as
  massive sudden blood loss because of aortic
  rupture.

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Monitoring during EVAR of AAA

• Appropriate catheters for homodynamic
  monitoring
• Large-bore intravenous catheter.
• Arterial catheter for continuous BP monitoring
  and to collect samples for ABG, Hb, clotting
  time.
• CVP line should be consider to provide central
  vasopressors delivery and to maintain adequate
  intravascular volume.
• PA catheter or TEE can provide more accurate
  assessment of cardiac function and intravascular
  volume in patients with poor LV function or renal
  failure.
• A Foley catheter is an additional measure of
  volume status.

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General Anesthesia, M.M.Mondecai,2004

• GA typically consist of a balance technique
  with low-dose inhalation agent and opioids.
• Neuromuscular blockers are typically not
  necessary.
• The case can be perform with laryngeal mask.
• GA provides
• maintain of potency of airway
• allows for homodynamic manipulation
• accommodate for variation in duration of
  operation
• reduce the possibility of patient movement
• allows for control of respiration during
  fluoroscopy

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General Anesthesia, M.M.Mondecai,2004

• Placement intravascular lines or monitors is
  more easier.
• Supine position tolerates better during long
  operation.
• GA is
• associated with more hypotensive episodes
• increased fluid requirement
• increased use of inotropic support compare
  to RA

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Regional Anesthesia, M.M.Mondecai,2004

• Spinal, epidural, and combined spinal-epidural
  techniques have been used.
• T 10 sensory level is needed for iliac
  arteries exposure provides fever homodynamic side
  effect.
• Advantages of EA
• ability to titrate
• achieve the appropriate sensory level
• accommodate variation in duration of the
  procedure
• minimize hemodynamic changes
• shorter postoperative hospital stay

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Regional Anesthesia, M.M.Mondecai,2004

• Potential disadvantages with RA
• difficulties in patient comfort while placing
  intravascular lines
• patient tolerance for supine position on the
  OR table
• need to convert to GA if procedure is
  converted to an open repair
• low risk of spinal or epidural hematoma while
  receiving intrapoperative Heparin

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Local anesthesia, M.M.Mondecai,2004

• Local anesthesia well tolerated for
  transfemoral approach
• Decrease fluid requirement
• Decrease operating time
• Decrease of innotropic agent
• Decrease of hospital stay
• Patient commonly feels pain during dilatation
  which resolves with deflation of balloon.
• Persistent pain after deflation of the balloon
  may indicate arterial rupture with extravasation
  and should be investigated.

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PVB vs GA for EVAR of AAA, J.Falkensammer et al,
2006 (Jacksonville, FL)

• 10 pt with AAA repair with PVB with propofol
  sedation ( 1 case conversion to GA due to block
  failure) vs 15 pt. with GA
• PVB (paravertebral blockade)
• less hypotension
• less blood pressure liability
• less postoperative PONY
• PVB can be perform safely in pt. with
  significant comorbidities

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RA or LA techniques, M.M.Mondecai,2004

• With RA or LA preparations must be made for
  conversion to GA
• acute aortic rupture with hypotension (
  hypotension may include an allergic reaction to
  contrast dye and a side effect of adenosine)
• in the event of open procedure
• if further access to the ileac arteries is
  needed
• if patient is unable to tolerate supine
  position
• innotropic and vasodilatating agent should be
  prepared for the treatment of homodynamic
  instability

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Proximal Graft Deployment, R.A.Kaplan et al,

• Induced hypotension during device deployment
  has been used successfully to assist in proximal
  placement and may reduce the magnitude of
  migration
• pharmacological induction of sinoatrial and
  atrioventricular nodal inhibition with high dose
  of Adenosine
• induced ventricular fibrillation (by
  applying an alternating current to the
  endocardial surface through a temporary
  transvenous ventricular pacing lead)
• using Nitroglycerin or Sodium Nitroprusside

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Postoperative care, M.M.Mondecai,2004

• Recovery after uncomplicated EVAR does not
  routinely require the use of ICU.
• Analgesic requirement are minimal and can
  managed with small boluses of opioids or NSAID.
• Postinflamation syndrome related to a systemic
  inflammatory response to graft material can
  occur, manifesting with fever, leukocytosis, and
  increase C-reactive protein concentration.
• Hyperepyxia can be associated with
  tachycardia.
• The average length of stay in the hospital is
  minimal.

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EUROSTAR DATA, 2006

• Influence of anesthesia on outcome after
  endovascular AAA repair.
• From 7/1997 to 8/2004, 5557 pt. underwent EVAR
  repair in 164 centers were enrolled in the
  EUROSTAR registry.
• General anesthesia (GA-G) - 3848 pt. (69)
• Regional anesthesia (RA-G) - 1399 pt. (25)
• Local anesthesia (LA-G) - 310 pt. (
  6)
• Multivariable logistic regression analysis was
  performed on early complications.

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EUROSTAR DATA , 2006
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EUROSTAR DATA, 2006

• EUROSTAR data indicate that patients appeared
  to benefit when a locoregional anesthetic
  technique was used in EVAR.
• Locoregional technique should be used more
  often to enhance the preoperative advantage of
  EVAR in the treating AAA.
• Ultimately, a prospective randomize study is
  necessary to clarify the question of which method
  of anesthesia is suitable.

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EVAR vs. open ruptured AAA repair, J.J. Visser,
et al 2006, Netherlands, MGH
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EVAR vs. open ruptured AAA repair, J.J. Visser,
et al 2006, Netherlands, MGH
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EVAR vs. open ruptured AAA repair, J,J, Visser,
2006

• Mortality and complications rates after EVAR
  may be similar compared with those after open
  surgery in patients treated for ruptured
  infrarenal AAA.

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If emergency EVAR associated with higher
secondary intervention in AAA repair

B.I. Orenan et al, 2006, Netherlands
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Is emergency EVAR associated with higher
secondary intervention in AAA repair ( B.I.
Orenan et al, 2006)

• To our surprise, emergency endovascular AAA
  repair did not present with higher secondary
  intervention rate at mid-term follow- up ( 38
  26 month).

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Long-term outcome after EVAR AAA The First
Decade, Brewster D.C et al, 2006, MGH

• 873 pt underwent EVAR since 1/1994 to 12/2005
• Mean follow up was 27 month
• 39 of pt had 2 or more major comorbidities
• 19 of pt. would be categorized as unfit for open
  repair
• Device deployment was successful in 99.3
• 30 day mortality was 1.8
• Freedom from AAA rupture was 97.6 at 5 years and
  94 at 9 years
• Significant risk factor for late AAA rupture
  included female gender and device related
  endoleak
• Aneurysm related death was avoided in 96
• 87 (10) pt. required reintervention, with 92
  being catheter-based and a success rate of 84
• Predictor for reintervention first generation
  device and late onset endoleak

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Long-term outcome after EVAR AAA The First
Decade, Brewster D.C et al, 2006, MGH

• Current generation stent graft correlated with
  significant improve outcome.
• Cumulative freedom from conversion to open
  repair was 93 at 5 through 9 years.
• Cumulative survival was 52 at 5 years.
• EVAR using contemporary devices is a save,
  effective, and durable method to prevent AAA
  rupture and aneurysm related death.
• Assuming suitable AAA anatomy, these data
  justify a broad application of EVAR across a wide
  spectrum of patients.

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2 year Outcomes after Conventional of EVAR of
AAADREAM Trial Group, 2005

• Randomized trial, multicenter comparing open
  repair with EVAR in 26 centers in Netherlands and
  4 centers in Belgium.
• Open repair
  EVAR
• 
  178 pt 173 pt
• 2 y survival rate 89.6
  89.7
• Aneurysm related death 5.7
  2.1
• Survival free of complications 65.9
  65.6
• The perioperative survival advantage with EVAR
  repair as compare with open repair is not
  sustained after the 1-st postoperative year.

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Cost EVAR repair, Abularrage CJ, et al. 2005
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Cost EVAR repair, Abularrage CJ, et al. 2005
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Endovascular TAA repair

• The first thoracic stent graft was deployed for
  TAA exclusion in 1992
• Cumulative clinical experience is estimated
  5000 implants worldwide has yielded short- to
  mid-term data that demonstrated promising
  results.
• 3 clinical trials are approval by FDA
• TAG (W.L. Gore and Associates, Inc),
  Talent (Medtronic,
  Inc),
  TX2 (Cook, Inc).
• The endoprosthesis are composed of a metal
  skeleton (nitinol, stainless steel, Elgiloy)
  covered with fabric ( polyester or
  polytetrafluoroethylene PTFE).
• Graft can be deployed by a self-expanding
  mechanism or balloon expansion.

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TAA repair

• With an incidence of 6 to 10 per 100 000
  person-years TAAa less common than AAA but
  remain life-threatening.
• With an associated mortality rate of 94, TAA
  rupture is usually a fatal event.
• The 5 years survival rate of unoperated TAA
  patients approximates 13, whereas 70 to 79 of
  those who undergo elective surgical intervention
  are alive at 5 years.
• The risk of rupture mandates consideration for
  surgical treatment in all patient who are
  suitable for operation.

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Complications TAA repair

• Mortality for TAA surgical repair ranges from
  5 to 20 in elective cases and to 50 in
  emergent situation.
• Major complications associated with surgical
  TAA repair include
• Renal and pulmonary failure
• Visceral and cardiac ischemia, stroke
• Paraplegia
• Paraplegia occurring in 5 to 20 of cases
  versus lt1 for AAA.
• For these reasons, a significant population of
  TAA patients are not candidate for open repair
  and have been without a treatment options until
  recently.

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Endovascular TAA repair

• Development of stent grafting in the TA has
  progress more slowly
• 1. The hemodynamic forces of the TA are
  significantly more aggressive and place greater
  mechanical demand of thoracic endografts. The
  potential for devise migration, kinking, and late
  structural failure are important concerns.
• 2 .Greater flexibility is required of
  thoracic devices to conform to the natural
  curvature and to the lesions with tortuous
  morphology.
• 3. Because larger devices are necessary
  arterial access is more problematic.
• 4. TAA can often extend beyond the
  boundaries of the descending TA and involve more
  proximal or distal aorta the desired.

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Anatomical Requirements for Repair of TAA

• A proximal neck at least 15 to 25 mm from the
  origin of the left subclavian artery.
• A distal neck at least 15 to 25 mm proximal to
  origin of the celiac artery.
• Adequate vascular access absence of severe
  tortuosity, calcification, or atherosclerotic
  plaque burden involving the aortic or pelvic
  vasculature.
• The transverse diameter of the proximal and
  distal neck should be within the range that
  available devices can appropriately accommodate.

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EVAR TAA Repair
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Indications for Endovascular Repair

• Patient for TAA repair considers their overall
  risk profile
• evidence of rapid enlargement of aneurysm,
  diameter gt 6cm,
  
  presence of symptoms
• Endovascular stent grafting is currently
  reserved for high-surgical-risk and nonoperative
  patients who have suitable anatomic features.
• High resolution 3D rendering of the aorta,
  catheter based angiography remains the gold
  standard which helps to select the appropriate
  device diameter and length.
• Determination of aneurysm location in relation
  to the left subclavian and celiac axis is up most
  importance.

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Requirements for EVAR Repair

• Vascular access route must be of sufficient
  size.
• Small-diameter of femoral arteries, tortuous,
  and excessive calcified of iliac arteries
  requiring more proximal retroperitoneal exposure.
• Severe stenosis and tortuosity of abdominal
  or thoracic aorta distal to the target are
  contraindication for endovascular repair.
• Treatment failure can occur.
• Follow up surveillance with serial CT scan at
  1, 6 and 12 months is recommend to monitor
  changes in aneurysm morphology, identify device
  failure and detect endoleaks.

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Endovascular Repair of TAA

• Successful device deployment is achieved in
  85 to 100 of cases.
• Preoperative mortality ranges from 0 to 14,
  falling within or below elective surgery
  mortality rates of 5 to 20.
• Outcomes have improved over time
• with accumulative technical experience
• use of commercially manufactured devices
• improved patient selection criteria

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Endovascular Repair of TAA

• Collective experiences of the EUROSTAR and
  United Kingdom Thoracic Endograft registries
• the largest series to date ( n249)
• demonstrate successful rate deployment in
  87 of cases
• 30-days mortality of 5 for elective cases
• paraplegia and endoleak rates of 4
• FDA phase II trial data from exclusive
  deployment of the Gore TAG endograft in 142 TAA
  patients reveal similar resuils
• technical success in 98
• 30-days mortality of 1.5
• endoleak in 8.8

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Complications

• Endoleak is less than reported for AAA
  endograft repair.
• More commonly at the proximal or distal
  attachment sides ( type I)
• represent direct communications between the
  aneurysm sac and aortic blood flow.
• Treatment options include
• transcatheter coil
• glue embolization
• balloon angioplasty
• placement of endovascular graft extention
• open repair

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Paraplegia

• Incidence of paraplegia is lower due to
• avoidance of aortic cross-clamping
• avoidance prolonged iatrogenic hypotension
• Occurrence of paraplegia is associated with
• concomitant or prior surgical AAA repair
  increased exclusion length because
  of the absence of lumbar and hypogastric
  collateral circulation.

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Strategies to Manage Paraplegia Risk after EVAR
Repair of TAA, AT Cheung,2005

• 75 pt ( male49, female26, age 75/-7.4
  years)
• Lumbar CSF drainage ( n23) and Somatosensory
  EP monitoring ( n15) were performed selectively
  in pt. with significant aneurysm extent or with
  previous AAA repair (n17).
• Spinal cord ischemia occurred in 5 pt. ( 6.6
  )
• 2 had SSEP loss after stent deployment
• 4 developed delayed-onset paraplegia
• 2 had full recovery in response to art.
  pressure augmentation alone
• 2 had full recovery
• 1 had near-complete recovery in response to
  art. pressure augmentation and
• CSF drainage
• The incidence of permanent paraplegia or
  paraparesis was 2.7 (2 0f 75)

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Risks Spinal Cord Ischemia (Chung et al, 2005)

• Previous AAA repair.
• Hypotension associated with an occult
  retroperitoneal bleeding.
• Severe atherosclerosis of the Thoracic aorta.
• Injury to the external iliac artery.
• Extend of the descending Thoracic aorta
  covered by graft.

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Strategies to Manage Paraplegia Risk after EVAR
Repair of TAA, AT Cheung,2005

• Early detection and intervention to augment
  spinal cord perfusion pressure was effective for
  decreasing the magnitude of injury or preventing
  permanent paraplegia from spinal cord ischemia
  after EVAR of descending TAA.
• Routine use of motor and somatosensory evoked
  potential monitoring,
• serial neurological assessment,
• arterial pressure augmentation,
• CSF drainage
• may benefit patients at risk for paraplegia.

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Stent graft vs open repair TAA, D.H.Stone et. Al,
2006, MGH
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Stent graft vs open repair TAA, D.H.Stone et. Al,
2006, MGH

• Operative mortality was halved with Sten-graft,
  with similar late survival for both groups.
• Reinterventions were required at a nearly
  identical rate for open and Stent-graft.
• Spinal cord injury were similar in both groups.

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Endovascular Repair of AAA and TAA

• The introduction of EVAR of aortic aneurysm
  has presented a unique treatment option to
  approximately half of the patients presenting for
  AAA repair.
  The immediate benefits of reducing
  early morbidity, blood loss, length of stay, and
  recovery have been proven.
• The long term success of the EVAR is of
  concern because of the need for lifelong
  surveillance, secondary intervention, and
  continued risk of the aneurysmal rupture .

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Endovascular Repair of AAA and TAA

• As the technology of this surgical technique
  continues to develop, there is hope that material
  and structural designs will help resolve some of
  these issues.
• Indications for endovascular stent graft
  replacement now extend well beyond elective AAA
  repair to include repair of ruptured AAA in
  patients with contained bleeding, TAA aneurysm,
  and aortic injuries caused by trauma.