Vascular: AAA Repair

Open AAA Repair

Selection of Approach

  • Transperitoneal Approach:
    • More Rapid Access (Best in Emergencies)
    • Better Access to Right Renal Artery
    • Better Access to Iliac/Femoral Arteries
  • Retroperitoneal Approach:
    • Better Access to Visceral & Supraceliac Aorta
    • Better Access to Left Renal Artery
    • Avoids Adhesions from Prior Operations
  • Controversy if Equivalent or Lower Complications with Retroperitoneal Approach

Transperitoneal Approach

  • Position: Supine & Arms Abducted
  • Exposure:
    • Midline Incision
    • Retract Transverse Colon Cephalad
    • Retract Small Bowel to the Right
    • Divide the Ligament of Treitz & Retract Duodenum to the Right
      • Avoid Injury to IMV
    • Incise Posterior Peritoneum from Ligament of Treitz Down to the Extent Necessary for Repair
      • Angle to the Right of Aortic Midline to Avoid Injury to IMA
    • If Suprarenal Clamp Needed – Open Posterior Peritoneum Up to the Level of the Renal Veins
      • May Require Renal Vein Division (Divide Close to IVC to Allow Collateral Drainage Through Gonadal, Adrenal & Lumbar Veins)
  • Repair:
    • Systemic Heparinization
    • Clamp Iliacs Distally & Proximal Aorta
      • Distal First to Prevent Thrombus Embolization from Proximal Clamp)
    • Incise an Aortotomy Longitudinally with a T-Shape on Either End
    • Preform Proximal End-to-End Anastomosis
      • First Clear Anastomotic Sites of Thrombus
    • Clear Thrombus from the Aneurysmal Sac
    • Preform Distal End-to-End Anastomoses
      • First Clear Anastomotic Sites of Thrombus
      • Allow Flushing of Graft & Back-Bleeding Before Completing the Anastomoses
  • Closure:
    • Achieve Hemostasis
    • Close Aneurysmal Sac Over the Graft
    • Close Posterior Peritoneum
    • Use Omentum to Separate Graft from Bowel if Unable to Close Sac or Peritoneum
      • Prevents Future Aortoenteric Fistula
    • Close Abdominal Wall

Retroperitoneal Approach

  • Position: Right Lateral Decubitus
  • Exposure:
    • Curved Skin Incision
      • Start Along the 10th Intercostal Space at the Posterior Axillary Line
      • Run onto the Abdomen Lateral to the Lateral Border of the Rectus Muscle
    • Bluntly Dissect Peritoneum Off the Abdominal Wall
    • Identify Left Psoas Muscle Retract Peritoneal/Retroperitoneal Contents Anteromedially
    • Identify & Protect Left Ureter
    • May Divide Left Diaphragmatic Crus to Better Access Supraceliac Aorta
  • Repair:
    • Systemic Heparinization
    • Clamp Iliacs Distally & Proximal Aorta
      • Distal First to Prevent Thrombus Embolization from Proximal Clamp)
    • Incise an Aortotomy Longitudinally with a T-Shape on Either End
    • Resect the Left Renal Artery with a Small Portion of Surrounding Aorta for Later
    • May Preform Endarterectomy or Deploy Stent in Stenosed Celiac or SMA
    • Preform Proximal End-to-End Anastomosis
      • Proximal End Must Be Beveled to Include the Celiac, SMA and Right Renal Artery
      • First Clear Anastomotic Sites of Thrombus
    • Anastomose Left Renal Artery Back to a Side-Branch of the Graft
    • Migrate Proximal Clamp Below the Renal Arteries to Minimize Ischemia Time
    • Clear Thrombus from the Aneurysmal Sac
    • Preform Distal End-to-End Anastomoses
      • First Clear Anastomotic Sites of Thrombus
      • Allow Flushing of Graft & Back-Bleeding Before Completing the Anastomoses
  • Closure:
    • Achieve Hemostasis
    • Return Peritoneal Sac to Normal Configuration
    • Close Abdominal Wall

Specific Vessel Considerations

  • IMA Reimplantation Indications:
    • SMA Stenosis
    • Large IMA
    • Backpressure < 40 mmHg (Poor Collaterals)
    • Previous Colectomy (Risk Injury to Collaterals)
  • Lumbar Arteries:
    • Ligate if Bleeding

Open AAA Repair 1

Endovascular Aneurysm Repair (EVAR)

Anatomic Requirements

  • Aortic Neck (Area Below Renal Arteries & Proximal to Aneurysmal Sac)
    • Diameter < 32 mm (To Allow the Largest Available Graft)
    • Length ≥ 10-15 mm
    • Angulation < 60 Degrees
  • Iliacs
    • External Iliac Diameter ≥ 7 mm
    • Normal Common Iliac Length ≥ 10-20 mm (Allow Adequate Seal)

EVAR Components 2

EVAR Requirements 3

Complications

Endoleak

  • Definition: Persistent Blood Flow into the Aneurysmal Sac After Graft Placement
  • Types: Mn
    • Type I: Incompetent Seal at Attachment Sites
      • Ia: Proximal End
      • Ib: Distal End
    • Type II: From Collaterals (IMA, Lumbars or Accessory Renals) – Most Common (76%)
    • Type III: From Overlap Sites or Tear
      • IIIa: Module Disconnection
      • IIIb: Fabric Disruption
    • Type IV: From Porous Graft Wall or Suture Holes
    • Type V: Endotension (Expansion Without Defined Leak)
  • Treatment:
    • Type I: Repeat Balloon Dilation or Additional Stents to Cover
    • Type II: Observe (Often Resolves Spontaneously)
      • Transarterial Embolization (TAE) if Expands > 5 mm in Follow Up
    • Type III: Additional Stents to Cover
    • Type IV: Observe (Typically Resolve After 24-Hours with Anticoagulation Reversal)
    • Type V: Repeat Endovascular Repair with New Lower-Porosity Graft

Endoleak Types 2

Mortality

  • Most Common Early Cause of Death: MI
  • Most Common Late Cause of Death: Renal Failure

Renal Failure

  • #1 Risk Factor of Any Complication: Cr > 1.8
  • Rates:
    • Acute Renal Failure: 15-20%
    • Dialysis-Dependent Renal Failure: 2.5%
  • Risk Factors:
    • Preoperative Hypotension #1
    • Age
    • Prolonged Clamp Time
    • Suprarenal Clamping

Colonic Ischemia

  • Most Common Site: Left Colon (From IMA Injury)
  • High Mortality (25-55%)
  • Risk Factors:
    • Preoperative Shock (Strongest Risk Factor)
    • Perioperative Transfusion Requirement
    • Ruptured Aneurysm
    • Open Repair
    • Proximal Extension
    • Perioperative Renal Failure Requiring Dialysis
    • Diabetes
    • Female Gender
    • *IMA Reimplantation Not Clearly Associated
  • Presentation: Early Bloody Diarrhea
  • Dx: Proctosigmoidoscopy (Friable Mucosa)
    • *Anoscopy Viewing Rectum Alone is Not Sufficient (Has Collateral Blood Flow)
  • Tx:
    • Partial Thickness: Bowel Rest
    • Full Thickness, Peritonitis or Uncertain: Laparotomy & Resection

Aortoenteric Fistula

  • Graft Erodes into Duodenum (Third-Fourth Portions) at the Proximal Graft Site
  • Sx: Herald Bleed with Hematemesis
  • Dx: EGD (First to Rule Out Other Source of Bleeding), CT
    • Tagged Nuclear WBC Scan if Others Negative
  • If Unstable: Temporize with an Aortic Stent Graft Over the Fistula
  • Definitive Tx Options: Excise All Synthetic Graft Material
    • Classic Technique: Extra-Anatomic Axillobifemoral Bypass & Fistula Closure
    • In Situ (Not Extra-Anatomic) Reconstruction Repair Options:
      • Lower Extremity Deep Veins
      • Cadaveric Human Aortic Homograft
      • Antibiotic-Impregnated Synthetic Grafts

Aortoenteric Fistula on EGD 4

Aortoenteric Fistula 4

Other Complications

  • Lower Extremity Ischemia
  • Spinal Cord Ischemia
  • Respiratory Failure & Pneumonia
  • VTE
  • Graft Infection
    • Most Common Organisms: Staph #1 & E. coli #2
    • Tx: Extra-Anatomic Bypass (Axillobifemoral)
  • Chylous Ascites
  • Major Vein Injury
  • Impotence
  • Pseudoaneurysm
  • Atherosclerotic Occlusion

Mnemonics

Endoleak Types

  • I – Basic Leak from Edges
  • II – From ‘Secondary’ Vessels
  • III – Envision a Tube (I) Within a Tube (II)
  • IV – “Doors”/Pores

References

  1. Piechota-Polanczyk A, Jozkowicz A, Nowak W, Eilenberg W, Neumayer C, Malinski T, Huk I, Brostjan C. The Abdominal Aortic Aneurysm and Intraluminal Thrombus: Current Concepts of Development and Treatment. Front Cardiovasc Med. 2015 May 26;2:19. (License: CC BY-4.0)
  2. England A, Mc Williams R. Endovascular aortic aneurysm repair (EVAR). Ulster Med J. 2013 Jan;82(1):3-10. (License: CC BY-NC-SA-4.0)
  3. Schanzer A, Messina L. Two decades of endovascular abdominal aortic aneurysm repair: enormous progress with serious lessons learned. J Am Heart Assoc. 2012 Jun;1(3):e000075. (License: CC BY-2.5)
  4. Shitara K, Wada R. Gastrointestinal bleeding after aortic surgery: a case report. Cases J. 2009 Nov 23;2:9074. (License: CC BY-2.0)