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Abdominal Aortic Endografts
T. Gregory Walker, MD, FSIR
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KEY FACTS

  • Terminology

    • Preprocedure

      • Procedure

        • Outcomes

          TERMINOLOGY

          • Definitions

            • Abdominal aortic aneurysm (AAA): Localized aortic dilatation exceeding normal diameter by > 50%
              • Various etiologies
                • Majority due to multifactorial degenerative process
                  • Proteolytic degradation of tunica media; basic pathophysiology of AAA development
                  • Significant association with atherosclerosis
                  • Genetic influence; high familial prevalence
                • Inflammatory aneurysms occur in up to 10%
                  • May be symptomatic with fever & pain
                  • May be immune-mediated process
                • Infectious (mycotic) AAA occur in 2%
                  • Usually due to local bacterial seeding of diseased aortic wall or seeding via vasa vasorum
                  • Known for rapid growth, rupture & high mortality
              • Anatomically classified based on renal arteries
                • Infrarenal AAA: Normal aortic segment ≥ 10 mm between renal arteries & most cephalad AAA extent
                  • ~ 90% of AAAs occur infrarenally
                  • Majority treated using endovascular techniques
                • Juxtarenal AAA: Aneurysm extends to renal artery level; normal-caliber aorta above that
                  • Evolving endovascular management techniques
                • Suprarenal AAA: Involves renal arteries & extends to include superior mesenteric & celiac arteries
                  • Complex endovascular &/or surgical treatment
                • AAA may or may not involve iliac arteries
              • Aneurysms also classified by configuration
                • Fusiform: AAA involves extended aortic section
                  • "True" aneurysm involving all 3 wall layers
                  • Typical appearance of degenerative aneurysm
                • Saccular: Focal AAA localized to aortic segment
                  • May be asymmetrical; may be pseudoaneurysm
                  • Infectious aneurysms often have this appearance
            • Iliac artery aneurysm (IAA): Abnormal arterial enlargement ≥ 50% of normal vessel diameter
              • Common iliac artery (CIA) aneurysm defined as transverse diameter > 1.5 cm
                • Most iliac artery aneurysms associated with abdominal aortic aneurysms
                  • Iliac aneurysms present in roughly 20% of AAA
                • Isolated iliac artery aneurysms uncommon
                  • 1-2% of all abdominal aneurysmal disease
                • Internal IAAs rare (≤ 0.4%)
                  • Typically associated with aortic & common iliac artery aneurysms
            • Endograft (stent-graft): Fabric-covered self-expanding stent; excludes vascular pathology from circulation
              • All endografts have 3 components
                • Delivery system for graft introduction, deployment
                • High radial force, self-expanding, metallic stent framework & attachment system
                  • Supports endoprosthesis, attaches to vasculature
                • Impermeable graft fabric surrounding stents
                  • Either expanded polytetrafluoroethylene (ePTFE) or woven polyester fabric composition
                  • Excludes pathology, provides new conduit
              • Endografts for AAA repair have different methods of fixation to vascular wall
                • Proximal endograft attachment methodology
                  • Suprarenal fixation: Bare metallic stent extends proximally above fabric-covered endograft; anchors to perirenal arterial tissues
                  • Infrarenal fixation: No components extend above renal arteries; fixation achieved via radial force of metallic stent which may have barbs
                • Distal endograft attachment methodology
                  • Iliac limbs may be straight, flared, or tapered to conform to anatomy; radial force secures limb
              • 3 basic abdominal aortic endograft configurations; modular designs allow combination of components into patient-specific vascular conduits
                • 1-piece graft body & unilateral limb extension; paired with separate contralateral docking limb
                  • Forms bifurcated graft; simulates aortic anatomy
                  • Most commonly used endograft configuration
                • 1-piece unibody self-expanding endograft; positioned directly upon aortic bifurcation
                  • 2nd component extended cephalad; attaches immediately below lowest renal artery
                • 1-piece aorto-uni-iliac endograft
                  • Modified bifurcated endograft that extends from aorta to single iliac artery distal attachment
                  • Requires surgically created femoro-femoral artery crossover bypass conduit
                  • Frequently used during endovascular aneurysm repair (EVAR) for AAA rupture
            • EVAR: Endoluminal placement of endograft to treat AAA & other pathology
              • Endograft extends proximal & distal to aneurysm
                • Endograft excludes aneurysm from arterial pressure
                  • Dilated & weakened aorta is not exposed to flow
                  • Aneurysm sac thromboses, negating rupture risk
              • Endograft must attach to relatively healthy arterial tissues proximal & distal to aneurysm sac
                • Must achieve effective seal at attachment sites to exclude AAA from continued perfusion, prevent device migration and progression of disease
          • Aneurysm Morphology & Vascular Anatomy

            • Aneurysm morphology
              • Proximal AAA neck: Distance between most inferior renal artery and beginning of aneurysm; preferred proximal seal zone for endograft
                • Many features of neck may affect seal
                  • Length & diameter
                  • Configuration of neck (e.g., straight, conical)
                  • Angle between axis of neck & suprarenal aorta
                  • Angle between axis of neck & infrarenal AAA
                  • Amount of thrombus/calcification in neck
              • Distal AAA neck: Distance between caudal aspect of aneurysm & aortic bifurcation
                • Some features of distal neck may affect EVAR
                  • Excessively small diameter may limit delivery &/or expansion of endograft components
                  • Neck angulation, calcification, & thrombus may impact endograft delivery & deployment
            • Vascular anatomy
              • Aortic branches arising in AAA treatment zone
                • Celiac artery: 1st major abdominal aortic branch; arises at lower margin of 12th thoracic vertebra
                  • Rarely involved in AAA treatment zone
                • Superior mesenteric artery (SMA): Origin from aorta anteriorly, just below celiac artery
                  • Suprarenal stent may extend to/cross origin
                • Renal arteries: Paired arteries that typically demarcate upper limit of proximal aortic neck
                  • Must preserve renal perfusion during/after EVAR
                  • Small accessory renal arteries arising from aneurysm sometimes sacrificed during EVAR
                • Inferior mesenteric artery (IMA): Origin above aortic bifurcation; known cause of type II endoleak
                  • Prophylactically embolized by some operators
                • Lumbar arteries: Paired vessels arise along dorsal aspect of abdominal aorta at each vertebral level
                  • Known cause of type II endoleak
                • Common iliac artery: Origin at aortic bifurcation; divides into external and internal iliac arteries
                  • Preferred distal seal zone for endograft limbs
                • External iliac artery: Extends from common iliac artery bifurcation to inguinal ligament; adequate vessel diameter necessary for endograft delivery
                  • Large common iliac artery aneurysm(s) may require limb extension into external iliac artery
                • Internal iliac (hypogastric) artery: Originates at common iliac artery bifurcation; has 2 trunks
                  • May require embolization or branch device if endograft limb is extended into external iliac artery
                • Common femoral artery: Continuation of external iliac artery below inguinal ligament
                  • Preferred/usual choice for EVAR arterial access

          PREPROCEDURE

          • Indications

            • Contraindications

              • Preprocedure Imaging

                • Getting Started

                  PROCEDURE

                  • Patient Position/Location

                    • Procedure Steps

                      • Alternative Procedures/Therapies

                        POST PROCEDURE

                        • Postprocedure Imaging

                          OUTCOMES

                          • Problems

                            • Complications

                              • Expected Outcome

                                Selected References

                                1. Powell JT et al: Meta-analysis of individual-patient data from EVAR-1, DREAM, OVER and ACE trials comparing outcomes of endovascular or open repair for abdominal aortic aneurysm over 5 years. Br J Surg. 104(3):166-178, 2017
                                2. Sala-Almonacil VA et al: Fenestrated and chimney endovascular aneurysm repair versus open surgery for complex abdominal aortic aneurysms. J Cardiovasc Surg (Torino). ePub, 2017
                                3. Hajibandeh S et al: Percutaneous access for endovascular aortic aneurysm repair: A systematic review and meta-analysis. Vascular. 24(6):638-648, 2016
                                4. Li Y et al: Endovascular versus open surgery repair of ruptured abdominal aortic aneurysms in hemodynamically unstable patients: Literature review and meta-analysis. Ann Vasc Surg. 32:135-44, 2016
                                5. Patel R et al: Endovascular versus open repair of abdominal aortic aneurysm in 15-years' follow-up of the UK endovascular aneurysm repair trial 1 (EVAR trial 1): a randomised controlled trial. Lancet. 388(10058):2366-2374, 2016
                                6. Peters AS et al: Current treatment strategies for ruptured abdominal aortic aneurysm. Langenbecks Arch Surg. 401(3):289-98, 2016
                                7. Spanos K et al: Transition from open surgery to endovascular treatment of abdominal aortic aneurysm rupture. Ann Vasc Surg. 36:85-91, 2016
                                8. Sörelius K et al: Endovascular treatment of mycotic aortic aneurysms: a European multicenter study. Circulation. 130(24):2136-42, 2014
                                9. Lee JT et al: Early experience with the snorkel technique for juxtarenal aneurysms. J Vasc Surg. 55(4):935-46; discussion 945-6, 2012
                                10. Malkawi AH et al: Percutaneous access for endovascular aneurysm repair: a systematic review. Eur J Vasc Endovasc Surg. 39(6):676-82, 2010
                                11. United Kingdom EVAR Trial Investigators et al: Endovascular versus open repair of abdominal aortic aneurysm. N Engl J Med. 362(20):1863-71, 2010
                                12. Walker TG et al: Clinical practice guidelines for endovascular abdominal aortic aneurysm repair: written by the Standards of Practice Committee for the Society of Interventional Radiology and endorsed by the Cardiovascular and Interventional Radiological Society of Europe and the Canadian Interventional Radiology Association. J Vasc Interv Radiol. 21(11):1632-55, 2010
                                Related Anatomy
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                                Related Differential Diagnoses
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                                References
                                Tables

                                Tables

                                KEY FACTS

                                • Terminology

                                  • Preprocedure

                                    • Procedure

                                      • Outcomes

                                        TERMINOLOGY

                                        • Definitions

                                          • Abdominal aortic aneurysm (AAA): Localized aortic dilatation exceeding normal diameter by > 50%
                                            • Various etiologies
                                              • Majority due to multifactorial degenerative process
                                                • Proteolytic degradation of tunica media; basic pathophysiology of AAA development
                                                • Significant association with atherosclerosis
                                                • Genetic influence; high familial prevalence
                                              • Inflammatory aneurysms occur in up to 10%
                                                • May be symptomatic with fever & pain
                                                • May be immune-mediated process
                                              • Infectious (mycotic) AAA occur in 2%
                                                • Usually due to local bacterial seeding of diseased aortic wall or seeding via vasa vasorum
                                                • Known for rapid growth, rupture & high mortality
                                            • Anatomically classified based on renal arteries
                                              • Infrarenal AAA: Normal aortic segment ≥ 10 mm between renal arteries & most cephalad AAA extent
                                                • ~ 90% of AAAs occur infrarenally
                                                • Majority treated using endovascular techniques
                                              • Juxtarenal AAA: Aneurysm extends to renal artery level; normal-caliber aorta above that
                                                • Evolving endovascular management techniques
                                              • Suprarenal AAA: Involves renal arteries & extends to include superior mesenteric & celiac arteries
                                                • Complex endovascular &/or surgical treatment
                                              • AAA may or may not involve iliac arteries
                                            • Aneurysms also classified by configuration
                                              • Fusiform: AAA involves extended aortic section
                                                • "True" aneurysm involving all 3 wall layers
                                                • Typical appearance of degenerative aneurysm
                                              • Saccular: Focal AAA localized to aortic segment
                                                • May be asymmetrical; may be pseudoaneurysm
                                                • Infectious aneurysms often have this appearance
                                          • Iliac artery aneurysm (IAA): Abnormal arterial enlargement ≥ 50% of normal vessel diameter
                                            • Common iliac artery (CIA) aneurysm defined as transverse diameter > 1.5 cm
                                              • Most iliac artery aneurysms associated with abdominal aortic aneurysms
                                                • Iliac aneurysms present in roughly 20% of AAA
                                              • Isolated iliac artery aneurysms uncommon
                                                • 1-2% of all abdominal aneurysmal disease
                                              • Internal IAAs rare (≤ 0.4%)
                                                • Typically associated with aortic & common iliac artery aneurysms
                                          • Endograft (stent-graft): Fabric-covered self-expanding stent; excludes vascular pathology from circulation
                                            • All endografts have 3 components
                                              • Delivery system for graft introduction, deployment
                                              • High radial force, self-expanding, metallic stent framework & attachment system
                                                • Supports endoprosthesis, attaches to vasculature
                                              • Impermeable graft fabric surrounding stents
                                                • Either expanded polytetrafluoroethylene (ePTFE) or woven polyester fabric composition
                                                • Excludes pathology, provides new conduit
                                            • Endografts for AAA repair have different methods of fixation to vascular wall
                                              • Proximal endograft attachment methodology
                                                • Suprarenal fixation: Bare metallic stent extends proximally above fabric-covered endograft; anchors to perirenal arterial tissues
                                                • Infrarenal fixation: No components extend above renal arteries; fixation achieved via radial force of metallic stent which may have barbs
                                              • Distal endograft attachment methodology
                                                • Iliac limbs may be straight, flared, or tapered to conform to anatomy; radial force secures limb
                                            • 3 basic abdominal aortic endograft configurations; modular designs allow combination of components into patient-specific vascular conduits
                                              • 1-piece graft body & unilateral limb extension; paired with separate contralateral docking limb
                                                • Forms bifurcated graft; simulates aortic anatomy
                                                • Most commonly used endograft configuration
                                              • 1-piece unibody self-expanding endograft; positioned directly upon aortic bifurcation
                                                • 2nd component extended cephalad; attaches immediately below lowest renal artery
                                              • 1-piece aorto-uni-iliac endograft
                                                • Modified bifurcated endograft that extends from aorta to single iliac artery distal attachment
                                                • Requires surgically created femoro-femoral artery crossover bypass conduit
                                                • Frequently used during endovascular aneurysm repair (EVAR) for AAA rupture
                                          • EVAR: Endoluminal placement of endograft to treat AAA & other pathology
                                            • Endograft extends proximal & distal to aneurysm
                                              • Endograft excludes aneurysm from arterial pressure
                                                • Dilated & weakened aorta is not exposed to flow
                                                • Aneurysm sac thromboses, negating rupture risk
                                            • Endograft must attach to relatively healthy arterial tissues proximal & distal to aneurysm sac
                                              • Must achieve effective seal at attachment sites to exclude AAA from continued perfusion, prevent device migration and progression of disease
                                        • Aneurysm Morphology & Vascular Anatomy

                                          • Aneurysm morphology
                                            • Proximal AAA neck: Distance between most inferior renal artery and beginning of aneurysm; preferred proximal seal zone for endograft
                                              • Many features of neck may affect seal
                                                • Length & diameter
                                                • Configuration of neck (e.g., straight, conical)
                                                • Angle between axis of neck & suprarenal aorta
                                                • Angle between axis of neck & infrarenal AAA
                                                • Amount of thrombus/calcification in neck
                                            • Distal AAA neck: Distance between caudal aspect of aneurysm & aortic bifurcation
                                              • Some features of distal neck may affect EVAR
                                                • Excessively small diameter may limit delivery &/or expansion of endograft components
                                                • Neck angulation, calcification, & thrombus may impact endograft delivery & deployment
                                          • Vascular anatomy
                                            • Aortic branches arising in AAA treatment zone
                                              • Celiac artery: 1st major abdominal aortic branch; arises at lower margin of 12th thoracic vertebra
                                                • Rarely involved in AAA treatment zone
                                              • Superior mesenteric artery (SMA): Origin from aorta anteriorly, just below celiac artery
                                                • Suprarenal stent may extend to/cross origin
                                              • Renal arteries: Paired arteries that typically demarcate upper limit of proximal aortic neck
                                                • Must preserve renal perfusion during/after EVAR
                                                • Small accessory renal arteries arising from aneurysm sometimes sacrificed during EVAR
                                              • Inferior mesenteric artery (IMA): Origin above aortic bifurcation; known cause of type II endoleak
                                                • Prophylactically embolized by some operators
                                              • Lumbar arteries: Paired vessels arise along dorsal aspect of abdominal aorta at each vertebral level
                                                • Known cause of type II endoleak
                                              • Common iliac artery: Origin at aortic bifurcation; divides into external and internal iliac arteries
                                                • Preferred distal seal zone for endograft limbs
                                              • External iliac artery: Extends from common iliac artery bifurcation to inguinal ligament; adequate vessel diameter necessary for endograft delivery
                                                • Large common iliac artery aneurysm(s) may require limb extension into external iliac artery
                                              • Internal iliac (hypogastric) artery: Originates at common iliac artery bifurcation; has 2 trunks
                                                • May require embolization or branch device if endograft limb is extended into external iliac artery
                                              • Common femoral artery: Continuation of external iliac artery below inguinal ligament
                                                • Preferred/usual choice for EVAR arterial access

                                        PREPROCEDURE

                                        • Indications

                                          • Contraindications

                                            • Preprocedure Imaging

                                              • Getting Started

                                                PROCEDURE

                                                • Patient Position/Location

                                                  • Procedure Steps

                                                    • Alternative Procedures/Therapies

                                                      POST PROCEDURE

                                                      • Postprocedure Imaging

                                                        OUTCOMES

                                                        • Problems

                                                          • Complications

                                                            • Expected Outcome

                                                              Selected References

                                                              1. Powell JT et al: Meta-analysis of individual-patient data from EVAR-1, DREAM, OVER and ACE trials comparing outcomes of endovascular or open repair for abdominal aortic aneurysm over 5 years. Br J Surg. 104(3):166-178, 2017
                                                              2. Sala-Almonacil VA et al: Fenestrated and chimney endovascular aneurysm repair versus open surgery for complex abdominal aortic aneurysms. J Cardiovasc Surg (Torino). ePub, 2017
                                                              3. Hajibandeh S et al: Percutaneous access for endovascular aortic aneurysm repair: A systematic review and meta-analysis. Vascular. 24(6):638-648, 2016
                                                              4. Li Y et al: Endovascular versus open surgery repair of ruptured abdominal aortic aneurysms in hemodynamically unstable patients: Literature review and meta-analysis. Ann Vasc Surg. 32:135-44, 2016
                                                              5. Patel R et al: Endovascular versus open repair of abdominal aortic aneurysm in 15-years' follow-up of the UK endovascular aneurysm repair trial 1 (EVAR trial 1): a randomised controlled trial. Lancet. 388(10058):2366-2374, 2016
                                                              6. Peters AS et al: Current treatment strategies for ruptured abdominal aortic aneurysm. Langenbecks Arch Surg. 401(3):289-98, 2016
                                                              7. Spanos K et al: Transition from open surgery to endovascular treatment of abdominal aortic aneurysm rupture. Ann Vasc Surg. 36:85-91, 2016
                                                              8. Sörelius K et al: Endovascular treatment of mycotic aortic aneurysms: a European multicenter study. Circulation. 130(24):2136-42, 2014
                                                              9. Lee JT et al: Early experience with the snorkel technique for juxtarenal aneurysms. J Vasc Surg. 55(4):935-46; discussion 945-6, 2012
                                                              10. Malkawi AH et al: Percutaneous access for endovascular aneurysm repair: a systematic review. Eur J Vasc Endovasc Surg. 39(6):676-82, 2010
                                                              11. United Kingdom EVAR Trial Investigators et al: Endovascular versus open repair of abdominal aortic aneurysm. N Engl J Med. 362(20):1863-71, 2010
                                                              12. Walker TG et al: Clinical practice guidelines for endovascular abdominal aortic aneurysm repair: written by the Standards of Practice Committee for the Society of Interventional Radiology and endorsed by the Cardiovascular and Interventional Radiological Society of Europe and the Canadian Interventional Radiology Association. J Vasc Interv Radiol. 21(11):1632-55, 2010