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Karen Ka Leung Chan, Wing Tai Siu,1 Kai Hung Fung, Kwok Kay Yau, Simon Kin Hung Wong and ... CHAN et al □. 158 .... Ho P, Law WL, Tung PH, et al.
Case Report

Acute Symptomatic Abdominal Aortic Aneurysm Secondary to Endovascular Stent Graft Associated Type II Endoleak Karen Ka Leung Chan, Wing Tai Siu,1 Kai Hung Fung, Kwok Kay Yau, Simon Kin Hung Wong and Michael Ka Wah Li, Department of Surgery, Pamela Youde Nethersole Eastern Hospital and 1 Department of Surgery, Prince of Wales Hospital, Hong Kong SAR.

Endovascular abdominal aneurysm repair (EVAR) is popular because of its low invasiveness and feasibility for high-risk patients. Endoleak is common after EVAR and is characterized by blood flow within the aneurysm sac but outside the stent graft. Type II or collateral endoleak commonly results from retrograde filling of the aneurysm from collateral visceral vessels, lumbar, inferior mesenteric, accessory renal or sacral arteries. Collateral leaks are generally thought to be benign and over half of the early leaks will seal spontaneously. Sporadically, collateral endoleak could lead to aneurysm sac pressurization and place the patient at ongoing risk of rupture. Herein, we report an uncommon case of early post-stent graft placement symptomatic abdominal aortic aneurysm associated with type II endoleak. [Asian J Surg 2006; 29(3):157–60] Key Words: symptomatic abdominal aortic aneurysm, type II endoleak

Introduction Endovascular abdominal aneurysm repair (EVAR) introduced a decade ago has been gaining popularity for its low invasiveness and feasibility for high-risk patients.1 Recent reports demonstrated good short- and mid-term results with low complication rates.2 Endoleak is common after EVAR and is characterized by blood flow within the aneurysm sac but outside the stent graft.3 The incidence for types I and II endoleaks is 43% and 35%, respectively.4 Type II or collateral endoleak commonly results from retrograde filling of the aneurysm from collateral visceral vessels, lumbar, inferior mesenteric, accessory renal or sacral arteries. Collateral leaks are generally thought to be benign and over half of the early leaks will seal spontaneously in surveillance imaging.5 Sporadically, collateral

endoleak could lead to aneurysm sac pressurization and place the patient at ongoing risk of rupture.6 Herein, we report an uncommon case of early post-stent graft placement symptomatic abdominal aortic aneurysm associated with type II endoleak.

Case report A 73-year-old man with diabetes mellitus and hypertension presented to the surgical outpatient clinic with a few weeks’ history of dyspepsia. Physical examination revealed an abdominal aortic aneurysm (AAA) that computed tomography (CT) showed to be 5.9 cm in diameter. Imaging evaluation revealed an infrarenal aneurysm with anatomical configuration amenable to endovascular repair (Figure 1). He underwent elective endovascular

Address correspondence and reprint requests to Dr Wing Tai Siu, Department of Surgery, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong SAR. E-mail: [email protected] ● Date of acceptance: 20 June 2005 © 2006 Elsevier. All rights reserved.

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A

B

Figure 1. Preoperative computed tomography angiography.

Figure 3. (A) Endoleak and periaortic haematoma. (B) Type II endoleak from inferior mesenteric artery (IMA) through anastomosis between the common hepatic artery and branches of IMA.

Figure 2. Completion aortogram shows satisfactory aneurysm exclusion.

placement of bifurcated stent graft with suprarenal hook using the Cook Zenith three-piece modular Flex system (William A. Cook, Brisbane, Australia). Intraoperative completion angiography confirmed satisfactory aneurysm exclusion (Figure 2). On postoperative day 3, he complained of persistent back pain that was not resolved with oral analgesic. Physical examination revealed mild tenderness over the aneurysm. Emergent contrast CT revealed a

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type II endoleak from the inferior mesenteric artery (IMA) and periaortic haematoma that was suggestive of contained aneurysm rupture (Figure 3). Urgent transfemoral angiography with superselective cannulation revealed a type II endoleak from an abnormal anastomosis between the common hepatic artery and branches of the IMA. The communicating artery was successfully embolized with three VortX vascular occlusion coils (Boston Scientific Corp., Natick, MA, USA) and one 10 cm helical platinum liquid coil delivered by means of microcatheter cannulation through the common hepatic artery (Figure 4). The patient’s back pain was completely relieved after the embolization, and he was discharged 3 days after the procedure. Surveillance duplex and CT scan subsequently

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■ ANEURYSM SECONDARY TO ENDOVASCULAR STENT GRAFT ASSOCIATED ENDOLEAK ■

Figure 4. Microcatheter coil embolization through the common hepatic artery.

showed no evidence of endoleak or aneurysm expansion at the 9-month follow-up.

Discussion Since Parodi et al’s description in 1990,1 endovascular stent graft placement has become a widely accepted alternative treatment for patients with AAA.2 Studies comparing open surgical versus endovascular repair of AAA demonstrated reduction in early perioperative morbidity and shorter length of hospital stay.2 Nonetheless, endoleak is common after EVAR.4,5,7 Due to the differences in imaging technology and techniques, the reported incidence of endoleak varies widely from 15% to 52%.7 The significance and natural history of retrograde flow endoleak in relation to aneurysm enlargement and rupture have not been well defined. Various reports documented that most early postoperative endoleaks sealed off spontaneously.5,7,8 However, aneurysm sac expansions have also been demonstrated to be more common among patients with endoleaks.8 The cumulative risk of aneurysm rupture is 1% per year following stent graft placement.9 Management of patients with collateral endoleaks is a matter of continuous debate.7 It is widely believed that type II endoleaks are mostly benign and pose no urgency for intervention.10 Notwithstanding, type II endoleak can rarely be a manifestation of concealed type I endoleak.11 Reports noted that some patients are at higher risk of developing collateral endoleaks.8 Intraoperative embolization of aortic collaterals has been advocated by some

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authors to reduce the incidence of type II endoleak, while others found that this approach failed to demonstrate the reduction in collateral endoleak.12 Most authors advocate regular imaging surveillance and intervention for those that persist more than 6 months with aneurysms expanding more than 5 mm.13,14 Others are in favour of aggressive treatment for type II endoleak, based on the evidence of pressure transmission from the collateral vessels to the aneurysm sac or size of the persisting endoleak cavity.15 Treatment of type II endoleaks can be performed via a transarterial or direct translumbar coil embolization. Endoleaks emanating from the IMA could be embolized through collaterals originating from the superior mesenteric artery.16 Nonetheless, collateral leaks are often associated with complex anastomosis that may be difficult to access. Albeit some authors advocate that coiling of endoleak is less effective when only the feeding vessels are addressed rather than including the endoleak vessel stem in the aneurysm sac.17 In the current case, we embolized the anomalous large collateral anastomosis through the hepatic artery due to the patient’s unusual anatomy. Alternatively, laparoscopic clipping of lumbar or inferior mesenteric arteries have also been reported to be effective in managing patients with collateral endoleaks.18 Conversions to open repair may be necessary when other modalities are ineffective in obliterating refractory endoleaks.16 Endoleaks after EVAR are usually asymptomatic and only become evident on surveillance imaging. Aneurysm rupture due to type II endoleak is uncommon; to our knowledge, there are only a few reports in the literature.6,19 The present case illustrates the potential risk of stent graft placement associated type II endoleaks that may precipitate acute aneurysm symptom. The actual initiator of aneurysm rupture in the current patient is unclear. The absence of type I endoleak on completion angiography and CT scan made an undetected type I endoleak less likely. Another possible mechanism would be rupture of aneurysm sac secondary to operative graft ballooning, in which the large IMA endoleak served as an aggravating factor for ongoing bleeding. Nonetheless, the prompt resolution of symptoms following embolization of the IMA collaterals implies that the IMA endoleak might have induced the aneurysm rupture. Notwithstanding, obliteration of the anomalous collateral could also markedly reduce the pressure of ongoing back bleeding even if type II endoleak might not be the initiator of aneurysm rupture.

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References 1. Parodi JC, Palmaz JC, Barone HD. Transfemoral intraluminal graft implantation for abdominal aortic aneurysm. Ann Vasc Surg 1991;5:491–9. 2. Towne JB. Endovascular treatment of abdominal aortic aneurysms. Am J Surg 2005;189:140–9. 3. White GH, Yu W, May J. “Endoleak”: a proposed new terminology to described incomplete aneurysm exclusion by an endoluminal graft. J Endovas Surg 1996;3:124–5. 4. Buth J, Laheij RJ. Early complications and endoleaks after endovascular abdominal aortic aneurysm repair: report of a multicenter study. J Vasc Surg 2000;31:134–46. 5. Buth J, Laheij RJF. On behalf of the EUROSTAR Collaborators. Early complications and endoleaks after endovascular abdominal aortic aneurysm repair: report of a multi-center study. J Vasc Surg 2000;31:134–46. 6. Hinchliffe RJ, Singh-Ranger R, Davidson IR, et al. Rupture of an abdominal aortic aneurysm secondary to type II endoleak. Eur J Vasc Endovasc Surg 2002;22:563–5. 7. Heikkinen MA, Arko FR, Zarins CK. What is the significance of endoleaks and endotension. Surg Clin North Am 2004;84:1337–52. 8. Velazquez OC, Baum RA, Carpenter JP, et al. Relationship between preoperative patency of the inferior mesenteric artery and subsequent occurrence of type II endoleak in patients undergoing endovascular repair of abdominal aortic aneurysms. J Vasc Surg 2000;32:777–88. 9. Buth J, Harris PL, van Marrewijk C. Causes and outcomes of open conversion and aneurysm rupture after endovascular abdominal aortic aneurysm repair: can type II endoleaks be dangerous? J Am Coll Surg 2002;194(Suppl 1):98S–102S. 10. Buth J, Harris PL, van Marrewijk C, et al. The significance and management of different types of endoleaks. Semin Vasc Surg 2003;16:95–102.

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11. Harris PL, Vallabhaneni SR, Desgranges P, et al. Incidence and risk factors of late rupture, conversion, and death after endovascular repair of infrarenal aortic aneurysms: the EUROSTAR experience. European Collaborators on stent/ graft techniques for aortic aneurysm repair. J Vasc Surg 2000; 32:739–49. 12. Gould DA, McWilliams R, Edwards RD, et al. Aortic side branch embolization before endovascular aneurysm repair: incidence of type II endoleak. J Vasc Interv Radiol 2001;12:337–41. 13. Veith FJ, Baum GD, Johnson BL, et al. Nature and significance of endoleaks and endotension: summary of opinions expressed at an international conference. J Vasc Surg 2002;35: 1029–35. 14. Steinmetz E, Rubin BG, Sanchez LA, et al. Type II endoleak after endovascular abdominal aortic aneurysm repair: a conservative approach with selective intervention is safe and cost-effective. J Vasc Surg 2004;39:306–13. 15. Timaran CH, Ohki T, Rhee SJ, et al. Predicting aneurysm enlargement in patients with persistent type II endoleaks. J Vasc Surg 2004;39:1157–62. 16. Faries PL, Cadot H, Agarwal G, et al. Management of endoleak after endovascular aneurysm repair: cuffs, coils, and conversion. J Vasc Surg 2003;37:1155–61. 17. Sheehan MK, Barbato J, Compton CN, et al. Effectiveness of coiling in the treatment of endoleaks after endovascular repair. J Vasc Surg 2004;40:430–4. 18. Ho P, Law WL, Tung PH, et al. Laparoscopic transperitoneal clipping of the inferior mesenteric artery for the management of type II endoleak after endovascular repair of an aneurysm. Surg Endosc 2004;18:870. 19. Fransen GA, Vallabhaneni SR Sr, van Marrewijk CJ, et al. EUROSTAR. Rupture of infra-renal aortic aneurysm after endovascular repair: a series from EUROSTAR registry. Eur J Vasc Endovasc Surg 2003;26:487–93.

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