- Email: [email protected]
Endovascular Exclusion of a Splenic Artery Aneurysm Using a Pipeline Embolization Device
BRIEF REPORT
Endovascular Exclusion of a Splenic Artery Aneurysm Using a Pipeline Embolization Device Robert J. Abraham, MD, FRCPC, A. Jehaan Illyas, MD, Tom Marotta, MD, FRCPC, Patrick Casey, MD, FRCSC, Brock Vair, MD, FRCSC, and Robert Berry, MD, FRCPC
ABSTRACT The Pipeline Embolization Device (ev3 Endovascular Inc, Plymouth, Minnesota) is a new endovascular device designed to exclude suitable intracranial aneurysms. A 56-year-old woman presented with a symptomatic 4.1-cm splenic artery aneurysm (SAA) that was successfully managed with a two-staged treatment plan involving selective segmental splenic artery embolization and subsequent deployment of a Pipeline Embolization Device across the aneurysm neck to exclude the aneurysm and maintain splenic perfusion.
ABBREVIATION SAA ⫽ splenic artery aneurysm
Splenic artery aneurysms (SAAs) are uncommon with a prevalence in healthy adults of ⬍ 1%. SAAs are being diagnosed more frequently because of the wide diffusion of medical imaging. They are often asymptomatic, but approximately 25% of patients become symptomatic; most patients present with epigastric or left upper quadrant pain (1). Treatment should be considered for symptomatic aneurysms, aneurysms in pregnant women or women of childbearing age, aneurysms in liver transplant recipients, and pseudoaneurysms (2– 6). Controversy exists regarding the size of the aneurysm as an indication for intervention in asymptomatic patients. However, most clinicians believe that aneurysms ⬎ 2 cm are an indication for intervention (4). The reported rate of rupture for SAAs is 2.9%–10.9% (4) with an associated mortality of 36% (7).
From the Departments of Diagnostic Imaging and Interventional Radiology (R.J.A., R.B.), and Surgery (P.C., B.V.), QE II Health Sciences Centre, Dalhousie University, Room 3316, Halifax Infirmary Site, 1796 Summer Street, Halifax, NS, Canada, B3H 3A7; Saba University School of Medicine (A.J.I.), Saba, Netherlands-Antilles; and Diagnostic & Therapeutic Neuroradiology (T.M.), University of Toronto, St. Michael’s Hospital, Toronto, Ontario, Canada. Received March 14, 2010; final revision received May 3, 2011; accepted September 9, 2011. Address correspondence to R.J.A.; E-mail: [email protected]
Endovascular therapy can be successfully performed with low morbidity and high success (6,8 –12). Available products for treatment of peripheral aneurysms include embolic agents (coils or liquid agents) and peripheral stent grafts, but each of these products has inherent limitations. The use of embolization agents for distal SAAs can result in splenic infarction and other complications including migration or misplacement of metallic coils, abscess formation, and, rarely, aneurysm rupture. Exclusion of aneurysms with preservation of flow can be obtained with the use of stent grafts, but the existing devices have stiff delivery systems that would make placement peripherally in a tortuous splenic artery quite challenging. The Pipeline Embolization Device (ev3 Endovascular Inc, Plymouth, Minnesota) is a self-expanding, microcatheter-delivered, stentlike device that has been successfully used to exclude cerebral aneurysms (Fig 1). It can be delivered easily to a peripheral location owing to the lowprofile nature of the microcatheter delivery system, and its cylindrical mesh design allows for exclusion of the aneurysm, while maintaining flow through the affected segment of the underlying artery (13–15). In this report, we describe the use of a Pipeline Embolization Device to successfully exclude a saccular distal SAA, while preserving flow to the splenic artery distal to the device.
R.J.A. has a royalty agreement with Cook, Inc. T.M. is a paid consultant for ev3 Incorporated Pipeline Embolization Device Proctor. None of the other authors have identified a conflict of interest. © SIR, 2012 J Vasc Interv Radiol 2012; 23:131–135 DOI: 10.1016/j.jvir.2011.09.015
CASE REPORT Institutional review board approval was obtained for this report. A 56-year-old hypertensive woman presented to an
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Figure 2. Axial CT image showing a large splenic artery aneurysm (arrows).
Figure 1. Ex vivo image of the Pipeline™ Embolization Device showing its flexible self-expanded braided mesh design. Copyright © Covidien. Used with permission.
outside hospital with intermittent left upper quadrant pain. There was a remote history of trauma related to a motor vehicle accident, which had resulted in vertebral compression fractures but no other injuries. Computed tomography (CT) scan performed on presentation showed a 4.1-cm diameter SAA without evidence of rupture. The aneurysm had measured 2.0 cm in diameter on a CT scan performed 4 years previously. CT angiography showed that the aneurysm was saccular in nature and the neck arose from the distal splenic artery at the crux of the first segmental bifurcation (Fig 2). Because of the distal location of the aneurysm, we believed that coil embolization across the neck of the aneurysm would result in relatively high risk for splenic infarction. Also, we believed that placement of a stent graft or conventional bare stent into the distal splenic artery would be difficult because of the small caliber of the vessel and the underlying arterial tortuosity and could increase risk for aneurysm rupture. Use of the Pipeline Embolization Device was considered the best alternative because it would be introduced through a microcatheter reducing overall risk and would preserve splenic perfusion. However, the relationship of the aneurysm with the origins of the segmental splenic arteries would require embolization of one of the segmental arteries to prevent retrograde flow back to the aneurysm. Elective staged procedures (selective superior segmental splenic artery embolization followed by separate Pipeline Embolization Device placement across the aneurysm neck and into the inferior segmental splenic artery) were
planned. The patient received Pneumovax-23 (Merck Frost Canada Ltd Kirkland, Quebec, Canada), Menactra (Sanofi Pasteur Ltd, Toronto, Ontario, Canada), and Act-HIB Haemophilus b (Sanofi Pasteur Ltd) vaccinations as an outpatient. Health Canada approval was obtained to use the Pipeline Embolization Device in this patient (U.S. Food and Drug Administration [FDA] and Health Canada approval is limited to cerebral indications). The patient was readmitted 7 days after discharge and brought to the interventional radiology suite (Axiom Artis dTA single plane flat detector; Siemens Medical, Erlangen, Germany). Under local anesthesia and moderate sedation, the right common femoral artery was accessed, and a 4-F vascular sheath (Terumo Corp, Tokyo, Japan) was placed. The celiac artery was catheterized selectively with a 4-F Slip-Cath C2 Cobra catheter (Cook, Inc, Bloomington, Indiana). The splenic artery was selectively catheterized with the 4-F Cobra catheter over a 0.035-inch hydrophilic angled Glidewire (Boston Scientific, Watertown, Massachusetts). Selective splenic arteriography confirmed that the aneurysm was located at the first branch point of the segmental splenic arteries and involved the origin of both vessels (Fig 3). A Renegade Microcatheter (Boston Scientific) and a 0.014-inch Transcend EX guide wire (Boston Scientific) were used for selective catheterization of the superior segmental splenic artery. Embolization of this vessel was successfully performed using multiple fibered microcoils (VortX/18 Diamond Shaped Fibered Platinum Coil; Boston Scientific, Watertown). The patient tolerated the procedure well, and there were no complications. The patient was discharged the next day. The patient was readmitted 1 month after the embolization procedure. The patient was premedicated with 300 mg of clopidogrel (Bristol-Myers Squibb and Sanofi-Aventis Canada, Inc, Laval, Quebec, Canada) and 81 mg of enteric-coated acetylsalicylic acid (Entrophen; Pharmascience, Inc, Montreal, Canada). The patient was brought to the interventional radiology suite, and under local anesthesia and moderate sedation, the right common femoral artery was accessed and a 6-F 40-cm Abraham vascular sheath
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Figure 3. Selective distal splenic artery angiogram showing SAA (arrowheads) and the relationship of superior (black arrows) and inferior (white arrow) segmental splenic arteries to the aneurysm neck (star).
Figure 4. Distal splenic artery angiogram showing successful embolization of the superior segmental artery with fibered microcoils (black arrows) and showing the relationship of the inferior segmental artery (white arrows) to the aneurysm.
(Cook, Inc) was placed in the abdominal aorta. The splenic artery was catheterized with a 5-F Glidecath C2 Cobra catheter (Terumo Corp) over a 0.035-inch hydrophilic Glide wire (Boston Scientific) and advanced to the mid– splenic artery level. Selective splenic arteriography confirmed occlusion of the superior segmental artery and patency of the inferior segmental splenic artery and continued opacification of the aneurysm (Fig 4). The 6-F guide sheath was advanced over the 5-F Cobra catheter and placed in the proximal celiac artery for support. The 5-F Glidecath Cobra was exchanged for a 6-F Mach 1 C2 guide catheter (Boston Scientific), which was advanced over the hydrophilic glide wire to the mid–splenic artery. A Marksman microcatheter (ev3 Endovascular Inc) and a Transcend EX Platinum tip guide wire (Boston Scientific) were advanced through the 6-F guide catheter and
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placed into the inferior segmental artery beyond the neck of the aneurysm. A 5.0 mm diameter ⫻ 20 mm long Pipeline Embolization Device (maximum unconstrained diameter for this device is 5.2 mm) was loaded into the microcatheter and advanced to the tip of the microcatheter. The microcatheter and Pipeline Embolization Device were withdrawn as a unit such that the distal portion of the device was positioned 1 cm beyond the center of the aneurysm neck. The microcatheter was withdrawn over the Pipeline Embolization Device to start deployment. During this maneuver, the tip of the device remained constrained by the distal retaining coil, and the exposed portion of the Pipeline Embolization Device mesh formed a very slender “cigar” shape (Fig 5a). The exposed portion of the Pipeline Embolization Device was released from the retaining coil by turning the core wire clockwise by two turns using the included torque device. Further deployment of the Pipeline Embolization Device required the use of a pull (microcatheter withdrawal) and push technique (advancement of the core delivery wire) to allow the mesh of the Pipeline Embolization Device to remain compact. The proximal portion of the device was deployed 1 cm proximal to the center of the aneurysm neck (Fig 5b). Angiography performed after deployment showed excellent flow through the Pipeline Embolization Device into a widely patent inferior segmental artery. Contrast material was noted to be stagnant in the aneurysm (Fig 5c). Hemostasis at the puncture site was established with a 6-F Angio-Seal Closure Device (St. Jude Medical, St. Paul, Minnesota). The patient tolerated the procedure well, and there were no complications. The patient was discharged the next day. The patient was to continue taking daily clopidogrel 75 mg for 6 weeks and daily enteric-coated acetylsalicylic acid 81 mg indefinitely. However, the patient developed episodic epistaxis 2 weeks after discharge, and clopidogrel was discontinued. Follow-up CT angiography performed 20 months after the procedure (Fig 6) showed complete exclusion of the SAA and a patent Pipeline Embolization Device and inferior segmental artery. The SAA had decreased to 3.4 cm in maximum span. Only a small focal area of splenic tissue showed evidence of infarction, and this was believed to be secondary to the original embolization procedure.
DISCUSSION Embolization for SAAs can be successfully performed while preserving flow to the spleen if the embolization is performed proximal to collateral vessels that will continue to perfuse the distal splenic artery. In the setting of proximal splenic artery occlusion, there are three main collateral pathways that preserve flow to the splenic parenchyma (gastroduodenal to epiploic arteries, transverse pancreatic to pancreatica magna to splenic artery, and left gastric to short gastric arteries). These occur proximal to the splenic hilum and splenic branch vessels (16). The SAA discussed in this report incorporated the most distal splenic artery and
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Figure 5. (a) Tip of the Pipeline Embolization Device placed distal to the aneurysm neck and partially exposed by withdrawing the microcatheter: tip of 6-F guide catheter (white arrowhead); proximal end of Pipeline Embolization Device (large black arrow); tip of Marksman microcatheter (long white arrow); constrained Pipeline Embolization Device mesh with slender cigar appearance (short white arrow); tip of protective retaining coil, which maintains the Pipeline Embolization Device in a constrained state (small black arrow); and platinum coil tip of integrated core wire (black arrowhead). (b) Pipeline Embolization Device (arrows) completely deployed across the aneurysm neck. (c) Angiogram obtained after deployment showing patency of the Pipeline Embolization Device (black arrows) and inferior segmental splenic artery, exclusion of aneurysm, and stasis of trapped contrast material within the aneurysm (white arrows). (Available in color online at www.jvir.org.)
Figure 6. Coronal reformatted CT image 20 months after the procedure showing a patent Pipeline Embolization Device (small arrow) and inferior segmental artery (long arrow) and confirming complete thrombosis of the SAA (arrowheads).
its bifurcation, which is beyond these collateral pathways. Embolization for the distal SAA in this case would have relatively high risk of splenic infarction (17). This risk was confirmed in our case because the first-stage coil embolization of the upper pole branch arising from the aneurysm resulted in infarction within that vascular territory. Previous authors have reported use of various peripheral stent grafts for the treatment of SAAs (10,18 –20). We considered low-profile covered stent platforms such as the GraftMaster stent graft (Abbott Vascular Devices, Redwood City, California) unsuitable for this case because we deemed the degree of vessel tortuosity too great to allow straightforward device placement. Direct coiling of the aneurysm would require stent-assisted coiling and numer-
ous coils. The relatively wide aneurysm neck would be problematic for liquid embolic agents such as n-butyl cyanoacrylate (Histoacryl; B. Braun Aesculap AG, Tuttlingen, Germany) or Onyx (ev3 Endovascular Inc) and could result in either incomplete treatment or partial or complete occlusion of the splenic artery. The Silk artery reconstruction device (Balt Extrusion, Montmorency, France) is another flow diversion device that could be used in this scenario. Reports have shown successful use of this device in the treatment of cerebral aneurysms (21). The Silk device is not approved by the FDA and requires Health Canada special access clearance in Canada. The Pipeline Embolization Device is attached to a flexible delivery wire, which has radiopaque end markers, and is packaged in an introducer sheath. This packaged device can be loaded into standard microcatheters of 0.027inch inner diameter (Pipeline Embolization Device Instruction for Use (IFU), ev3 Endovascular Inc, Plymouth, Minnesota) (14). First the microcatheter is placed beyond the site of the aneurysm neck, and then the device is pushed through the microcatheter to the target site. The distal end of the device should be placed at least 3– 4 mm beyond the aneurysm neck. The device is initially unsheathed by withdrawing the microcatheter, while maintaining the position of the device itself by stabilizing the delivery wire; the distal end of the device is exposed. After a sufficient length of the device is exposed, it releases from the delivery wire spontaneously or with clockwise rotation of the delivery wire (Pipeline Embolization Device Instruction for Use (IFU), ev3 Endovascular Inc., Plymouth, Minnesota). Once anchored in the distal landing zone, the device is deployed by a combination of microcatheter withdrawal and forward pressure on the delivery wire. On release from the delivery system and when properly positioned at the desired location in the vessel, the implant expands to cover the neck of the aneurysm. After deployment, it forms a
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high-coverage mesh of approximately 30%–35% by area (14). The degree of metal surface area coverage can be manipulated by varying the technique of device deployment. Performing greater microcatheter withdrawal as opposed to guide wire advancement results in less compaction of the mesh and enough flow through the interstices to allow perforators to remain patent, which is particularly important in the cerebral circulation. Greater guide wire advancement as opposed to catheter withdrawal results in greater compaction of the mesh, decreasing flow through the interstices of the device. The latter technique was chosen for treatment of the SAA in this case report. The device undergoes approximately 65% shortening during deployment depending on diameter of the device chosen and parent artery ( Pipeline Embolization Device Instruction for Use (IFU), ev3 Endovascular Inc, Plymouth, Minnesota). Multiple devices can be deployed within each other (telescoped) to create a composite endovascular construct (14). Endovascular reconstruction with the Pipeline Embolization Device may represent an optimal treatment strategy, particularly if splenic flow would be compromised by other treatment options. The Pipeline Embolization Device offers a low-profile system that is delivered through a microcatheter, which allows it to reach the distal arterial anatomy and yet preserve distal arterial flow resulting in a more physiologic treatment option. There is also a conceptual advantage to using the Pipeline Embolization Device in that a dense cylindrical mesh is built to reconstruct a de novo vessel through the diseased segment. Kallmes et al (14) showed that this endovascular mesh acts like a scaffolding for endothelial and neointimal overgrowth, bridging the aneurysm neck and resulting in complete aneurysmal occlusion on angiography. Fiorella et al (15) described this complete incorporation of the Pipeline Embolization Device into the affected artery as “endovascular re-paving” and stated that the Pipeline Embolization Device allows the artery to act as if it were “steel-reinforced.” In a previous study, the same authors showed that intracranial aneurysms treated with this device were angiographically stable after 1 year of follow-up (13). This study supports evidence that a vessel reconstructed with a Pipeline Embolization Device can be durable, although more studies are needed to confirm its long-term effect on postoperative prognosis. The decision to place the patient on low-dose aspirin and clopidogrel was based on published reports using this regimen when treating intracranial aneurysms with the Pipeline Embolization Device (13–15), established coronary stent data, and our own personal experience with small-caliber arterial stents. However, the use of antiplatelet therapy with the Pipeline Embolization Device has not been specifically studied. Based on the present case, we believe the Pipeline Embolization Device offers a low-profile treatment option for visceral and peripheral aneurysms that may have advantages compared with other contemporary open surgical and endovascular therapies. Additional experience is needed to
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determine the specific clinical settings in which use of this device may be beneficial.
REFERENCES 1. Pasha SF, Gloviczki P, Stanson, AW, Kamath PS. Splanchnic artery aneurysms. Mayo Clin Proc 2007; 82:472– 479. 2. Arca MJ, Gagner M, Heniford BT, Sullivan TM, Beven EG. Splenic artery aneurysms: methods of laparoscopic repair. J Vasc Surg 1999; 30:184 –188. 3. Zelenock G, Stanley J. Splanchnic artery aneurysms. In: Rutherford R, editor. Vascular surgery. 5th ed. Philadelphia: WB Saunders; 2000:1373. 4. Abbas MA, Stone WM, Fowl RJ, et al. Splenic artery aneurysms: two decades experience at Mayo Clinic. Ann Vasc Surg 2002; 16:442– 449. 5. Berceli SA. Hepatic and splenic artery aneurysms. Semin Vasc Surg 2005; 18:196 –201. 6. Reidy JF, Rowe PH, Ellis FG. Splenic artery aneurysm embolization— the preferred technique to surgery. Clin Radiol 1990; 41:281–282. 7. Schmittling ZC, McLafferty R. Transcatheter embolization of a splenic artery aneurysm. J Vasc Surg 2004; 40:1049. 8. Piffaretti G, Tozzi M, Lomazzi C, Rivolta N. Splenic artery aneurysms: postembolization syndrome and surgical complications. Am J Surg 2007; 193:166 –170. 9. Guillon R, Garcier JM, Abergel A, et al. Management of splenic artery aneurysms and false aneurysms with endovascular treatment in 12 patients. Cardiovasc Intervent Radiol 2003; 26:256 –260. 10. Arepally A, Dagli M, Hofmann LV, Kim HS, Cooper M, Klein A. Treatment of splenic artery aneurysm with use of a stentgraft. J Vasc Interv Radiol 2002; 13:631– 633. 11. McDermott VG, Shlansky-Goldberg R, Cope C. Endovascular management of splenic artery aneurysms and pseudoaneurysms. Cardiovasc Intervent Radiol 1994; 17:179 –184. 12. de Perot M, Buhler L, Deleaval J, et al. Management of true aneurysms of the splenic artery. Am J Surg 1998; 175:466 – 468. 13. Fiorella D, Woo HH, Albuquerque FC, Nelson PK. Definitive reconstruction of circumferential, fusiform intracranial aneurysms with the pipeline embolization device. Neurosurgery 2008; 62:1115–1121. 14. Kallmes DF, Ding YH, Dai D, Kadirvel R, Lewis DA, Cloft HJ: A new endoluminal, flow-disrupting device for treatment of saccular aneurysms. Stroke 2007; 38:2346 –2352. 15. Fiorella D, Kelly ME, Albuquerque FC, Nelson PK. Curative reconstruction of a giant midbasilar trunk aneurysm with the pipeline embolization device: case report. Neurosurgery 2009; 64:1– 6. 16. Schwalke MA, Crowley JP, Spencer P, et al. Splenic artery ligation for splenic salvage: clinical experience and immune function. J Trauma 1991; 31:385–388. 17. Yamamoto S, Hirota S, Maeda H, et al. Transcatheter coil embolization of splenic artery aneurysm. Cardiovasc Interv Radiol 2008; 31:527–534. 18. Yoon HK, Lindh M, Uher P, Lindblad B, Ivancev K. Stentgraft repair of a splenic artery aneurysm. Cardiovasc Intervent Radiol 2001; 24:200–203. 19. Moyer HR, Hiramoto JS, Wilson MW, Reddy P, Messina LM, Schneider DB. Stent-graft repair of a splenic artery aneurysm. J Vasc Surg 2005; 41:897. 20. Larson RA, Solomon J, Carpenter JP. Stent graft repair of visceral artery aneurysms. J Vasc Surg 2002; 36:1260 –1263. 21. Kulcsár Z, Ernemann U, Wetzel SG, et al. High-profile flow diverter (silk) implantation in the basilar artery: efficacy in the treatment of aneurysms and the role of the perforators. Stroke 2010; 41:1690 –1696.
FURTHER READING Busuttil RW, Brin BJ. The diagnosis and management of visceral artery aneurysms. Surgery 1980; 88:619 – 624. Holdsworth RJ, Gunn A. Ruptured splenic artery aneurysm in pregnancy: a review. Br J Obstet Gynaecol 1992; 99:595–597. Lee PC, Rhee RY, Gordon RY, Fung JJ, Webster MW. Management of splenic artery aneurysms: the significance of portal and essential hypertension. J Am Coll Surg 1999; 189:483– 490. Shanley CJ, Shah NL, Messina LM. Common splanchnic artery aneurysms: splenic, hepatic, and celiac. Ann Vasc Surg 1996; 10:315–322. Yamamoto S, Hirota S, Maeda H, et al. Transcatheter coil embolization of splenic artery aneurysm. Cardiovasc Interv Radiol 2008; 31:527–534.
Endovascular Exclusion of a Splenic Artery Aneurysm Using a Pipeline Embolization Device Robert J. Abraham, MD, FRCPC, A. Jehaan Illyas, MD, Tom Marotta, MD, FRCPC, Patrick Casey, MD, FRCSC, Brock Vair, MD, FRCSC, and Robert Berry, MD, FRCPC
ABSTRACT The Pipeline Embolization Device (ev3 Endovascular Inc, Plymouth, Minnesota) is a new endovascular device designed to exclude suitable intracranial aneurysms. A 56-year-old woman presented with a symptomatic 4.1-cm splenic artery aneurysm (SAA) that was successfully managed with a two-staged treatment plan involving selective segmental splenic artery embolization and subsequent deployment of a Pipeline Embolization Device across the aneurysm neck to exclude the aneurysm and maintain splenic perfusion.
ABBREVIATION SAA ⫽ splenic artery aneurysm
Splenic artery aneurysms (SAAs) are uncommon with a prevalence in healthy adults of ⬍ 1%. SAAs are being diagnosed more frequently because of the wide diffusion of medical imaging. They are often asymptomatic, but approximately 25% of patients become symptomatic; most patients present with epigastric or left upper quadrant pain (1). Treatment should be considered for symptomatic aneurysms, aneurysms in pregnant women or women of childbearing age, aneurysms in liver transplant recipients, and pseudoaneurysms (2– 6). Controversy exists regarding the size of the aneurysm as an indication for intervention in asymptomatic patients. However, most clinicians believe that aneurysms ⬎ 2 cm are an indication for intervention (4). The reported rate of rupture for SAAs is 2.9%–10.9% (4) with an associated mortality of 36% (7).
From the Departments of Diagnostic Imaging and Interventional Radiology (R.J.A., R.B.), and Surgery (P.C., B.V.), QE II Health Sciences Centre, Dalhousie University, Room 3316, Halifax Infirmary Site, 1796 Summer Street, Halifax, NS, Canada, B3H 3A7; Saba University School of Medicine (A.J.I.), Saba, Netherlands-Antilles; and Diagnostic & Therapeutic Neuroradiology (T.M.), University of Toronto, St. Michael’s Hospital, Toronto, Ontario, Canada. Received March 14, 2010; final revision received May 3, 2011; accepted September 9, 2011. Address correspondence to R.J.A.; E-mail: [email protected]
Endovascular therapy can be successfully performed with low morbidity and high success (6,8 –12). Available products for treatment of peripheral aneurysms include embolic agents (coils or liquid agents) and peripheral stent grafts, but each of these products has inherent limitations. The use of embolization agents for distal SAAs can result in splenic infarction and other complications including migration or misplacement of metallic coils, abscess formation, and, rarely, aneurysm rupture. Exclusion of aneurysms with preservation of flow can be obtained with the use of stent grafts, but the existing devices have stiff delivery systems that would make placement peripherally in a tortuous splenic artery quite challenging. The Pipeline Embolization Device (ev3 Endovascular Inc, Plymouth, Minnesota) is a self-expanding, microcatheter-delivered, stentlike device that has been successfully used to exclude cerebral aneurysms (Fig 1). It can be delivered easily to a peripheral location owing to the lowprofile nature of the microcatheter delivery system, and its cylindrical mesh design allows for exclusion of the aneurysm, while maintaining flow through the affected segment of the underlying artery (13–15). In this report, we describe the use of a Pipeline Embolization Device to successfully exclude a saccular distal SAA, while preserving flow to the splenic artery distal to the device.
R.J.A. has a royalty agreement with Cook, Inc. T.M. is a paid consultant for ev3 Incorporated Pipeline Embolization Device Proctor. None of the other authors have identified a conflict of interest. © SIR, 2012 J Vasc Interv Radiol 2012; 23:131–135 DOI: 10.1016/j.jvir.2011.09.015
CASE REPORT Institutional review board approval was obtained for this report. A 56-year-old hypertensive woman presented to an
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Figure 2. Axial CT image showing a large splenic artery aneurysm (arrows).
Figure 1. Ex vivo image of the Pipeline™ Embolization Device showing its flexible self-expanded braided mesh design. Copyright © Covidien. Used with permission.
outside hospital with intermittent left upper quadrant pain. There was a remote history of trauma related to a motor vehicle accident, which had resulted in vertebral compression fractures but no other injuries. Computed tomography (CT) scan performed on presentation showed a 4.1-cm diameter SAA without evidence of rupture. The aneurysm had measured 2.0 cm in diameter on a CT scan performed 4 years previously. CT angiography showed that the aneurysm was saccular in nature and the neck arose from the distal splenic artery at the crux of the first segmental bifurcation (Fig 2). Because of the distal location of the aneurysm, we believed that coil embolization across the neck of the aneurysm would result in relatively high risk for splenic infarction. Also, we believed that placement of a stent graft or conventional bare stent into the distal splenic artery would be difficult because of the small caliber of the vessel and the underlying arterial tortuosity and could increase risk for aneurysm rupture. Use of the Pipeline Embolization Device was considered the best alternative because it would be introduced through a microcatheter reducing overall risk and would preserve splenic perfusion. However, the relationship of the aneurysm with the origins of the segmental splenic arteries would require embolization of one of the segmental arteries to prevent retrograde flow back to the aneurysm. Elective staged procedures (selective superior segmental splenic artery embolization followed by separate Pipeline Embolization Device placement across the aneurysm neck and into the inferior segmental splenic artery) were
planned. The patient received Pneumovax-23 (Merck Frost Canada Ltd Kirkland, Quebec, Canada), Menactra (Sanofi Pasteur Ltd, Toronto, Ontario, Canada), and Act-HIB Haemophilus b (Sanofi Pasteur Ltd) vaccinations as an outpatient. Health Canada approval was obtained to use the Pipeline Embolization Device in this patient (U.S. Food and Drug Administration [FDA] and Health Canada approval is limited to cerebral indications). The patient was readmitted 7 days after discharge and brought to the interventional radiology suite (Axiom Artis dTA single plane flat detector; Siemens Medical, Erlangen, Germany). Under local anesthesia and moderate sedation, the right common femoral artery was accessed, and a 4-F vascular sheath (Terumo Corp, Tokyo, Japan) was placed. The celiac artery was catheterized selectively with a 4-F Slip-Cath C2 Cobra catheter (Cook, Inc, Bloomington, Indiana). The splenic artery was selectively catheterized with the 4-F Cobra catheter over a 0.035-inch hydrophilic angled Glidewire (Boston Scientific, Watertown, Massachusetts). Selective splenic arteriography confirmed that the aneurysm was located at the first branch point of the segmental splenic arteries and involved the origin of both vessels (Fig 3). A Renegade Microcatheter (Boston Scientific) and a 0.014-inch Transcend EX guide wire (Boston Scientific) were used for selective catheterization of the superior segmental splenic artery. Embolization of this vessel was successfully performed using multiple fibered microcoils (VortX/18 Diamond Shaped Fibered Platinum Coil; Boston Scientific, Watertown). The patient tolerated the procedure well, and there were no complications. The patient was discharged the next day. The patient was readmitted 1 month after the embolization procedure. The patient was premedicated with 300 mg of clopidogrel (Bristol-Myers Squibb and Sanofi-Aventis Canada, Inc, Laval, Quebec, Canada) and 81 mg of enteric-coated acetylsalicylic acid (Entrophen; Pharmascience, Inc, Montreal, Canada). The patient was brought to the interventional radiology suite, and under local anesthesia and moderate sedation, the right common femoral artery was accessed and a 6-F 40-cm Abraham vascular sheath
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Figure 3. Selective distal splenic artery angiogram showing SAA (arrowheads) and the relationship of superior (black arrows) and inferior (white arrow) segmental splenic arteries to the aneurysm neck (star).
Figure 4. Distal splenic artery angiogram showing successful embolization of the superior segmental artery with fibered microcoils (black arrows) and showing the relationship of the inferior segmental artery (white arrows) to the aneurysm.
(Cook, Inc) was placed in the abdominal aorta. The splenic artery was catheterized with a 5-F Glidecath C2 Cobra catheter (Terumo Corp) over a 0.035-inch hydrophilic Glide wire (Boston Scientific) and advanced to the mid– splenic artery level. Selective splenic arteriography confirmed occlusion of the superior segmental artery and patency of the inferior segmental splenic artery and continued opacification of the aneurysm (Fig 4). The 6-F guide sheath was advanced over the 5-F Cobra catheter and placed in the proximal celiac artery for support. The 5-F Glidecath Cobra was exchanged for a 6-F Mach 1 C2 guide catheter (Boston Scientific), which was advanced over the hydrophilic glide wire to the mid–splenic artery. A Marksman microcatheter (ev3 Endovascular Inc) and a Transcend EX Platinum tip guide wire (Boston Scientific) were advanced through the 6-F guide catheter and
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placed into the inferior segmental artery beyond the neck of the aneurysm. A 5.0 mm diameter ⫻ 20 mm long Pipeline Embolization Device (maximum unconstrained diameter for this device is 5.2 mm) was loaded into the microcatheter and advanced to the tip of the microcatheter. The microcatheter and Pipeline Embolization Device were withdrawn as a unit such that the distal portion of the device was positioned 1 cm beyond the center of the aneurysm neck. The microcatheter was withdrawn over the Pipeline Embolization Device to start deployment. During this maneuver, the tip of the device remained constrained by the distal retaining coil, and the exposed portion of the Pipeline Embolization Device mesh formed a very slender “cigar” shape (Fig 5a). The exposed portion of the Pipeline Embolization Device was released from the retaining coil by turning the core wire clockwise by two turns using the included torque device. Further deployment of the Pipeline Embolization Device required the use of a pull (microcatheter withdrawal) and push technique (advancement of the core delivery wire) to allow the mesh of the Pipeline Embolization Device to remain compact. The proximal portion of the device was deployed 1 cm proximal to the center of the aneurysm neck (Fig 5b). Angiography performed after deployment showed excellent flow through the Pipeline Embolization Device into a widely patent inferior segmental artery. Contrast material was noted to be stagnant in the aneurysm (Fig 5c). Hemostasis at the puncture site was established with a 6-F Angio-Seal Closure Device (St. Jude Medical, St. Paul, Minnesota). The patient tolerated the procedure well, and there were no complications. The patient was discharged the next day. The patient was to continue taking daily clopidogrel 75 mg for 6 weeks and daily enteric-coated acetylsalicylic acid 81 mg indefinitely. However, the patient developed episodic epistaxis 2 weeks after discharge, and clopidogrel was discontinued. Follow-up CT angiography performed 20 months after the procedure (Fig 6) showed complete exclusion of the SAA and a patent Pipeline Embolization Device and inferior segmental artery. The SAA had decreased to 3.4 cm in maximum span. Only a small focal area of splenic tissue showed evidence of infarction, and this was believed to be secondary to the original embolization procedure.
DISCUSSION Embolization for SAAs can be successfully performed while preserving flow to the spleen if the embolization is performed proximal to collateral vessels that will continue to perfuse the distal splenic artery. In the setting of proximal splenic artery occlusion, there are three main collateral pathways that preserve flow to the splenic parenchyma (gastroduodenal to epiploic arteries, transverse pancreatic to pancreatica magna to splenic artery, and left gastric to short gastric arteries). These occur proximal to the splenic hilum and splenic branch vessels (16). The SAA discussed in this report incorporated the most distal splenic artery and
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Figure 5. (a) Tip of the Pipeline Embolization Device placed distal to the aneurysm neck and partially exposed by withdrawing the microcatheter: tip of 6-F guide catheter (white arrowhead); proximal end of Pipeline Embolization Device (large black arrow); tip of Marksman microcatheter (long white arrow); constrained Pipeline Embolization Device mesh with slender cigar appearance (short white arrow); tip of protective retaining coil, which maintains the Pipeline Embolization Device in a constrained state (small black arrow); and platinum coil tip of integrated core wire (black arrowhead). (b) Pipeline Embolization Device (arrows) completely deployed across the aneurysm neck. (c) Angiogram obtained after deployment showing patency of the Pipeline Embolization Device (black arrows) and inferior segmental splenic artery, exclusion of aneurysm, and stasis of trapped contrast material within the aneurysm (white arrows). (Available in color online at www.jvir.org.)
Figure 6. Coronal reformatted CT image 20 months after the procedure showing a patent Pipeline Embolization Device (small arrow) and inferior segmental artery (long arrow) and confirming complete thrombosis of the SAA (arrowheads).
its bifurcation, which is beyond these collateral pathways. Embolization for the distal SAA in this case would have relatively high risk of splenic infarction (17). This risk was confirmed in our case because the first-stage coil embolization of the upper pole branch arising from the aneurysm resulted in infarction within that vascular territory. Previous authors have reported use of various peripheral stent grafts for the treatment of SAAs (10,18 –20). We considered low-profile covered stent platforms such as the GraftMaster stent graft (Abbott Vascular Devices, Redwood City, California) unsuitable for this case because we deemed the degree of vessel tortuosity too great to allow straightforward device placement. Direct coiling of the aneurysm would require stent-assisted coiling and numer-
ous coils. The relatively wide aneurysm neck would be problematic for liquid embolic agents such as n-butyl cyanoacrylate (Histoacryl; B. Braun Aesculap AG, Tuttlingen, Germany) or Onyx (ev3 Endovascular Inc) and could result in either incomplete treatment or partial or complete occlusion of the splenic artery. The Silk artery reconstruction device (Balt Extrusion, Montmorency, France) is another flow diversion device that could be used in this scenario. Reports have shown successful use of this device in the treatment of cerebral aneurysms (21). The Silk device is not approved by the FDA and requires Health Canada special access clearance in Canada. The Pipeline Embolization Device is attached to a flexible delivery wire, which has radiopaque end markers, and is packaged in an introducer sheath. This packaged device can be loaded into standard microcatheters of 0.027inch inner diameter (Pipeline Embolization Device Instruction for Use (IFU), ev3 Endovascular Inc, Plymouth, Minnesota) (14). First the microcatheter is placed beyond the site of the aneurysm neck, and then the device is pushed through the microcatheter to the target site. The distal end of the device should be placed at least 3– 4 mm beyond the aneurysm neck. The device is initially unsheathed by withdrawing the microcatheter, while maintaining the position of the device itself by stabilizing the delivery wire; the distal end of the device is exposed. After a sufficient length of the device is exposed, it releases from the delivery wire spontaneously or with clockwise rotation of the delivery wire (Pipeline Embolization Device Instruction for Use (IFU), ev3 Endovascular Inc., Plymouth, Minnesota). Once anchored in the distal landing zone, the device is deployed by a combination of microcatheter withdrawal and forward pressure on the delivery wire. On release from the delivery system and when properly positioned at the desired location in the vessel, the implant expands to cover the neck of the aneurysm. After deployment, it forms a
Volume 23 䡲 Number 1 䡲 January 䡲 2012
high-coverage mesh of approximately 30%–35% by area (14). The degree of metal surface area coverage can be manipulated by varying the technique of device deployment. Performing greater microcatheter withdrawal as opposed to guide wire advancement results in less compaction of the mesh and enough flow through the interstices to allow perforators to remain patent, which is particularly important in the cerebral circulation. Greater guide wire advancement as opposed to catheter withdrawal results in greater compaction of the mesh, decreasing flow through the interstices of the device. The latter technique was chosen for treatment of the SAA in this case report. The device undergoes approximately 65% shortening during deployment depending on diameter of the device chosen and parent artery ( Pipeline Embolization Device Instruction for Use (IFU), ev3 Endovascular Inc, Plymouth, Minnesota). Multiple devices can be deployed within each other (telescoped) to create a composite endovascular construct (14). Endovascular reconstruction with the Pipeline Embolization Device may represent an optimal treatment strategy, particularly if splenic flow would be compromised by other treatment options. The Pipeline Embolization Device offers a low-profile system that is delivered through a microcatheter, which allows it to reach the distal arterial anatomy and yet preserve distal arterial flow resulting in a more physiologic treatment option. There is also a conceptual advantage to using the Pipeline Embolization Device in that a dense cylindrical mesh is built to reconstruct a de novo vessel through the diseased segment. Kallmes et al (14) showed that this endovascular mesh acts like a scaffolding for endothelial and neointimal overgrowth, bridging the aneurysm neck and resulting in complete aneurysmal occlusion on angiography. Fiorella et al (15) described this complete incorporation of the Pipeline Embolization Device into the affected artery as “endovascular re-paving” and stated that the Pipeline Embolization Device allows the artery to act as if it were “steel-reinforced.” In a previous study, the same authors showed that intracranial aneurysms treated with this device were angiographically stable after 1 year of follow-up (13). This study supports evidence that a vessel reconstructed with a Pipeline Embolization Device can be durable, although more studies are needed to confirm its long-term effect on postoperative prognosis. The decision to place the patient on low-dose aspirin and clopidogrel was based on published reports using this regimen when treating intracranial aneurysms with the Pipeline Embolization Device (13–15), established coronary stent data, and our own personal experience with small-caliber arterial stents. However, the use of antiplatelet therapy with the Pipeline Embolization Device has not been specifically studied. Based on the present case, we believe the Pipeline Embolization Device offers a low-profile treatment option for visceral and peripheral aneurysms that may have advantages compared with other contemporary open surgical and endovascular therapies. Additional experience is needed to
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determine the specific clinical settings in which use of this device may be beneficial.
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FURTHER READING Busuttil RW, Brin BJ. The diagnosis and management of visceral artery aneurysms. Surgery 1980; 88:619 – 624. Holdsworth RJ, Gunn A. Ruptured splenic artery aneurysm in pregnancy: a review. Br J Obstet Gynaecol 1992; 99:595–597. Lee PC, Rhee RY, Gordon RY, Fung JJ, Webster MW. Management of splenic artery aneurysms: the significance of portal and essential hypertension. J Am Coll Surg 1999; 189:483– 490. Shanley CJ, Shah NL, Messina LM. Common splanchnic artery aneurysms: splenic, hepatic, and celiac. Ann Vasc Surg 1996; 10:315–322. Yamamoto S, Hirota S, Maeda H, et al. Transcatheter coil embolization of splenic artery aneurysm. Cardiovasc Interv Radiol 2008; 31:527–534.