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Preliminary Retrograde Visceral Artery Reconstruction for Thoracoabdominal Aortic Aneurysms
Papers Presented to the Southern California Vascular Surgical Society Preliminary Retrograde Visceral Artery Reconstruction for Thoracoabdominal Aortic Aneurysms Alexander B. Chao, Kevin Major, Douglas B. Hood, Kaushal R. Patel, Vincent L. Rowe, and Fred A. Weaver, Los Angeles, California
The recent availability of thoracic endografts has expanded the options for treatment of thoracoabdominal aortic pathology. However, disease that involves the visceral aortic segment presents a special challenge due to the need to preserve mesenteric perfusion. We present three patients in whom preliminary retrograde visceral artery reconstruction was used as an adjunct prior to endovascular repair.
The recent availability of thoracic endografts has expanded the options for treatment of thoracoabdominal aortic pathology. However, disease that involves the visceral aortic segment presents a special challenge due to the need to preserve mesenteric perfusion. We present three patients in whom preliminary retrograde visceral artery reconstruction (PReVAR) was used as an adjunct prior to endovascular repair. A review of the current endovascular thoracoabdominal experience in the literature is presented. Endovascular repair of abdominal and, more recently, descending thoracic aortic aneurysms has been embraced by the vascular community in unprecedented fashion. The management of aneurysms involving major aortic branches, however, represents a particular challenge to the endovascular surgeon. The orifices of the major visceral branches,
Presented at the 24th Annual Meeting of the Southern California Vascular Surgical Society, Temecula, CA, May 5-7, 2006. Division of Vascular Surgery and Endovascular Therapy, Keck School of Medicine, University of Southern California, Los Angeles, CA. Correspondence to: Fred A. Weaver, MD, 1510 San Pablo Street, Suite 514, Los Angeles, CA 90033-4612, USA, E-mail: fweaver@ surgery.usc.edu Ann Vasc Surg 2007; 21: 123-128 DOI: 10.1016/j.avsg.2006.10.011 Ó Annals of Vascular Surgery Inc. Published online: March 9, 2007
including the mesenteric and renal arteries, cannot simply be covered by an endovascular graft without risk of end-organ ischemia. Adjunctive procedures to maintain perfusion in these branches must be undertaken to allow successful endovascular exclusion of the aneurysmal aortic segment. Fenestrated grafts that will allow complete endovascular repair are being developed and may ultimately prove successful. However, these grafts are not currently available outside of clinical research trials and will likely require substantial technical expertise in the endovascular arena to achieve favorable outcomes. The open surgical approach to visceral artery revascularization, on the other hand, is a technique familiar to all vascular surgeons. This report summarizes our small experience with open reconstruction of visceral vessels to allow subsequent endovascular exclusion of aneurysms located in the upper abdominal aorta. We have adopted PReVAR as a staged operation before endovascular repair using commercially available grafts for select patients with thoracoabdominal aortic aneurysms (TAAAs).
CASE REPORTS Case 1 A 77-year-old female presented with abdominal pain and weight loss of unknown origin. She was found to have 123
124 Chao et al.
a Crawford type II TAAA, with diameters of 6.6 cm in the thoracic portion and 5.0 cm in the infrarenal portion (Fig. 1). The visceral segment of the aorta was of relatively normal caliber. A complete workup including upper and lower gastrointestinal (GI) endoscopy was unremarkable. The thoracic aneurysm extended down to the celiac axis, leaving no distal landing zone for a thoracic endograft. She was first prepared for open transabdominal repair of the infrarenal aortic segment with a bifurcated prosthetic graft and four-vessel visceral reconstruction (Fig. 2). To reconstruct the renal arteries, 7 mm polytetrafluoroethylene (PTFE) grafts were sewn end-to-side to the main body of the aortic graft and to each renal artery. In order to reconstruct the mesenteric vessels, a second bifurcated graft was sewn in an end-to-side fashion to the proximal right limb of the aortic graft. These two additional limbs were then sutured in an end-to-side fashion to the superior mesenteric artery (SMA) and celiac artery (CA). The visceral arteries were ligated between their aortic origins and the graft anastomoses to prevent retrograde flow back into the aorta after endograft placement, a potential source of type II endoleaks. Her postoperative course was remarkable only for diarrhea, which resolved after 4 weeks. Three months later, she underwent endovascular repair of the thoracic aneurysm using the TAG device (W. L. Gore and Associates, Flagstaff, AZ). The distal landing zone for the thoracic endograft was within the main body of the infrarenal graft proximal to the origins of the renal artery bypass grafts. Endograft placement required the use of an iliac conduit originating from the left limb of the infrarenal graft, exposed via a left retroperitoneal approach. Operative time for the PReVAR was 8 hr and 20 min. Endovascular repair of the TAAA required 3 hr and 20 min. A computed tomographic (CT) scan at 6 months post-PReVAR (4 months post-TAG) demonstrated a small type II endoleak, presumably originating from an intercostal artery, without aneurysm enlargement. All graft limbs were patent.
Case 2 A 55-year-old male underwent repair of the descending thoracic aorta 6 years ago for aneurysmal degeneration of a chronic dissection. He presented 4 years later with a symptomatic abdominal aortic aneurysm (AAA), at which time he underwent open repair consisting of aortic fenestration, graft replacement of the infrarenal aorta, bypass grafts to the right renal artery and SMA, and reimplantation of the inferior mesenteric artery. Over the next 2 years, follow-up demonstrated enlargement of the visceral aortic segment to over 6 cm in diameter. The previous right renal artery bypass was occluded, while the SMA graft was patent. PReVAR was performed with reconstruction of both renal arteries and the CA with a graft originating from the left graft limb (Figs. 3 and 4). Operative time was 8 hr and 40 min. His postoperative course was complicated by an episode of partial small bowel obstruction, requiring readmission and conservative management. Three months later, the visceral aortic
Annals of Vascular Surgery
Fig. 1. Crawford type II TAAA with 6.6 cm thoracic and 5.0 cm infrarenal abdominal aneurysm. Although the visceral segment is uninvolved, there is no adequate landing zone for an endograft. aneurysm was excluded with a TAG device, landing proximally in the previous thoracic graft and distally in the abdominal graft. Access for the TAG deployment sheath was through a conduit sewn to the external iliac artery contralateral to the mesenteric bypass. Operative time was 3 hr and 30 min. He was returned to the operating room on postoperative day 2 for evacuation of a wound hematoma. Follow-up CT scan at 7 months post-PReVAR (5 months post-TAG) revealed a type II endoleak without aneurysm enlargement. All graft limbs were patent.
Case 3 A 76-year-old female had previously undergone open repair of the ascending aorta and proximal descending thoracic aorta for aneurysmal disease. Over the subsequent follow-up period, the distal descending thoracic aorta
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Fig. 2. Intraoperative photo showing completed PReVAR. Arrows indicate PTFE limbs originating from the main body of the AAA repair graft and traveling to bilateral renal arteries. Arrowhead indicates 14 7 mm bifurcated graft originating from the right limb of the AAA repair graft and traveling to the CA and mesenteric artery.
also enlarged to 5.4 cm, with the dilated segment extending to just below the renal arteries. PReVAR of the CA, SMA, and both renal arteries using a graft originating from the right common iliac artery was performed. Three months later, she underwent TAG placement from the thoracic graft proximally to the infrarenal abdominal aorta. Intraoperative angiography revealed patent CA and bilateral renal artery bypass grafts, with an unexpected asymptomatic occlusion of the SMA graft (Fig. 5). There was good collateral compensation from the CA. Operative times for PReVAR and TAG were 5 hr and 50 min and 2 hr and 40 min, respectively. Follow-up CT scan at 6 months post-PReVAR (4 months post-TAG) showed a type II endoleak without aneurysm enlargement. The CA graft continued to provide collateral flow to the SMA.
Surgical Methods and Results All patients had good recovery except for minor complications. We staged all endograft placements 2-4 months following PReVAR. All patients had extensive to near complete coverage of the native aorta, with no instance of paraplegia. In no patient was coverage of the left subclavian or hypogastric arteries required. Spinal drains were used and a cerebral spinal fluid pressure of 10 mm Hg was maintained for 48 hr postoperatively. Intraoperative and postoperative blood pressure was maintained at >120 mm Hg systolic, with a mean arterial pressure >70 mm Hg (requiring the use of fluid bolus and vasopressors as necessary). Serum creatinine was unchanged in all patients. There were no demonstrated endoleaks.
Fig. 3. Three-dimensional rendering of CT scan data showing TAAA in patient 2. Arrow points to retrograde bypass coming off left graft limb of AAA repair. The three limbs travel to bilateral renal arteries and the CA. The SMA had been previously bypassed.
DISCUSSION Open repair of TAAA remains a formidable undertaking. Cambria et al.,1 practicing at a center that has extensive experience performing these repairs, reported a mortality rate of 8.3%, including both elective and emergent repairs. With segmental intercostal artery reimplantation and epidural cooling, the paraplegia rate was 10.6%. Other complications included renal failure (13.5%, with 4.8% requiring dialysis), cardiac complications (13.8%, including myocardial infarction in 4%), and pulmonary problems (44%). Reoperation was required in 25% of patients, including tracheostomy, gastrostomy, and reexploration for bleeding or ischemia. These results serve as a benchmark but may not be realistically attainable at most centers. Analysis of 1,542 patients from the Nationwide Inpatient Sample revealed average mortality rates ranging from 15% in highvolume centers to 27.4% in low-volume centers.2 This difference persisted after adjustment for demographic factors and comorbidities. Results based on individual surgeon volume showed a similar disparity, with average mortality rates of 11% and 26% for high- and low-volume surgeons, respectively. The impact of endovascular treatment of abdominal and, more recently, thoracic aortic aneurysms
126 Chao et al.
Fig. 4. Cross-sectional image from CT scan of patient 2. Arrows indicate PTFE limbs originating from the main body of the AAA repair graft and traveling to bilateral renal arteries. Arrowheads indicate two graft limbs traveling in retrograde fashion to supply the CA and superior mesenteric artery.
has been unprecedented. Treatment of aneurysms involving the major aortic branches, however, remains problematic, with solutions ranging from simple coverage of select branches (left subclavian, celiac, hypogastric arteries) to the more complex branched or fenestrated graft technology.3,4 Complete endovascular repair using fenestrated or branched grafts may allow TAAA repair with lower mortality and morbidity rates; but published data are only now becoming available, and widespread experience is lacking. A recent article from the Cleveland Clinic details the results in 50 patients treated with fenestrated grafts, of which nine were placed for repair of TAAAs.5 These results are encouraging and a testament to their expertise. Technical success in the TAAA group was 89% (8/9). Mortality was 22% (2/9). These were associated with paralysis and renal failure. No endoleaks were evident at 12-month follow-up (n ¼ 5). The authors caution that the application of fenestrated technology to TAAA ‘‘remains challenging in all facets’’ and recommend expertise with iliac branched grafts and simple fenestrated grafts before addressing the treatment of suprarenal and thoracoabdominal aneurysms. In the discussion of that paper, Fillinger6 emphasizes the complexity of current technology and points out that fluoroscopy times averaged 117 min for TAAA. Fillinger6 concludes
Annals of Vascular Surgery
Fig. 5. Angiogram 3 months postop from PReVAR, performed at the time of TAG placement. There was an unexpected finding of occlusion of graft limb to the SMA. The celiac limb is patent, providing collateral flow to the native SMA.
that branched-graft repair for TAAA is not ‘‘something that can or should be adopted by the average center in the very near future.’’ A smaller series including four patients treated with branched grafts for TAAA was also recently published. Treatment was complicated by graft rotation in one patient, resulting in occlusion of the left renal artery and a dissection that occluded the right common iliac artery; this patient ultimately died.7 It is clear that deployment of fenestrated endovascular grafts is technically intricate. Anatomic selection criteria have yet to be defined. How this technology will ultimately affect treatment in the general population over the next decade is unclear. The described PReVAR procedure may be most applicable in patients at highest risk of morbidity from standard open repair through a large thoracoabdominal incision. High-risk patients include those with chronic obstructive pulmonary disease, coronary artery disease, and chronic renal insufficiency. The procedure avoids the potential pulmonary complications associated with a thoracic operation, has potentially decreased individual organ ischemia time, and obviates aortic crossclamping. Patients with significant medical comorbidities, along with reoperative candidates, may benefit the most from PReVAR with endoluminal aneurysm exclusion. Admittedly, experience with this technique is limited, and there are no direct
Vol. 21, No. 2, 2007
Preliminary retrograde visceral artery reconstruction
Table I. Summary of reports describing complete visceral (three- or four-vessel) reconstruction followed by EVAR Patients (n) 14
Bonardelli et al. Fulton et al.15 Lundbom et al.8 Kotsis et al.11 Quinones-Baldrich et al.16 Flye et al.17 Agostinelli et al.18 Rubin19 Rimmer and Wolfe20 Total
1 1 4 4 3 1 6 1 22
Mortality
0 0 25% 25% 0 0 0 17% 0 14%
data supporting a lower complication rate compared to open TAAA repair. We contend that the PReVAR/ endovascular aortic repair (EVAR) procedure, although not without complications, is a reasonable alternative in centers with a solid open and endovascular practice but without access to branched or fenestrated endograft technology. While we have used PReVAR in a highly select group of complex patients, its proper applicability is evolving. The data from limited small case series (Table I) suggest that mortality rates remain substantial, perhaps indicating that this procedure is being used in only the highest-risk patients.8 A large case series (published in abstract form only) including 22 patients undergoing PReVAR followed by exclusion of the thoracoabdominal aorta documented an elective mortality of 17.6%.9 The necessity of bypass to both the CA and SMA is debatable. We have favored dual revascularization because of the possibility of devastating complications that may occur after acute occlusion of the CA.10,11 In our third case example, an asymptomatic occlusion of the SMA graft was discovered at the time of aneurysm endografting. Graft occlusion most likely was the result of a technical failure. Fortunately, the celiac graft was patent and provided collateral flow. Asymptomatic occlusion of mesenteric grafts has been well documented in other reports.12 We recently treated a patient (not reported here) with TAAA and a concomitant stenosis of the CA at the distal landing zone of a planned endovascular graft. In this instance, we did not perform preliminary celiac revascularization and simply covered the origin of the celiac with the distal end of the endograft; there were no adverse clinical sequelae or endoleak. At this time, our conservative recommendation is to revascularize both the CA and SMA in patients without preexisting occlusive
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disease of these branches. Of course, ligation of the mesenteric and renal artery origins proximal to the bypass graft implantation sites is also recommended to avoid type II endoleaks after endograft implantation. The timing of endograft deployment after visceral reconstruction is controversial. Many cases in the literature were performed at the same setting, with the stent graft placed immediately following the PReVAR procedure. We performed delayed endografting largely because of practical concerns at our particular facility. We use a dedicated operating room angiography suite for all EVAR procedures. The angiography table is suboptimal for a prolonged open operation, with compromised lighting and an inability to attach fixed retractors. The PReVAR itself may be a long procedure that lasts several hours. Theoretically, the fluid shifts and hemodynamic instability associated with a major intraabdominal operation may place the patient at higher risk of paraplegia if performed in conjunction with thoracic endografting. Because of these issues, we have elected to perform staged repair. As a note of caution, however, rupture has been described in the interval between PReVAR and planned endovascular aneurysm exclusion.13 If there is a significant delay between open visceral reconstruction and the endografting procedure, reimaging with CT angiography may be advisable to reassess the relevant anatomy and document patency of the visceral grafts.
CONCLUSION The treatment of aneurysms involving the visceral aortic segment is complex. PReVAR followed by endovascular aneurysm exclusion offers one option for the management of this condition that has several potential advantages over open aneurysm repair. While early experience suggests that the results of PReVAR compare favorably with other management strategies, more experience is necessary to determine the ultimate place of this technique in the therapeutic armamentarium. REFERENCES 1. Cambria RP, Clouse WD, Davison JK, et al. Thoracoabdominal aneurysm repair: results with 337 operations performed over a 15 year interval. Ann Surg 2002;236:471-479. 2. Cowan JA, Jr, Dimick JB, Henke PK, et al. Surgical treatment of intact thoracoabdominal aortic aneurysms in the United States: hospital and surgeon volume-related outcomes. J Vasc Surg 2003;37:1169-1174. 3. Peterson BG, Eskandari MK, Gleason TG, Morasch MD. Utility of left subclavian artery revascularization in association
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4.
5.
6.
7.
8.
9.
10. 11.
12.
with endoluminal repair of acute and chronic thoracic aortic pathology. J Vasc Surg 2006;43:433-439. Lawrence-Brown M, Sieunarine K, Van Schie G, et al. Hybrid open-endoluminal technique for repair of thoracoabdominal aneurysm involving the celiac axis. J Endovasc Ther 2000;7:513-519. Greenberg RK, West K, Pfaff K, et al. Beyond the aortic bifurcation: branched endovascular grafts for thoracoabdominal and aortoiliac aneurysms. J Vasc Surg 2006;43: 879-886. Fillinger MF. Beyond the aortic bifurcation: Branched endovascular grafts for thoracoabdominal and aortoiliac aneurysms. J Vasc Surg 2006;43:886. Anderson JL, Adam DJ, Berce M, et al. Repair of thoracoabdominal aortic aneurysms with fenestrated and branched endovascular stent grafts. J Vasc Surg 2005;42:600-607. Lundbom J, Hatlinghus S, Odegard A, et al. Combined open and endovascular treatment of complex aortic disease. Vascular 2004;12:93-98. Black SA, Wofe JHN, Clark M, Hamady M, Cheshire JW, Jenkins MP. Complex thoraco-abdominal aortic aneurysms: endovascular exclusion with visceral revascularization. J Vasc Surg 2006;43:1081-1089. Farber MA. Visceral vessel relocation techniques. J Vasc Surg 2006;43:81A-84A. Kotsis T, Scharrer-Pamler R, Kapfer X, et al. Treatment of thoracoabdominal aortic aneurysms with a combined endovascular and surgical approach. Int Angiol 2003;22: 125-133. McMillan WD, McCarthy WJ, Bresticker MR, et al. Mesenteric artery bypass: objective patency determination. J Vasc Surg 1995;21:729-740.
Annals of Vascular Surgery
13. Cambria RP. Extra-anatomic visceral revascularization and endovascular stent-grafting for complex thoracoabdominal aortic lesions: expert commentary. Perspect Vasc Surg Endovasc Ther 2005;17:234-235. 14. Bonardelli S, De Lucia M, Cervi E, et al. Combined endovascular and surgical approach (hybrid treatment) for management of type IV thoracoabdominal aneurysm. Vascular 2005;2:124-128. 15. Fulton JJ, Farber MA, Marston WA, et al. Endovascular stent-graft repair of pararenal and type IV thoracoabdominal aortic aneurysms with adjunctive visceral reconstruction. J Vasc Surg 2005;41:191-198. 16. Quinones-Baldrich WJ, Panetta TF, Vescera CL, et al. Repair of type IV thoracoabdominal aneurysm with a combined endovascular and surgical approach. J Vasc Surg 1999;30: 555-560. 17. Flye MW, Choi ET, Sanchez LA, et al. Retrograde visceral vessel revascularization followed by endovascular aneurysm exclusion as an alternative to open surgical repair of thoracoabdominal aortic aneurysm. J Vasc Surg 2004;39:454-458. 18. Agostinelli A, Saccani S, Budillon AM, et al. Repair of coexistent infrarenal and thorcoabdominal aortic aneurysm: combined endovascular and open surgical procedure with visceral vessel relocation. J Thorac Cardiovasc Surg 2002;124:184-185. 19. Rubin BG. Extra-anatomic visceral revascularization and endovascular stent-grafting for complex thoracoabdominal aortic lesions. Perspect Vasc Surg Endovasc Ther 2005;17: 227-234. 20. Rimmer J, Wolfe JHN. Type III thoracoabdominal aortic aneurysm repair: a combined surgical and endovascular approach. Eur J Vasc Endovasc Surg 2003;26:677-679.
The recent availability of thoracic endografts has expanded the options for treatment of thoracoabdominal aortic pathology. However, disease that involves the visceral aortic segment presents a special challenge due to the need to preserve mesenteric perfusion. We present three patients in whom preliminary retrograde visceral artery reconstruction was used as an adjunct prior to endovascular repair.
The recent availability of thoracic endografts has expanded the options for treatment of thoracoabdominal aortic pathology. However, disease that involves the visceral aortic segment presents a special challenge due to the need to preserve mesenteric perfusion. We present three patients in whom preliminary retrograde visceral artery reconstruction (PReVAR) was used as an adjunct prior to endovascular repair. A review of the current endovascular thoracoabdominal experience in the literature is presented. Endovascular repair of abdominal and, more recently, descending thoracic aortic aneurysms has been embraced by the vascular community in unprecedented fashion. The management of aneurysms involving major aortic branches, however, represents a particular challenge to the endovascular surgeon. The orifices of the major visceral branches,
Presented at the 24th Annual Meeting of the Southern California Vascular Surgical Society, Temecula, CA, May 5-7, 2006. Division of Vascular Surgery and Endovascular Therapy, Keck School of Medicine, University of Southern California, Los Angeles, CA. Correspondence to: Fred A. Weaver, MD, 1510 San Pablo Street, Suite 514, Los Angeles, CA 90033-4612, USA, E-mail: fweaver@ surgery.usc.edu Ann Vasc Surg 2007; 21: 123-128 DOI: 10.1016/j.avsg.2006.10.011 Ó Annals of Vascular Surgery Inc. Published online: March 9, 2007
including the mesenteric and renal arteries, cannot simply be covered by an endovascular graft without risk of end-organ ischemia. Adjunctive procedures to maintain perfusion in these branches must be undertaken to allow successful endovascular exclusion of the aneurysmal aortic segment. Fenestrated grafts that will allow complete endovascular repair are being developed and may ultimately prove successful. However, these grafts are not currently available outside of clinical research trials and will likely require substantial technical expertise in the endovascular arena to achieve favorable outcomes. The open surgical approach to visceral artery revascularization, on the other hand, is a technique familiar to all vascular surgeons. This report summarizes our small experience with open reconstruction of visceral vessels to allow subsequent endovascular exclusion of aneurysms located in the upper abdominal aorta. We have adopted PReVAR as a staged operation before endovascular repair using commercially available grafts for select patients with thoracoabdominal aortic aneurysms (TAAAs).
CASE REPORTS Case 1 A 77-year-old female presented with abdominal pain and weight loss of unknown origin. She was found to have 123
124 Chao et al.
a Crawford type II TAAA, with diameters of 6.6 cm in the thoracic portion and 5.0 cm in the infrarenal portion (Fig. 1). The visceral segment of the aorta was of relatively normal caliber. A complete workup including upper and lower gastrointestinal (GI) endoscopy was unremarkable. The thoracic aneurysm extended down to the celiac axis, leaving no distal landing zone for a thoracic endograft. She was first prepared for open transabdominal repair of the infrarenal aortic segment with a bifurcated prosthetic graft and four-vessel visceral reconstruction (Fig. 2). To reconstruct the renal arteries, 7 mm polytetrafluoroethylene (PTFE) grafts were sewn end-to-side to the main body of the aortic graft and to each renal artery. In order to reconstruct the mesenteric vessels, a second bifurcated graft was sewn in an end-to-side fashion to the proximal right limb of the aortic graft. These two additional limbs were then sutured in an end-to-side fashion to the superior mesenteric artery (SMA) and celiac artery (CA). The visceral arteries were ligated between their aortic origins and the graft anastomoses to prevent retrograde flow back into the aorta after endograft placement, a potential source of type II endoleaks. Her postoperative course was remarkable only for diarrhea, which resolved after 4 weeks. Three months later, she underwent endovascular repair of the thoracic aneurysm using the TAG device (W. L. Gore and Associates, Flagstaff, AZ). The distal landing zone for the thoracic endograft was within the main body of the infrarenal graft proximal to the origins of the renal artery bypass grafts. Endograft placement required the use of an iliac conduit originating from the left limb of the infrarenal graft, exposed via a left retroperitoneal approach. Operative time for the PReVAR was 8 hr and 20 min. Endovascular repair of the TAAA required 3 hr and 20 min. A computed tomographic (CT) scan at 6 months post-PReVAR (4 months post-TAG) demonstrated a small type II endoleak, presumably originating from an intercostal artery, without aneurysm enlargement. All graft limbs were patent.
Case 2 A 55-year-old male underwent repair of the descending thoracic aorta 6 years ago for aneurysmal degeneration of a chronic dissection. He presented 4 years later with a symptomatic abdominal aortic aneurysm (AAA), at which time he underwent open repair consisting of aortic fenestration, graft replacement of the infrarenal aorta, bypass grafts to the right renal artery and SMA, and reimplantation of the inferior mesenteric artery. Over the next 2 years, follow-up demonstrated enlargement of the visceral aortic segment to over 6 cm in diameter. The previous right renal artery bypass was occluded, while the SMA graft was patent. PReVAR was performed with reconstruction of both renal arteries and the CA with a graft originating from the left graft limb (Figs. 3 and 4). Operative time was 8 hr and 40 min. His postoperative course was complicated by an episode of partial small bowel obstruction, requiring readmission and conservative management. Three months later, the visceral aortic
Annals of Vascular Surgery
Fig. 1. Crawford type II TAAA with 6.6 cm thoracic and 5.0 cm infrarenal abdominal aneurysm. Although the visceral segment is uninvolved, there is no adequate landing zone for an endograft. aneurysm was excluded with a TAG device, landing proximally in the previous thoracic graft and distally in the abdominal graft. Access for the TAG deployment sheath was through a conduit sewn to the external iliac artery contralateral to the mesenteric bypass. Operative time was 3 hr and 30 min. He was returned to the operating room on postoperative day 2 for evacuation of a wound hematoma. Follow-up CT scan at 7 months post-PReVAR (5 months post-TAG) revealed a type II endoleak without aneurysm enlargement. All graft limbs were patent.
Case 3 A 76-year-old female had previously undergone open repair of the ascending aorta and proximal descending thoracic aorta for aneurysmal disease. Over the subsequent follow-up period, the distal descending thoracic aorta
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Fig. 2. Intraoperative photo showing completed PReVAR. Arrows indicate PTFE limbs originating from the main body of the AAA repair graft and traveling to bilateral renal arteries. Arrowhead indicates 14 7 mm bifurcated graft originating from the right limb of the AAA repair graft and traveling to the CA and mesenteric artery.
also enlarged to 5.4 cm, with the dilated segment extending to just below the renal arteries. PReVAR of the CA, SMA, and both renal arteries using a graft originating from the right common iliac artery was performed. Three months later, she underwent TAG placement from the thoracic graft proximally to the infrarenal abdominal aorta. Intraoperative angiography revealed patent CA and bilateral renal artery bypass grafts, with an unexpected asymptomatic occlusion of the SMA graft (Fig. 5). There was good collateral compensation from the CA. Operative times for PReVAR and TAG were 5 hr and 50 min and 2 hr and 40 min, respectively. Follow-up CT scan at 6 months post-PReVAR (4 months post-TAG) showed a type II endoleak without aneurysm enlargement. The CA graft continued to provide collateral flow to the SMA.
Surgical Methods and Results All patients had good recovery except for minor complications. We staged all endograft placements 2-4 months following PReVAR. All patients had extensive to near complete coverage of the native aorta, with no instance of paraplegia. In no patient was coverage of the left subclavian or hypogastric arteries required. Spinal drains were used and a cerebral spinal fluid pressure of 10 mm Hg was maintained for 48 hr postoperatively. Intraoperative and postoperative blood pressure was maintained at >120 mm Hg systolic, with a mean arterial pressure >70 mm Hg (requiring the use of fluid bolus and vasopressors as necessary). Serum creatinine was unchanged in all patients. There were no demonstrated endoleaks.
Fig. 3. Three-dimensional rendering of CT scan data showing TAAA in patient 2. Arrow points to retrograde bypass coming off left graft limb of AAA repair. The three limbs travel to bilateral renal arteries and the CA. The SMA had been previously bypassed.
DISCUSSION Open repair of TAAA remains a formidable undertaking. Cambria et al.,1 practicing at a center that has extensive experience performing these repairs, reported a mortality rate of 8.3%, including both elective and emergent repairs. With segmental intercostal artery reimplantation and epidural cooling, the paraplegia rate was 10.6%. Other complications included renal failure (13.5%, with 4.8% requiring dialysis), cardiac complications (13.8%, including myocardial infarction in 4%), and pulmonary problems (44%). Reoperation was required in 25% of patients, including tracheostomy, gastrostomy, and reexploration for bleeding or ischemia. These results serve as a benchmark but may not be realistically attainable at most centers. Analysis of 1,542 patients from the Nationwide Inpatient Sample revealed average mortality rates ranging from 15% in highvolume centers to 27.4% in low-volume centers.2 This difference persisted after adjustment for demographic factors and comorbidities. Results based on individual surgeon volume showed a similar disparity, with average mortality rates of 11% and 26% for high- and low-volume surgeons, respectively. The impact of endovascular treatment of abdominal and, more recently, thoracic aortic aneurysms
126 Chao et al.
Fig. 4. Cross-sectional image from CT scan of patient 2. Arrows indicate PTFE limbs originating from the main body of the AAA repair graft and traveling to bilateral renal arteries. Arrowheads indicate two graft limbs traveling in retrograde fashion to supply the CA and superior mesenteric artery.
has been unprecedented. Treatment of aneurysms involving the major aortic branches, however, remains problematic, with solutions ranging from simple coverage of select branches (left subclavian, celiac, hypogastric arteries) to the more complex branched or fenestrated graft technology.3,4 Complete endovascular repair using fenestrated or branched grafts may allow TAAA repair with lower mortality and morbidity rates; but published data are only now becoming available, and widespread experience is lacking. A recent article from the Cleveland Clinic details the results in 50 patients treated with fenestrated grafts, of which nine were placed for repair of TAAAs.5 These results are encouraging and a testament to their expertise. Technical success in the TAAA group was 89% (8/9). Mortality was 22% (2/9). These were associated with paralysis and renal failure. No endoleaks were evident at 12-month follow-up (n ¼ 5). The authors caution that the application of fenestrated technology to TAAA ‘‘remains challenging in all facets’’ and recommend expertise with iliac branched grafts and simple fenestrated grafts before addressing the treatment of suprarenal and thoracoabdominal aneurysms. In the discussion of that paper, Fillinger6 emphasizes the complexity of current technology and points out that fluoroscopy times averaged 117 min for TAAA. Fillinger6 concludes
Annals of Vascular Surgery
Fig. 5. Angiogram 3 months postop from PReVAR, performed at the time of TAG placement. There was an unexpected finding of occlusion of graft limb to the SMA. The celiac limb is patent, providing collateral flow to the native SMA.
that branched-graft repair for TAAA is not ‘‘something that can or should be adopted by the average center in the very near future.’’ A smaller series including four patients treated with branched grafts for TAAA was also recently published. Treatment was complicated by graft rotation in one patient, resulting in occlusion of the left renal artery and a dissection that occluded the right common iliac artery; this patient ultimately died.7 It is clear that deployment of fenestrated endovascular grafts is technically intricate. Anatomic selection criteria have yet to be defined. How this technology will ultimately affect treatment in the general population over the next decade is unclear. The described PReVAR procedure may be most applicable in patients at highest risk of morbidity from standard open repair through a large thoracoabdominal incision. High-risk patients include those with chronic obstructive pulmonary disease, coronary artery disease, and chronic renal insufficiency. The procedure avoids the potential pulmonary complications associated with a thoracic operation, has potentially decreased individual organ ischemia time, and obviates aortic crossclamping. Patients with significant medical comorbidities, along with reoperative candidates, may benefit the most from PReVAR with endoluminal aneurysm exclusion. Admittedly, experience with this technique is limited, and there are no direct
Vol. 21, No. 2, 2007
Preliminary retrograde visceral artery reconstruction
Table I. Summary of reports describing complete visceral (three- or four-vessel) reconstruction followed by EVAR Patients (n) 14
Bonardelli et al. Fulton et al.15 Lundbom et al.8 Kotsis et al.11 Quinones-Baldrich et al.16 Flye et al.17 Agostinelli et al.18 Rubin19 Rimmer and Wolfe20 Total
1 1 4 4 3 1 6 1 22
Mortality
0 0 25% 25% 0 0 0 17% 0 14%
data supporting a lower complication rate compared to open TAAA repair. We contend that the PReVAR/ endovascular aortic repair (EVAR) procedure, although not without complications, is a reasonable alternative in centers with a solid open and endovascular practice but without access to branched or fenestrated endograft technology. While we have used PReVAR in a highly select group of complex patients, its proper applicability is evolving. The data from limited small case series (Table I) suggest that mortality rates remain substantial, perhaps indicating that this procedure is being used in only the highest-risk patients.8 A large case series (published in abstract form only) including 22 patients undergoing PReVAR followed by exclusion of the thoracoabdominal aorta documented an elective mortality of 17.6%.9 The necessity of bypass to both the CA and SMA is debatable. We have favored dual revascularization because of the possibility of devastating complications that may occur after acute occlusion of the CA.10,11 In our third case example, an asymptomatic occlusion of the SMA graft was discovered at the time of aneurysm endografting. Graft occlusion most likely was the result of a technical failure. Fortunately, the celiac graft was patent and provided collateral flow. Asymptomatic occlusion of mesenteric grafts has been well documented in other reports.12 We recently treated a patient (not reported here) with TAAA and a concomitant stenosis of the CA at the distal landing zone of a planned endovascular graft. In this instance, we did not perform preliminary celiac revascularization and simply covered the origin of the celiac with the distal end of the endograft; there were no adverse clinical sequelae or endoleak. At this time, our conservative recommendation is to revascularize both the CA and SMA in patients without preexisting occlusive
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disease of these branches. Of course, ligation of the mesenteric and renal artery origins proximal to the bypass graft implantation sites is also recommended to avoid type II endoleaks after endograft implantation. The timing of endograft deployment after visceral reconstruction is controversial. Many cases in the literature were performed at the same setting, with the stent graft placed immediately following the PReVAR procedure. We performed delayed endografting largely because of practical concerns at our particular facility. We use a dedicated operating room angiography suite for all EVAR procedures. The angiography table is suboptimal for a prolonged open operation, with compromised lighting and an inability to attach fixed retractors. The PReVAR itself may be a long procedure that lasts several hours. Theoretically, the fluid shifts and hemodynamic instability associated with a major intraabdominal operation may place the patient at higher risk of paraplegia if performed in conjunction with thoracic endografting. Because of these issues, we have elected to perform staged repair. As a note of caution, however, rupture has been described in the interval between PReVAR and planned endovascular aneurysm exclusion.13 If there is a significant delay between open visceral reconstruction and the endografting procedure, reimaging with CT angiography may be advisable to reassess the relevant anatomy and document patency of the visceral grafts.
CONCLUSION The treatment of aneurysms involving the visceral aortic segment is complex. PReVAR followed by endovascular aneurysm exclusion offers one option for the management of this condition that has several potential advantages over open aneurysm repair. While early experience suggests that the results of PReVAR compare favorably with other management strategies, more experience is necessary to determine the ultimate place of this technique in the therapeutic armamentarium. REFERENCES 1. Cambria RP, Clouse WD, Davison JK, et al. Thoracoabdominal aneurysm repair: results with 337 operations performed over a 15 year interval. Ann Surg 2002;236:471-479. 2. Cowan JA, Jr, Dimick JB, Henke PK, et al. Surgical treatment of intact thoracoabdominal aortic aneurysms in the United States: hospital and surgeon volume-related outcomes. J Vasc Surg 2003;37:1169-1174. 3. Peterson BG, Eskandari MK, Gleason TG, Morasch MD. Utility of left subclavian artery revascularization in association
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