Two-Graft Repair of Very Proximal Superior Mesenteric Artery Aneurysms: A Technical Note Jeffrey L. Ballard, MD, FACS,1 Jill Reiss, MD,2 Ahmed M. Abou-Zamzam, MD, FACS,2 Theodore H. Teruya, MD,2 and Christian Bianchi, MD,2 Orange and Loma Linda, California
Visceral artery aneurysms are found in only 0.2% of the general population. Among these, aneurysms of the superior mesenteric artery (SMA) are very unusual and account for only 5.5 % to 8 %. Risk of rupture or embolization is the impetus for their definitive treatment and this should be performed in acceptable candidates. These aneurysms are typically located distal to the origin of the SMA and this situation lends itself to interposition grafting as a means of both aneurysm repair and reestablishment of prograde SMA blood flow. However, SMA origin aneurysms that arise directly from the abdominal aorta add a degree of complexity because the vascular reconstruction must include the diseased visceral aorta as well as the SMA. In this article we report successful operative treatment of large aneurysms at the origin of the superior mesenteric artery using a two-graft technique in two elderly patients.
INTRODUCTION Visceral artery aneurysms are found in only 0.2% of the general population. Among these, aneurysms of the superior mesenteric artery (SMA) are very unusual and account for only 5.5 to 8%.1-8 Risk of rupture or embolization is the impetus for their definitive treatment, and this should be performed in acceptable candidates. These aneurysms are typically located distal to the origin of the SMA, and this situation lends itself to interposition grafting as a means of both aneurysm repair and reestablishment of prograde SMA blood flow.1-8 However, SMA origin aneurysms that arise directly from the abdominal aorta add a degree of complexity because the vascular reconstruction must include the diseased visceral aorta as well as the SMA. In this technical note, we report successful 1 Department of Surgery, University of California, Irvine, Orange, CA, USA. 2 Division of Vascular Surgery, Loma Linda University Medical Center, Loma Linda, CA, USA. Presented at the Twenty-second Annual Meeting of the Southern California Vascular Surgical Society, La Jolla, CA, April 30-May 2, 2004. Correspondence to: Jeffrey L. Ballard, MD, FACS, 1140 W. La Veta Avenue, Suite 850, Orange, CA 92868, USA, E-mail: jlb@ vascularspecialistsoc.com
Ann Vasc Surg 2005; 19: 465-469 DOI: 10.1007/s10016-005-4655-0 Annals of Vascular Surgery Inc. Published online: June 27, 2005
operative treatment of large aneurysms at the origin of the SMA using a two-graft technique in two elderly patients.
CASE REPORT An 83-year-old man with past medical history significant for hypertension, chronic renal insufficiency, and aortobifemoral bypass for infrarenal aortic aneurysm was found to have a pulsatile epigastric mass during a routine physical examination. Abdominal ultrasound suggested aneurysmal dilation (4 cm) of the proximal SMA with ectasia of the visceral abdominal aorta above the previous infrarenal aneurysm repair. This finding prompted a computed tomographic scan (Fig. 1) and his referral to our tertiary care facility. Preoperative screening included a negative dobutamine stress echocardiogram and minimal carotid disease by duplex ultrasound examination. Three weeks prior to surgery, the patient began hemodialysis via a right arm arteriovenous fistula. This was placed months before for declining renal function with recent serum creatinine of 5 mg/dl. Despite severe renal disease, this elderly patient leads an active life, enjoying golfing and walking with his wife of 65 years; and the decision was made to proceed with surgery. At surgery, a dual lumen endotracheal tube was used and the patient was placed in the right lateral decubitus position to facilitate a thoracoabdominal 465
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Fig. 1. CT scan demonstrating very proximal SMA aneurysm.
approach. The incision was based on the eighth intercostal space and carried across the costal margin in a paramedian plane. The left lung was deflated to facilitate safe entry into the left thorax, and numerous adhesions were lysed to separate the lung base from the diaphragm. Below this level, mobilizing GerotaÕs fascia and the peritoneal contents off the psoas muscle and undersurface of the diaphragm developed an extraperitoneal plane of dissection. Left nephrectomy was performed to enhance surgical exposure of the visceral aorta, and medial rotation of the peritoneal contents facilitated exposure of the proximal celiac axis and aneurysmal SMA (Fig. 2). Careful dissection of the neurovascular tissue around the aneurysm facilitated exposure of the nonaneurysmal distal aspect of the SMA. At this juncture, it was obvious that the base of the SMA aneurysm extended into the visceral aorta without a defined neck. Therefore, this portion of the visceral aorta required graft replacement to prevent blowout of the weakened aortic wall. In addition, the origin of the celiac artery appeared to be in jeopardy of irreparable injury or occlusion during SMA reconstruction due to its juxtaposition with the large aneurysm. This surgical dilemma was effectively treated using a variation of the two-graft approach, which we have previously described for thoracoabdominal aortic aneurysm repair.9 A 12 · 6 mm bifurcated Dacron graft (Sulzer Vascutek, Inchinnan, UK) was secured to the side of the uninvolved descending thoracic aorta using a side-biting
clamp to minimize distal visceral and extremity ischemia. End-to-end bypass was then completed at the celiac artery level with one limb of the bifurcated graft after its transection and secure proximal ligation flush with the visceral aorta. A straight vascular occluding clamp was then placed across the base of the SMA aneurysm, and a second clamp was positioned beyond the farthest extension of the dilated artery. End-to-end bypass to the distal normal caliber SMA was then completed using the second limb of the bifurcated graft (Fig. 3). Intraoperative duplex ultrasound confirmed widely patent anastomoses. An aortic occluding clamp was then placed across the distal descending thoracic aorta just below the bifurcated graft. A 20 mm Dacron tube graft was used to facilitate in-line aorto-aortic reconstruction from the distal descending thoracic aorta to the proximal aspect of the old aortobifemoral graft (Fig. 4). The right renal artery was oversewn from within the opened aorta because the patient was already on dialysis. The postoperative course was uneventful. The patient was discharged 4 days after surgery to our in-house rehabilitation service as a bridge between hospital and home. The patient remained well after surgery until his death due to complications of renal failure 16 months later. Interestingly, 2 weeks after this case, another patient (77-year-old male) presented with similar radiographic findings after a workup for vague abdominal pain. His very proximal 3.5 cm SMA
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Fig. 2. Intraoperative photograph of SMA aneurysm and celiac artery (right vessel loop). Left vessel loop is around nonaneurysmal distal SMA.
Fig. 3. Intraoperative photograph demonstrating descending thoracic aorta-tosuperior mesenteric/celiac artery bypass with bifurcated Dacron graft. Note intact SMA aneurysm between the graft limbs.
aneurysm (Fig. 5) and frankly aneurysmal abdominal aorta were repaired using a specially designed trifurcated Dacron graft to create end-toend bypasses from the descending thoracic aorta to the celiac, superior mesenteric, and left renal arteries.9 Thereafter, the diseased abdominal aorta was replaced with an in-line Dacron tube graft, with reimplantation of the right renal artery.9
DISCUSSION Visceral artery aneurysms are an unusual finding in general, and most are located in either the splenic or hepatic arteries. SMA involvement is the third most common type of reported splanchnic artery aneurym.1-8 Previous reports indicate that most of these were a result of bacterial seeding from endocarditis or septicemia.1-8,10-12 However, more
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Fig. 4. Intraoperative photograph demonstrating final surgical reconstruction with second in-line aortoaortic Dacron graft from descending thoracic aorta to old infrarenal.
Fig. 5. CT scan demonstrating very proximal SMA aneurysm in second patient.
recent reports demonstrate atherosclerosis as the leading cause of this particular arterial dilation.3 The SMA aneurysms in our cases appeared to be atherosclerotic in origin. Nonatherosclerotic visceral artery aneurysms are often multiple, and these etiologies include arterial dissection, polyarthritis nodosa, posttraumatic, inflammation from pancreatitis, MarfanÕs syndrome, Ehlers-Danlos syndrome, TakayasuÕs artentis, a1-antitrypsin deficiency, and fibromuscular dysplasia.10-14 Symptoms of an SMA aneurysm are often subtle, and patients may present with chronic nonspecific or postprandial abdominal pain.1-8 Some present with acute complications of rupture or dissection.1-8,15 A pulsatile abdominal mass or bruit may be present in up to 50% of cases.2 Asymptomatic aneurysms have increased in incidence because of
the use of CT, sonography, and arteriography to aid in the diagnosis of vague abdominal complaints.1-8 Risk of rupture or embolization is the impetus for surgical repair in acceptable operative candidates. The appropriate operative repair technique is based on anatomic features of the aneurysm, patency of the SMA, visceral collateral circulation, and blood supply to the small intestine. Most SMA aneurysms are not at the origin and can be surgically repaired by ligation/exclusion, resection with or without graft reconstruction, or endoaneurysmorrhaphy.1-8 Revascularization is mandatory if bowel ischemia is present or a possibility. Otherwise, exclusion by simple ligation or by endovascular means may be adequate treatment for the usual distal-based SMA aneurysm that is accompanied by a well-developed collateral system.1-8
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The proximal nonaneurysmal portion of the SMA can serve as an inflow source for graft reconstruction, thereby potentially avoiding problems associated with graft kinking and retrograde graft flow.13 However, bypass grafts originating from the supra- or infrarenal aorta or iliac artery are frequently used to avoid dissection in and around the proximal aspect of the SMA.1-8,13 The saphenous vein is the preferred conduit if the aneurysm is infected or if intestinal ischemia is the presenting feature. Reimplantation of the distal SMA to the infrarenal aorta has been performed after aneurysm exclusion, and endovascular means of repair are being reported with increasing frequency.8,15-17 Despite the merits of the previously mentioned methods of repair, the two cases presented in this technical note had unique features that complicated the reconstruction. When a visceral artery aneurysm involves its origin and the adjacent aorta, it is impossible to simply ligate the aneurysm and reconstruct the SMA. The visceral aorta required graft replacement in both of our cases, and this necessitated celiac artery reconstruction as a secondary part of each procedure. The briefly mentioned second case required preservation of the renal arteries as well because this patient was not dialysis-dependent. These two cases further demonstrate the utility and flexibility of the two-graft technique for repair of complex aortic pathology.9
CONCLUSIONS Very proximal SMA aneurysm is an unusual vascular problem that is not suitable for the usually described repair methods. Surgical intervention is recommended in acceptable operative candidates due to the high risk of rupture or embolization. The unique methods of surgical reconstruction as described in this report allow a safe approach with minimal visceral ischemia and definitive aneurysm repair. REFERENCES 1. Stanley JC, Zelenock GB. Splanchnic artery aneurysms In: Rutherford, RB, ed. Vascular Surgery, 5th ed. Philadelphia W.B. Saunders: , 2000, pp 1369-1382.
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2. Messina LM, Stanley CJ. Mesenteric ischemia: visceral artery aneurysms. Surg Clin North Am 1997;77:425-440. 3. Stone WM, Abbas M, Cherry KJ, Fowl RJ, Gloviczki P. Superior mesenteric artery aneurysms: is presence an indicator for intervention? J Vasc Surg 2002;36:234237. 4. Grego FG, Lepidi S, Ragazzi R, Iurilli V, Stramana R, Deriu GP. Visceral artery aneurysms: a single center experience. Cardiovasc Surg 2003;11:19-25. 5. Zimmerman-Klima PM, Wixon CL, Bogey WM Jr, Lalikos JF, Powell CS. Considerations in the management of aneurysms of the superior mesenteric artery. Ann Vasc Surg 2000;14:410-414. 6. Lorelli DR, Cambria RA, Seabrook GR, Towne JB. Diagnosis and management of aneurysms involving the superior mesenteric artery and its branches—a report of four cases. Vasc Endovasc Surg 2003;37:59-66. 7. Kanazawa S, Inada H, Murakami T, et al. The diagnosis and management of splanchnic artery aneurysms. Report of 8 cases. J Cardiovasc Surg 1997;38:479-485. 8. Komori K, Mori E, Yamaoka T, et al. Successful resection of superior mesenteric artery aneurysm. A case report and review of literature. J Cardiovasc Surg 2000;41: 475-478. 9. Ballard JL, Abou-Zamzam AM Jr, Teruya TH. Type III and IV thoracoabdominal aortic aneurysm repair: results of trifurcated/two-graft technique. J Vasc Surg 2002;36:211216. 10. Kojima A, Shindo S, Kubota K, et al. Successful surgical treatment of a patient with multiple visceral artery aneurysms due to fibromuscular dysplasia. Cardiovasc Surg 2002;10:157-260. 11. Javerliat I, Becquemin JP, dÕAudiffret A. Spontaneous isolated dissection of the superior mesenteric artery. Eur J Vasc Endovasc Surg 2003;25:180-184. 12. Ohmi M, Yasunori K, Atsushi I, Masahiro O, Superior mesenteric artery aneurysm secondary to infectious endocarditis. J. Cardiovasc Surg 1990;30:115-117. 13. Cormier F, Ferry J, Artru B, Wechsler B, Cormier JM. Dissecting aneurysms of the main trunk of the superior mesenteric artery. J Vasc Surg 1992;15:424-430. 14. Mitchell MB, McAnena OJ, Rutherford RB. Ruptured mesenteric artery aneurysm in a patient with alphal-antitrypsin deficiency: etiologic complications. J Vasc Surg 1993;17. 420-442. 15. Ishida M, Kato N, Hirano T, et al. Dissecting aneurysm of the superior mesenteric artery successfully treated by endovascular stent-graft placement. Cardiovasc Intervent Radiol 2003;26:403-406. 16. Rocek M, Peregrin JH, Dutka J, Ryska M, Belina F, Lastovckova J. Percutaneous treatment of a superior mesenteric artery pseudoaneurysm using a stent-graft. AJR Am J Roentgeno 2002;178:1459-1461. 17. Gabelmann A, Gorich J, Merkle EM. Endovascular treatment of visceral artery aneurysms. J Endovasc Ther 2002; 9:38-47.