LETTERS TO T H E E D I T O R S The Editors invite readers to submit letters commenting on the contents of articles that appear in the Journal. Also welcome are brief communications in letter form reporting investigative or clinical observations without extensive documentation and with brief bibliography (five titles or less), not requiring peer review but open to critique by readers. Letters to the Editors should be no more than 500 words in length and they may have to be edited for publication.

Superior mesenteric artery syndrome after end-to-side aortofemoral bypass To the Editors: Extrinsic compression of the third portion o f the duodenum by the superior mesenteric artery (SMA) was first described by Von Rokitansky in 1861. A number of factors have been described causing this syndrome. 1-3We describe a previously unreported cause of the SMA syndrome occurring after an aortofemoral bypass procedure. A 56-year-old thin woman with aortoiliac occlusive disease and severe bilateral external iliac stcnoses underwent aortobifemoral bypass graft placement witch a 14 mm x 7 mm woven Dacron graft. The proximal anastomosis was performed above the origin of the inferior mcs-

Fig. 1. Upper gastrointestinal barium contrast study demonstrating a very distended and ptotic stomach with an abrupt oblique obstruction to contrast flow in the third portion of the duodenum (arrow). 726

enteric artery in an en&to-side fashion to maintain flow to the hypogastric arteries. After surgery a partial small bowel obstruction developed. An upper gastrointestinal barium study was performed. It demonstrated a dilated stomach and obstruction in the third portion of the duodenttm, with some passage of contrast distally, consistent with compression from the superior mesenteric pedicle (Fig. 1). Conservative therapy for an incomplete obstruction was unsuccessful. An intravenous digital subtraction angiogram demonstrated the distance between the SMA and graft, in the region of the duodenum, to be decreased to 2.2 mm and an angle of only 9 degrees between the SMA and the aorta (Fig. 2). This was measured in the area of obstruction seen on the barium study. Recurrent abdominal distension and vomiting prompted surgical intervention. At laparotomy no congenital anomalies of rotation were found, but the duodenum was dilated to 6 cm proximal to the crossover of the SMA over the underlying aortic prosthesis. Distal to the graft, at the ligament ofTreitz, a normal-sized jejunum was found. A side-to-side retrocolic duodenojejunostomy was performed. The patient had slow

Fig. 2. Digital subtraction aortogram showing the takeoff of the SMA from the aorta (open arrowJ and the narrowed space evident between the SMA and the end-to-side aortic graft (arrowhead).

Volume ll Number 5 May 1990

return of gastric motility after surgery, but eventually restuned normal oral feedings. The third portion of the duodenum lies between the SMA and the aorta at the level of the second lumbar vertebra. Any process that either elevates the aorta anteriorly or pushes the SMA posteriorly may compress the duodenum between these two structures and produce an obstruction. Edwards and Katzen 4 repotted a patient with an abdominal aortic aneurysm and an acute anterior angulation that effectively compressed the duodenum against the overlying SMA. In a computer-assisted search of the English-language literature, we found no previous report of the SMA syndrome after aortofemoral bypass grafting. In our patient the end-to-side placement of the graft above the inferior mesenteric artery appears to have compressed the duodenum between it and the overlying SMA. An end-to-end anastomosis may have prevented this complication. Sebesta et al.s and Reasbeck, 6 however, have both reported a patient with postoperative hemorrhage within the aneurysmal sac after abdominal aneurysmectomy and repair with a straight graft who subsequently developed an SMA syndrome. Lord et al.7 described four patients with duodenal obstruction after 161 abdominal aortic reconstructions. Two of these were explored and found to have adhesions between the aortic graft and overlying duodenum. The other two patients, treated successfiflly with conservative therapy, may have actually been patients with the SMA syndrome that were not correctly diagnosed. The diagnosis of SMA syndrome is first suggested by symptoms o f a small bowel obstruction and confirmed by an upper gastrointestinal study. 2,8 Angiography is a complementary procedure. Selective SMA angiography allows one to measure the angle between the origin of the SMA and the aorta as well as the distance in between, through which the duodenum must pass. An average normal angle on angiography has been found to be between 37 to 56 degrees, with a norm~ distance of 18 mm. 3,8 In patients with the SMA syndrome, the angle is reduced to 8 to 11 degrees and the distance to approximately 3 ram? ,s,9 Initial therapy should be conservative.~ However, Marchant et al.10 fotmd conservative therapy successful in only three of 13 patients. If conservative therapy fails, surgical intervention is required. Some authors favor sectioning of the ligament of Treitz to relieve the obstruction and repositioning the jejunum and ileum into the right side of the abdomenY ° DuviC 1 has transposed the duodenum anterior to the superior mesenteric vessels in 10 patients. A gastrojejunostomy is a suboptimal alternative to bypass the obstruction? ,8The procedure of choice favored by most authors is a side-to-side retrocolic duodenojejunostomy proximal to the point of obstructionY ,9 Duodenal obstruction by the SMA after aortic reconstruction is a syndrome that needs to be considered in patients with postoperative small bowel obstruction. Endto-side proximal aortic anastomoses may be more prone to this complication. If conservative therapy is unsuccess-

Letters to the editors

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ful, surgical intervention is required in the form of a duodenojejunostomy. John Blebea, MD Harry C. Sax, MD Kevin J. Geary, MD Kenneth Ouriel, MD

Department of Surgery University of Rochester Medical Center Rochester, NY 14642

REFERENCES 1. Sapkas G, O'Brien JP. Vascular compression of the duodenum (cast syndrome) associated with the treatment of spinal deformities. A report of six cases. Arch Orthop Trattma Surg 1981;98:7-11. 2. Hines JR, Gore RM, Ballantyne GH. Superior mesenteric artery syndrome. Diagnostic criteria and therapeutic approaches. Am J Surg 1984;148:630-2. 3. Mansberger AR, Hearn JB, Byers RM, et al. Vascular compression of the duodenum. Am J Surg 1968;115:89-96. 4. Edwards KC, Katzen BT. Superior mesenteric artery syndrome due to large dissecting abdominal aortic aneurysm. Am J Gastroenterol 1984;79(1):72-74. 5. Sebesta P, Pirk J, Fifipova H. Superior mesenteric artery syndrome following abdominal aneurysm resection and replacement. J Thor Cardiovasc Surg 1987;3:378-81. 6. Reasbeck PG. Vascular compression of the duodenum following resection of an abdominal aortic aneurysm. N Z Med J 1980;92:198-9. 7. Lord RS, Nankivell C, Graham AR, Tracy GD. Duodenal obstruction following aortic reconstruction. Ann Vasc Surg 1987;1:587-90. 8. Lukes PJ, Rolny P, Nilson AE, et al. Diagnostic value of hypotonic duodenography in superior mesenteric artery syndrome. Acta Chir Scand 1978;144:39-43. 9. Gustafson L, Falk A, Lukes PJ, Gamklou R. Diagnosis and treatment of superior mesenteric artery syndrome. Br J Surg 1984;71:499-501. 10. Marchant EA, Alvear DT, Fagelman KM. True clinical entity of vascular compression of the duodenum in adolescence. Surg Gynecol Obstet 1989;168:381-6. 11. Duvie SOA. Anterior transposition of the third part of the duodenum in the management of chronic duodenal compression by the superior mesenteric artery. Int Surg 1988;73: 140-3.

Management o f renovascular hypertension in the elderly population To the Editors:

The data presented by the highly experienced and highly respected surgical group from Winston-Salem, N.C., J VAsc SURG 1989;10:266-73, whose experience in matters of renovascular hypertension is extensive, hardly justifies the conclusions reached by the authors that " . . . in properly selected patients operative management has acceptable short-term results, albeit with an increased operative risk." Not only does the paper not elucidate how to properly