Aortic False Aneurysms After Prosthetic Reconstruction of the Infrarenal Aorta

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1 Aortic False Aneurysms After Prosthetic Reconstruction of the Infrarenal Aorta Christian Gautier, MD, Herv6 Borie, MD, Pierre Lagneau, MD, Paris, France False aneurysm of the infrarenal aorta was found at the site of proximal anastomosis in 13 patients after vascular reconstruction for lower limb arterial disease. The grafts involved were aortoprosthetic in one patient, aortobiiliac in two patients, and aortobifemoral in 10 patients. They had been implanted eight years prior to reoperation on the average (range six months to 15 years). False aneurysm was diagnosed because of abdominal pain in four cases, embolism in two cases, intestinal hemorrhage in one case, and during routine sonographic or computed tomographic (CT) scan surveillance in the six other cases. Femoral false aneurysm was associated in eight of 10 cases with femoral anastomoses. Aortic false aneurysms were repaired by interposition of a prosthetic tube between the infrarenal aorta and the original prosthetic graft in 11 cases and by changing the aortobifemoral graft in two cases. In one further case, repair was accomplished by implanting an aortobifemoral prosthetic graft laterally on a prosthetic tube interposed between the infrarenal aorta and the body of the original prosthetic graft, which continued to irrigate the internal lilac arteries. There was no mortality. Thrombosis of a prosthetic branch occurred in one case and was treated by thrombectomy. One patient underwent reoperation for intestinal obstruction. Two others had distal embolism responsible for toe necrosis. Anastomotic false aneurysms should be looked for routinely during the surveillance of prosthetic grafts implanted on the infrarenal aorta, especially when femoral false aneurysm is found. Preservation of pelvic vascularization must be an integral part of management. (Ann Vasc Surg 1992;6: ). KEY WORDS: Aorta; false aneurysm; arterial prosthesis; late aortoiliac disease; peripheral vascular disease. False aneurysms frequently complicate arterial prosthetic grafts. Several studies concerning the site of false aneurysms have shown that the aorta was involved only rarely [1-7]. The goals of this study were to individualize and address the specific From the Service de Chirurgie Vasculaire, HOpital Saint- Michel, Paris, France. Presented at the Annual Meeting of the SociOt~ de Chirurgie Vasculaire de Langue Franqaise, May 18-19, 1990, Nancy, France. Reprint requests: C. Gautier, MD, Service de Chirurgie Vascutaire, HOpital Saint-Michel, 33 rue Olivier de Serres, Paris, France. problems and surgical risks associated with aortic false aneurysms. PATIENTS AND METHODS Between January 1989 and December 1989, 13 patients (11 males and two females), whose mean age was 63 years (range 52 to 83 years) were operated on for aortic false aneurysms. Three patients had been operated on for aneurysm of the aorta and 10 for occlusive disease of the lower limbs. In the second group of I0 patients, the anastomosis was end-to-end in four cases and endto-side in six. In six cases, aortic false aneurysm 413

2 ANNALS OF 414 AORTIC FALSE ANEUR YSMS VASCULAR SURGERY false aneurysm or because of the proximity of the renal arteries. In 12 cases, the renal vein was dissected and retracted cephalad, in order to find a new, undissected plane. In one case, the renal vein was divided to gain control of the aorta without any untoward consequences on renal function [8]. The aortic false aneurysm was laid open in all cases. In 11 cases, a prosthetic tube was interposed between the infrarenal aorta and the original prosthetic graft (Fig. 3). The entire prosthetic graft was replaced in three cases because of associated femoral false aneurysms or degradation or dilatation of the graft. In one case, bilateral femoral false aneurysm was associated with stenosis of both external iliac arteries, and a bifurcated prosthetic graft was implanted end-to-side on a prosthetic tube replacing the infrarenal aorta in order to preserve internal lilac artery flow and treat the associated femoral false aneurysm simultaneously (Fig. 4). Fig. 1. Arteriogram showing dilatation of aortic anastomosis leading to suspect an anastomotic false aneurysm. was symptomatic, being revealed by abdominal or dorsal pain in four cases, and embolic complications in two cases. In one case, intestinal hemorrhage occurred and was feared to be due to prosthetoenteric fistula, but, at operation, bleeding was found to be due to Meckel's diverticulum. In five cases, aortic false aneurysm was discovered during workup of femoral false aneurysms. In one case, aortic false aneurysm was disclosed by routine sonographic surveillance of an aortobiiliac prosthetic graft. Aortograms were obtained for all patients in order to evaluate the lilac (and notably the internal) arteries and to help choose the type of reconstruction (Fig. 1). Contrast medium enhanced computed tomographic (CT) scans (obtained for the last five patients only) showed irregularities at the aortoprosthetic junction with lateral saccular expansions, occasionally visualized by contrast medium and often associated with mural thrombosis (Fig. 2). The aorta was clamped infrarenally in I I cases, while in two cases it was necessary to clamp the suprarenal aorta because of the volume of the aortic RESULTS There was no postoperative mortality. In one case, one of the prosthetic branches occluded and was treated by thrombectomy. One patient underwent reoperation for intestinal obstruction. Two patients experienced distal embolism with localized toe necrosis but without requiring amputation. Two patients were lost to follow-up. All the other patients were alive with a mean follow-up of two years. One patient died of an otorhinolaryngological carcinoma two years after reconstruction. There were no cases of recurrence of aortic false aneurysm during ulterior sonographic surveillance. No further arteriograms or CT scans were performed. DISCUSSION The incidence of aortic false aneurysm after infrarenal aortic surgery is difficult to evaluate. Only prospective studies with sufficiently prolonged follow-up can be of any help. Szilagyi and associates [4] followed 1,438 patients operated on for aortoiliac occlusive disease during a 30 year period between 1954 and They found three aortic false aneurysms, an incidence of 0.21%, all occurring after lateral implantation on the aorta. Mehigan and colleagues [2] found only one femoral false aneurysm out of 290 anastomoses performed for aneurysm (0.2%). Van Den Akker and coworkers [7] encountered 21 aortic false aneurysms in 438 aortic anastomoses (4.8%) performed for occlusive disease and followed for 15 years. The difference in results in these series can most likely be explained by the improvement in surveillance. Presently, smaller aortic false aneurysms are detected with sonography and CT scan. Routine CT studies of

3 VOLUME 6 AORTIC FALSE ANEUR YSMS 415 NO Fig, 2. CT scan showing lateral contrast-enhanced saccular expansion on left margin of aortic anastomosis, end-to-side aortic anastomoses [9] have demonstrated images suggestive of aortic false aneurysms in up to 15.4% of cases. It is, however, difficult to eliminate a simple dilatation of the prosthetic graft or of the site of aortic implantation when the anastomosis has been performed end-to-side. The causes of false aneurysms are multiple. Several of these causes are difficult to analyze, because they are not quantifiable, such as the quality and tightness of the sutures. Silk suture material has been abandoned since the study of Moore and Hall [10]. Prosthetic dilatation has been incriminated in the onset of false aneurysm [11,12], but the quality of today's prosthetic grafts should make this cause rare. The question of knitted or woven prosthetic material does not seem to intervene [13]. Implantations of prosthetic graft laterally on the aorta seem to promote false aneurysm formation as compared with end-to-end anastomoses. Van den Akker and associates [7] found a significant difference between disease-free actuarial curves at 10 years, with 97.5% of patients having end-to-end implantations, versus 75.9% end-to-side [7]. Undermining of the vessel wall by associated endarterectomy or insertion of the prosthetic graft material in an area for which the risk of atheroma is great have also been suggested. The frequent association of aortic and femoral false aneurysms leads to consideration of factors such as hypertension, hyperlipidemia, or ongoing evolution of atheroma as prognostic factors [3,12,14]. Later onset of aortic false aneurysms, associated with better surveillance, seem to argue further in favor of improved control of vascular risk factors [3]. When the diagnosis of aortic false aneurysm is formally established on sonography or especially CT scan, in the absence of general contraindications, surgical intervention is recommended to avoid thromboembolism, but above all to preclude retroperitoneal or digestive complications. Treiman and colleagues [13] followed three patients with aortic false aneurysms less than 4 cm in diameter. All aortic false aneurysms increased in diameter in less than one year, and one ruptured. In order to simplify the surgical procedure, our preference is to place a new bypass tube end-to-end between the infrarenal aorta and the original prosthetic graft. In the case of associated femoral false aneurysms, and when the common iliac artery is

4 ANNALS OF 416 AORTIC FALSE ANEURYSMS VASCULAR SURGERY j) 5 / d Fig. 3. Treatment of aortic false aneurysm by interposition of prosthetic tube between infrarenal aorta and original prosthetic graft. (Right) Vascularization of internal lilac artery is retrograde; (Left) with vascularization in case of associated femoral false aneurysm, an interposition femoral graft should be used. occluded, the procedure should include implantation of a bifurcated prosthetic graft end-to-side at the femoral level in order to ensure retrograde flow to the internal iliac arteries. Likewise, internal iliac or inferior mesenteric artery vascularity can be compromised when bilateral external iliac occlusion exists and an original end-to-side anastomosis is changed to an end-to-end anastomosis. In this setting, as in one of our patients, a bifurcated prosthetic graft can be implanted on a prosthetic tube graft interposed between the infrarenal aorta and the original prosthetic graft or the distal portion of the infrarenal aorta [15]. There was no mortality in our series, contrasting with mortality rates of 2% for Dennis and cowork- Fig. 4. Technique shows aorto-aortic prosthetic tube with reimplantation or change of original graft when retrograde internal lilac artery retrograde flow is compromised. ers [3], 4.4% for Szilagyi and associates [4], and 8% for Treiman and coworkers [13]. Although the follow-up period in this series was short, there were no cases of recurrence of aortic false aneurysms. In our opinion, however, this risk seems small in the absence of associated septic complications. CONCLUSION Anastomotic false aneurysm of the aorta occurs rarely, complicating between 0.2% and 4.8% of aortic anastomoses of prosthetic bypass to the lower limbs originating on the infrarenal aorta. Present diagnostic investigations (sonography, digital subtraction arteriograms, and CT scan), currently employed in routine long-term surveillance of

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