Late results of preferential use of tube versus bifurcation grafts for abdominal aortic aneurysmectomy

The advantages of tube versus bifurcation graft replacement of abdominal aortic aneurysms are well known, yet the risk of future development of iliac occlusive or aneurysmal disease still leads many to use bifurcation grafts routinely. Several studies have reported little risk of this development when patients are followed clinically. They suffer, however, from lack of an objective means of identifying iliac aneurysms. Among 83 patients undergoing abdominal aortic aneurysmectomy during a 53 month period, 36 who had received a tube graft were available for follow-up. After a mean of 54 months from the time of surgery, these patients were evaluated by abdominal and pelvic computed tomography to determine the incidence of subsequent iliac aneurysm formation. No patient had developed symptoms or signs of iliac occlusive disease during this interval. In addition, no residual aortic aneurysms or new iliac aneurysms were noted. In the absence of iliac occlusive or aneurysmal disease, straight graft replacement is the preferred therapy for abdominal aortic aneurysms. The risk of future development of these lesions is minimal.     

Is the preferential use of polytetrafluoroethylene grafts for femoropopliteal bypass justified?

The objective of this review is to analyze the long-term results of femoropopliteal bypass done preferentially with polytetrafluoroethylene (PTFE) grafts in patients who presumably had saphenous vein available. The results are analyzed according to preoperative variables in an attempt to determine those instances in which PTFE grafts may be preferred for the first reconstruction and to identify those patients who benefited from vein preservation. From 1979 to 1985, 146 femoropopliteal bypass operations were performed in 120 patients with 6 mm PTFE grafts used preferentially. The results with follow-up at 5 years are analyzed by actuarial methods. The patency rate at hospital discharge was 100%. The overall primary patency rate at 5 years was 57%. Reconstructions above the knee (101) and below the knee (45) had significantly different 5-year patency rates (63% vs 44%, p less than 0.03). Sixty-two reconstructions done to alleviate disabling claudication had a 5-year primary patency rate of 69% and no amputations. Eighty-one reconstructions were done to treat critical ischemia with a 5-year patency rate of 49% and a 5-year foot salvage rate of 73%. When secondary operations were required to treat graft failures, the 4-year cumulative patency rate of the secondary reconstruction was 18% when performed with a prosthetic graft, in contrast to 70% when performed with the spared saphenous vein. We conclude that femoropopliteal reconstruction with PTFE grafts is a reasonable alternative for older patients with disabling claudication. Patients with critical ischemia will likely benefit from preservation of the vein with initial femoropopliteal reconstruction done with PTFE. Staged infrainguinal revascularization for foot salvage may improve present results. In this regard the sequence PTFE-then-vein carries a higher predicted patency rate than the sequence vein-then-PTFE.     

Clinical experience with a bifurcated endovascular graft for abdominal aortic aneurysm repair

Purpose: The purpose of this study was to test a transfemoral system of bifurcated endovascular graft insertion for aortic aneurysm repair.Methods: Bifurcated endovascular grafts were inserted through bilateral femoral artery cutdowns in 41 patients. The results were assessed by completion angiography and follow-up computed tomography.Results: The second half of the study included more aneurysms 6 cm or larger (p < 0.05) and more instances of short proximal neck (p < 0.05), proximal neck angulation (p < 0.05), and iliac angulation (p < 0.05). Despite the increasingly challenging anatomy, the results were better in the second half of the study as illustrated by the lower overall combined morbidity/mortality rate (15% vs 50%) and higher overall success rate (85% versus 65%). The mortality rate for the series as a whole was 7.5%. Mean follow-up was 18.8 months for the first 20 patients and 10.9 months for the second 20. The commonest complication in the first half of the study was graft thrombosis (n = 5). This complication was absent from the second half of the study because of routine adjunctive stenting. Two patients died of complications of endovascular repair. In both cases aneurysm rupture on the third postoperative day was associated with coagulopathy and angiographic signs of perigraft leak.Conclusion: Aneurysm exclusion with a bifurcated endovascular graft was feasible in a wide range of patients, but when the aneurysm was not entirely excluded from the circulation, the risk of rupture persisted. (J Vasc Surg 1996;24:655-66.)     

Frame dislocation of body middle rings in endovascular stent tube grafts.

OBJECTIVES: To understand the cause, and propose a mechanism for frame dislocation in endovascular grafts. MATERIALS AND METHODS: Five tube grafts were explanted due to secondary distal leakage 15-21 months after operation. One bifurcated graft was removed during emergency operation after aortic rupture caused by secondary leakage. A second bifurcated graft was harvested from a patient with thrombotic occlusion of one limb, who died after transurethral prostatic resection. The inside of the grafts were examined endoscopically. The stent was inspected after removal of the fabric, broken ligatures were counted and examined by scanning electron microscopy. The fabric strength was tested by probe puncture. RESULTS: We found 17-44% of the stent ligatures of the body middle rings to be loose. The knots were intact. Degradation of the polyester textile was not observed. CONCLUSIONS: Continuous movements in the grafted aorta and blood pressure impose permanent stress to the stent frame and the polyester fabric resulting in morphological changes in the body middle ring of grafts. The clinical implications of the suture breakages are unknown although they may be related to distal secondary leakage in tube grafts.     

Migration of a bifurcated endovascular graft into an iliac aneurysm: endovascular salvage and future prevention--a case report

The FDA approval of endovascular grafts for the treatment of abdominal aortic aneurysms has been associated with a dramatic increase in the use of these devices. Major referral centers are reporting the treatment of 75% to 80% of their patients with infrarenal abdominal aortic aneurysms with endovascular devices. The large quantity of endovascular devices being used has produced a growing number of management issues that are often not predictable during the preoperative assessment. These issues require complex intraoperative decision making and innovative techniques for their management as reflected by the subsequent case report. An 82-year-old patient presented with a 7.8-cm abdominal aortic aneurysm. The aneurysm extended into the common iliac arteries bilaterally. The right common iliac artery was 6.5 cm and the left common iliac artery was 2.0 cm in maximal diameter. The preoperative work-up, including a computed tomography scan and arteriogram, suggested that he would be a potential candidate for endovascular repair. The plan was to extend the graft into the right external iliac artery after embolization of the right hypogastric artery and to seal the left limb in the ectatic left common iliac artery using an aortic extender cuff. During the endovascular repair of the aortoiliac aneurysms using the AneuRx bifurcated graft, the main device became dislodged from its infrarenal attachment site and migrated into the large right common iliac artery aneurysm with the iliac limb ending in the distal external iliac artery. A new bifurcated device was deployed from the left side to attempt an endovascular salvage of the difficult situation. The new graft was partially deployed down to the iliac limb. This allowed cannulation of the contralateral stump through the original endovascular graft that had migrated distally. The two grafts were connected with a long iliac limb. This allowed stabilization of the endovascular reconstruction by increasing its columnar strength. The deployment of the second bifurcated graft was completed and the central core with the runners removed safely without migration of the second bifurcated component. The reconstruction was completed with an aortic cuff in the left common iliac artery. The use of the aortic cuff was useful to preserve the left hypogastric artery. No intraoperative endoleak was noted. The patient did well and was discharged the day following the procedure. The follow-up computed tomography scan shows the abdominal aortic aneurysm excluded by the endovascular graft with a defunctionalized portion of one bifurcated graft within the right common iliac aneurysm. There is no evidence of endoleak and the abdominal aortic aneurysm had decreased in size at 6 months. This case demonstrates one of the unique management problems that may arise during endovascular graft placement. Events that initially would suggest failure of the endoluminal treatment may be corrected using advanced endovascular techniques by an experienced surgeon. However, there will be times that the prudent decision will be conversion to open repair. Only good clinical judgement and adequate training will prevent catastrophic outcomes.     

Transfemoral insertion of a bifurcated endovascular graft for aortic aneurysm repair: the first 22 patients

The purpose of this study was to evaluate and optimize a system of transfemoral bifurcated graft insertion for endovascular repair of infrarenal aortic aneurysm. Grafts were inserted through bilateral femoral arteriotomies in 22 patients. Placement was guided by fluoroscopy. Results were assessed by completion angiography, with computed tomography scanning or duplex ultrasonography at 1,3 and 6 months. The first 11 insertions were complicated by failed insertion in two cases, proximal leakage in one, graft limb thrombosis in five and wound infection in one. The second 11 insertions were complicated by retrograde leakage around the distal graft orifice in two patients. One of these was associated with aneurysm rupture, leading to the sole mortality of the series. There were no instances of graft migration or embolism. In conclusion, the lessons learned during the first 11 insertions were responsible for the improved results apparent in the second 11 insertions. When applied in properly selected patients, transfemoral insertion of a bifurcated graft is a reliable method of isolating an aortic aneurysm from the circulation.     

Use of a bifurcated endovascular graft for treatment of endograft migration with major endoleak

The purpose of this study was to describe the use of a bifurcated endovascular graft to treat endograft migration with major endoleaks. We present four patients who presented at a mean of 72.0 months after their initial endovascular abdominal aortic aneurysm repair. Three patients had type I endoleaks resulting from proximal attachment failure and graft migration. A fourth patient had separation of a proximal aortic cuff from a migrated main body device resulting in a type III endoleak. All were treated with a bifurcated Zenith (Cook Medical Incorporated, Bloomington, IN, USA) endovascular graft. There was 100% technical success with no perioperative complications. On follow-up, one patient died of unrelated causes at five months. The mean survival for the remaining three patients was 37 months. In conclusion, treatment with a bifurcated Zenith endograft has advantages over the use of an aortic cuff or aortouniiliac reconstruction. To perform this technique, there must be a sufficient distance between the proximal landing zone and the flow divider of the migrated endograft to allow for deployment of the Zenith device. While there remain limitations in its applicability, the use of a bifurcated endovascular graft is a viable alternative for endovascular salvage in treatment of endograft migration with major endoleaks.     

Early results of a flexible bifurcated endovascular stent-graft (Aorfix)

AIM: First generation stent-grafts were associated with low applicability, high conversion rates due to technical failure and low durability. Second generation stent-grafts need to address these problems in order to secure endovascular aneurysm repair (EVAR) as a viable option to open repair in patients with abdominal aortic aneurysms (AAA). The early results of a second-generation stent-graft (Aorfix) for the treatment of AAA are reported. METHODS: A European multi-centre study of the Aorfix bifurcated endovascular stent-graft was performed. The Aorfix stent-grafts were inserted according to a predefined clinical protocol in 4 centres experienced in EVAR and all data was collected prospectively on a central database. RESULTS: A total of 24 patients underwent attempted aneurysm repair with the Aorfix stent-graft. There were no conversions to open repair. One technical failure resulted in insertion of another stent-graft. At 30-day follow-up there had been no secondary endovascular or open interventions. There were only 2 endoleaks, both of which were type II. CONCLUSIONS: Aorfix currently offers early results, which are at least as good as other second-generation stent-grafts. It has given satisfactory results with highly angulated proximal necks and may improve the treatment outlook for these patients. Whether the unique design features increase durability and reduce long-term complications remains to be seen.     

A new endovascular approach to treatment of acute iliac limb occlusions of bifurcated aortic stent grafts with an exoskeleton

Endovascular aneurysm repair continues to become increasingly popular. As the number of implanted endografts increases, complications will increase as well. We report a new approach to endovascular treatment in two patients with acute iliac limb occlusions of a bifurcated aortic endograft with an endoskeleton. Neither patient required femoral-femoral bypass grafting because of unilateral limb ischemia. We believe this is the optimal primary approach in patients with a bifurcated stent graft with an endoskeleton.     

Multicenter trial of the PowerLink bifurcated system for endovascular aortic aneurysm repair

PURPOSE: The purpose of this study was to assess the results of abdominal aortic aneurysm repair with the PowerLink bifurcated endovascular graft (Endologix, Inc, Irvine, Calif). METHOD: Twelve centers used the PowerLink bifurcated system for elective endovascular aneurysm repair in 118 patients recruited during a 16-month interval and followed for a 25-month interval (mean follow-up, 16 months) as part of a pivotal US Food and Drug Administration trial. Stent grafts were oversized by 10% to 20% relative to computed tomographic scan-based diameter measurements. All repairs were performed in the operating room through one surgically exposed femoral artery and a contralateral 9F sheath percutaneously placed. Results were assessed with contrast-enhanced computed tomography and plain abdominal radiography at 1, 6, and 12 months after surgery. RESULTS: Three failed insertions and one late conversion for endoleak remediation occurred, resulting in four conversions (3.3%) to open surgery. Of the failed insertions, two were from a faulty delivery system design, which was corrected. No failures occurred after the modification. One perioperative death (0.8%) occurred that was not device related. Eight late deaths were from unrelated causes, and one was from complications after reoperation for treatment of an endoleak. Endoleaks were noted in 19 patients (16%) at the time of the endograft procedure: 12 resolved spontaneously, four resolved with secondary interventions (three type I, one type II), and three underwent observation, yielding a 30-day endoleak rate of 5.9%. Two graft limb thromboses (0.8%) were seen. One graft migration (0.8%) was of no clinical significance. No ruptures or wire fractures were found. The mean aneurysm diameter was reduced from 51 mm (preoperative) to 45 mm (12 months; P <.0001). CONCLUSION: The PowerLink system appears to be safe and effectively protects patients from abdominal aortic aneurysm rupture over the short to medium term. The low endoleak rate is superior to that reported for other devices. The graft and stent materials have thus far been free from failure and fatigue. The sutureless stent and endoskeleton design confer a number of unique advantages and challenges. Careful follow-up over the longer term is necessary to assure the durability of these results.     

A saphenous alternative: preferential use of superficial femoral and popliteal veins as femoropopliteal bypass grafts

Our experience with 100 superficial femoral and popliteal veins over a 12 year period has established a firm basis for their preferential use as femoropopliteal bypass grafts. Deep leg veins are currently used in two thirds of primary femoropopliteal bypass candidates. Groups identifiable preoperatively in whom results have been inferior include patients with excessively large grafts, black patients, and those with extremely poor runoff. Patients who will develop distal anastomotic hyperplasia, a fourth problem group, cannot be detected preoperatively but can be diagnosed and managed effectively. Disadvantages of superficial femoral and popliteal vein use include longer and more traumatic operations, increased early limb swelling, and the need for preoperative venography and postoperative arteriography to achieve optimum results. The most important advantage of preferential deep leg vein use is the high patency rate at 2 years with the expectation, already being realized, of significantly reduced intrinsic graft failures in the later years. Saphenous vein preservation constitutes a major additional bonus.     

Aorto uni-iliac modification of a bifurcated stent graft for endovascular aneurysm repair: Expanding the versatility of a modular device

As endografting technology advances, anatomical constraints limiting access and deployment have become less of a burden. While unsuitable candidates for endografting exist, these patients are becoming less frequent. To broaden the applicability of endovascular abdominal aortic aneurysm repair (EVAR), we have modified the bifurcated AneuRx device into a unilimb modular prosthesis, by placing an aortic extender cuff across the flow divider, thus excluding its contralateral limb. This technique was used with success in 3 groups of patients: with occlusion of 1 iliac artery, with a nontraversable iliac stenosis, or with a small calcific aortic bifurcation. In these patients, anatomy can make it difficult, if not impossible, to place a bifurcated stent graft. Whether as a planned preoperative procedure or as a ;;bail-out' maneuver, this procedure has been successful in avoiding open surgical conversion.     

Preliminary clinical use of a new bifurcated graft for peripheral vascular surgery

We describe herein a technique of performing a unilateral common ilio-bilateral femoropopliteal bypass using a small diameter bifurcated graft. The prosthesis, manufactured by Vascutek Ltd., is made of a gelatin-impregnated knitted Dacron graft with an externally ringed support. The diameter of the primary tube is 8 mm with a length of 25 cm, and the secondary tube has a diameter of 7 mm with a length of 75 cm. A total of six patients were operated on using this procedure, through an extraperitoneal approach. Postoperative angiographies showed excellent graft patency and Doppler ultrasound studies revealed a significant increase in the ankle-brachial pressure index in all patients. Using this newly designed small-diameter bifurcated graft, complete revascularization of multilevel occlusive disease can be performed with low operative mortality, and satisfactory relief of the ischemic symptoms can be achieved by the bilateral sequential proximal and distal bypasses.     

Practical considerations in fabric vascular grafts. Introduction of a new bifurcated graft

A new bifurcation graft is introduced which conforms to the anatomic requirements of the aortoiliac segment. The graft material is made of 70 denier Dacron fiber manufactured in a warp-knit to prevent excessive fraying and to decrease porosity. Porosity studies indicate that the new material is approximately half as porous as other available Dacron graft materials. The new graft sizes of 12 by 7 and 14 by 8 mm more closely approximate the human aorta and common iliac arteries than do other available standard bifurcation grafts.The new bifurcation prosthesis has been used as an arterial bypass graft in 135 patients requiring surgery for aortoiliac occlusive disease. Of these patients, 64 per cent did not require blood replacement during surgery. The early operative results are comparable with those of other reported series.