Abdominal aortic aneurysm treatment: preliminary results with the Talent stent-graft system

Percutaneous Modular Stent-Grafts in the Treatment of Abdominal Aortic Aneurysms

Purpose:

To describe a newly designed bifurcated modular stent-graft and assess the feasibility and safety of its use in the treatment of abdominal aortic aneurysms (AAA).

Methods:

Thirteen patients (10 men; mean age 61.2±16 years, range 57–78) with AAAs underwent treatment with a bifurcated stent-graft consisting of 4 components: an unsupported bifurcated stent-graft, an inner bare stent, and 2 stent-grafts. The system was placed sequentially through a percutaneously introduced 12-F sheath; the preloaded bifurcated main body of the stent-graft was deployed first, followed by the inner bare stent and individual stent-graft limbs through separate 10-F sheaths. Spiral computed tomography (CT) was performed before treatment and at 1 week, 3 months, and then at 6-month intervals.

Results:

The stent-grafts were successfully deployed in all patients, although 3 types of procedure-related adverse events occurred: left limb kinking in 1, postimplantation syndrome (fever, leukocytosis, and decreased platelet count) in 5, and a small access site arteriovenous fistula in 1. Postprocedural angiography and 1-week follow-up CT scanning did not identify any endoleaks. At a mean 9.2±4.6-month follow-up, all devices were intact, with complete exclusion of the aneurysms and no endoleaks.

Conclusions:

This newly designed bifurcated modular stent-graft appears to be effective for percutaneous AAA repair; further investigation is warranted.

[Endovascular repair of aortic aneurysm--preliminary results]

INTRODUCTION

Endovascular aneurysm repair (EVAR) has been introduced into clinical practice at the beginning of the 90's of the last century. Because of economic, political and social problems during the last 25 years, the introduction of this procedure in Serbia was not possible.

OBJECTIVE

The aim of this study was to present preliminary experiences and results of the Clinic for Vascular Surgery of the Serbian Clinical Centre in Belgrade in endovascular treatment of thoracic and abdominal aortic aneurysms.

METHODS

The procedure was performed in 33 patients (3 female and 30 male), aged from 42 to 83 years. Ten patients had a descending thoracic aorta aneurysm (three atherosclerotic, four traumatic--three chronic and one acute as a part of polytrauma, one dissected, two penetrated atherosclerotic ulcers), while 23 patients had the abdominal aortic aneurysm, one ruptured and two isolated iliac artery aneurysms. The indications for EVAR were isthmic aneurismal localisation, aged over 80 years and associated comorbidity (cardiac, pulmonary and cerebrovasular diseases, previous thoracotomy or multiple laparotomies associated with abdominal infection, idiopathic thrombocitopaenia). All of these patients had three or more risk factors. The diagnosis was established using duplex ultrasonography, angiography and MSCT. In the case of thoracic aneurysm, a Medtronic-Valiant endovascular stent graft was implanted, while for the abdominal aortic aneurysm Medtronic-Talent endovascular stent grafts with delivery systems were used. In three patients, following EVAR a surgical repair of the femoral artery aneurysm was performed, and in another three patients femoro-femoral cross over bypass followed implantation of aortouniiliac stent graft.

RESULTS

During procedure and follow-up period (mean 1.6 years), there were: one death, one conversion, one endoleak type 1, six patients with endoleak type 2 that disappeared during the follow-up period, one early graft thrombosis. No other complications, including aneurysm expansion, collapse, deformity and migration of the endovascular stent grafts, were registered.

CONCLUSION

According to all medical and economic aspects, we recommend EVAR to treat acute traumatic thoracic aortic aneurysm, as well as in elderly and high-risk patients with abdominal or thoracic aneurysms, when open surgery is related to a significantly higher mortality and morbidity.

Systematic Review and Meta-analysis of 12 Years of Endovascular Abdominal Aortic Aneurysm Repair

BACKGROUND

Endovascular repair (ER) of abdominal aortic aneurysm (AAA) is a new technique, and reported rates of endoleak, conversion to open repair, rupture and mortality vary widely. The aim of this study was to estimate these rates from the published data, and examine how this has changed as more patients have undergone ER.

METHODS

A systematic review and meta-analysis of publications identified through searches of the electronic databases EMBASE and Medline. All publications quoting endoleak, conversion to open repair, rupture and mortality rates for a series of patients undergoing ER were included.

RESULTS

163 studies pertaining to 28,862 patients undergoing ER were identified as relevant for the review and meta-analysis. The pooled estimate for operative mortality was 3.3% (95% confidence interval 2.9 to 3.6%). The pooled estimate for type 1 endoleaks was 10.5% (95% confidence interval 9.0 to 12.1%), with an annual rate of 8.4% (95% confidence interval 5.7% to 12.2%). The pooled estimate of type 2,3 and 4 endoleaks was 13.7% (95% confidence interval 12.3 to 15.3%), with an annual rate of 10.2% (95% confidence interval 7.4% to 14.1%). The pooled estimate for primary conversion to open repair was 3.8% (95% confidence interval 3.2 to 4.4%), and for secondary conversion to open repair 3.4% (95% confidence interval 2.8 to 4.2%). The pooled estimate for post-operative rupture was 1.3% (95% confidence interval 1.1 to 1.7%), with an annual rupture rate of 0.6% (95% confidence interval 0.5% to 0.8%). Multivariate meta-regression analysis showed that rates of operative mortality, post-operative rupture and total number of endoleaks all fell significantly (p<0.05) over time.

CONCLUSIONS

This study demonstrates a low mortality and a gradual reduction in vascular morbidity and mortality associated with endovascular repair since it was first introduced.

Midterm Follow-up of a Single-center Experience of Endovascular Repair of Abdominal Aortic Aneurysms with Use of the Talent Stent-Graft

PURPOSE

To review the midterm results of endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms (AAAs) with the Talent stent-graft.

MATERIALS AND METHODS

All patients who underwent EVAR of AAAs with Talent stent-grafts from February 1998 to April 2002 at a single institution were monitored for a minimum of 2 years or until an endpoint of death or rupture was reached.

RESULTS

There were 68 eligible patients, who were monitored for a mean period of 39 months (range, 24-72 months). Forty-nine (72.9%) were alive at 2 years; among the 19 deaths, two resulted from aneurysm rupture and the other 17 were unrelated to EVAR. There was one immediate conversion to open repair and five primary proximal endoleaks; the remaining 62 patients (91.2%) all had a technically successful procedure. There were 33 endoleaks during follow-up: 23 (69.7%) were treated conservatively and 10 (30.3%) underwent secondary intervention in the form of embolization (n=2), attempted embolization (n=2), endovascular stent-graft placement (n=3), combined stent-graft placement and embolization (n=1), or surgical conversion (n=2). Overall, there were five persistent endoleaks, and the remaining patients were free of endoleak at their last review or endpoint. Three stent-grafts migrated and required further endovascular intervention. Wire fracture was seen in two stents but presented no clinical sequelae. There was one case of graft limb thrombosis that required surgical thrombectomy.

CONCLUSIONS

EVAR of AAAs with use of the Talent stent-graft is a promising and acceptable alternative to open surgery. Our 30-day mortality rate of zero compares extremely well with historical data from open surgery and the findings of more recently published trials. The risk of endoleak and uncertainty over durability require long-term surveillance.

Endovascular aneurysm repair with the Talent stent-graft

PURPOSE

Evaluation of the Talent endovascular aortic stent graft in the management of abdominal aortic aneurysms.

MATERIALS AND METHODS

Thirty-eight patients with suitable abdominal aortic aneurysms were treated over an 18-month period using the modular Talent stent graft. The suprarenal Talent device was deployed in 31 cases. Clinical follow-up of all patients has been performed by clinical examination, contrast-enhanced CT, and Duplex ultrasound for a mean period of 12.5 months.

RESULTS

Graft placement was successful in all 38 patients. The immediate exclusion rate was 84%, the 1-month primary exclusion rate was 92.1%, and the 3-month exclusion rate was 97%. There were no deaths in the first 30 days, one death at 3 months due to a presumed rupture, and one other death at 1 year due to carcinomatosis. There have been no migrations or renal complications in the suprarenal group.

CONCLUSIONS

Our short- and medium-term results are comparable with other published Talent stent-graft series. Suprarenal graft fixation is a safe procedure that may aid in preventing graft migration. Long-term follow-up is required to assess the durability of the suprarenal Talent device.

Aortomonoiliac stent-grafts for abdominal aortic aneurysm repair: association with iliofemoral crossover grafts

PURPOSE

To analyze the outcome of endovascular exclusion of abdominal aortic aneurysm (AAA) using aortomonoiliac stent-grafts.

METHODS

Fifty-seven consecutive patients (49 men; median age 70, range 56-89) with AAA >5 cm were treated in a 6-year period with the conical ELLA stent-graft. Forty-two (73.9%) patients were classified ASA (American Society of Anesthesiologists) IV and 6 as ASA V. In the majority of cases, the implantation procedure featured device delivery through the external iliac artery, transrenal placement of a bare stent in selected cases, and an iliofemoral crossover graft through a prevesical tunnel.

RESULTS

Successful deployment was achieved in 56 (98.2%) patients. Mean time to discharge was 8.7 days (range 2-125). Two patients died in the 30-day period. Nine endoleaks occurred in 8 (14%) patients; 4 required further intervention. Mean follow-up was 35.3 months (range 1-66), during which 5 patients died from unrelated causes. No late endoleak, graft occlusion, device twisting/migration, or aneurysm rupture was observed. No correlation between type I endoleaks and unfavorable proximal neck or iliac artery anatomical characteristics could be found. Primary technical and clinical success rates were 86.0% and 94.7%, respectively.

CONCLUSIONS

In this approach, the crossover graft remains in a retropubic space and consequently does not have all the disadvantages of a subcutaneously placed prosthesis. The results achieved in this group of high-risk patients support recommendation of this technique as a simple and safe alternative to bifurcated systems.

Factors and forces influencing stent-graft migration after endovascular aortic aneurysm repair

PURPOSE

To assess and validate the clinical features predisposing to stent-graft migration and to calculate the distal displacement forces exerted at the proximal fixation site following endovascular aortic aneurysm repair (EVAR).

METHODS

Demographic, anatomical, and graft-related features from 2862 patients were analyzed in a regression model to identify variables associated with stent-graft migration, which was defined as device movement >5 mm or considered significant by the investigator. Using the principles of continuity and momentum, a mathematical model of blood flow was created. The pulse pressure, proximal aortic and distal iliac diameters, and the degree of iliac angulation were varied in the calculations, and the distal displacement force exerted at the proximal fixation site was calculated.

RESULTS

Ninety-nine patients developed stent-graft migration, which was clinically relevant in 85 (3.0%). Hypertension (p=0.015), smoking (p=0.009), maximal aortic diameter (p=0.004), and distal transverse aortic diameter (p=0.03) correlated with migration in the univariate analysis, but iliac angulation did not quite achieve significance (p=0.06). On multivariate analysis, current smoking, hypertension, distal transverse aortic diameter, maximum common iliac diameter, and increasing proximal graft size were significantly associated with stent-graft migration. The mathematical model calculated the distal displacement force exerted on the proximal fixation site of the stent-graft and validated the clinical findings. The ratio of graft-diameter change from proximal aorta to distal iliac influenced the greatest increase in the displacement force.

CONCLUSIONS

The mathematical model validated hypertension, aneurysm morphology, and endograft size as clinical factors significantly associated with stent-graft migration. These findings may have important implications for the choice and design of future stent-grafts.

Short-term results of endovascular AAA repair with the Excluder bifurcated stent-graft

PURPOSE

To evaluate the safety and efficacy of endovascular abdominal aortic aneurysm (AAA) repair with a commercial modular stent-graft.

METHODS

Between February 1998 and May 2000, 66 consecutive patients (56 men; mean age 70 years, range 51-87) were recruited for a single-center study to examine the safety and efficacy of the Excluder stent-graft for endovascular AAA repair. The patients were predominantly asymptomatic (2 symptomatic) and categorized as ASA III or IV (62, 94%), with aneurysms that ranged from 35 to 89 mm in diameter (mean 56). Surveillance included clinical examination and computed tomographic aortography at discharge, 6 weeks, and at 6, 12, and 24 months.

RESULTS

All endoprostheses were implanted as intended, but 1 patient succumbed to an intraprocedural brainstem infarction (1.5% 30-day mortality rate). The major and minor morbidity rates were 21% and 4.5%, respectively. Primary technical success at discharge was 68% (45/66), largely as the result of a 30% (20/66) endoleak rate. The aneurysm exclusion rate at 30 days was 88%. During the mean 5.8-month follow-up, no device migration, limb kinking, aneurysm rupture, or limb thrombosis was observed.

CONCLUSIONS

Endoluminal AAA repair with the bifurcated Excluder stent-graft is safe and efficacious in the short term. Longer surveillance will have to demonstrate if the excellent early results can be maintained over the years.

Endovascular placement of a nitinol-ePTFE stent-graft for abdominal aortic aneurysms: initial and midterm results

PURPOSE

Because first-generation stent-grafts did not meet initial expectations, a recently designed nitinol-expanded polytetrafluoroethylene (ePTFE) stent-graft was tested for treatment of abdominal aortic aneurysms (AAAs) in a prospective clinical study. The primary study endpoints were technical success and safety.

MATERIALS AND METHODS

A nitinol-ePTFE self-expandable stent-graft (Excluder) was used to treat 72 patients with AAAs. The median follow-up period was 21.5 months +/- 13 (range, 1-46 mo).

RESULTS

Primary technical success in accurate placement of the device was achieved in 70 of 72 patients (97%). Complete exclusion of the aneurysm from arterial flow was achieved in 57 of 72 patients (79.2%). Three type I leaks were observed during implantation and were immediately corrected with a proximal cuff prosthesis in two patients. Fourteen of 72 patients (19.4%) had a type II leak. Major complications were observed in three patients (4.1%), including one death in the early postinterventional period (one of 72, 1.4%). At 3 months, aneurysms were excluded in 70 of 71 patients (98.6%), and at 12 months, aneurysms were occluded in 29 of 30 patients (96.7%). The maximum diameter of the aneurysm decreased from 55 mm +/- 11 (median +/- SD) before intervention to 53 mm +/- 13 at 6 and 12 months. None of the patients showed aneurysm growth.

CONCLUSION

This newly designed stent-graft proved to be effective and safe for treatment of AAAs.

Evaluation of abdominal aortic aneurysm after endoluminal treatment: comparison of color Doppler sonography with biphasic helical CT

OBJECTIVE

The purpose of this study is to compare color Doppler sonography with biphasic helical CT in the evaluation of abdominal aortic aneurysms after endovascular repair.

MATERIALS AND METHODS

Fifty-five patients prospectively underwent both color Doppler sonography and helical CT within 7 days after treatment by endovascular stent-graft. Aneurysmal thrombosis, the patency of the grafts, and the presence of a leak were evaluated in all patients. When a perigraft leak was observed, an attempt was made to identify its origin and outflow vessels. Helical CT was considered the gold standard technique.

RESULTS

Helical CT revealed aneurysmal thrombosis in 33 patients and a perigraft leak in 22 patients. In five patients, helical CT detected a small perigraft leak not shown by color Doppler sonography. In three patients with suboptimal examinations, color Doppler sonography revealed a suspected perigraft leak that was not confirmed by helical CT. In these eight patients, the perigraft leak was sealed or no longer observed during follow-up. Compared with enhanced helical CT, the sensitivity and specificity of color Doppler sonography for the diagnosis of a perigraft leak were 77% and 90%, respectively. In seven other patients, helical CT was superior to color Doppler sonography in detecting the origin of the perigraft leak and the outflow vessels. Two iliac artery dissections and one distal migration of the prosthesis were revealed only by helical CT.

CONCLUSION

Although color Doppler sonography may detect substantial perigraft leaks, helical CT is superior for detecting the origin of the perigraft leak, the outflow vessels, and the detection of complications related to the procedure.

Outcome after endovascular abdominal aortic aneurysm repair: a meta-analysis

PURPOSE

To determine the frequencies of complications and risk factors for complications following endovascular abdominal aortic aneurysm (AAA) repair (EVAR).

METHODS

Thirty-nine articles published between October 1995 and October 1999 in English, German, French, or Dutch were identified in electronic databases. All articles reported perioperative (30-day) complications on 2387 patients, while postoperative complications (>30 days) were reported on 1645 patients in 30 of 39 studies. Data were pooled and subjected to multivariable logistic regression analysis to identify risk factors for death, endoleak, rupture, conversion, and local and systemic complications. Effects of risk factors were expressed as odds ratios (OR) with 95% confidence interval (CI).

RESULTS

Mean follow-up was 13.9 months (range 4-29). The perioperative death rate (3.7%) was lower than postoperative mortality (5.0% per annum). The risks for both endoleak (13.1%) and conversion (5.0%) were higher in the perioperative period than postoperatively (5.4% and 1.4% per annum, respectively). Independent risk factors for perioperative complications were: general anesthesia (death: OR = 5.1, 95% CI 1.9-13.3); EVT graft (endoleak: OR = 3.0, 95% CI 1.3-7.0); female sex (rupture: OR = 2.8, 95% CI 1.4-5.8); hypertension (conversion: OR = 0.03, 95% CI 0.0-0.3); age >70 years (conversion: OR = 3.5, 95% CI 1.3-9.2); and team experience >30 patients (conversion: OR = 3.0, 95% CI 1.2-1.6). Independent risk factors for postoperative complications were: predischarge examination (death: OR = 0.2, 95% CI 0.0-0.7); follow-up 30 days after operation (death: OR = 0.3, 95% CI 0.1-1.0); and female sex (rupture: OR = 1.4, 95% CI 0.5-4.4; conversion: OR 6.8, 95% CI 2.0-23.4; and systemic complications: OR = 2.9, 95% CI 1.1-7.5).

CONCLUSIONS

The risk of complications after EVAR is high, supporting the cautious use of EVAR. Both patient characteristics and procedural variables were independent risk factors for complications. To avoid the limitations of this study, the results of randomized clinical trials must determine if EVAR offers a safe and durable alternative to open AAA repair.

Neointima formation after stent implantation in an experimental model of restenosis: polytetrafluoroethylene-covered versus uncovered stainless steel stents

The aim of the study was to assess whether stents covered with a membrane of polytetrafluoroethylene spanned over the mashes of a sandwich-configured double stent (n = 15) prevent migration of smooth muscle cells through stent spaces, leading to less neointima formation compared with uncovered stainless steel stents (n = 14) in iliac arteries of male Chinchilla Bastard rabbits (n = 18). Lumen stenosis was assessed by quantitative angiography immediately before the animals were killed 5 weeks after stent deployment. Neointima formation was quantified by histomorphometric analysis. There were large regional and individual differences in neointima formation, leading locally to a significantly higher degree of stenosis in covered stents (histologically, 76.0 +/- 13.7 vs. 62.9 +/- 12.9%; angiographically, 33.5 +/- 21.1 vs. 7.8 +/- 8.8%) compared with uncovered stents, though mean neointimal and lumen area values were not significantly different. In conclusion, polytetrafluoroethylene-covered stents do not prevent neointima formation compared with uncovered stents. Although the membrane reduces local smooth muscle cell migration, the neointima hyperplasia at the proximal and distal ends of a covered stent stimulates migration along its longitudinal axis. In this stent-restenosis model, regional and individual proliferation processes and not the membrane-covering strut-to-strut distances determine lumen restenosis.

Aortic and arterial aneurysms in behçet disease: management with stent-grafts--initial experience

PURPOSE

To assess the application of stent-grafts in the management of aortic and arterial aneurysms in patients with Behçet disease.

MATERIALS AND METHODS

Nine aneurysms in seven patients were managed with various types of stent-grafts. Diagnoses were based on clinical findings. The aortic aneurysms (n = 3) were thoracic (n = 1), suprarenal (n = 1), or infrarenal (n = 1). The arterial aneurysms (n = 6) were in the right and left subclavian (n = 2), right common carotid (n = 2), right brachiocephalic (n = 1), or left common iliac arteries (n = 1). A tandem connection of Gianturco stent covered with polytetrafluorethylene was placed in three aneurysms, and a balloon-expandable stent was placed in six.

RESULTS

The stent-graft was successfully placed in all patients. Immediate follow-up angiography revealed complete exclusion of the aneurysm in all cases. Follow-up computed tomography performed 3 days to 2 weeks later revealed complete exclusion and thrombosis of the aneurysm and patency of the stent-graft in six patients. In one patient, total occlusion of the artery with a stent occurred due to flow disturbance caused by double lesions. During follow-up (range, 6-59 months; mean, 28 months), the aneurysm resolved and completely regressed in four patients. A recurrent aneurysm at the distal margin of previously inserted stent-graft was successfully managed with an additional stent-graft.

CONCLUSION

The findings in this initial experience suggest that stent-graft insertion may be a safe and effective alternative to surgical treatment of aortic and arterial aneurysms in patients with Behçet disease.

Analysis of initial CT findings after endovascular repair of abdominal aortic aneurysm

PURPOSE

To determine the spectrum and frequency of specific computed tomographic (CT) findings in the acute period after endovascular repair of abdominal aortic aneurysm (AAA).

MATERIALS AND METHODS

CT images obtained 1--3 days after endograft placement were evaluated in 88 patients. The images were analyzed for stent position, appearance of endograft components, perigraft leak, and postoperative findings including air and acute thrombus within the aneurysm and air surrounding the femoral-femoral bypass graft. Findings that could be misinterpreted as perigraft leak were evaluated.

RESULTS

Fifteen (17%) of 88 patients had perigraft leak in the acute postoperative period. The bare segment of the proximal self-expanding stent covered one or both renal arteries in 54 (61%) patients. One patient had CT evidence of renovascular compromise. Postoperative air was within the aneurysmal sac in 51 (58%) patients and surrounded the femoral-femoral bypass graft in 67 (94%) of 71 patients in whom the grafts were evaluated with CT. Mottled attenuation within the aneurysmal sac was seen in 50 (57%) patients. Forty-six (52%) patients had calcifications within longstanding thrombus. In 31 (35%) patients, findings that could have been misinterpreted as perigraft leak were identified.

CONCLUSION

Accurate analysis of CT findings after endovascular AAA repair requires careful review of all available CT images (preprocedural and pre- and postcontrast) and clear understanding of specific stent-graft components and placement.

Prognosis of patients turned down for conventional abdominal aortic aneurysm repair in the endovascular and sonographic era: Szilagyi revisited?

PURPOSE

The United Kingdom Small Aneurysm study has demonstrated the low risk of rupture in aneurysms less than 5.5 cm in diameter. With the advent of endoluminal techniques, patients considered unfit to undergo laparotomy are now considered for endovascular repair. However, the natural history of aneurysms larger than 5.5 cm remains uncertain, especially when severe comorbidity is present. In our center, we prospectively maintain records of all patients for whom elective aneurysm surgery was refused. This study documented the outcome of all patients referred with abdominal aortic aneurysms (AAAs) larger than 5.5 cm in diameter who were turned down for elective open repair and determined the cause of death and risk of rupture in all patients.

METHODS

Details of all patients with AAAs from January 5, 1989, to January 5, 1999, were recorded, and demographic details on all patients with AAAs larger than 5.5 cm were collected. Copies of death certificates were obtained from the Office of National Statistics, local in-hospital patient records, and general practitioner records. Results of postmortem examinations were also obtained. Aneurysms were stratified according to their size at presentation (5.5-5.9 cm, 6.0-7.0 cm, and > 7.0 cm), and the reasons no intervention was made were documented.

RESULTS

A total of 106 patients were turned down for elective aneurysm surgery in the 10-year period (10.6 per year). The mean age of the patients was 78.4 years (SD, 7.4), and 70 were men and 36 were women. At the end of the study, 76 patients (71.7%) had died. Overall, the 3-year survival rate was 17%. Patients with AAAs larger than 7.0 cm lived a median of 9 months. A ruptured aneurysm was certified as a cause of death in 36% of the patients with an AAA of 5.5 to 5.9 cm, in 50% of the patients with an AAA of 6 to 7.0 cm, and 55% of the patients with an AAA larger than 7.0 cm. Reasons given for not intervening were patient refusal (31 cases), the patient being "unfit for surgery" (18 cases), the "advanced age" of the patient (18 cases), cardiac disease (9 cases), cancer (9 cases), respiratory disease (6 cases), and other (15 cases).

CONCLUSION

Although we recognize the problems with death certification, we found that rupture was a significant cause of death in patients with an untreated AAA that was larger than 5.5 cm. Although little difference in outcome was observed in aneurysms in the 5.5 to 7.0 cm size range, patients with an AAA that was larger than 7.0 cm seemed to have a much poorer prognosis.

Treatment of Stanford type B aortic dissection with stent-grafts: preliminary results

PURPOSE

To evaluate the feasibility and safety of endovascular stent-graft placement in treating Stanford type B aortic dissection.

MATERIALS AND METHODS

Seven patients underwent endovascular stent-graft placement for type B aortic dissection. Five patients had acute and two had chronic dissection. In five patients, the proximal entry tear was within 2 cm of the origin of the left subclavian artery, and in two patients it was beyond this site. In three patients, the noncovered proximal portion of the stent-graft was placed across the origin of the left subclavian artery. The efficacy of the procedure was assessed at follow-up studies 3, 6, 12, and 24 months after intervention.

RESULTS

The procedure was technically and clinically successful in six patients (86%). The left subclavian artery remained patent in all patients. In two patients with involvement of aortic branches, endovascular stent-graft placement restored adequate blood flow to the compromised branches. One patient was readmitted 1 month later because the dissection extended into the ascending aorta. In all but this patient, closure of the entry tear and thrombosis of the false lumen along the stent-graft were achieved. All false lumina shrank considerably. The mean follow-up time was 14 months (range, 1-25 months).

CONCLUSION

Type B aortic dissections within and beyond 2 cm of the origin of the left subclavian artery can be treated safely and effectively by means of endovascular stent-graft placement.

Limb kinking in supported and unsupported abdominal aortic stent-grafts

PURPOSE

The occurrence of kinking of stent-graft limbs depends on the patient's anatomy and the device used. The purpose of this investigation was to determine the rates of limb kinking in supported and unsupported aortic stent-grafts.

MATERIALS AND METHODS

The authors performed a retrospective review of patients undergoing placement of either a Guidant Ancure/EGS or Medtronic Talent aortic stent-graft for the treatment of abdominal aortic aneurysm as part of separate phase II and phase III clinical trials. The records of 91 consecutive patients with 149 limbs were reviewed. The type and configuration of each device and any procedure performed specifically relating to limb patency was recorded. An analysis was then performed comparing the rates of kinking in supported and unsupported groups. A review of the literature was also performed.

RESULTS

Overall, there was kinking in 18 of 149 limbs (12%). In the supported stent-graft group, 48 bifurcated and 26 aortomonoiliac grafts were placed, with a total of 122 limbs at risk. Six limbs (5%) in five patients required intervention as a result of limb kinking. Stents were placed intraoperatively in two limbs (2%) and postoperatively in four limbs (3%) for thrombosis or severe stenosis. In the unsupported group, 12 bifurcated and three aortomonoiliac grafts were placed, with a total of 27 limbs at risk. Twelve limbs (44%) in eight patients required some type of intervention as a result of limb kinking. Stents were placed intraoperatively in seven limbs (26%) and postoperatively in five limbs (19%) for thrombosis or severe stenosis. Rates of limb kinking were significantly different between the supported and unsupported groups (P < .0001).

CONCLUSIONS

The use of supported versus unsupported stent-grafts impacts the occurrence of limb kinking. A direct comparison of the groups suggests that an unsupported stent-graft will be more than 15 times more likely than a supported system to require intervention because of kinking.

The impact of stent design on proximal stent-graft fixation in the abdominal aorta: an experimental study

OBJECTIVE

to study the proximal fixation of different aortic stent grafts in comparison to a hand-sewn anastomosis.

DESIGN

experimental study.

MATERIAL

the infrarenal aorta of 16 human cadavers were exposed, left in situ and transected 3 cm above the aortic bifurcation to mimic an infrarenal aortic neck. Stent grafts were deployed through a sheath 5 cm into the aorta. Ancure, Talent, Vanguard, Zenith and a Palmaz based stent graft were assessed. In addition a polyester graft was anastomosed to the aorta by running sutures. Distal force was applied to the grafts in increments of 0.5 Newton until the stent grafts were completely dislodged from the aorta. The displacement force (DF) was thereby determined.

RESULTS

a force of 150 N (140-160) applied to the hand-sewn graft resulted in tearing of the aorta, without breakage of the sutures. The median displacement force was for Talent 4.5 N (1.3-5.5), Vanguard 9.0 N (3. 5-12), Ancure 12.5 N (12-14), Zenith 24 N (23-26.5) and Palmaz 25 N (17-25). Ballooning the stent after deployment improved fixation in some cases.

CONCLUSIONS

a sutured anastomosis fixates a graft better than any stent design tested. Hooks and barbs improve the fixation of self-expandable stents. Balloon dilatation of the proximal stent after deployment might increase fixation further. Balloon expandable stents seem to provide good fixation without the use of hooks and barbs.

Bovine type I collagen as an endovascular stent-graft material: biocompatibility study in rabbits

PURPOSE

To study the biocompatibility of a bovine type I collagen preparation as a material for small-vessel stent-grafts in rabbits.

MATERIALS AND METHODS

A composite nitinol-collagen endovascular stent-graft with a 4-mm inner diameter was deployed in the abdominal aorta in nine rabbits. Angiography was performed, and the rabbits were sacrificed at 1, 2, and 7 days and at 1 and 3 months. The portion of the aorta containing the stent-graft was excised and was histologically evaluated.

RESULTS

All stent-grafts were patent at all time points. On days 1, 2, and 7 after implantation, scattered red and white blood cells adhered to the stent-graft. At 1 month, the stent-graft was endothelialized and was infiltrated with fibroblasts that deposited collagen within the interstices of the implanted collagen material. At 3 months, there was additional collagen deposition within the interstices of the stent-graft that did not narrow the lumen of the stent-grafts.

CONCLUSION

Type I collagen as a intravascular stent-graft material is biocompatible for at least 3 months in rabbits. It is rapidly endothelialized and does not cause reactive stenosis. As a versatile and biocompatible polymer, collagen is potentially useful in the construction of endovascular stent-grafts for use in human arteries.

Embolotherapy of persistent endoleaks after endovascular repair of abdominal aortic aneurysm with the ancure-endovascular technologies endograft system

PURPOSE

Endoleak is a potential complication after endovascular repair of abdominal aortic aneurysm (AAA). It may result in continued growth of the aneurysm and potentially result in aneurysm rupture. The authors present their experience with embolotherapy in patients with persistent perigraft flow treated with the Ancure-Endovascular Technologies endograft system.

MATERIALS AND METHODS

Between February 1996 and August 1998, 54 patients underwent successful repair of AAA with use of the Ancure system. All underwent operative angiography and discharge computed tomography (CT). Follow-up included CT at 6, 12, and 24 months, and CT was also performed at 3 months if an endoleak was present on the discharge CT. Persistent endoleak was defined as perigraft flow still present on the 6-month CT. Seven of 21 initial endoleaks persisted at 6 months. Six patients returned for embolization of the perigraft space and outflow vessels including lumbar arteries and the inferior mesenteric artery (IMA).

RESULTS

Five of the six patients had leaks from the proximal (n = 1) or distal attachment sites (n = 4) of the Ancure system with outflow into lumbar arteries and/or the IMA; one leak was caused by retrograde IMA flow. The six patients underwent nine embolization procedures with only one minor complication. Follow-up CT showed complete resolution of endoleak and decrease in size of the aneurysm sac in all patients.

CONCLUSIONS

Although endoleak is commonly seen initially with the Ancure system, persistent leak occurred in 13% of the patients in the study. Persistent flow in most patients arises from a graft attachment site combined with patent outflow vessels such as the IMA or lumbar arteries. Persistent endoleaks can be effectively and safely embolized with use of a combination of coil embolization of the perigraft space and embolization of outflow vessels. Such intervention resulted in a decrease in size of the aneurysm sac.

Custom bifurcated stent-graft for abdominal aortic aneurysms: initial experience

PURPOSE

To describe a custom bifurcated stent-graft for possible treatment of abdominal aortic aneurysm (AAA).

MATERIALS AND METHODS

Five male patients (mean age, 76 +/- 6 years), who had AAA (mean diameter, 4.7 +/- 0.4 cm) and who were considered to be at high risk for conventional surgery, were treated with a custom modular bifurcated stent-graft constructed with bifurcated 24-mm x 12-mm (upper body diameter x iliac limb diameter) Cooley Veri-Soft Woven polyester grafts and Gianturco-Rösch Z stents. The stent-graft body was delivered through 20-22-F sheaths, and the contralateral iliac limb was delivered through a 16-F sheath by means of surgical exposure of the common femoral arteries. A flared distal limb extender (12 mm to 14 mm) was created for one patient to accommodate a large common iliac artery.

RESULTS

Stent-grafts were successfully deployed without complications in all five patients. There were no proximal or distal leaks. A lumbar-to-inferior mesenteric artery leak was seen in one patient at 24 hours. At 6-month follow-up, all devices were intact, with complete exclusion and shrinkage of the aneurysm in four of five patients. Aneurysm size remained stable in the one patient with a lumbar-to-inferior mesenteric artery leak.

CONCLUSION

A custom, bifurcated stent-graft was utilized for endovascular treatment of AAA. Long-term follow-up is necessary for the device.

Aortoduodenal fistula: a late complication of intraluminal exclusion of an infrarenal aortic aneurysm

During recent years, considerable clinical experience has been gained with endoluminal stent-graft procedures. Several studies have shown promising results up to a period of 4.5 years. However, long-term follow-up studies are still limited. Late endoleaks caused by stent-graft migration, disconnection of single components in modular stent-grafts, and limb thrombosis have been observed as long-term complications. We report a case in which a migrated and kinked bifurcated stent-graft caused an aortoduodenal fistula 20 months after stent-graft insertion. To our knowledge, such a complication has not been reported before.

Rectum and sigmoid colon necrosis due to cholesterol embolization after implantation of an aortic stent-graft

Endovascular treatment of abdominal aortic aneurysms (AAAs) with stent-grafts is increasingly performed. Recent studies have shown that stent-graft placement for AAA is technically feasible and can effectively exclude aneurysms from the circulation. However, complications related to the procedure, such as graft thrombosis, migration of the prosthesis, peripheral embolization, and leaks with incomplete exclusion of the aneurysmal sac, have been reported. We report a case of rectum and sigmoid colon necrosis with fatal outcome due to cholesterol embolization after implantation of a stent-graft for an infrarenal AAA.

Devices for aortic aneurysm repair

Although the technical success and short-term efficacy of endovascular grafts have now been demonstrated, the long-term durability of grafts used in the aorta remains to be proven. No long-term data are yet available regarding device durability or patient outcome beyond the initial few years. Recent evidence shows that the ability of endovascular grafts to cause shrinkage and regression of aortic aneurysms may have a paradoxic effect of distorting the endograft itself, thus causing geometric changes within the supporting metallic framework and, ultimately, device failure (Fig. 9). Thus, the desired positive effect of the device may, ironically, lead to its eventual failure.

Endoleak after stent-graft treatment of abdominal aortic aneurysm: a meta-analysis of clinical studies

BACKGROUND

Endoleak is the major complication after endovascular treatment of abdominal aortic aneurysm (AAA) and its incidence seems to remain significant. Little is known about the association of device type and configuration with respect to the incidence, location, time of onset and fate of endoleakage.

METHODS

A meta-analysis was performed via a Medline search of clinical studies after 1995 dealing with the endovascular treatment of AAA. Details of number of patients treated, configuration and type of endovascular device were collected. Data concerning site of origin, time of occurrence and fate of the endoleak were retrieved, along with information on change in diameter of the aneurysm with time.

RESULTS

The 23 publications included reported on 1189 patients. The 1118 patients with successfully inserted transfemoral endovascular grafts experienced 270 endoleaks (24 per cent). The majority arose from the distal stent attachment site (36 per cent), were present immediately after stent-graft placement (66 per cent) and were persistent in time (37 per cent). Tube grafts were more frequently affected by endoleakage (35 per cent; P < 0.0001), especially at the distal stent attachment site (51 per cent), than bifurcated grafts (18 per cent; P = 0.004) and aortounilateral devices (20 per cent; P = 0.70). Self- expandable stent-grafts were more frequently associated with endoleaks (25 per cent) than balloon-expandable stent-grafts (17 per cent) (P = 0.037).

CONCLUSION

Endovascular treatment of AAA is an evolving field. Even after the initial learning curve and attention to device-related problems, it is still accompanied by a significant number of endoleaks. Uniform presentation of results of treatment is necessary for analysing the effect of differences between patients, aneurysm morphology and device type.

Distal migration of stent-grafts after endovascular repair of abdominal aortic aneurysms

PURPOSE

To analyze patients after endovascular repair of abdominal aortic aneurysm (AAA) with respect to distal migration of stent-grafts and its underlying causes.

MATERIALS AND METHODS

Sixty-five patients underwent endovascular repair between January 1994 and February 1997. There were seven women and 58 men, with a mean age of 71 years (range, 51-84 years). Three patients died in the perioperative period (one of myocardial infarction and two of multiorgan failure) and two patients died within 4 months of the procedure of non-procedure-related causes. In addition, two patients were followed at another hospital. The remaining 58 patients were followed up with spiral computed tomography scans at 1, 3, and 6 months, and biannually thereafter. Angiography was performed at 1 month and 1 year after the procedure and additionally when deemed clinically necessary. Mean follow-up was 29 months (range, 1-49). Migration more than 5 mm was considered significant.

RESULTS

Twenty-six patients (45%) showed distal migration of stent-grafts during follow-up. Mean follow-up time at detection of migration was 13 months (range, 1-36 months). Thirteen cases of migration were ascribed to dilatation of the proximal aneurysmal neck during follow-up. Ten cases of migration were ascribed to causes other than neck dilatation or poor patient selection. In three cases, no obvious cause for the migration was found. The migration was complete in eight cases, leading to late conversion to open surgical repair. On two of these occasions, complete migration lead to aneurysm rupture. In addition, four patients received additional stent-grafts as proximal extensions.

CONCLUSIONS

Distal migration of stent-grafts after endovascular AAA repair occurred frequently in this series. Dilatation of the proximal aneurysmal neck is a major cause of distal migration of stent-grafts. Improved proximal fixation is needed to secure long-term durability.

Endoluminal treatment of infrarenal aortic aneurysms: clinical experience with the Talent stent-graft system

PURPOSE

To evaluate the safety and efficacy of the Talent stent-graft (TSG) system in the endoluminal treatment of infrarenal abdominal aortic aneurysms (AAAs).

PATIENTS AND METHODS

Endoluminal treatment of an AAA was attempted in 30 men with a mean age of 70.5 years (range, 51-83 years). Seven patients had AAAs suitable for treatment with a tube graft. In the other patients, treatment with a bifurcated TSG was planned. All procedures were performed as a combined surgical-radiologic procedure in an angiographic room.

RESULTS

Primary technical success was achieved in 25 of 30 patients (83%). Technical failures were due to misplacement of the TSG (n = 2) with proximal leakage as a consequence, inability to gain access via the iliac arteries (n = 1), and a distal leakage (n = 2). Secondary interventions (n = 2) and spontaneous thrombosis of a distal leak (n = 1) increased the secondary technical success rate to 93% (28 of 30). Two procedures were converted to open surgery (conversion rate = 6%). One patient died during the first 30 days after uncomplicated stent-graft insertion because of myocardial infarction (30-day mortality = 5%). No complications occurred during a mean follow-up of 15.4 months (range, 6-19 months). The maximum diameter of the AAA decreased in eight patients and remained unchanged in the remaining patients. No increase in diameter was observed. No late endoleak or migration of the TSG was observed.

CONCLUSION

The TSG-system revealed satisfactory initial and early follow-up results. Treatment of AAAs with this stent-graft system is feasible. The technical success rate in carefully selected patients should be 90% or more. However, long-term observations are necessary to determine if the encouraging early results of this type of therapy can be preserved during long-term follow-up.

Imaging of abdominal aortic aneurysms after endoluminal repair

The recently published clinical trials of endoluminal repair of aortic aneurysms underline the need for a close imaging follow-up of patients undergoing these procedures. This article discusses the role of different imaging modalities in the evaluation of these patients.