Importance of graft configuration in outcome of endoluminal aortic aneurysm repair: a 5-year analysis by the life table method

Frequency, Predictive Factors, and Consequences of Stent-Graft Kink following Endovascular AAA Repair

Purpose:

To determine from the EUROSTAR registry the incidence of stent-graft kink, predictive factors for kinking, and the consequences of this complication on graft patency and aneurysm exclusion.

Methods:

From January 1994 to June 2002, 4613 patients who underwent endovascular aneurysm repair were registered in the EUROSTAR registry. Presence of kink was determined according to the information available on the follow-up Case Record Form. The population was divided into those with and without stent-graft kink. Patient characteristics, morphological aneurysm features, team experience, type of device, period of implantation, and outcome were compared between the groups by univariate analysis. Significant factors were subsequently submitted to a multivariate Cox proportional hazard analysis.

Results:

One hundred seventy (3.7%) patients were reported as having a kink of the stent-graft during a mean follow-up of 21 months (range 1–72). Gender, neck angulation, team experience, period of implantation, ASA classification, and device type were independent predictors of kink. The presence of a kink was significantly associated with type I endoleaks (proximal and distal), type III endoleaks (midgraft), graft stenosis, graft limb thrombosis, graft migration, and conversion to open repair. No relationship was found between a decrease in the aneurysm diameter and the occurrence of stent-graft kink.

Conclusions:

Kinks of stent-grafts were infrequent events in the intermediate term. Patients most at risk were women with angulated aortic necks treated by a minimally experienced team. Kinks are potentially damaging events because they may lead to delayed device-related endoleaks, graft stenosis, thrombosis, and conversion to open repair. They appear more closely associated to graft migration than to aneurysm diameter reduction.

Abdominal aortic aneurysms: endovascular options and outcomes - proliferating therapy, but effective?

Abdominal aortic aneurysm (AAA) has a reported prevalence rate of 1.4% in the US. AAA rupture accounts for an estimated 15,000 deaths per year, rendering it the 10th leading cause of death in men over the age of 55. Endovascular repair (EVR) has proliferated in the last two decades as an increasingly popular alternative to traditional open surgery, and is now the default treatment in the majority of centres worldwide. This review article outlines the evidence supporting this stance. The development of EVR is reviewed, alongside trends in utilisation of this therapy over time. The evidence for the relative short-term and long-term outcomes of EVR and open AAA repair is discussed, and ongoing controversies surrounding the use of EVR are considered.

Reprinted article "Realistic expectations for patients with stent-graft treatment of abdominal aortic aneurysms. Results of a European multicentre registry"

OBJECTIVE

The outcomes for patients after endovascular treatment of abdominal aortic aneurysm (AAA) are determined primarily by the endpoints of death and endoleaks, the latter representing continued risk of rupture. The data of a multicentre registry were analysed with regard to the early outcome of stent-graft procedures for AAA and the complications associated with this treatment. In addition, the results during follow-up were analysed by determining mortality and endoleak development as separate endpoints and as a combined endpoint defined as endoleak-free survival.

SETTING

38 European institutions of Vascular Surgery collaborating in a multicentre registry project.

PATIENTS AND METHODS

899 patients with AAA underwent between May 1994 and March 1998 elective endovascular repair (818 men and 81 women; mean age 69 years). 80 (8.9%) of the patients had medical conditions that excluded them from open repair. 818 (91%) of patients had a bifurcated device, 63 (7%) had a straight tube graft, and only 18 (2%) had an aorto-uni-iliac device. Clinical examination and contrast-enhanced computed tomography was performed at fixed follow-up intervals to assess increase or decrease of the maximum transverse diameter (MTD). Endoleaks observed at follow-up were discriminated into persistent endoleak and temporary endoleak. The latter is defined as single time observed endoleaks or with two or more negative imaging studies between observed endoleaks. Life-table analyses were used to calculate the rates of freedom-from-endoleak (no endoleak at any time), freedom-from-persistent endoleak (no persistent endoleak), patient survival, and persistent-endoleak-free-survival.

RESULTS

The median follow-up of this patient series was 6.2 months. The ratio between observed and expected follow-up data was 82% for the overall follow-up period. However, at 18 months of follow-up this rate was only 45%. The number of patients followed during this period was sufficient to allow statistically meaningful assessment. The MTD in patients with temporary endoleaks demonstrated a significant decrease at 6 to 12 months compared to preoperative values (mean 57 and 53 respectively, p = 0.004). In patients with persistent endoleaks there was no change between the preoperative and 6-month MTD (mean 57 and 60 mm respectively). At 6 and 18 months freedom-from-endoleak was 83% and 74% and freedom-from-persistent endoleak was 93% and 90%, respectively. The 18-month cumulative patient survival was 88% and the main outcome measure, the persistent endoleak-free-survival was 79%.

CONCLUSIONS

The MTD decreases in patients with temporary endoleak, but not in patients with persistent endoleak. Therefore, the use of the rate of freedom-from-persistent endoleak, reflecting absence of persisting endoleaks to estimate the prognosis with regard to the AAA, is justified. Determining persistent endoleak-free survival appears a rational approach to provide a realistic outlook for patients with stent-grafted AAA. The observed 18-month endoleak-free survival reflects a satisfactory mid-term result.

Durability of endovascular infrarenal aneurysm repair: when does late failure occur and why?

The first commercially available stent grafts were unable to withstand the hemodynamic forces of the vascular environment. The past 15 years have seen a gradual improvement in long-term stent graft performance as designs evolved through the elimination of features associated with late failure and the replication of features associated with durable success. Clinical experience provides the following principles on which to base device design and implantation techniques. Few patients have an adequate length of non-dilated aorta distal to the aneurysm to allow implantation of an aorto-aortic stent graft; bifurcated stent grafts are usually required for AAA repair. Friction, column strength and tissue ingrowth do not prevent migration of the stent graft from its attachment within the neck into the aneurysm; some form of active fixation is required, usually in the form of barbs. Any movement between the apex of a stent and the overlying graft material will erode the fabric; stents and grafts need to move as a single unit. Nitinol is versatile, but fragile; Nitinol components must be polished to eliminate all surface irregularities and they cannot be subjected to compression loading, or excessive pulsatile movement. The neck of an aneurysm is unstable; it will dilate unless protected by a securely fixed, non-compliant stent graft. The aneurysm does not heal; freedom from risk of rupture depends on durable depressurization of the sac. The sole objective of image-based follow-up is the early detection, and catheter-based correction, of device failure. Once any given design has been in use long enough to identify its failure modes, the frequency of follow-up studies can be adjusted accordingly. However, it takes a long time to identify all the potential forms of late failure, and pre-clinical testing remains an imprecise science. New, or recently modified, devices cannot necessarily be assumed to be as durable as their predecessors.

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.

Endovascular treatment of abdominal aortic aneurysms--6 years of experience with Ella stent-graft system

PURPOSE

Evaluation of 6-year results of abdominal aortic aneurysm (AAA) treatment by Ella stent-grafts with regard to safety and effectivity in relation to morphology of the aneurysm.

METHODS

From a group of 172 patients with AAA, in whom elective endovascular treatment was considered, 120 of them (69.8%) were found to be suitable for this type of therapy. The bifurcated type of stent-graft was implanted in 97 patients, uniiliacal type in 19 patients and only four patients were found to be suitable for tubular type of stent-graft. Additional necessary procedures (internal iliac artery occlusion or contralateral common iliac artery occlusion in a group of patients with uniiliacal type of stent-graft) were performed surgically during the stent-graft implantation. CT and US controls were performed at 3, 6 and 12 months after implantation, later every 12 months.

RESULTS

Primary technical success was achieved in 109 of the 120 patients (91%). Primary endoleak was recorded in 11 patients (primary endoleak type Ia in seven patients, type Ib in three patients and type IIIa in one patient). Assisted technical success after reintervention or spontaneous seal was 98.3%. Surgical conversion was indicated in two patients (1.7%). Perioperative mortality rate was 3.3%. Total average follow-up period was 20.7 months (range from 2 to 60 months). In nine patients (7.5%) secondary endoleak type II was found at control CT or US, in three patients partial thrombosis of the stent-graft was found. There was no aneurysm rupture during follow-up.

CONCLUSION

Treatment of AAA with Ella stent-graft system is effective and safe. Bifurcated stent-graft is the most frequently used type. Uniiliacal type of stent-graft is used by us only in cases of complicated morphology.

Salvage of a difficult situation: method for conversion of failed endograft

Complications of endovascular aneurysm repair can be difficult to manage. One of the more difficult situations is conversion to open surgery because of a failed endograft. We describe a technique for conversion that allows the proximal attachment system to remain intact. It may also enable infrarenal clamping of the aorta during the operation. The anastomosis is performed by incorporating the proximal attachment system of the endograft. This technique simplifies both vascular control of the aorta and the necessary reconstruction during creation of the proximal anastomosis. We believe this technique has important advantages when conversion of a failed endograft is required.

Failure of endovascular aortoaortic tube grafts: a plea for preferential use of bifurcated grafts

OBJECTIVE

Aortoaortic tube graft repair was the first technique used for the endovascular treatment of abdominal aortic aneurysms (AAAs). However, progressive changes in the morphology of the distal aortic neck may be responsible for procedural failure. This study examines the use of aortoaortic tube prostheses and analyzes the factors that contributed to their failure and the methods used for their subsequent repair.

METHODS

During a 7-year period, 462 patients with abdominal aortic aneurysms underwent endovascular aortic aneurysm repair. Of these, 65 patients (14%) underwent treatment with aortoaortic tube endoprostheses. Aortoaortic tube prostheses used included Talent (n = 44) (Medtronic-Worldmedical, Sunrise, Fla), Vanguard (n = 8) (Boston Scientific, Natick, Mass), EVT/Ancure (n = 4) (Guidant, Menlo Park, Calif), and physician-fabricated (n = 9). All the tube graft procedures were performed in the operating room with fluoroscopic guidance. The average age of patients for aortoaortic tube grafts was 74.5 years, and 48 of the patients were men. Failure was defined as aneurysm expansion, any type I endoleak, or type II endoleak persistent after 6 months.

RESULTS

No aneurysm ruptures or perioperative deaths were seen. Retrograde aneurysm perfusion from lumbar or inferior mesenteric arteries (type II endoleak) that persisted beyond 6 months was present in three patients. Proximal attachment site endoleaks were present in two patients. No distal implantation site endoleaks were present within 1 month of the initial endovascular repair; however, endoleaks at the distal attachment site developed in 12 patients subsequently and included all graft types (Talent, n = 6; Vanguard, n = 2; Ancure/EVT, n = 1; physician-fabricated, n = 3). The average time interval to failure was 12.9 months. Preoperative distal aortic neck length showed a significant correlation with the subsequent development of distal endoleak (endoleak, 16.6 +/- 6.8 versus no endoleak, 23.3 +/- 9.6; P =.03). Preoperative distal aortic neck diameter, however, did not show significance (23.8 +/- 5.2 versus 22.6 +/- 4.7; P = not significant).

CONCLUSION

Endovascular aortoaortic tube grafts are vulnerable to failure even when initial exclusion of the aneurysm is successful. A significant association is seen between distal neck length and eventual failure. Because of the propensity toward eventual failure, the use of aortoaortic tube grafts in the infrarenal aorta cannot be recommended for typical fusiform aneurysms, even when an adequate distal neck appears to be present.

Surgical conversion after endovascular grafting for abdominal aortic aneurysms

PURPOSE

To analyze the indications, results, and technical problems associated with conversion after endoluminal repair of abdominal aortic aneurysms (AAA) based on a 6-year experience in endovascular grafting.

METHODS

From August 1994 to May 2000, 520 patients with AAA were deemed candidates for endovascular therapy based on data from contrast-enhanced computed tomography and aortography. Any conversions were performed using an open operation modified according to the indication for conversion, elapsed time from the endoluminal repair, and type of endograft (tube, bifurcated, infra-/suprarenal fixation).

RESULTS

Conversion to open repair was required in 37 (7.1%) cases: 23 tube grafts and 14 bifurcated devices. Seventeen (3.2%) conversions occurred at the original operation and 20 (3.8%) were performed secondarily. Indications for primary conversion were mainly device defects (n = 5) or access problems (n = 5), while secondary conversion was primarily owing to type I endoleak (n = 16). The conversion rate was significantly higher in modular devices (5.9%) than unibody designs (1.4%) (p = 0.003). The rate of primary conversions diminished from 10.9% in 1994-1995 to 2.4% between 1996 and 2000, as did the overall mortality rate, from 8.3% in the first time period to 0% in the second for elective conversions, but emergency operations had 40% mortality.

CONCLUSIONS

Most AAAs require bifurcated devices for complete exclusion, and older model modular grafts have higher conversion rates. Primary conversion decreases as more experience in endoluminal grafting is acquired. Emergency open repair results in a high mortality rate.

The evolution of Z stent-based stent-grafts for endovascular aneurysm repair: a life-table analysis of 7.5-year followup

BACKGROUND

The purpose of this study was to analyze the impact of stent-graft design and operator skills on outcomes after endovascular abdominal aortic aneurysm repair.

STUDY DESIGN

One hundred sixty-four patients (mean age 71 years) underwent stent-graft repair. Patients were treated with four different types of stent-graft: first-generation (n = 58) and second-generation (n = 17) Ivancev-Malmö monoiliac stent-grafts (IM I and IM II, respectively) combined with femoral-femoral crossover, Chuter bifurcated stent-graft (n = 15), and the Zenith stent-graft (n = 74). Patients underwent digital subtraction angiography and contrast CT preoperatively and were then followed with CT scans postoperatively. Recently, followup was changed to CT scanning at 1 month and 1 year postoperatively and annually thereafter. Ultrasonographic duplex scanning substitutes in the remaining followup. Changes in aneurysm diameters and occurrence of endoleaks were recorded. Short- and midterm mortality and complications and postoperative secondary interventions were recorded, and life-table analysis for intervention-free stent-graft survival was calculated.

RESULTS

Immediate and late conversions and 30-day mortality were reduced for second- (IM II and Zenith) compared with first-generation stent-grafts (IM I and Chuter). Stent-graft migrations occurred only with the IM I and Chuter stent-grafts. Type I endoleak was significantly more common in first-generation stent-grafts. First-generation stent-grafts required significantly more secondary interventions than second-generation stent-grafts up to 30 months postoperatively.

CONCLUSION

Enhanced stent-graft design has improved the probability of stent-graft success after endovascular abdominal aortic aneurysm repair. Better technical skills and increased use of intraoperative adjunctive procedures may also have contributed to improved results.

Internal iliac artery embolization before endovascular repair of abdominal aortic aneurysms: frequency, efficacy, and clinical results

OBJECTIVE

The aim of our study was to assess the frequency, efficacy, and incidence of adverse effects of internal iliac artery embolization.

MATERIALS AND METHODS

Of 343 patients examined for stent-graft repair, 147 were suitable for endovascular treatment. Fifty-five patients underwent preprocedural embolization of the internal iliac artery either unilaterally (46 patients) or bilaterally (nine patients). Successful embolization was assessed angiographically and with helical CT follow-up examinations. Colonic ischemia was ruled out clinically or colonoscopically. Buttock claudication, and sexual dysfunction in men, were evaluated through a questionnaire.

RESULTS

Embolization of the internal iliac artery increased by 16% the percentage of patients for whom endovascular repair was suitable. After successful embolization in all patients, routine CT follow-up examinations after a mean time of 16.7 months showed no evidence of endoleaks related to retrograde perfusion via embolized internal iliac arteries. Nevertheless, in all patients who had undergone embolization, a primary endoleak was detected in 43.4% at the first postoperative CT examination. None of our patients had evidence of colonic ischemia. Clinical follow-up data of 46 patients were available. Of these patients, mild to severe new onset buttock claudication was found in 13 (36.1%) of 36 patients with unilateral, and in eight (80%) of 10 patients with bilateral, internal iliac artery embolization (p = 0.03). Five (25%) of 20 men had an erectile dysfunction after the procedure.

CONCLUSION

Embolization of the internal iliac artery is a safe and efficient procedure that increases the applicability for endovascular repair of aortoiliac aneurysms. However, buttock claudication and erectile dysfunction are a drawback in a substantial number of patients.

Impact of endovascular repair for abdominal aortic aneurysms in octogenarians

A total of 50 consecutive patients (86% male; median age, 82 years) underwent endovascular repair of abdominal aortic aneurysms (AAAs) ranging from 4.0 to 9.0 cm (median, 5.2 cm). Efficacy of aneurysm exclusion was assessed by angiography, duplex scan, and/or contrast-enhanced computed tomography (CT). Acute technical success was 82%. Access failed in one patient, and immediate conversion to open operation was required in two patients. Improper deployment of the endoluminal graft (ELG) across the renal arteries occurred in one patient. The median operation time, estimated blood loss, packed red blood cells received, contrast volume, and length of intensive care and hospital stay were 128 min, 200 mL, 0.1 unit, 297 mL, 0.9 days, and 3 days, respectively. ELG limb thrombosis was seen in one patient. There were 4 (8%) early endoleaks, and 2 endoleaks were discovered in other patients at 3 and 6 months. Local/vascular and remote/systemic postoperative complications were seen in 13 (26%) and 9 (18%) patients, respectively. At a median follow-up of 11 months (range 2 to 36 months), clinical success was 78%. The aneurysm sac diameter (n = 49) decreased from a preoperative median of 5.2 to 4.7 cm (p = 0.0001). Technical success was high, and results at 11 months were satisfactory. Long-term outcomes require further study.

The impact of stent-graft development on outcome of AAA repair--a 7-year experience

OBJECTIVE

to analyse the impact of stent-graft (SG) design and operator skill on the outcome of endovascular AAA repair.

DESIGN

prospective non-randomised open.

MATERIAL

a total of 158 patients (mean age 71) underwent SG repair. Patients were treated with five different types of SG: first (n =58) and second ( n =17) generation Ivancev-Malmö monoiliac SG (IM I and IM II respectively) combined with femoral-femoral crossover, Chuter bifurcated SG (n =15), Vanguard SG ( n =15) and the Zenith SG ( n =53).

METHODS

patients underwent DSA and contrast CT preoperatively and were then followed with CT and digital scans. Recently, one change in AAA diameter and endoleaks (EL) were recorded. Mortality, complications and secondary interventions were recorded and life-table analysis for intervention-free SG survival calculated.

RESULTS

immediate and late conversions as well as 30-day mortality were reduced for 2nd (Zenith and Vanguard) compared to 1st generation SG (IM I, Im II and chuter). SG migrations occurred only with the IM I and Chuter SG. Type I EL were significantly more common in 1st generation SG. First generation SG required significantly more secondary interventions than 2nd SG up to 20 months post-operatively. The number of unplanned intraoperative adjunctive manoeuvres was increased with 2nd SG.

CONCLUSIONS

enhanced SG design has improved the probability of SG success after endovascular AAA repair. Better technical skills may also have contributed to improved results.

Endoluminal repair of abdominal aortic aneurysms - state of the art

This paper considers the historical aspects of endovascular aneursym repair; the major findings of our Departments experience over an 812-year period and reviews recent developments in endovascular prostheses. Analysis of 400 patients undergoing primary repair of abdominal aortic aneurysm between 1992 and 2000 revealed a perioperative mortality rate of 2.7% and primary conversion rate of 5%. With sequential studies it was shown that the outcome was better with bifurcated/aorto uni iliac grafts than tube grafts; better with second generation prostheses than first generation protheses and that survival in consecutive patients treated concurrently by open repair and endoluminal repair was superior in the endoluminal group. Endoluminal AAA repair is at a critical point of its development. It is unquestioned that it can dramatically reduce the need for intensive care and length of hospital stay and more recently it has been reported that survival is improved compared with open repair. The need for lifetime surveillance, the probability of graft failure and need for re-intervention, however, negate some of the advantages. The small incidence of unpredictable rupture following endoluminal AAA repair is a timely reminder of the need for continued careful follow-up.

Endoluminal aortic grafting with renal and superior mesenteric artery incorporation by graft fenestration

PURPOSE

To explore the use of juxta- and suprarenal aortic segments for endograft fixation in abdominal aortic aneurysm (AAA) patients and to develop methods of graft implantation that use endograft fenestrations to preserve renal and visceral vessel perfusion.

METHODS

From August 1998 to May 2000, 13 AAA patients with unsuitable infrarenal aortic necks were treated with custom-designed endovascular grafts employing the juxta- and suprarenal aortic segments for proximal sealing. Flow to 33 renal and superior mesenteric arteries was maintained via graft fenestrations that were aligned by use of radiopaque graft markers. The fenestration-orifice interface for renal arteries was secured with modified balloon-expandable stents.

RESULTS

All fenestrated grafts were deployed as planned, and all target vessels (33/33) were preserved. Two patients did not receive any stents, one being the first in the series and another who had incorporation of a renal accessory artery only. Without the use of transgraft stenting, 5 renal arteries would have been occluded by the endograft or poorly perfused. Procedural success was 100%. No conversion to open operation or graft-related complications occurred. There was no primary endoleak in any patient by angiographic criteria. Two patients required additional surgical procedures related to access vessels. Periprocedural mortality at 30 days was nil. Follow-up ranging from 3 to 24 months on all patients has not demonstrated any proximal or distal endoleaks. One stented renal vessel has occluded; all other arteries remain patent at last examination.

CONCLUSIONS

This study has demonstrated the ability to successfully place a multifenestrated endoluminal graft in an aortic aneurysm using juxta- and suprarenal aortic segments to obtain a satisfactory seal. Stenting of the fenestration-renal ostium junction has helped to maintain renal patency.

Endoleak as a predictor of outcome after endovascular aneurysm repair: AneuRx multicenter clinical trial

OBJECTIVE

The purpose of this study was to determine whether evidence of blood flow in the aneurysm sac (endoleak) is a meaningful predictor of clinical outcome after successful endovascular aneurysm repair.

METHODS

We reviewed all patients in Phase II of the AneuRx Multicenter Clinical Trial with successful stent graft implantation and predischarge contrast computed tomographic (CT) imaging. The clinical outcome of patients with evidence of endoleak was compared with the outcome of patients without evidence of endoleak. The CT endoleak status before hospital discharge at 6, 12, and 24 months was determined by each clinical center as well as by an independent core laboratory. Endoleak status at 1 month was assessed with duplex scanning examination or CT at each center without confirmation by the core laboratory.

RESULTS

Centers reported endoleaks in 152 (38%) of 398 patients on predischarge CT, whereas the core laboratory reported endoleaks in 50% of these patients (P <.001). The center-reported endoleak rate decreased to 13% at 1 month. Follow-up extended to 2 years (mean, 10 +/- 4 months). One patient had aneurysm rupture and underwent successful open repair at 14 months. This patient had a Type I endoleak at discharge but no endoleak at 1 month or at subsequent follow-up times. There were no differences between patients with and patients without endoleak at discharge in the following outcome measures: patient survival, aneurysm rupture, surgical conversion, the need for an additional procedure for endoleak or graft patency, aneurysm enlargement more than 5 mm, the appearance of a new endoleak, or stent graft migration. Despite a higher endoleak rate identified by the core laboratory, neither the endoleak rate reported by the core laboratory nor the endoleak rate reported by the center at discharge was significantly related to subsequent outcome measures. Patients with endoleak at 1 month were more likely to undergo an additional procedure for endoleak than patients without endoleaks. Patients with Type I endoleaks at discharge and patients with endoleak at 1 month were more likely to experience aneurysm enlargement at 1 year. However, there was no difference in patient survival, aneurysm rupture rate, or primary or secondary success rate between patients with or without endoleak. Actuarial survival of all patients undergoing endovascular aneurysm repair was 96% at 1 year and was independent of endoleak status. Primary outcome success was 92% at 12 months and 88% at 18 months. Secondary outcome success was 96% at 12 months and 94% at 18 months.

CONCLUSIONS

The presence or absence of endoleak on CT scan before hospital discharge does not appear to predict patient survival or aneurysm rupture rate after endovascular aneurysm repair using the AneuRx stent graft. Although the identification of blood flow in the aneurysm sac after endovascular repair is a meaningful finding and may at times indicate inadequate stent graft fixation, the usefulness of endoleak as a primary indicator of procedural success or failure is unclear. Therefore, all patients who have undergone endovascular aneurysm repair should be carefully followed up regardless of endoleak status.

Comparison of first- and second-generation prostheses for endoluminal repair of abdominal aortic aneurysms: a 6-year study with life table analysis

PURPOSE

The outcome of endoluminal repair of abdominal aortic aneurysms with two generations of prostheses was analyzed and compared.

METHODS

Between May 1992 and December 1998, 266 patients underwent elective endoluminal repair of an AAA. First-generation prostheses were used in 118 patients (group I), and second-generation prostheses were used in 148 patients (group II). The two groups were similar in age, sex, and size of AAA. The proportion of patients with comorbidities was higher in group I than in group II, but not significantly. First-generation devices were characterized by large (24F internal diameter) delivery systems, one-piece construction, and a lack of metallic support throughout their length. Second-generation devices had smaller (21F or smaller internal diameter) delivery systems, modular construction, and a metallic frame throughout the length of the prostheses. The major end-point criteria were survival and successful endoluminal repair. Success was defined as the exclusion of the aneurysm sac from the circulation, with stability or the reduction in AAA maximum transverse diameter. Persistent endoleaks were classified as failures, irrespective of whether they were subsequently corrected by means of secondary endovascular intervention. The minimum follow-up period was 5 months for each of the 266 patients. Analysis was performed by means of the life-table method.

RESULTS

Perioperative mortality was not significantly different between group I (4.2%) and group II (2.7%). There was a statistically significant difference between the survival curves of the two generations, which favored group II (P =.012). There was a significant (P <.001) difference between the two generations of patients in their conditional probability of graft failure when the competing risk of all-cause mortality was considered. Second-generation patients were at a lower risk of graft failure than first-generation patients. The probability of failure, expressed as a proportion of grafts failing at 2 years, was 0.15 for patients with second-generation prostheses and 0.33 for patients with first-generation prostheses.

CONCLUSION

Endoluminal AAA repair is a safe procedure, whether first- or second-generation prostheses are used. Survival and probability of graft success were significantly higher with second-generation prostheses than with first-generation prostheses. This improvement in outcome resulted from a combination of increasing clinical experience and advances in technology. A more accurate evaluation of the role of the endoluminal method in AAA repair would be achieved by studying patients in whom second-generation devices were used, rather than longer term studies in which first- and second-generation devices were used.

Utility and reliability of endovascular aortouniiliac with femorofemoral crossover graft for aortoiliac aneurysmal disease

OBJECTIVE

The purpose of this study was to determine the early efficacy of endovascular aortouniiliac stent grafts with femorofemoral bypass graft in the treatment of aortoiliac aneurysmal disease.

METHODS

We analyzed 51 consecutive patients from January 1997 to March 1999 with a mean follow-up of 15.8 months. Patients ranged in age from 44 to 93 years (mean, 75 years) with a mean aortic aneurysm diameter of 6.2 cm. Technical success was achieved in 50 patients; one patient required conversion to open repair intraoperatively. We placed 28 custom-made and 22 commercial devices. The mean operative time was 223 minutes. The endograft was extended to the external iliac artery in 42% of cases. The contralateral common iliac artery was occluded using either a closed covered stent or intraluminal coils.

RESULTS

The median hospital stay was 4 days with an average intensive care unit stay of 0.25 days. There were no operative mortalities. Two patients died during follow-up from unrelated conditions. Endoleaks occurred in 11 patients (22%); seven patients (14%) required intervention (four catheter based, three operative). Other complications occurred in 38% of patients but were largely remote or wound related. One femorofemoral bypass graft occluded immediately postoperatively as a result of an intraprocedural external iliac dissection yielding a 98% primary patency and 100% secondary patency. Clinical success was achieved in 88% of patients.

CONCLUSIONS

These data suggest that this strategy represents a reliable method of repair of aortoiliac aneurysmal disease and extends the capability of an endoluminal approach to patients with complex iliac anatomy.

Early complications and endoleaks after endovascular abdominal aortic aneurysm repair: report of a multicenter study

OBJECTIVE

The aim of this study was the identification of risk factors for adverse events and the assessment of the early success rate in 1554 patients with abdominal aortic aneurysms (AAAs) who underwent treatment with endovascular technique between January 1994 and March 1999. For this purpose, the clinical and procedural data were correlated with observed complications and endoleaks.

METHODS

The data were collected from 56 European centers and submitted to a central registry. Patient characteristics, aortoiliac anatomic features, operative technical details, types of devices used, and experience of the teams of physicians were correlated with the occurrence of complications and endoleaks. The technical success rate was assessed according to the Society for Vascular Surgery/International Society for Cardiovascular Surgery, North American Chapter, guidelines. For the assessment of correlations between risk factors and adverse events, a multivariate logistic regression analysis was used.

RESULTS

The operative complications were grouped into three categories: failure to complete the procedure (39 patients, of which 27 underwent a conversion to an open AAA repair; 2.5%); device-related or procedure-related complications (149 patients; 10%); and arterial complications (51 patients; 3%). The most important risk factors for failure to complete the procedure included an aneurysm diameter of 60 mm or more and the need for adjuvant procedures. The factors that predicted device-related and arterial complications were the experience of the team with endovascular AAA treatment and the need for adjuvant procedures. Forty patients (2.6%) died within 30 days after operation. American Society of Anesthesiologists III and IV operative risk classification results predicted higher mortality rates than did American Society of Anesthesiologists operative risk classification I and II results. The patients who underwent operation in 1994, the first year documented in this registry, and those who required adjuvant procedures also had an increased risk of perioperative death. The incidence rate of systemic complications within the first 30 days (279 patients; 18%) was higher in patients aged 75 years or more, in patients with an impaired cardiac status, and in patients considered unfit for an open procedure. An endoleak was detected at the completion of the procedure in 16% of the cases and was still present after 1 month in 9%. The risk factors for primary endoleaks were female gender and age of 75 years and older. The observed technical success rate in this patient series was 72%.

CONCLUSION

The learning curve of the doctors and the need for adjuvant procedures were independent risk factors of operative device-related and arterial complications. The importance of proper instruction during an institution's initial phase with this treatment is emphasized by these observations. Although the endovascular management of AAAs is less stressful than open surgery, systemic complications were still the most common adverse events during the first postoperative month. These complications were associated with several patient-related factors, including advanced age, impaired cardiac status, and poor general medical condition. These observations may be a guide for improved patient selection for endovascular AAA repair.

Endovascular treatment of abdominal aortic aneurysms in Norway: the first 100 patients

OBJECTIVES

to present the first 100 consecutive endograft implantations for abdominal aortic aneurysms (AAAs) in Norway.

DESIGN

retrospective study of 100 consecutive graft implantations, performed at five University Hospitals during 1995 to 1997.

MATERIAL

one hundred patients with a median age of 70 years were included. In all patients the Vanguard modular system (Boston Scientific Corp.) was used. Ninety-four of the 100 patients were treated under regional anaesthesia. A completion angiography was done to evaluate the position of the graft and whether endoleaks were present.

RESULTS

two patients died within 30 days, one due to cardiac insufficiency and another due to haemorrhage during the procedure. There were four early conversions to open repair. At discharge eight patients had an endoleak, while retrograde flow into the aneurysmal sac was observed in four patients. During the follow-up period one conversion to open repair became necessary due to graft migration. Four late leaks were all repaired successfully using endovascular techniques. Five cases of retrograde filling were detected and embolisation with coils was performed in two cases, while three were observed. Seven graft-limb occlusions occurred during the follow-up period and four of these required treatment.

CONCLUSIONS

endovascular AAA repair should be regarded as an experimental treatment, although the short term results are promising. Close follow-up of patients with CT scans or arteriography is necessary.

Standard and new treatments for abdominal aortic aneurysms: the value of the Montefiore endovascular grafts for difficult aneurysms

The mortality rate following rupture of an abdominal aortic aneurysm (AAA) is 80-90% and the main goal of treatment is to prevent rupture. Treatment of the aneurysm is generally recommended for patients with an aneurysm larger than 5 cm in diameter, and the only effective treatment has been to replace the aneurysm with a prosthetic graft. Traditionally, this is performed through a major laparotomy; that is, open surgical repair, which itself carries a mortality rate of 4-8% and requires a hospital stay of 7-10 days. In addition, some sick patients are deemed a prohibitive risk for such major surgery and, therefore, treatment may be deferred. Endovascular grafts (EVGs) that enable treatment of patients with AAA without the need for laparotomy were developed in the hope of improving on the shortcomings of the standard repair technique. In addition to the various industry-made EVGs the authors have been using a surgeon-made Montefiore Endovascular Grafting System (MEGS). The recent introduction of several industry-made devices has prompted some to postulate that MEGS is no longer required. The 60 patients with AAA treated from 1 July 1997 to 30 June 1998 were evaluated for the inclusion criteria for industry-made EVG protocols. Those excluded from these protocols were evaluated for the MEGS. Open surgical repair was reserved for those unsuitable for any EVG repair or those not consenting to EVG repair. Thirty-seven percent of all cases could be treated with an industry-made device. By using the MEGS, an additional 43% of the cases could be treated endovascularly. In total, 80% of AAAs were able to be treated endovascularly. The reasons for excluding patients from industry-made devices were a combination of the following factors: (1) Short (<1.5 cm) or angulated (>60) proximal necks, (2) iliac artery aneurysms, (3) small, diseased or tortuous access arteries, and (4) small distal aortas. The mean length of stay for those treated endovascularly was 2.3 days, whereas it was 9 days for those treated by open surgery. There was no difference in the morbidity and mortality rates. EVG repair is feasible and safe for the majority of patients with AAAs; however, long-term durability is yet to be shown. Despite the availability of industry-made devices, there appears to be a continuing role for MEGS, especially for difficult aneurysms including those patients with complex anatomy and those with ruptured AAAs.

Endovascular repair of abdominal aortic aneurysms: where do we stand?

Endovascular repair of abdominal aortic aneurysms has evolved dramatically within the past few years. In light of the potential to reduce morbidity and mortality associated with open surgical repair, endoluminal grafting offers therapeutic options to patients who are not surgical candidates because of comorbidities. With the development of bifurcated devices, more complex aneurysms may be treated by endovascular grafting. Although successful placement of endovascular grafts requires a pronounced learning curve, including appropriate patient selection, midterm results seem consistent with those of traditional open repair of aneurysms. This review describes the current indications, minimal requirements, different devices and associated techniques, and potential complications of endoluminal repair of abdominal aortic aneurysms. Future aspects of endoluminal grafting are also discussed.

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.

Mid-term results of a second generation bifurcated endovascular graft for abdominal aortic aneurysm repair: the French Vanguard trial

PURPOSE

The purpose of this study was to evaluate prospectively the results of the bifurcated Vanguard endovascular graft for abdominal aortic aneurysm (AAA) repair.

METHODS

Seventy-five patients, with a median age of 69.6 years (range, 48 to 88 years) and asymptomatic AAAs, were recruited in 14 French vascular institutions. An independent committee validated the indications for endovascular repair, and all the implantations were supervised by a well-trained medico-technical assistant. Further independent committees reviewed patient data, clinical data, and imaging follow-up examination. The main endpoints were implantation success, mortality, morbidity, reinterventions, and aneurysm evolution assessed with serial computed tomographic (CT) scanning.

RESULTS

All the grafts were successfully implanted, resulting in a 100% success rate on an intent-to-treat basis. At discharge, there were no deaths, six significant local complications (8%) that necessitated surgery, no vascular complications, and six systemic complications (8%). The average durations of intensive care unit and hospital stays were 26 +/- 6 hours and 6 +/- 2.54 days, respectively. Predischarge CT scan results showed five type I and 18 type II endoleaks (total, 30%). At the end of the follow-up period (mean duration, 18.35 +/- 4.12 months; range, 17 days to 24 months), seven patients (9%) had died: one from sepsis, five from unrelated causes, and one from aneurysm rupture. The 2-year cumulative survival rate was 86% +/- 5.9%. Twenty-one subsequent endovascular or vascular procedures were necessitated (28%) in 17 patients (23%) to treat graft limb occlusion or stenosis (n = 9 patients) or to seal an endoleak (n = 8 patients). The 2-year cumulative survival rate free of reintervention was 67% +/- 7%. On CT scans, the mean AAA diameter decreased from 54 mm +/- 8.9 (range, 45 to 80 mm) before surgery to 51.6 mm +/- 9.1 at 6 months and to 43.4 mm +/- 4.4 at the end of the follow-up period (P =.001). Persistent endoleak was significantly associated with an increase in diameter (4 of 5 [80%] vs 1 of 47 [2%]; P =.001).

CONCLUSION

In selected patients, the bifurcated Vanguard endovascular graft may be implanted with a low mortality and morbidity rate and a favorable mid-term survival rate. The decrease of the aneurysm size is a strong argument in favor of the efficiency of the device. However, lasting endoleaks with increased aneurysm diameter and occurrence of limb graft stenosis or occlusion raise concerns and justify a careful long-term follow-up monitoring of all patients who undergo treatment with endovascular technique.

Realistic expectations for patients with stent-graft treatment of abdominal aortic aneurysms. Results of a European multicentre registry

OBJECTIVE

the outcomes for patients after endovascular treatment of abdominal aortic aneurysm (AAA) are determined primarily by the endpoints of death and endoleaks, the latter representing continued risk of rupture. The data of a multicentre registry were analysed with regard to the early outcome of stent-graft procedures for AAA and the complications associated with this treatment. In addition, the results during follow-up were analysed by determining mortality and endoleak development as separate endpoints and as a combined endpoint defined as endoleak-free survival.

SETTING

38 European institutions of Vascular Surgery collaborating in a multicentre registry project.

PATIENTS AND METHODS

899 patients with AAA underwent between May 1994 and March 1998 elective endovascular repair (818 men and 81 women; mean age 69 years). 80 (8.9%) of the patients had medical conditions that excluded them from open repair. 818 (91%) of patients had a bifurcated device, 63 (7%) had a straight tube graft, and only 18 (2%) had an aorto-uni-iliac device. Clinical examination and contrast-enhanced computed tomography was performed at fixed follow-up intervals to assess increase or decrease of the maximum transverse diameter (MTD). Endoleaks observed at follow-up were discriminated into persistent endoleak and temporary endoleak. The latter is defined as single time observed endoleaks or with two or more negative imaging studies between observed endoleaks. Life-table analyses were used to calculate the rates of freedom-from-endoleak (no endoleak at any time), freedom-from-persistent endoleak (no persistent endoleak), patient survival, and persistent-endoleak-free-survival.

RESULTS

the median follow-up of this patient series was 6.2 months. The ratio between observed and expected follow-up data was 82% for the overall follow-up period. However, at 18 months of follow-up this rate was only 45%. The number of patients followed during this period was sufficient to allow statistically meaningful assessment. The MTD in patients with temporary endoleaks demonstrated a significant decrease at 6 to 12 months compared to preoperative values (mean 57 and 53 respectively, p =0.004). In patients with persistent endoleaks there was no change between the preoperative and 6-month MTD (mean 57 and 60 mm respectively). At 6 and 18 months freedom-from-endoleak was 83% and 74% and freedom-from-persistent endoleak was 93% and 90%, respectively. The 18-month cumulative patient survival was 88% and the main outcome measure, the persistent endoleak-free-survival was 79%.

CONCLUSIONS

the MTD decreases in patients with temporary endoleak, but not in patients with persistent endoleak. Therefore, the use of the rate of freedom-from-persistent endoleak, reflecting absence of persisting endoleaks to estimate the prognosis with regard to the AAA, is justified. Determining persistent endoleak-free survival appears a rational approach to provide a realistic outlook for patients with stent-grafted AAA. The observed 18-month endoleak-free survival reflects a satisfactory mid-term result.

Abdominal Aortic Aneurysms

The mortality rate after the rupture of an abdominal aortic aneurysm is 80% to 90%; therefore, the main goal of treatment is to prevent rupture. Patients with abdominal aortic aneurysms smaller than 5 cm in diameter should be managed conservatively under close surveillance with either computed tomography or sonography every 3 to 12 months. Patients should be informed that most aneurysms continue to enlarge at an average rate of 2 to 4 mm per year and that there is a 1% to 5% annual risk for sudden rupture. Treatment of the aneurysm is generally recommended if it is larger than 5 cm in diameter, and the only effective treatment is replacement of the aneurysm with a prosthetic graft. This can be performed through a laparotomy or a groin incision using an endovascular graft. Open surgical repair carries a mortality rate of 2% to 8% and requires a hospital stay of 7 to 10 days. Patients receiving endovascular grafts can be discharged within 1 to 3 days. Long-term durability has yet to be proven, however.