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

Identifying and addressing the limitations of EVAR technology

INTRODUCTION

Endovascular aortic repair (EVAR) has improved over the last two decades. Approximately 80% of the patients presenting with an abdominal aortic aneurysm (AAA) is nowadays primarily treated with EVAR.

AREAS COVERED

In this review, the differences between endovascular and open repair, the clinical characteristics needed for EVAR, the role of clinical imaging and the developments in EVAR technology will be discussed. Early mortality is lower in EVAR as compared to open repair, whereas this benefit is lost after 3 years postoperatively. EVAR comes with a high reintervention rate, with endoleak being the most important predictive factor for reintervention. Expanding technical possibilities have allowed surgeons to choose from a palate of endovascular approaches in aneurysm patients with challenging anatomies.

EXPERT COMMENTARY

Although EVAR has taken a giant leap forward in development, the new developments have seemed to surpass the long-term limitations with older devices. It is important to start focusing on the current limitations of EVAR, in particular the durability of devices in the human variable anatomic and dynamic environment.

A Custom-Made Treovance® Abdominal Aortic Aneurysm Endograft to Correct Late Failure of Trombone Technique with a Tube Endograft

BACKGROUND

Unfavorable anatomy is one of the major limitations of endovascular aortic aneurysm repair (EVAR) with specifically adverse proximal neck morphology excluding many patients from receiving the standard endograft devices. Thoracic tube endografts have been used to overcome the issue of wide infrarenal necks, either as a sole device (single tubes or double tubes using the trombone technique) or as the proximal part of a bifurcated device fixed to the aortic bifurcation or infrarenally oriented. However, custom-made large proximal diameter bifurcated endograft designs have never been used.

METHODS

We present the case of a 56-year-old man with Marfan syndrome, suffering abdominal aortic aneurysm (AAA) enlargement from a type Ib endoleak after previous EVAR with 2 Endofit tube endografts (trombone technique). He was considered unfit for open surgery while possible alternatives such as fenestrated endovascular AAA repair and chimney technique were excluded.

RESULTS

The patient was treated with a custom-made 44-mm proximal diameter, bifurcated Bolton Medical Treovance device with technical and clinical success. No immediate or perioperative complications were noted. Follow-up after 6 months showed graft patency and no endoleak of any type.

CONCLUSIONS

This alternative technique for hostile proximal neck management is promising and needs long-term follow-up; an issue which is discussed within the broader context of custom-made device regulations.

Trends in endovascular aneurysm repair research: bibliometric analysis from 1994 to 2017

Purpose

Since endovascular aneurysm repair (EVAR) was first introduced in 1991, it has undergone rapid technical and quantitative developments. We analyzed the characteristics and trends of EVAR research through bibliometric analysis.

Methods

Comprehensive online searches focused on EVAR were performed from January 1994 to August 2017. The following information was collected: title, year of publication, countries' contribution, authorship, subspecialty, institution, subject category, and top 10 cited articles.

Results

A significant increase was demonstrated globally in the number of annual publications on EVAR. The highest number of publications was from the United States (n = 849, 35.08%), followed by England (n = 343, 14.17%), and the institutions with highest number of publications were Stanford University (n = 61, 2.52%) and Skane University Hospital Malmo (n = 45, 1.86%). The Journal of Vascular Surgery published approximately one quarter of the total publications. Vascular surgeons produced the most publications (n = 1871, 78.14%), followed by radiologists (n = 377, 15.58%) and cardiologists (n = 73, 3.02%). The most studied topics on EVAR were complications and procedures. The number of publications on complex EVAR and EVAR in juxtarenal aneurysm has increased more from 2013 to 2017 (5.1%, 9.5%) compared with from 1998 to 2002 (2.1%, 1.8%).

Conclusion

Our bibliometric analysis showed the characteristics and trends of publications on EVAR over a period of 25 years. The results of the bibliometric analysis revealed the quantitative improvements of publications and the qualitative improvements in challenging EVAR.

Endovascular therapeutic options for the treatment of aortoiliac aneurysms

About 20% of patients with abdominal aortic aneurysms have associated iliac aneurysms. Distal sealing during the endovascular treatment of aortic-iliac aneurysms is a challenge that has led to the emergence of several technical options to achieve this goal over the years. Internal iliac artery embolization is associated with the risk of ischemic complications, such as gluteal necrosis, lower limb neurological deficit, colonic ischemia, impotence and gluteal claudication. This article summarizes the technical options for endovascular treatment of aortoiliac aneurysms with different approaches to preserving the patency of internal iliac arteries.

Combined Surgical and Endovascular Removal of Thrombus Entirely Occluding a Bifurcated Aortic Stent-Graft

Purpose:

To explore a method combining interventional, endovascular, and conventional surgical techniques for treating a completely occluded bifurcated stent-graft after endovascular aortic aneurysm repair.

Methods and Results:

A 60-year-old patient underwent endovascular repair of an abdominal aortic aneurysm (AAA) with a Talent bifurcated stent-graft. Five months later, after chronic thrombotic occlusion of the right iliac limb, he presented with acute occlusion of the entire stent-graft. Local intra-arterial infiltration thrombolysis successfully reconstituted flow through the main aortic segment and left iliac limb. With a combination of conventional surgical and intraoperative endovascular procedures, thrombectomy and recanalization of the right iliac limb was completed by stenting a severe stenosis of the proximal iliac limb.

Conclusions:

A combination of techniques may be essential for successful management of thrombotic complications after endovascular AAA repair.

Retrograde Fenestration of Endoluminal Grafts from Target Vessels: Feasibility, Technique, and Potential Usage

Purpose:

To report initial experiments involving a new method for percutaneous intraprocedural stent-graft fenestration from the target vessel.

Technique:

In bench and canine models, the fabric of an implanted Zenith endograft was punctured easily using the stiff end of a coronary 0.014-inch guidewire delivered through the target vessel (e.g., renal or iliac artery). A 20-G cutting needle was passed over the coronary wire to enlarge the puncture site, followed by a cutting balloon to create a fenestration that was of sufficient size to allow deployment of a stent.

Conclusions:

In vivo endograft fenestration of a Zenith endograft is feasible. In addition to providing a percutaneous means of intentionally fenestrating a stent-graft from the artery to be perfused, the technique has potential application as a bailout maneuver after inadvertent side branch occlusion. Although the time to achieve successful fenestration in the experimental model was long, refinement may achieve performance times adequate to maintain viability of the end organ.

European Experience with a System for Bifurcated Stent-Graft Insertion

Purpose:

To test an endovascular aneurysm exclusion system in the presence of a wide range of challenging anatomic features.

Methods:

Bifurcated endovascular stent-grafts were inserted in 52 patients and followed with serial computed tomography for up to 3 years. The device underwent several modifications during this time, the most significant of which represent the difference between the homemade (n = 42) and industry-made (n = 10) versions.

Results:

The initial procedural success rate was 92% in the homemade group and 100% in the industry-made group. In the 3 years of follow-up, the long-term success rate was 64% in the homemade group and 90% in the industry-made group. The primary reasons for failure in the homemade group were graft thrombosis due to kinking early in the series and proximal stent migration later in our experience. All cases of migration occurred when the neck was < 15 mm in length, the neck was lined with thrombus, or the stent was implanted > 15 mm from the renal arteries. Kinking was subsequently overcome by implanting Wallstents throughout the graft limbs. The sole failure in the industry-made group was a case in which collateral perfusion reached the aneurysm through patent lumbar arteries.

Conclusions:

The fruits of this experience are a better technique, a better device, and, most importantly, a better understanding of the system's limits, as reflected in the current selection criteria.

The Need for Clinical Trials of Endovascular Abdominal Aortic Aneurysm Stent-Graft Repair: The EUROSTAR Project

EUROSTAR(EUROpean collaborators on Stent-graft Techniques for abdominal aortic Aneurysm Repair) was established for the purpose of combining and studying data on endovascular abdominal aortic aneurysm (AAA) repair. EUROSTAR is independent of any commercial interest and has as its ultimate goal an independent, scientifically reliable assessment of endovascular AAA grafting. A standardized case record form is used for data collection and transmission, and the database is maintained in a central registry office. A comprehensive set of clinical, imaging, technical, and laboratory data obtained at initial admission and follow-up are recorded; these data are analyzed periodically and reports generated on the collated experience.

As a first priority, an observational study without controls was initiated in July 1996 to address the issues of procedural safety, device durability, and long-term effect upon the aneurysms. Several ancillary studies have been initiated, including a “Retrieval and Analysis Study” for the evaluation of explanted devices. While a randomized study does not seem feasible at present, this may be organized at the appropriate time when the devices and techniques become more standardized.

Torsion and Kinking of Unsupported Aortic Endografts: Treatment by Endovascular Intervention

Purpose:

To describe the management strategies used to deal with twisted aortic endografts.

Methods and Results:

Two patients with successfully excluded aortic aneurysms developed symptoms referable to previously undetected twists in their endografts (one EndoVascular Technologies [EVT] and one customized aortomonoiliac device). The limb graft occlusion in the EVT graft was treated surgically with a femorofemoral bypass, but the aortomonoiliac endograft was salvaged with percutaneous implantation of a Wallstent. During another aortomonoiliac procedure, suboptimal flow through the endograft was traced to contortion of the endograft as it passed over an angulated proximal aneurysm neck. An X-large Palmaz stent was deployed to support the graft at this point.

Conclusions:

Unsupported aortic endografts may develop twists and kinks during deployment that can lead to low outflow and graft occlusion. Endovascular techniques are available to repair these defects postoperatively, although more precise intraoperative assessment tools may identify these problems so that they can be corrected at the initial intervention.

A Method for Adjusting a Malpositioned Bifurcated Aortic Endograft

Purpose:

To report the successful application of a method to adjust a malpositioned bifurcated stent-graft after endovascular aortic aneurysm repair.

Method and Results:

A 62-year-old male patient underwent endovascular repair of a 5.1-cm abdominal aortic aneurysm (AAA) with a Vanguard bifurcated stent-graft. After complete deployment of the stent-graft, the intraoperative completion angiogram disclosed unexpected occlusion of the left renal artery. Intra-aortic adjustment of the bifurcated graft was possible with a crossover guidewire, which was pulled caudally. The method worked perfectly to restore blood flow to the left renal artery. The patient is well 16 months postoperatively without any evidence of endoleak or graft migration; the left renal artery remains open.

Conclusions:

A technique is demonstrated for intra-aortic repositioning of a bifurcated stent-graft to correct insufficient deployment. If required, this technique should be attempted before conversion to an open procedure.

An Experimental Model for the Acute and Chronic Evaluation of Intra-Aneurysmal Pressure

Purpose:

To develop an animal model for the acute and chronic monitoring of pressure within abdominal aortic aneurysms (AAAs) to be treated with endovascular grafts.

Methods:

A strain-gauge pressure transducer was placed within an AAA created from a prosthetic vascular graft. Prosthetic aneurysms were implanted into 17 canine infrarenal aortas. The intra-aneurysmal pressure was monitored and correlated with noninvasive forelimb sphygmomanometry for 2 weeks. After this time, an intravascular manometer catheter was passed into the aneurysm. Simultaneous pressure measurements were obtained using the implanted strain-gauge pressure transducer, the manometer catheter, and the forelimb sphygmomanometer. Angiography was performed to assess intraluminal morphology, aneurysm anastomoses, and adjoining aortic vessels. In addition, two control animals underwent intra-aneurysmal pressure monitoring after standard surgical aneurysm repair.

Results:

There was excellent correlation (r = 0.97) between the pressure measurements obtained with the implanted strain-gauge pressure transducer and the intravascular manometer. Close correlation was also observed between the implanted strain-gauge transducer and the forelimb sphygmomanometer (r = 0.88) during postprocedural monitoring. Intra-aneurysmal pressure was lowered dramatically by surgical exclusion (aneurysm: 15/5 ± 7/4 mmHg; systemic: 124/66 ± 34/17 mmHg; p < 0.001). The prosthetic aneurysms were successfully imaged with angiography.

Conclusions:

This animal model provides an accurate and reproducible means for measuring intra-aneurysmal pressure on an acute and chronic basis. It may be possible to use this model in the assessment of endovascular devices to determine their efficacy in reducing intra-aneurysmal pressure. Evaluation of complications associated with their use, such as patent aneurysm side branches, perigraft channels, and perianastomotic reflux, may also be possible.

Changes in Referral Practice, Workload, and Operative Mortality after Establishment of an Endovascular Abdominal Aortic Aneurysm Program

Purpose:

To determine the change in referral practice following establishment of an endovascular abdominal aortic aneurysm (AAA) program.

Methods:

A prospective audit of all elective admissions for AAA was established in January 1994 at the initiation of an endovascular AAA program. A comparison was made between this cohort and the elective AAA repairs performed between 1981 and 1993.

Results:

Since January 1994, 213 AAA patients (177 men; median age 73 years, range 54 to 88) have been referred for potential endovascular aneurysm repair. To date, 142 patients have undergone elective surgery (41 endovascular and 101 conventional). Between 1981 and 1993, 304 patients (255 men; median age 69 years, range 45 to 86) had elective aneurysm repair. Comparison of the two time periods has revealed significant increases in the number of tertiary referrals (41.8% versus 9.5%, p < 0.01), annual operations (50 versus 23, p < 0.05), and overall mortality (12% versus 6.7%, p < 0.05), the latter attended by a significant increase in cardiorespiratory comorbidity.

Conclusions:

The higher elective AAA mortality rate since the establishment of an endovascular program reflects a change in referral practice and may be directly attributable to an increase in the number of high-risk patients. An endovascular AAA program has clinical and financial implications for the hospital concerned.

Dilatation of the Infrarenal Aneurysm Neck after Endovascular Exclusion of Abdominal Aortic Aneurysm

Purpose:

To determine the fate of the infrarenal aneurysm neck and suprarenal aorta after endovascular exclusion of abdominal aortic aneurysms (AAAs).

Methods:

Thirty-four patients underwent endovascular AAA repair between January 1994 and December 1995 using custom-made stent-grafts constructed from polyester graft material and modified self-expanding Gianturco Z-stents sutured to the graft orifices. Thirty-one patients were available for follow-up. Pre- and postimplantation diameters were measured using spiral computed tomography in the infrarenal aneurysm neck and the suprarenal aorta at the level of the superior mesenteric artery (SMA).

Results:

The mean follow-up time was 25 months. There was a significant increase of the diameter of the infrarenal aneurysm neck (+ 1.65 mm, p = 0.002), but not in the aorta at the level of the SMA (+ 0.52 mm, p = 0.100). There was no difference in the change in diameter in the infrarenal neck in the group with a stent adjacent to the level of measurement (n = 20) compared with the group without an adjacent stent (n = 11, p = 0.790). There was no correlation between preimplantation size of the infrarenal neck and its diameter change (r = 0.14, p = 0.488). There was no correlation (r = 0.10, p = 0.603) or association (chi-square test, p = 0.211) between aortic diameter change at the level of the SMA and the infrarenal neck.

Conclusions:

This investigation shows a significant dilatation of the infrarenal aneurysm neck, but not in the suprarenal aorta, after endovascular AAA repair with this device. The clinical significance of these findings is unclear. Whether such a dilatation in the infrarenal aneurysm neck may affect the long-term attachment of stent-grafts remains to be shown in the future.

Endovascular grafts for abdominal aortic aneurysm

During the last two decades, endovascular technology has revolutionized the management of patients with abdominal aortic aneurysm (AAA). Today, endovascular aortic repair (EVAR) is the treatment of choice for the majority of patients with an AAA. Randomized controlled trials provide robust evidence for the indication of AAA repair and the rationale for the use of EVAR in selected patients. However, despite that, practice varies and several areas need further elucidation. Important future challenges and areas of research include the role of medical therapy in AAA, whether the indication for repair should be any different in women and in the elderly, and long-term follow-up of patients undergoing complex EVAR with adjuncts, both for elective treatment and for ruptured AAA. Continuous rapid technical and clinical development is to be expected. In this paper, we review the current practice and evidence of stenting in AAA.

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.

Conversion to open repair after endografting for abdominal aortic aneurysm: a review of causes, incidence, results, and surgical techniques of reconstruction

PURPOSE

To review the incidence, causes, and mortality rates of early and late conversion to open surgery after endovascular aneurysm repair (EVAR) of abdominal aortic aneurysm (AAA).

METHODS

A systematic search of the English-language literature from 2002 to 2009 was performed by interrogation of the PubMed, MEDLINE, and EMBASE databases. Studies were included if they: (1) had >100 patients treated with EVAR and (2) provided adequate data to calculate incidence and associated mortality rates. The search yielded 13 articles with sufficient data to analyze early conversion (12,236 patients, 178 conversions) and 15 articles with available data for late conversion (14,298 patients, 279 conversions).

RESULTS

The rate of early conversion among the 13 articles reviewed ranged from 0.8% to 5.9%; more recent studies carried lower rates of early conversion. Mortality rates of early conversion varied between 0% and 28.5%. Overall, there were 178 (1.5%) early conversions among the 12,236 AAAs treated with EVAR, with an average mortality of 12.4%. The rates of late conversion ranged from 0.4% to 22%. Of the 14,289 AAA patients undergoing endovascular repair, 279 (1.9%) required late conversion; the mortality rate was 10%.

CONCLUSION

Though the incidence is gradually declining, secondary interventions persist as the Achilles' heel of EVAR. A lifelong follow-up strategy for AAA patients treated with EVAR is essential for early detection and treatment of complications of the procedure. Vascular surgeons should be familiar with the complex open conversion procedures.

Endovascular management of iliac rupture during endovascular aneurysm repair

BACKGROUND

Inadequate iliac artery diameter, calcification, and tortuosity are associated with increased incidence of iliac injury during abdominal (EVAR) and thoracic endovascular aneurysm repair (TEVAR). Despite careful preoperative assessment and use of iliac conduits, inadvertent iliac rupture is a source of morbidity and mortality. This report details our single-center, 10-year experience with intraoperative iliac artery rupture and describes a successful endovascular salvage technique.

METHODS

All patients undergoing EVAR and TEVAR between August 1997 and June 2008 were reviewed. Computed tomography (CT) measurements of access vessels were obtained for all patients. The smallest diameter of the external or common iliac artery was used to determine suitability for access based on the instructions for use for each device. Patients who underwent repair of a procedure-related iliac artery rupture were identified. Outcomes among patients who did not have an access vessel rupture (nonruptured group) and those who did (ruptured group) were compared. Patency of the endovascular iliac repair is reported.

RESULTS

During the study period, 369 EVARs and 67 TEVARs were performed. Eleven iliac conduits were used, all during TEVAR (16%). There were 18 ruptured iliac arteries in 17 patients; 11 EVAR patients (2.98%) sustained iliac rupture vs six TEVAR patients (8.9%). One EVAR patient was converted to open repair. Seventeen ruptures in 16 patients were successfully treated with endovascular stent graft placement. Iliac rupture was more likely to occur during TEVAR (8.9%) than EVAR (2.98%; P = .0239, Fisher exact test). Significantly more women were in the ruptured group (76% vs 19%; P < .0001, Fisher exact test). Patients in the ruptured group had longer lengths of stay (7.6 vs 5.1 days; P = .0895, t test), no 30-day mortality, but a procedure-related mortality of 11.8%. In the nonrupture group, 30-day mortality was 6.6% (4 of 61) and 2.8% (10 of 358) for TEVAR and EVAR, respectively, and procedure-related mortality was 9.8% (6 of 61) and 3.1% (11 of 358). For endovascular repair of iliac rupture, primary and primary-assisted patency was 88.2% and 94.1%, respectively, with median follow-up of 40 months (range 10-115 months).

CONCLUSION

Iliac rupture during EVAR or TEVAR can be successfully managed with endovascular stent grafting. Higher mortality and length of stay associated with iliac artery rupture confirm that there is no substitute for prevention. Access vessels of all patients undergoing EVAR should be examined closely for suitability. The threshold for using an iliac conduit, especially in women undergoing TEVAR, should be low.

How to design the optimal stent graft--what have we learnt?

It is now more than 20 years since the first report of stent graft insertion in the human arterial system was published. The first "homemade" devices proved that the technique was possible but could not show any durability. Using these devices, it was possible to get a good seal but not a good anchorage. Not even the first generation of commercially available stent grafts proved to be durable. First after gaining knowledge about the forces acting on the stent graft, it was realized that attachment was important for the durability and the hooks and barbs or a longitudinal stability are needed to minimise the risk for distal migration. Not much of a difference in the overall performance is noticed between the ePTFE graft or the polyester graft or when comparing stainless steel stents with those made out of nitinol. The systems are made much more flexible and hydrophilic leading to a better performance and a greater chance of percutaneous approach. The optimal stent graft is not out on the market yet, but hopefully will come with further development.

Early Computed Tomographic Angiography after Endovascular Aneurysm Repair: Worthwhile or Worthless?

This study evaluated the value of computed tomographic angiography (CTA) early after an endovascular aneurysm repair (EVAR) in relation to CTA 3 months after EVAR. We retrospectively reviewed all elective EVAR patients with available postprocedural and 3-month follow-up CTAs who were treated between 1996 and 2006. CTAs were analyzed for EVAR-related complications in terms of endoleaks, migration, and stent graft thrombosis. Secondary procedures and other complications within a 4-month time interval after EVAR were noted and analyzed for any association with the postprocedural CTA. During the study period, 291 patients (275 men), with a mean age of 71 years, underwent elective EVAR. All had postprocedural and 3-month follow-up CTAs, which detected 93 (32%) endoleaks (8 type I, 84 type II, 1 type III) and 1 stent graft thrombosis. These findings resulted in four secondary interventions (one interposition cuff, two extension cuffs, one conversion). All reinterventions were successfully done in an elective setting. During the first 3 postoperative months, five other reinterventions were required for acute ischemia in four patients (three Fogarty procedures, one femorofemoral crossover bypass) or groin infection in one patient. Eight patients died, but none of the deaths were related to abdominal aortic aneurysm or EVAR (four cardiac, two pulmonary, one gastric bleeding, one carcinoma). At 3 months, 43 endoleaks (3 type I, 40 type II), 3 stent graft thromboses, and 1 stent graft migration were seen. In two patients (0.7%), a new endoleak was diagnosed compared with the postprocedural CTAs. In 287 (99%) of 291 patients, the postprocedural CTA did not influence our treatment policy in the first 3 months after EVAR. More than half of the early endoleaks were self-limiting, and new endoleaks were seen in only two patients (< 1%) at the 3-month follow-up CTA. After an uneventful EVAR procedure, it is safe to leave out the early postprocedural CTA.

The fate of infrarenal abdominal aortic aneurysms after stent grafting: influence of thrombosis at side branch ostia

PURPOSE

To evaluate the effect of postoperative thrombosis of the side branch ostia on the shrinkage of endoluminally treated abdominal aortic aneurysms with patent side branch vessels.

MATERIALS AND METHODS

Thirty-three patients were followed up with serial computed tomography (CT). Special attention was paid to presence or absence of retrograde enhancement of the side branch ostia after the covering of the patent side branch vessels by the stent graft and aneurysm diameter change on postoperative CT. Preoperative CT was also reviewed to assess the number of patent side branch vessels, degree of aneurysm wall calcification, and thickness of the mural thrombus. The patients with type 2 endoleak were excluded from this evaluation. The patients were divided into 2 groups, the nonthrombosed and thrombosed groups, based on presence or absence of retrograde enhancement of the side branch ostia as depicted on all postoperative CT.

RESULTS

Type 1 endoleak was not seen in all patients. Preoperative diameter of the aneurysm was 4.75 +/- 0.18 cm in the thrombosed group (n = 12) and 4.98 +/- 0.35 cm in the nonthrombosed group (n = 8). There were no significant differences in follow-up periods, preoperative diameter of the aneurysm, number of patent side branch vessels, degrees of aneurysm wall calcification, and thickness of the mural thrombus between the 2 groups. The mean diameter of the aneurysm in the nonthrombosed group did not change at 3 and 6 months then first decreased at 12 months after the stent grafting. However, in the thrombosed group, the mean diameter of the aneurysm had decreased at 3 months after stent grafting. Thereafter, the aneurysms continuously shrank.

CONCLUSIONS

Postoperative thrombosis of the side branch ostia may predict favorable shrinkage of endoluminally treated aneurysms.

Renal transplantation after endovascular repair of abdominal aortic aneurysm

An increasing number of abdominal aortic aneurysms (AAA) occur in renal failure patients because of strong association between atherosclerosis and chronic kidney disease. Endovascular aneurysm repair (EVAR) has proven to be an effective modality to treat AAA, particularly in patients with renal disease, because of its several advantages over the standard open procedure, including lower morbidity, shorter operative time, and shorter hospital stay. A Medline search showed a single publication on renal transplantation (RT) following EVAR of AAA. In this context, we report our case of successful RT in a patient who had undergone EVAR 2 years prior for a 5.7-cm AAA. No stent-related complications, such as graft occlusion, dislodgement, dissection, or endoleak, were observed in the perioperative period. The transplanted kidney had primary function leading to a stable serum creatinine of 115 micromol/L at 6 months. Although the long-term outcome of RT after endovascular repair of AAA remains unknown, currently available evidence shows favorable outcomes of EVAR in the normal population, in patients with renal diseases, and in RT recipients; hence, RT should not be denied to renal failure patients who have undergone EVAR in the past.

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.

Complications of Endovascular Repair of Abdominal Aortic Aneurysms: A Review

The endovascular procedure for repair of abdominal aortic aneurysms has had an enormous impact on the treatment of this challenging disease. Complications, however, do occur and it is important to have a thorough understanding of the array of complications and appropriate management strategies. In this review of endovascular complications, we describe early and late complications paying particular attention to preventive, treatment and surveillance strategies.

Fate of Endoleaks Detected by CT Angiography and Missed by Color Duplex Ultrasound in Endovascular Grafts for Abdominal Aortic Aneurysms

PURPOSE

To analyze the clinical implications of endoleaks documented by computed tomographic angiography (CTA) and missed by color duplex ultrasound (CDU).

METHODS

During a recent 5-year period, 232 patients underwent endovascular aortic reconstruction (EVAR) and were followed according to a protocol that included CTA and CDU at 1 month and every 6 months thereafter. CTA was the gold standard for determining the presence of endoleaks. The size of the AAA sac at the latest postoperative follow-up was compared to the preoperative size and correlated to the type of endoleak and clinical outcome. This study analyzed only patients with endoleak documented by CTA and CDU and specifically analyzed the outcome of patients with false negative CDU studies for endoleaks.

RESULTS

Thirty-nine endoleaks were documented in 35 (15%) of 232 patients using CTA. Four patients had both early and late endoleaks. The mean follow-up was 25 months (range 1-64). CDU was more helpful in detecting type I endoleaks than type II endoleaks (89% versus 58%, p<0.05). There were 18 (46%) type I endoleaks (12 early, 6 late) detected by CTA; 16 (89%) of these were detected by CDU (2 late endoleaks missed). Nineteen (49%) type II endoleaks (16 early, 3 late) were diagnosed using CTA, 11 (58%) of which were detected by CDU (6 early and 2 late missed). Of the 2 (5%) early type IV endoleaks found on CTA, 1 (50%) was missed by CDU. Overall, CDU failed to identify endoleak in 11 (28%) of 39 endoleaks [2 late type I, 8 type II (6 early, 2 late), and 1 early type IV]. Consequences to treatment occurred in 2 (20%): 1 type I endoleak required treatment and 1 type II endoleak would have missed treatment.

CONCLUSION

CDU has a lower sensitivity in detecting endoleak, particularly type II; therefore, EVAR surveillance should not be based solely on CDU. Although a significant number of type II endoleaks resolved spontaneously, intervention can be offered for type II endoleaks if associated with an increasing sac size.

Technical feasibility and biocompatibility of a newly designed separating stent-graft in the normal canine aorta

OBJECTIVE

The objectives of this study were to assess the performance of a newly designed separating stent-graft system with respect to the technical feasibility of transfemoral deployment, the maintenance of vessel patency, and stent deformity due to mechanical defects; and to evaluate its in vivo healing characteristics, including thrombus formation, and endothelial covering of the stent-graft when placed in the normal aorta of a canine model.

CONCLUSION

The newly designed separating stent-graft allowed accurate deployment without migration. This animal study also provided an opportunity to examine the healing process associated with an ultrathin polyester fabric nitinol stent and showed predictable healing characteristics in the normal thoracic aorta in this canine model.

What Determines and Are the Consequences of Surveillance Intensity after Endovascular Abdominal Aortic Aneurysm Repair?

Follow-up examinations are advised 1, 3, 6, 12, 18, and 24 months and yearly thereafter by the European Collaborating Group on Stent-Graft Techniques for Abdominal Aortic Aneurysm Repair (EUROSTAR). The aim of this study was to evaluate the determinants and consequences of surveillance completeness. Patients who underwent endovascular abdominal aortic aneurysm repair between October 1996 and August 2004 and enrolled in the EUROSTAR registry were analyzed. Two groups were compared: patients who attended all scheduled visits (group A) and those who came infrequently (group B). Odds ratios and hazard rates (HRs) with 95% confidence intervals (CIs) were determined to detect which patient characteristics and complications were associated with follow-up intensity. Of the 4,433 patients, 1,538 (35%) attended all scheduled visits until the end of follow-up (group A). Analysis of patient characteristics demonstrated that intensive visitors were more often smokers, hyperlipemic, and considered unfit for open surgery or general anesthesia. Complications during follow-up, including endoleaks (24% vs. 20%), kinking (3.5% vs. 2.5%), and migration (4.9% vs. 3.5%), appeared significantly more frequently in group A. Despite intensive follow-up of this category, still a greater proportion died (12% vs. 9%, adjusted HR = 1.5, 95% CI 1.2-1.8). After 84 months of follow-up, the cumulative survival rates in groups A and B were 71% and 74%, respectively (p < 0.0001). It seems that follow-up intensity was based on baseline patient characteristics. High-risk patients had, despite more intensive surveillance, still more complications after adjustment for patient, morphological, and center-specific characteristics. Further assessment is indicated to evaluate the effectiveness of different frequencies of surveillance visits.

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.

Fabric tears as a new cause of type III endoleak with ancure endograft

PURPOSE

We present two case reports of type IIIb endoleak. One was due to fabric erosion caused by placement of a stent (Wallstent; W. L. Gore & Associates, Flagstaff, Ariz) after endovascular aneurysm repair; the other arose spontaneously. In both cases, an Ancure endograft (Guidant/EVT, Menlo Park, Calif) was placed.

CASE REPORTS

In case 1, a large endoleak developed 36 months after uncomplicated endovascular treatment of an abdominal aortic aneurysm. In case 2, endoleak developed 30 months after a complicated procedure. In both cases, two Wallstents were used to treat type I endoleak and limb kinking in the first postoperative months. One type III endoleak was within the endograft at the level of the stents.

CONCLUSION

To our knowledge, these are the first type III endoleaks reported in association with Ancure endografts. Placement of Wallstents inside endografts is of concern, and another indication for close monitoring during follow-up.

Color-flow duplex ultrasound scan versus computed tomographic scan in the surveillance of endovascular aneurysm repair

OBJECTIVE

The purpose of this study is to compare both computed tomographic scan (CT) and color flow duplex ultrasound scanning (CDU) as surveillance modalities for clinically significant endoleaks and to evaluate concordance in abdominal aortic aneurysm (AAA) diameter measurements in patients after endovascular aneurysm repair (EVAR) in a busy hospital vascular laboratory.

METHODS

We conducted a retrospective review of all patients who underwent endovascular repair of abdominal aortic aneurysms between February 1996 and November 2002 and had same-day CT and CDU studies. Ninety-seven patients enrolled in phase II clinical studies of Ancure devices had long-term follow-up with both modalities. The other patients underwent simultaneous studies, usually only at the 1-month postoperative visit. Peripheral vascular studies were performed by two certified vascular technicians; all CT scans were reviewed by one vascular surgeon. CT was used as the standard against which the sensitivity, specificity, negative predictive value, and positive predictive value of CDU in endoleak detection was determined. Statistics were performed by using the paired t test; a P value <.05 was considered significant. Kappa statistic was used to assess the correlation between CDU and CT in identifying endoleaks. The correlation between CT and CDU in AAA size measurements as well as in serial size measurements was also determined.

RESULTS

Four hundred ninety-five same-day CT and CDU examinations were reviewed in 281 patients. Patients had an average follow-up of 34.6 months (range, 1 to 72 months). Thirty-five leaks were identified among the patients studied (12.4% overall). In comparison with CT, diagnosis of endoleak with ultrasound scanning was associated with a sensitivity of 42.9%, specificity of 96.0%, positive predictive value of 53.9%, and negative predictive value of 93.9%. The correlation between the two modalities was modest (kappa statistic 0.427). The minor axis transverse diameter as measured by ultrasound and CT scans (4.81 +/- 1.1 cm on CT and 4.55 +/- 1.1 cm on ultrasound) correlated closely (r =.93, P <.001.) Seventy percent of paired studies differed by < or =5 mm. Changes in aneurysm size throughout follow-up were -.29 +/-.71 cm on CT scan -.34 +/-.57 cm on duplex ultrasound scan. The correlation coefficient was.65 (P <.001). There was no significant difference in the change as measured by either modality on the paired t test.

CONCLUSIONS

Although CDU demonstrates a high degree of correlation with CT scan in determining aneurysm size change over time, it has a low sensitivity and positive predictive value in endoleak detection. In the hospital vascular laboratory at a large tertiary care center, CDU cannot effectively replace CT scan in surveillance after EVAR.

Durability of femorofemoral bypass grafting after aortouniiliac endovascular aneurysm repair

INTRODUCTION

Endovascular aneurysm repair (EVAR) with aortouniiliac prostheses extends the morphologic range of aneurysms that can be treated and is potentially a more rapid and simple operation than bifurcated endovascular repair. It may, however, be limited by durability of the femorofemoral extra-anatomic bypass graft required to revascularize the contralateral lower limb. Previous studies of femorofemoral bypass grafts were performed almost exclusively in patients with occlusive disease. An 8-year single center experience with use of the femorofemoral bypass graft in aneurysmal disease is reported.

METHODS

All patients undergoing EVAR with an aortouniiliac endovascular stent graft over eight years (1994-2002) at a single institution were included in a retrospective study. Patient data were collected from a prospectively maintained local endovascular database. All patients gave informed consent and were part of an endovascular program approved by the local ethics committee.

RESULTS

Over the 8 years, 231 patients underwent EVAR with an aortouniiliac endovascular stent-graft. Median follow-up was 22 months. Localized wound complications were observed in 25 patients (11%). Cumulative 3-year patency rate for the femorofemoral bypass graft was 91%. At the end of 5 years 83% of grafts remained patent.

CONCLUSIONS

The femorofemoral bypass graft used during EVAR with aortouniliac stent grafts offers encouraging medium and long-term patency. When graft occlusion occurs, it is usually directly attributable to inadequate inflow from the endovascular stent graft itself or to endoluminal damage of the external iliac artery. Awareness and early detection of stent-graft distortion or complications in the external iliac artery may result in improved patency rates.

Detection of endoleaks after endovascular repair of abdominal aortic aneurysm: value of unenhanced and delayed helical CT acquisitions

PURPOSE

To assess unenhanced and delayed phase computed tomographic (CT) images combined with arterial phase images for detecting endoleaks after endovascular treatment for abdominal aortic aneurysm (AAA).

MATERIALS AND METHODS

CT scans were retrospectively evaluated for the presence of endoleaks after endovascular treatment of AAAs in 33 patients with endoleak (positive group) and 40 patients without evidence of endoleak or aneurysm enlargement (negative group). All patients underwent unenhanced and biphasic contrast material-enhanced CT. The CT scans were reviewed in the following combinations: (a) arterial phase and unenhanced scans (uniphasic/unenhanced set), (b) arterial and delayed phase scans only (biphasic set), and (c) arterial and delayed phase scans with unenhanced scans (complete set). Each set was reviewed by two radiologists blinded to the diagnosis of endoleak. Findings were recorded as positive, negative, or indeterminate for endoleak.

RESULTS

Within the positive group, endoleaks were diagnosed with the uniphasic/unenhanced, biphasic, and complete image sets in 30 (91%), 32 (97%), and 33 (100%) patients, respectively. With the uniphasic/unenhanced set, three (9%) endoleaks (seen only on delayed phase images) were missed. With the biphasic set, one (3%) endoleak was interpreted as indeterminate. Within the negative group, uniphasic/unenhanced, biphasic, and complete image sets were negative for endoleaks in 100%, 80%, and 100% of patients, respectively. With the biphasic set, results were indeterminate in 20% of cases.

CONCLUSION

A delayed CT acquisition enables detection of additional endoleaks, while an unenhanced acquisition helps eliminate indeterminate results. Thus, both acquisitions contribute to accurate diagnosis of endoleaks when combined with an arterial phase acquisition.

The Zenith aortic stent-graft: a 5-year single-center experience

PURPOSE

To evaluate the efficacy and midterm results of the Zenith stent-graft in the treatment of abdominal aortic aneurysms (AAA).

METHODS

Since March 1994, 364 patients have undergone endovascular repair of infrarenal AAA. Of the 94 who were treated with the Zenith stent-graft from 1996 to 2002, 88 patients (82 men; mean age 72.6 +/- 6.5 years, range 47-88) with at least 6-month follow-up were analyzed. Sixty-one (69.3%) patients were considered at high risk for intervention; 7 ruptured AAAs were treated emergently. In all, 68 (77.3%) bifurcated stent-grafts (including 18 TriFab systems) and 20 aortomonoiliac configurations were used. Cumulative data on endoleak, migration, secondary procedures, and survival were evaluated with Kaplan-Meier analyses.

RESULTS

Implantation success was 97.7%; 2 (2.3%) access-related failures were converted to open repair (1 immediate, 1 at 3 months). There were 3 (3.4%) graft limb thromboses (2 immediate, 1 late), 3 (3.4%) cases of colon ischemia due to embolization in 1 and hypogastric artery occlusion in 2, and 1 (1.1%) renal infarction due to embolism. Three (3.4%) patients died within 30 days. Eleven (12.5%) endoleaks and 1 (1.1%) late endograft migration were recorded. The 5-year cumulative endoleak and migration rates were 15% and 7%, respectively. Sixty-three (71.6%) patients did not present any complication related to the repair during a mean follow-up of 20.6 +/- 14.9 months (range 6-68); notably, no complications were associated with the 18 TriFab systems. Six (6.8%) secondary procedures were performed (31% 5-year cumulative secondary procedural rate). All 6 (6.8%) aneurysm-related deaths (the 3 perioperative, 2 from late AAA rupture, and 1 during a secondary procedure) and 14 of 18 (20.4%) non-aneurysm-related deaths occurred in high-risk patients; the 5-year cumulative survival rates were 57% for any death and 92% for aneurysm-related deaths.

CONCLUSIONS

The Zenith stent-graft appears both safe and effective in terms of midterm outcome of endovascular aortic aneurysm repair.

Initial results of endovascular repair of abdominal aortic aneurysms with a self-expanding stent-graft

PURPOSE

This study was performed to evaluate the authors' experience with the endovascular treatment of abdominal aortic aneurysm (AAA) with use of a self-expanding nitinol stent covered with a polyester fabric device and to report the implant's technical features, the immediate results, and the outcome 30 days after device implantation.

MATERIALS AND METHODS

From June 1997 to December 2001, we admitted 169 patients diagnosed with AAA. Of these, 134 were suitable to undergo endovascular repair with use of the Talent stent-graft. In one patient, it was technically impossible to proceed with the implantation procedure. Therefore, a total of 133 patients were treated with use of this technique (78.7%). The average age was 70.7 years (range, 52-88 y). There were 119 men and 14 women. Computed tomographic follow-up was done between the 15th and 30th postoperative days.

RESULTS

The stent-grafts were successfully implanted in all 133 patients. Complications during the procedure included three type-I endoleaks (2.3%) and four iliac artery ruptures (3.0%), which were effectively treated by means of aortic or iliac extension grafts, respectively. The average surgical time was 2.92 hours (from 1.67 h to 7 h). Of the stent-grafts used, 125 were bifurcated (94.0%), two were straight tube grafts (1.5%), and six were conical aortouniiliac grafts (4.5%). Custom-made grafts were used in 62 patients (46.6%) and standard grafts were used in 71 (53.4%). Suprarenal fixation was performed in 117 patients (88%). One female patient developed a serious pulmonary embolism. Eight patients (6.0%) developed serious systemic inflammatory syndrome; two died of disseminated intravascular coagulopathy. There were two additional deaths, one from refractory shock and one suddenly from an unknown cause (total mortality rate, 3.0%). During the postoperative period, 70.3% of the patients developed mild fever (37.6 degrees C-38.9 degrees C). The average length of stay in the intensive care unit was 1.3 days (ranging from 1 d to 12 d) and the total hospitalization time was 4.2 days. Six type-II endoleaks were observed: two were corrected by video laparoscopy-assisted inferior mesenteric artery interruption and the other four were clinically followed up.

CONCLUSIONS

The exclusion of AAA by endovascular techniques with use of the Talent device was possible in the majority of cases with a low incidence of complications. The most common serious postprocedural complication was systemic inflammatory syndrome.

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.

Intra-aneurysm sac pressure--the holy grail of endoluminal grafting of AAA

OBJECTIVES

To relate intra-aneurysm sac pressure during endoluminal AAA repair to early and late endoleak, as well as to the aneurysm size upon follow-up.

DESIGN

Prospective clinical investigation.

METHODS AND PATIENTS

In 46 patients who had their AAAs treated by a stent graft (group I), intra-operative pressure measurement was performed (aorta uni-iliac stent grafts: 25 cases, bifurcated stent grafts: 21 cases). In 18 patients with open repair (group II) flow in the inferior mesenteric artery, and the pressure in the aneurysm sac was measured, before and after aortic and iliac cross clamping. Values are given in median with range.

RESULTS

In group I, complete exclusion of AAA (no endoleak on intra-operative control angiogram) resulted in a statistically significant decrease in mean sac pressure from 74 (55-101) to 47 (4-104) mmHg. Pulse pressure reduced from 67 (34-103) to 8 (0-74) mmHg. In 11 patients a proximal type I endoleak was sealed by balloon modeling, after which the mean sac pressure reduced from 63 (14-91) to 52 (4-74) mmHg (n.s. versus patients with primary seal). Intra-operative pressure did not correlate with change in AAA diameter during twelve months follow-up. In group II, cross clamping of the proximal aorta significantly reduced mean sac pressure to 32 (21-55) mmHg, and the pulse pressure to 0 (0-13) mmHg (p < 0.05). Subsequent cross clamping of the iliac arteries did not significantly change the pressures.

CONCLUSIONS

Measurement of intra-aneurysm sac pressure can help to detect and treat endoleaks during endoluminal grafting. However, the intra-operative sac pressure did not predict the fate of aneurysm during follow up. Compared to open repair of AAA, the sac pressure after endoluminal grafting remains significantly higher, in relation to pulse pressure.

Ruptured abdominal aortic aneurysm after endovascular repair

OBJECTIVE

The purpose of this study was to present the experience with aneurysm rupture after deployment of Guidant/EVT (Guidant) endografts and review previously reported cases with other devices.

METHODS

Records from Guidant/EVT clinical trials and postmarket approval databases from February 1993 to August 2000 were analyzed to identify patients with rupture and to extract pertinent data. Previously reported cases were obtained with a Medline search.

RESULTS

Seven ruptures were found with Guidant/EVT devices. Five of these occurred among the 686 patients in US Food and Drug Administration protocols (group I) who were followed for a mean of 41.8 +/- 21.9 months and limited to the subgroup of 93 first generation tube endografts. Two ruptures occurred in group II (3260 patients after market approval with limited follow-up), specifically in the subgroup of 166 patients who underwent treatment with second generation tube grafts. No ruptures were found in patients with bifurcation or unilateral iliac implants followed for a mean of 37.5 months. All ruptures were caused by distal aortic type I endoleaks on the basis of attachment system fractures (first generation devices only), aortic neck dilatations, persistent primary endoleaks, migration, overlooked imaging abnormalities, refused reintervention, and poor patient selection. The mortality rate was 57% (4/7) overall and was 50% for surgical repair (3/6). A literature search identified 40 additional ruptures related to other devices, for a total of 47. All 44 that were documented with adequate data were caused by endoleaks (26 type I, 2 type II, 11 type III, and 5 source not reported). Other contributing factors were graft module separation and graft wall deterioration. The overall mortality rate for the combined series was 50%, with an operative mortality rate of 41%.

CONCLUSION

Postendograft AAA rupture is infrequent, although the true incidence rate is unclear because of inadequate follow-up of individual device designs. Tube endografts should be limited to the rare patient with ideal anatomy, no other alternatives, and at high risk for standard open repair. Prevention of aneurysm rupture requires long-term surveillance with attention to subtle imaging abnormalities and the establishment of reliable follow-up protocols for specific devices. The outcome of postendograft aneurysm rupture is similar to that of rupture without prior endograft therapy.

A multicenter experience with the Talent endovascular graft for the treatment of abdominal aortic aneurysms

OBJECTIVE

The Talent endovascular graft has been used in the treatment of abdominal aortic aneurysms (AAAs) in more than 13,000 patients worldwide. However, information regarding the results of its use has been limited. This report describes the experience with 368 patients with AAAs who underwent treatment at four medical centers as part of an investigator-sponsored investigational device exemption trial.

METHODS

Patients with AAAs were enrolled at four sites during a 32-month period from January 1999 to July 2001. All patients underwent treatment for infrarenal AAA with the Talent endovascular graft. Repair was performed with transrenal stent fixation under epidural (362/368 patients; 98.3%), local (4/368 patients; 1.1%), or general (2/368 patients; 0.5%) anesthesia. The average diameters were: maximum aortic aneurysm, 6.2 +/- 1.2 cm; proximal aortic fixation site, 2.6 +/- 0.4 cm; and distal iliac fixation site, 1.4 +/- 0.6 cm. Bifurcated grafts were used in 276 of 366 patients (75%), aortouniiliac in 57 of 366 patients (16%), and tube aortoaortic in 33 of 366 patients (9%). Multiple comorbid medical conditions were present in all patients (average, 4.7 conditions/patient). The mean age was 75.8 years, and 85% of the patients were male. Follow-up period ranged from 2 to 33 months (mean, 7.3 months).

RESULTS

Endovascular graft deployment was accomplished in 366 of 368 patients. In the 263 patients followed for at least 6 months after endovascular repair, AAA diameter decreased by 5 mm or more in 83 patients (32%); diameter remained unchanged (change < 5 mm) in 157 patients (60%) and increased by 5 mm or more in 23 patients (8.7%). Major morbidity occurred in 46 of 368 patients (12.5%), and minor morbidity occurred in 31 of 368 (8.4%). The 30-day mortality rate was 1.9%. Secondary procedures were performed in 32 patients (8.7%). Late rupture occurred in two patients, and late deaths unrelated to AAA occurred in 32 patients (8.7%) during the follow-up period. The primary technical success rate for all patients was 93.4%. The 30-day primary procedural success rate was 73.3%. The 30-day secondary procedural success rate was significantly higher at 85.8%. Computed tomographic scan was performed within 1 month after surgery in 349 patients. An endoleak was present in 43 of 349 patients (12.3%). These endoleaks were comprised of 10 attachment site (type I; 2.9%), 31 retrograde side-branch (type II; 8.9%), and two transgraft (type III; 0.6%).

CONCLUSION

These midterm findings show a high degree of technical and procedural success achieved in a patient population with extensive comorbid medical illnesses with low perioperative morbidity and mortality rates. Further follow-up study will be necessary to determine the effectiveness of the Talent endograft for the long-term treatment of AAA.

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.

Endovascular aneurysm repair: Magnetic resonance monitoring of histological organization processes in the excluded aneurysm

BACKGROUND

The purpose of the present study was to systematically analyze the histopathologic organization processes in excluded aneurysms after endovascular stenting and to develop a noninvasive monitoring method for these processes using MRI.

METHODS AND RESULTS

In 36 mongrel dogs, autologous aortic aneurysms were created. Endovascular treatment was performed using covered stents. Follow-up was after 1 week, 6 weeks, and 6 months. MRI was performed with T2-weighted turbo-spin-echo sequences and T1-weighted spin-echo sequences and was repeated after contrast bolus with gadolinium. Histopathologic findings were correlated to signal intensities (SIs) of MRI images. SIs of distinct areas were analyzed and related to the SI of the reference tissue (SI ratio). The histological organization process was gradated in the following 4 classes: class 0, detritus without organization; classes I and II, connective tissue proliferation with increasing fiber synthesis; and class III, dense fibrous connective tissue. The SI ratios of T2-weighted images were significantly reduced from 4.76 in detritus (0) to 1.70 in dense fibrous connective tissue (III) as a function of histopathologic classes. SI ratios of T1-weighted images were reduced from 1.84 (0) to 1.12 (III). Contrast bolus with gadolinium-DTPA showed no change of SI ratio in detritus (0.99) but an increase from 1.12 (I) to 1.70 (III) as organization increased.

CONCLUSIONS

The histological organization of excluded aneurysms can be monitored by MRI. Progressive organization is indicated by decreasing SIs in T2- and an increasing signal increase in T1-weighted images after gadolinium bolus.