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

Endovascular Aneurysm Repair With AFX Stent-Grafts or Tube Grafts for Sacciform Infrarenal Pathologies in a Narrow Aortic Anatomy

PURPOSE

The objective of this study was to compare the outcomes of patients treated with tube grafts and AFX stent-graft in the narrow infrarenal aortic anatomy.

MATERIALS AND METHODS

Patients with penetrating aortic ulcers (PAUs) or sacciform aneurysms of the infrarenal aorta and an aortic bifurcation diameter ≤20 mm who underwent endovascular aneurysm repair (EVAR) with bifurcated AFX or tube stent-grafts (TUBE) between 2012 and 2020 were included. Demographic data and the outcome of the AFX group were compared with the TUBE group. All morphological measurements in the preoperative and postoperative computed tomography scans were performed in the aortic centerline.

RESULTS

Fifty-one patients (female: 12/51; 29%; median age: 72 years [63, 77]) with a median follow-up of 10 (3, 39) months, were included, of whom 35/51 (69%) had PAUs and 11/51 were symptomatic (22%). The aortic bifurcation diameter was 17 mm (15, 18) with severe calcifications in 25/51 (49%). The distal aortic landing zone was longer in the TUBE group (9 mm vs 24 mm; p<0.001). The technical success was 96% with a median aneurysm shrinkage of 8% (3, 13), which was comparable between the groups (p=0.264). Periprocedural mortality, conversion to open surgery, myocardial infarction, and stroke were not observed. Two type Ia endoleaks (EL) and 2 type Ib EL occurred, all in the TUBE group (Type 1 EL; 19 vs 0%; p=0.013). The limb patency in the AFX group was 100%. One patient with a tube graft developed an infrarenal aortic thrombosis 40 months after the intervention. The reintervention rate in the TUBE group was higher (14 vs 0%; p=0.032) and included 3 aortic cuff implantations and 1 covered endovascular aortic reconstruction of aortic bifurcation (CERAB).

CONCLUSION

AFX stent-graft showed a lower rate of type I endoleaks and reinterventions in sacciform infrarenal aortic pathologies during the early and midterm follow-up.

Short-term and Mid-term Outcomes after Use of the Native Infrarenal Aorta as Distal Landing Zone for Fenestrated-Branched Endovascular Aortic Repair

BACKGROUND

This study aimed to examine outcomes after use of the native infrarenal aorta as distal landing zone for fenestrated-branched endovascular aortic repair (F-BEVAR) of pararenal-thoracoabdominal aortic aneurysms (PRAA-TAAA).

METHODS

All F-BEVAR procedures for treatment of PRAA-TAAA (2011-2019) at 2 aortic centers were examined. The outcomes of interest were as follows: i) technical success, ii) perioperative morbidity, iii) preservation of lumbar arteries and the inferior mesenteric artery, iv) type IB endoleaks, v) reinterventions, vi) survival, vii) aneurysm sac behavior, and viii) infrarenal aortic changes.

RESULTS

Twenty consecutive patients with distal landing in the native infrarenal aorta were included (median age 71 years; 25% men). The median number of visible lumbar arteries at baseline was 7, and a patent inferior mesenteric artery (IMA) before the operation was present in 19 (95%) of the cases. There were no deaths within 30 days. One patient (5%), operated on with a 4-BEVAR for a type 2 TAAA, experienced spinal cord ischemia (permanent paraplegia). The median decrease in the number of visible lumbar arteries at the first postoperative scan was 3 from the baseline value, whereas a patent IMA was preserved in 12 out of 19 patients. Only in one case (5%), a type IB endoleak was noted for an overall technical success rate of 95%, which required a standard EVAR 20 months after the initial operation. The median follow-up duration for the study cohort was 491 days; all patients were alive at the longest available individual follow-up, and no instances of new-onset type IB endoleaks were observed. Another 3 late reinterventions (in addition to the one mentioned previously) were performed during midterm follow-up, all because of target vessel instability. In patients with ≥12 months of follow-up after the index procedure (n = 12, 60% of the entire cohort), no instances of aneurysm sac increase >5 mm were noted; the median largest aortic diameter was 51 mm with a median difference from baseline of -6 mm. The median distal landing zone diameter increase was 4 mm from baseline but never beyond the nominal stent-graft diameter, whereas the median aortic bifurcation diameter differed 1 mm from baseline.

CONCLUSIONS

This preliminary experience shows that the use of the native infrarenal aorta as a distal landing zone for F-BEVAR is safe in the short term and midterm in patients with suitable anatomy, allowing the sparing of collateral vessels. Longer follow-up is warranted to assess durability.

Double Tube Stent-Grafts for Infrarenal Aortic Aneurysm: A New Concept

Purpose:

To present the concept of double tube stent-grafts and examine the indications for and results achieved with these devices.

Methods:

From January 1, 2000, to December 31, 2005, 759 patients who underwent endovascular repair of infrarenal aortic aneurysms at 2 centers. Of these, 45 (5.9%) patients received a double tube stent-graft; complete operative and follow-up data were available for retrospective analysis in 41 patients (33 men; mean age 73.1±8.9 years). Diameters measured before stent-graft implantation and at follow-up (12, 24, 36, and 48 months) with clinical examination, 2-phase computed tomographic angiography, duplex sonography, and biplanar abdominal radiography were tested for significant changes using ANOVA with the Bonferroni-Dunn correction. Late outcomes (clinical success and endoleak) were analyzed by the Kaplan-Meier method.

Results:

The postoperative complication rate was 12.2%, with 2.4% systemic complications (1 patient with angina pectoris); the early mortality rate was 0%. Mean follow-up was 21.9±12.8 months (range 12–61) for the 41 patients. Four (9.8%) patients died during follow-up of cardiac causes (n=2), lung cancer (n=1), and bowel ischemia (n=1). Four (9.8%) endoleaks were observed during follow-up: 1 distal type I, 2 type II, and 1 type III. Maximum aneurysm diameters shrank from 52.0±9.5 mm preoperatively to 44.0±10.8 mm (p<0.0001) postoperatively at the latest available follow-up.

Conclusion:

Our study supports the use of this double tube technique for repair of appropriate saccular infrarenal aortic aneurysms. The double tube stent-graft method appears safe in terms of endoleaks and migration, so we recommend that it be considered an option of endovascular aortic aneurysm therapy.

Ten-Year Outcomes after Endovascular Aneurysm Repair (Evar) and Magnitude of Additional Procedures

Background and Aims:

With any new technology complications are possible, and problems with first-generation aortic stentgrafts have been extensively reported. The long-term outcome of this patient population and the magnitude of additional secondary procedures are, however, less well covered.

Materials and Methods:

Between February 1997 and November 1999, 48 patients (44 men and 4 women; mean age 70 years; range 54–85) with AAA (average 57mm, range 40–90mm) were treated with a Vanguard® endoprosthesis. Stentgrafts were sized by CT and angiography-based measurements. Results were continuously assessed using contrast-enhanced CT before discharge, 1, 3, 6 and 12 months after the procedure and thereafter annually. Since 2001 plain abdominal X-rays have been performed annually.

Results:

The technical implant success rate was 100%. Median follow-up was 91 months (range 7.6–120 months). None of the patients was lost during this period. Hospital mortality was 0%. There were 25 subsequent deaths (52%), the most common cause being coronary artery disease. There were ten late conversions to open surgical repair, including three emergency operations: two due to rupture and one to thrombosis. EVAR-related complications were encountered in 43 patients (90%): 12 primary endoleaks (all type II), 36 late endoleaks (16 type I, 2 type II and 18 type III), 22 migrations, 25 row separations, 20 thromboses, one endotension and 3 ruptures of the AAA. Secondary procedures were required in 39 patients (81%): 1 re-endografting by aortoiliac bifurcated graft and 3 with a uni-iliac graft; 33 limb graft repairs were performed and 19 infrarenal cuffs were placed. There were 4 late embolizations and 4 attempts, and 6 thrombolyses, four of which were successful. Further, 9 femoro-femoral crossover by-pass and 2 axillo-femoral by-pass operations and 2 amputations were carried out during the follow-up. Only one patient was alive without complications.

Conclusions:

The impact of long-term follow-up of patients treated with the new technology was emphasized in this patient population. A careful surveillance protocol and active endovascular treatment of complications can yield acceptable results and low AAA rupture and aneurysm mortality rates, also with the first-generation endovascular graft. A new technology, however, may involve unpredictable problems which can magnify the workload and incur high costs over several years after the initial procedure.

Secondary modification into aortouniiliac configuration to salvage failed endovascular aneurysm repair is safe and effective but not associated with higher intervention rates during long-term follow-up

BACKGROUND

Reports of secondary modifications into aortouniiliac configuration to salvage-failed endovascular aneurysm repair (EVAR) are limited. We evaluated long-term results after these procedures and compared them with those after primary aortouniiliac endografting (AUE).

METHODS

A retrospective review of all EVAR performed from March 1995 until July 2011 was conducted. Patients were included when primary AUE (group I) or modification into aortouniiliac configuration (group II) was done.

RESULTS

Data analysis obtained 27 group I and 23 group II patients. Salvage of failed EVAR could be achieved in 96% of group II patients, and mortality was zero. Frequency of adverse events and amount of interventions to maintain aneurysm exclusion were not increased after secondary AUE. Kaplan-Meier estimates for long-term survival between groups were comparable (P = .36).

CONCLUSIONS

Secondary AUE allows correction of graft-related endoleaks potentially leading to late aneurysm rupture. Complications and adverse events throughout long-term follow-up were not necessarily increased when compared with primary AUE.

Endovascular repair of infrarenal focal aortic pathology with limited aortic coverage

BACKGROUND

Endovascular abdominal aortic aneurysm repair (EVAR) for degenerative abdominal aortic aneurysm (AAA) requires complete aortic exclusion to prevent ongoing aneurysmal degeneration in a diseased aorta. Focal infrarenal aortic pathology, such as penetrating atherosclerotic ulcer (PAU), saccular aneurysm, and/or intramural hematoma (IMH) may not necessitate complete aortic coverage. Here, we review our experience with endovascular management of focal aortic pathology with limited aortic coverage.

METHODS

A prospectively maintained institutional database of patients undergoing EVAR was retrospectively reviewed to identify all patients treated with a nonbifurcated device (Current Procedural Terminology code: 34,800). Patients without a diagnosis of PAU, saccular aneurysm, IMH, or iatrogenic pseudoaneurysm were excluded. Medical records and imaging studies were reviewed for confirmation of focal aortic pathology. Preoperative imaging and intraoperative details were reviewed. Outcome measures included technical success, symptom-free survival, and freedom from reintervention.

RESULTS

Eight patients were identified who underwent repair of a focal aortic defect with an endovascular tube graft from 2004-2011. Six patients underwent surgery for 7 saccular pseudoaneurysms and 2 patients had iatrogenic infrarenal pseudoaneurysms. Six saccular aneurysms were associated with PAU. Seven patients (88%) were men; the median age was 76 years (range: 50-85 years). Four patients (50%) had symptoms attributable to their aneurysm (2 abdominal pain, 1 gastrointestinal symptoms, 1 lower extremity emboli). Aneurysm repair was classified as urgent in 2 patients (25%). Six patients (75%) required placement of a single aortic component, the other 2 patients (25%) required 2 components. All devices used were Zenith (Cook, Inc., Bloomington, IN) ancillary components. The median device diameter was 22 mm (range: 18-28 mm), while the median device length was 56.5 mm (range: 39-80 mm). The technical success rate was 100%. There were no early graft-related complications. All symptomatic patients experienced improvement or resolution of symptoms. In all cases, radiologic follow-up at 1 month showed stable or decreasing aneurysm size. No endoleaks were detected and no patients have required reintervention to date.

CONCLUSIONS

The optimal management of many focal infrarenal aortic defects, particularly those that are incidentally discovered, remains unclear. Our experience with endovascular repair of focal aortic pathology with limited aortic coverage suggests this approach is technically feasible and associated with excellent early results.

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.

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.

Percutaneous treatment of infrarenal aortic aneurysm with a polytetrafluoroethylene-covered nitinol stent-graft via a 10-F introducer sheath

Two patients with dissecting (n = 1) and saccular (n = 1) aneurysms of the infrarenal abdominal aorta with very narrow proximal and distal aortic necks underwent treatment with percutaneous implantation of self-expandable polytetrafluoroethylene (PTFE)-covered nitinol stent-grafts on an off-label basis. The stent-grafts had maximum diameters of 13.5 mm and were deployed via 10-F introducer sheaths. Complete coverage of both aneurysms was achieved without evidence of endoleaks. The only complication observed was a pseudoaneurysm of the femoral access site in one patient, which was treated conservatively. Based on the experience described in this report, an aortic aneurysm with a narrow aortic neck can be safely treated with a PTFE-covered nitinol stent-graft.

Endovascular aneurysm repair: current and future status

Endovascular aneurysm repair has rapidly expanded since its introduction in the early 1990s. Early experiences were associated with high rates of complications including conversion to open repair. Perioperative morbidity and mortality results have improved but these concerns have been replaced by questions about long-term durability. Gradually, too, these problems have been addressed. Challenges of today include the ability to roll out the endovascular technique to patients with adverse aneurysm morphology. Fenestrated and branch stent-graft technology is in its infancy. Only now are we beginning to fully understand the advantages, limitations, and complications of such technology. This paper outlines some of the concepts and discusses the controversies and challenges facing clinicians involved in endovascular aneurysm surgery today and in the future.

Tube Stent-Grafts for Infrarenal Aortic Aneurysm: A Matched-Paired Analysis Based on EUROSTAR Data

OBJECTIVE

Tube stent-grafts for treatment of infrarenal aortic aneurysms (AAAs) are a nearly forgotten concept. For focal aortic pathologies tube stent-grafts may be a treatment option. We have performed a retrospective matched-paired analysis of the EUROSTAR registry regarding the outcome of tube vs. bifurcated stent-grafts for AAA. Tapered aortomonoiliac stent-grafts were not the objective of this study.

MATERIALS AND METHODS

From July 1997 to June 2006, 7581 patients who underwent an endovascular AAA repair were entered in the EUROSTAR registry by 164 centers. One hundred fifty-three patients were treated with tube stent-grafts. For each of these 153 patients we selected one patient from a bifurcated stent-graft group (BGG-original, 7428 patients) matched according to gender, ASA, age, AAA diameter, and type of anesthesia. Differences in preoperative details between the two study groups were analyzed using chi-square test for discrete variables and Wilcoxon rank-sum test for continuous variables. Multivariate logistic regression analysis was performed on early complications. Midterm outcomes (>30 days) were analyzed by Kaplan-Meier and multivariate Cox proportional hazard model.

RESULTS

The duration of the procedure was shorter in the tube stent-graft group (TGG; 102.3 +/- 52.2) than in BGG (128.3 +/- 55.0; p = 0.0002). Type II endoleak was less frequent in TGG (4.0%; mean follow-up, 23.12 +/- 23.9 months) than in BGG (14.3%; mean follow-up, 20.77 +/- 20.0 months; p = 0.0394). Type I endoleaks and migration were distributed equally, without significant differences between the groups. Combined 30-day and late mortality was higher for TGG (p = 0.0346) and was obviously not aneurysm related.

CONCLUSIONS

We conclude that after selection of patients, tube stent-grafts for infrarenal aortic repair can be performed with great safety regarding endoleaks and migration. The combined higher 30-day mortality and non-aneurysm-related mortality during follow-up were mainly caused by cardiac failures in our sample.

Endovascular abdominal aortic aneurysm repair

The operative mortality following conventional abdominal aortic aneurysm (AAA) repair has not fallen significantly over the past two decades. Since its inception in 1991, endovascular aneurysm repair (EVAR) has provided an alternative to open AAA repair and perhaps an opportunity to improve operative mortality. Two recent large randomised trials have demonstrated the short and medium term benefit of EVAR over open AAA repair, although data on the long term efficacy of the technique are still lacking. This review aimed at providing an overview of EVAR and a discussion of the potential benefits and current limitations of the technique.

Endovascular repair of a saccular infrarenal aortic aneurysm in a liver transplant patient

Saccular infrarenal aortic aneurysms are rare lesions that usually require prompt surgical repair. In clinical situations where morbidity and mortality associated with open aortic surgery appear to be prohibitively high, an endovascular approach may serve as a life-saving alternative. We report successful endovascular repair of a symptomatic saccular infrarenal aortic aneurysm in a complicated liver transplant patient.

Stent-Grafts for Unruptured Abdominal Aortic Aneurysms: Current Status

Aortic stent-grafts were introduced at the beginning of the 1990s as a less invasive method of dealing with aortic aneurysms in patients with poor cardiovascular reserve. The numbers of procedures performed worldwide has increased exponentially despite the current lack of any substantial evidence for long-term efficacy in comparison with the gold standard of open surgical grafting. This review summarizes the evolution of the abdominal aortic stent-graft, the techniques used for assessment and deployment, and the effect of the procedure on both the patient and the device. The recent publication of two national multicenter trials has confirmed that the endovascular technique confers a 2.5-fold reduction in 30-day mortality in comparison with open surgery. However, over 4 years of follow-up, there is a 3-fold increase in the risk of reintervention and the overall costs are 30% greater with endovascular repair. Although the improvement in aneurysm-related mortality persists in the mid-term, because of the initial reduction in perioperative mortality, the all-cause mortality rate at 4 years is actually no better than for open surgery. Longer-term data from the randomized trials are awaited as well as results from the latest trials utilizing state-of-the-art devices. Whilst the overall management of abdominal aortic aneurysms has undoubtedly benefited from the introduction of stent-grafts, open repair currently remains the gold standard treatment.

Systematic review of recent evidence for the safety and efficacy of elective endovascular repair in the management of infrarenal abdominal aortic aneurysm

Background

Conventional management of abdominal aortic aneurysm (AAA) is by open repair and is associated with a mortality rate of 2–6 per cent. Endovascular aneurysm repair (EVAR) is an alternative technique first introduced in 1991. A systematic review was undertaken of the evidence for the safety and efficacy of elective EVAR in the management of asymptomatic infrarenal AAA.

Methods

Thirteen electronic bibliographical databases were searched, covering biomedical, health-related, science and social science literature. Outcomes were assessed with respect to efficacy (successful deployment, technical success, conversion rates and secondary intervention rates) and safety (30-day mortality rate, procedure morbidity rates and technical issues—endoleaks, graft thrombosis, stenosis and migration).

Results

Of 606 reports identified, 61 met the inclusion criteria (three randomized and 15 non-randomized controlled trials, and 43 uncontrolled studies). There were 29 059 participants in total; 19 804 underwent EVAR. Deployment was successful in 97·6 per cent of cases. Technical success (complete aneurysm exclusion) was 81·9 per cent at discharge and 88·8 per cent at 30 days. Secondary intervention to treat endoleak or maintain graft patency was required in 16·2 per cent of patients. Mean stay in the intensive care unit and mean hospital stay were significantly shorter following EVAR. The 30-day mortality rate for EVAR was 1·6 per cent (randomized controlled trials) and 2·0 per cent in nonrandomized trials and case series. Technical complications comprised stent migration (4·0 per cent), graft limb thrombosis (3·9 per cent), endoleak (type I, 6·8 per cent; type II, 10·3 per cent; type III, 4·2 per cent) and access artery injury (4·8 per cent).

Discussion

EVAR is technically effective and safe, with lower short-term morbidity and mortality rates than open surgery. However, there is a need for extended follow-up as the long-term success of EVAR in preventing aneurysm-related deaths is not yet known.

Midterm Survival After Endovascular Versus Open Repair of Infrarenal Aortic Aneurysms

PURPOSE

To report the midterm survival after endovascular repair (ER) of infrarenal aortic aneurysms and to compare the outcomes to contemporaneous patients treated with open repair (OR).

METHODS

Between January 1995 and December 2001, 498 patients were treated for abdominal aortic aneurysm: 289 (52%) underwent OR and 209 (48%) underwent ER at a single center. Preoperative risk factors were graded according to the SVS/AAVS risk stratification. A computerized database was used to record demographic, clinical, and follow-up data.

RESULTS

Significant benefits (p<0.0001) were observed in the ER group in terms of mean procedural time (163+/-66 versus 132+/-61 minutes), mean blood loss (1268+/-923 versus 122.5+/-284 mL), and mean hospital length of stay (16.24+/-13.3 versus 9.3+/-11.6 days). The perioperative mortality for OR and ER patients were, respectively, 5.1% and 1.5% (p=0.04). The mean follow-up was 40 months in the OR group (range 0-85) and 19 months in the ER group (range 2-80). Contact was lost with 31 (6%) patients during the study. No overall survival advantage was observed for OR over ER, and comparison of OR and ER according the risk classifications did not yield any significant differences. No patients died of aneurysm rupture, but 7 ER patients had to be converted to open surgery. The cumulative freedoms from reinterventions at 4 years for the OR and ER groups, respectively, were 87% and 63% (p=0.001). Patients treated by OR had better clinical success (p=0.001). Patients in the ER group without iliac artery aneurysm showed a significant improvement (p=0.035) over patients with aneurysmal iliac arteries.

CONCLUSIONS

Over the 7 years of this study, ER realized its goal: prevention of aneurysm rupture. Despite a greater number of reinterventions for ER patients, no overall survival difference was observed.

Endovascular treatment of abdominal aortic aneurysms

BACKGROUND

Endovascular treatment of abdominal aortic aneurysms is a rapidly evolving technique that has gained broad acceptance in the treatment of patients with abdominal aortic aneurysms.

METHODS

A review of the English literature was done to determine the short- and long-term outcomes of endovascular repair of abdominal aortic aneurysms. Reports of complications such as endoleak, graft migration, graft limb occlusion, aneurysm rupture, and aneurysm enlargement were evaluated.

RESULTS

Short-term results of endovascular repair of abdominal aortic aneurysms are excellent. The necessity for open conversions is less than 5%. The cumulative risk of aneurysm rupture is approximately 1% per year. The coverall incidence of graft limb occlusion was 2.8% in the follow-up period. The cumulative risk for a secondary procedure was 12% at 1 year, 24% at 2 years, and 35% at 3 years. Moderate and severe neck angulation was associated with an increased incidence of adverse events in the follow-up period. Endografts have the potential to become infected and develop aortoduodenal fistula. The treatment of ruptured aneurysms with endovascular grafts has been successful and a technique that is increasingly used.

CONCLUSION

Endovascular treatment of abdominal aortic aneurysm is an effective technique with excellent short-term results. The long-term results remain to be determined. Ongoing surveillance is necessary to avoid late complications of aneurysm rupture.

Cumulative sum failure analysis of the learning curve with endovascular abdominal aortic aneurysm repair

PURPOSE

The purpose of this study was to evaluate the importance of experience and the learning curve with endovascular abdominal aortic aneurysm (AAA) repair.

METHODS

A retrospective analysis was performed of all elective endovascular AAA repairs attempted by an individual surgeon and radiologist over a 4-year period. The primary outcome variable was achievement and 30-day maintenance of initial clinical success as defined by the Society for Vascular Surgery/American Association of Vascular Surgery reporting standards. Following standard statistical analysis, the cumulative sum (CUSUM) method was used to analyze the learning curve, with a predetermined acceptable failure rate of 10% and calculated 80% alert and 95% alarm lines.

RESULTS

Ninety-six elective endovascular AAA repairs were attempted by this team between 1998 and 2002 (mean age 74 +/- 0.8 years; mean aneurysm diameter 5.98 +/- 0.8 cm). Initial clinical success was achieved and maintained in 85 of 96 patients (88.5%). Although results were acceptable throughout the study period, improved results with respect to the target failure rate (10%) were not achieved until 60 patients were treated. The learning or CUSUM curves did not differ for different device manufacturers, with improved results being achieved following 20 implantations of each device. The results did differ when comparing aortouniiliac grafts (n = 27) and bifurcated grafts (n = 64). Results with bifurcated grafts remained consistent throughout the study period, whereas with aortouniiliac grafts, results improved after only a few procedures in comparison with the target failure rate.

CONCLUSION

Success rates with endovascular aneurysm repair will improve with an individual's experience. The CUSUM method is a valuable tool in the evaluation of this learning curve, which has credentialing and training implications. Although acceptable results were obtained throughout the study period, this analysis indicates that 60 endovascular aneurysm repairs, or 20 with an individual device, are necessary before optimal rates of initial clinical success can be achieved. These results can be achieved more readily with aortouniiliac grafts than with bifurcated grafts.

Aortoiliac morphologic correlations in aneurysms undergoing endovascular repair

PURPOSE

The feasibility of endovascular aneurysm repair depends on morphologic characteristics of the aortoiliac segment. Knowledge of such characteristics is relevant to safe deployment of a particular device in a single patient and to development of new devices for use in patients with a broader spectrum of anatomic variations.

METHODS

We evaluated findings on computed tomography scans for 277 patients being considered for endovascular aneurysm repair. Aortic neck length and angulation estimates were generated with three-dimensional trigonometry. Specific centerline points were recorded, corresponding to the aorta at the celiac axis, lowest renal artery, cranial aspect of the aneurysm sac, aortic terminus, right hypogastric artery origin, and left hypogastric origin. Aortic neck thrombus and calcium content were recorded, and neck conicity was calculated in degrees. Statistical analysis was performed with the Spearman rank correlation. Data are expressed as median and interquartile range.

RESULTS

Median diameter of the aneurysms was 52 mm (interquartile range, 48-59 mm) in minor axis and 56 mm (interquartile range, 51-64 mm) in major axis, and median length was 88 mm (interquartile range, 74-103 mm). Median proximal aortic neck diameter was 26 mm (interquartile range, 22-29 mm), and median neck length was 30 mm (interquartile range, 18-45 mm). The common iliac arteries were similar in diameter (right artery, 16 mm [interquartile range, 13-20 mm]; left artery, 15 mm [interquartile range, 11-18 mm]) and length (right, 59 mm [interquartile range, 50-69 mm]; left, 60 mm [interquartile range, 49-70 mm]). Median angulation of the infrarenal aortic neck was 40 degrees (interquartile range, 29-51 degrees), and median angulation of the suprarenal segment was 45 degrees (interquartile range, 36-57 degrees). By gender, sac diameter, proximal neck diameter, and iliac artery diameter were significantly larger in men. Significant linear associations were identified between sac diameter and sac length, neck angulation, and iliac artery diameter. As the length of the aneurysm sac increased the proximal aortic neck length decreased. Conversely, as the sac length decreased sac eccentricity increased. Mural thrombus content within the neck increased with increasing neck diameter.

CONCLUSIONS

There is considerable variability in aortoiliac morphologic parameters. Significant associations were found between various morphologic variables, links that are presumably related to a shared pathogenesis for aberration in aortoiliac diameter, length, and angulation. Ultimately this information can be used to develop new endovascular devices with broader applicability and improved long-term results.

Endovascular repair of abdominal aortic aneurysms: the Cleveland Clinic experience with five different devices

The endovascular repair of abdominal aortic aneurysms is associated with long-term durability that is inferior to that of traditional open surgical repair. Device migration, endoleak, and limb thrombosis continue to plague currently available devices, culminating in an unacceptably high rate of secondary procedures and, in rare cases, failure to protect the patient from rupture. A review of the available literature yields a few caveats: certain correlations that exist between device design features and the risk of graft-related complications during and after implantation. Noteworthy in this regard are associations between bulky deployment systems and iliofemoral arterial injury, unsupported (nonstented) graft limbs and thrombotic occlusion, fabric/stent motion and fabric degeneration, rigid endoskeletons and limb disunion, as well as passive proximal attachment and device migration. Whereas the last decade has witnessed improvement in endograft device design, endovascular aneurysm repair still must be considered a technology in evolution. Early benefit of reduced periprocedural morbidity is negatively affected by inferior long-term durability of current technology. Nevertheless, many patients, particularly those who are elderly or infirm, may choose to accept the limitations of current endovascular technology to avoid the increased morbidity of traditional open surgical aneurysm repair.

Nature, frequency, and predictors of secondary procedures after endovascular repair of abdominal aortic aneurysm

OBJECTIVES

Endovascular stent grafting offers a potentially less invasive option for treatment of abdominal aortic aneurysm. Clinical benefit has been demonstrated with respect to early parameters such as blood transfusion, return of gastrointestinal function, and length of hospital stay. Endovascular repair, however, has been criticized on the basis of inferior long-term outcome. Secondary procedures may be necessary to address durability issues such as migration, high-pressure endoleak, graft limb thrombosis, and degeneration of the stent-fabric structure itself, issues that may compromise the primary goal of aneurysm repair, protection from rupture.

METHODS

Between 1996 and 2002, 703 patients underwent endovascular treatment of infrarenal abdominal aortic aneurysm at The Cleveland Clinic Foundation. During this time, five devices were used: Ancure, AneuRx, Excluder, Talent, and Zenith. Outcome was assessed with physical examination, lower extremity arterial studies, plain abdominal radiography, and computed tomography at discharge, at 1, 6, and 12 months postoperatively, and annually thereafter. Secondary procedures were defined as any procedure, exclusive of diagnostic angiography, performed after stent graft implantation, directed at treatment of aneurysm-related events. Multivariable statistical techniques for censored data (Cox proportional hazards modeling) were used to determine baseline parameters associated with need for secondary procedures over follow-up, with calculation of hazards ratio (HR) and 95% confidence interval (CI).

RESULTS

Patient follow-up averaged 12.2 +/- 11.7 months. Patient survival was 90% +/- 1.4% at 1 year, 78% +/- 2.6% at 2 years, and 70% +/- 3.8% at 3 years. Aneurysm rupture occurred in 3 patients (0.4%), accounting for rupture risk of 1.4% over the first 2 years of follow-up (Kaplan-Meier method). Overall, 128 secondary procedures were required in 104 patients (15%), with a cumulative risk of 12% +/- 1.5% at 1 year, 24% +/- 2.8% at 2 years, and 35% +/- 4.4% at 3 years after stent graft implantation. Among the secondary procedures, new stent grafts and extensions were placed in 34 patients (27%), embolization of endoleak was performed in 33 patients (26%), and open surgical conversion was undertaken in 11 patients (9%). Periprocedural mortality of secondary procedures was 8% overall, but was 18% for patients undergoing open surgical conversion. Multivariable modeling identified the date the procedure was performed (HR, 1.53 per 3-month period of study; CI, 1.22-1.92; P <.001) and aneurysm size (HR, 1.35 per centimeter of minor axis; CI, 1.13-1.60; P <.001) as independent predictors of need for secondary procedures.

CONCLUSIONS

Current endovascular devices are associated with a relatively high rate of complications over mid-term follow-up, culminating in frequent need for secondary remedial procedures. With strict follow-up imaging compliance, however, risk for rupture and aneurysm-related death remain exceedingly low. Newer technology may achieve improved durability and a lower requirement for secondary procedures, while maintaining the minimally invasive nature of presently available devices.

Endovascular treatment of failed prior abdominal aortic aneurysm repair

Failure of endovascular or conventional abdominal aortic aneurysm (AAA) repair may occur as a result of attachment site endoleak (type I) or paraanastomotic aneurysm and pseudoaneurysm formation. This study examined the results of the use of secondary endovascular grafts for the treatment of failed prior infrarenal AAA repair procedures. Forty-seven patients were treated with endovascular grafts. These included 14 patients with type I endoleaks (5 proximal, 8 distal, 1 proximal and distal) and 33 patients with paraanastomotic aneurysms after standard open surgical AAA repair (3 proximal aorta, 5 distal aorta, 21 iliac, 4 proximal and distal). The interval between the primary aortic procedure and the endovascular repair was significantly shorter for failed endovascular procedures (mean, 18.2 months; range, 1-42 months) than for failed conventional procedures (mean, 108.9 months; range, 12-216 months) (p <0.01). The endovascular devices used for correction of the failed AAA repairs were Talent (23), physician-made (19), AneuRx (2), Vanguard (2), and Excluder (1). Transrenal fixation was used for repair of all proximal anastomotic failures. Mean follow-up after reintervention was 12.2 months in patients with failed endovascular grafts and 10.6 months in patients with failed conventional grafts. Patient demographics were as follows: average age, 78 years; 36 male and 11 female; and 4.1 comorbid medical conditions per patient. The endovascular graft was successfully deployed in all 47 cases; 1 patient experienced a persistent proximal attachment site endoleak after endograft deployment. Endovascular grafts may be used to treat previously failed endovascular and conventional AAA repair procedures with good short- and intermediate-term results. Endovascular treatments in these cases may avoid the difficulties of aortic reoperation or AAA repair in the setting of prior endovascular aortic grafting.