First report of a late type III endoleak from fabric tears of a Zenith stent graft

Management of Endoleaks After Elective Infrarenal Aortic Endovascular Aneurysm Repair: A Review

Importance

Endovascular aneurysm repair (EVAR) is the dominant treatment strategy for abdominal aortic aneurysms, encompassing 80% of all repairs in the United States. Endoleaks are ubiquitous and affect 30% of patients treated by EVAR, potentially leading to sac enlargement and increased risk of rupture. The care of EVAR patients requires long-term surveillance by a multidisciplinary team. Accordingly, physicians should be familiar with the fundamentals of endoleak management to achieve optimal outcomes, including timely referral for remediation or providing counseling and reassurance when needed.

Observations

PubMed and the Cochrane database were searched for articles published between January 2002 and December 2022 in English, addressing epidemiology, diagnosis, and management of endoleaks after EVAR. Endoleaks can be detected intraoperatively or years later, making lifelong surveillance mandatory. Type I and III have the highest risk of rupture (7.5% at 2 years and 8.9% at 1 year, respectively) and should be treated when identified. Intervention should be considered for other types of endoleak when associated with aneurysm sac growth larger than 5 mm based on current guidelines. Type II endoleaks are the most common, accounting for 50% of all endoleaks. Up to 90% of type II endoleaks resolve spontaneously or are not associated with sac enlargement, requiring only observation. Although the risk of rupture is less than 1%, cases that require reintervention are challenging. Recurrence is common despite endovascular treatment, and rupture can occur without evidence of sac growth. Type IV endoleaks and endotension are uncommon, are typically benign, and primarily should be observed.

Conclusions and Relevance

Endoleak management depends on the type and presence of sac expansion. Type I and III endoleaks require intervention. Type II endoleaks should be observed and treated selectively in patients with significant sac expansion. Since endoleaks can appear any time after EVAR, at least 1 contrast-enhanced computed tomographic angiogram or duplex ultrasound by an experienced laboratory is recommended every 5 years.

Incidence, Long Term Clinical Outcomes, and Risk Factor Analysis of Type III Endoleaks Following Endovascular Repair of Abdominal Aortic Aneurysm

OBJECTIVE

To assess the real world incidence, outcomes, and risk factors of type III endoleaks (TIIIEL) after endovascular aneurysm repair (EVAR).

METHODS

This was a single centre, retrospective, observational, cohort study. All patients with abdominal aortic aneurysms (AAAs) receiving EVAR between 1994 and 2020 were collected prospectively and reviewed. The primary outcome was the cumulative incidence and impact on survival of TIIIELs, either defined as disconnections of modular graft components (TIIIaEL) or fabric defects (TIIIbEL). Secondary outcomes included risk factor analysis evaluating baseline morphological and stent graft details, as well as a comparison of TIIIaEL and TIIIbEL.

RESULTS

In total, 2 565 EVARs were performed and 95 (3.7%) TIIIELs were diagnosed at a median interval of 49.5 months (interquartile range [IQR] 19.4, 67.6). Estimated TIIIEL incidence at five years was 6.8%, 2.2%, and 3.6% for first and second generation, third and fourth generation, and fifth and sixth generation, respectively. The survival rate in patients without any high flow endoleak was 88.0%, 67.9%, 56.9%, and 52.1%, while in TIIIEL patients it was 98.6%, 77.2%, 49.8%, and 32.3% at one, five, 10, and 15 years, respectively (p = .77). The distribution of TIIIaEL and TIIIbEL was 70.5% and 29.5%, respectively. TIIIbEL received a higher rate of open treatment (28.6% vs. 7.5%; p = .005) and device or procedure related re-interventions (35.7% vs. 13.4%; p = .013). Fourteen (15.4%) recurrent TIIIELs were diagnosed at a median of 16.8 months (IQR 7.6, 32.1). Old generation endografts (hazard ratio [HR] 2.1, 95% confidence interval [CI] 1.3 - 3.4; p = .002) and non-proprietary extensions (HR 3.6, 95% CI 1.9 - 6.8; p < .001), and angulated and calcified aneurysm neck (HR 3.6, 95% CI 1.2 - 10.6; p = .017) were risk factors for TIIIEL. Every 10 mm maximum AAA diameter increase presented a 1.4 fold higher risk of TIIIEL.

CONCLUSION

TIIIEL is a severe condition that is often fatal if left untreated. Old endografts, the implantation of non-proprietary extensions, large AAAs, and angulated and calcified necks are risk factors for TIIIEL that require careful follow up due to the high rate of recurrence.

Type IIIb endoleak due to stent suture line fabric breakage in the Endurant stent graft: a case report

Background

Early type IIIb endoleak is a very rare complication of endovascular aneurysm repair (EVAR).

Case presentation

An 87-year-old man was diagnosed with infrarenal abdominal aortic aneurysm. The patient underwent EVAR using the Endurant stent graft. Postoperative color duplex ultrasound revealed a regular row of pulsatile blood flow from the main body and left leg. The blood flow appeared to be bleeding from the stent suture lines because of its regularity. Type IIIb endoleak was suspected due to stent suture line fabric breakage but was not treated surgically or endovascularly because of the patient’s poor general health status. Six months later, contrast-enhanced CT demonstrated a deformation and enlargement of the aneurysm sac as well as an oozing of the contrast medium on the main body and left limb. Thereafter, he died of a subdural hematoma due to a fall. Autopsy showed no visible abnormal erosion or holes on the graft fabric, suggesting that suture line fabric breakage may have existed during the manufacturing process.

Conclusions

Although rare, type IIIb endoleaks can occur even in the perioperative period after EVAR. Early type IIIb endoleaks may not resolve spontaneously and should be treated promptly, if possible.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40792-022-01415-8.

A preliminary analysis of late structural failures of the Navion stent graft in the treatment of descending thoracic aortic aneurysms

OBJECTIVE

Patients in the Valiant Evo U.S. and international clinical trials had positive short-term outcomes; however, late structural failures, including type IIIb endoleaks have been recently discovered. Type IIIb endoleaks are serious adverse events because the repressurization of the aneurysm sac increases the risk of rupture. The purpose of the present study was to detail the imaging patterns associated with the structural failures with the aim of increasing awareness of failing graft presentation, early recognition, and prompt treatment.

METHODS

The Valiant Evo clinical trial was a prospective, single-arm investigation of a thoracic stent graft system. With the recent late structural failures, sites were requested to submit all available imaging studies to date to allow the core laboratory to assess for structural failures such as type IIIb endoleaks, stent ring fractures, and stent ring enlargement. Of the 100 patients originally enrolled in the trial from 2016 to 2018, the core laboratory assessed the imaging studies performed at ≥1 year for 83 patients.

RESULTS

No structural failures of the graft were reported through 1 year of follow-up. At 1 to 4 years, graft structural failures were detected in 11 patients with descending thoracic aortic aneurysms. Of the 11 patients, 5 had a type IIIb endoleak. Four of the five had imaging findings showing stent fractures consistent with the location of the graft seam and one had a type IIIb endoleak attributed to calcium erosion with no stent fracture or ring enlargement. Of the four patients with stent fracture in line with the graft seam, three underwent a relining procedure that successfully excluded the type IIIb endoleak. One of these three patients died 4 days later of suspected thoracic aortic rupture because the distal thoracic endovascular aortic repair extension had been landed in a previously dissected and fragile section of the aorta. The remaining six patients had had stent ring enlargement. One of the six patients had had persistent aneurysm expansion from the time of implantation onward and had died of unknown causes. The remaining five patients have continued to be monitored.

CONCLUSIONS

In the present preliminary analysis, the imaging patterns associated with type IIIb endoleaks, stent fractures, and stent ring enlargement appear to be related to the loss of seam integrity or detachment of the stent rings from the surface of the graft material. The imaging patterns we have detailed should be closely monitored using computed tomography angiography surveillance to allow structural failures to be promptly identified and treated.

Editor's Choice - Detection of Late Complications After Endovascular Abdominal Aortic Aneurysm Repair and Implications for Follow up Based on Retrospective Assessment of a Two Centre Cohort

OBJECTIVE

Endovascular aortic aneurysm repair (EVAR) is associated with the risk of late complications and mandates follow up. This retrospective study assessed post-EVAR complications in a two centre cohort. The study evaluated the rate of complications presenting with symptoms vs. those detected by imaging follow up. Additionally, the agreement between DUS and CTA in detecting complications was assessed in patients with both.

METHODS

All EVAR patients from 1998 to 2012 in two centres were included. Complications were classified based on whether they were symptomatic or detected by imaging, as well as based on imaging detection modality (DUS or CTA). For patients who had undergone DUS and CTA within three months of each other, the kappa coefficient of agreement was assessed.

RESULTS

Four hundred and fifty-four patients treated by EVAR were identified. The median follow up time was 5.2 (IQR 2.8-7.6) years. One hundred and eighteen patients (26%) developed 176 complications. One hundred and six (60.2%) of the complications were asymptomatic, and 70 (39.8%) were symptomatic. Two hundred and fifty-three patients had imaging with both modalities within three months of each other; the kappa coefficient for agreement between CTA and DUS for detecting clinically significant complications was 0.91. Regarding CTA as the standard modality, DUS had a sensitivity of 88.8% (95% CI 77.3-95.8%) and a specificity of 99.4% (95% CI 97.1-99.9%). Three of the complications missed by DUS were related to loss of proximal and distal seal, all occurring in patients with short sealing length on first post-operative CT scan.

CONCLUSION

Approximately a quarter of the patients developed complications, the majority of which were asymptomatic, underlining the importance of adequate surveillance. There was good agreement between CTA and DUS in detecting complications. Clinically significant complications related to inadequate seal were missed by DUS, suggesting that CTA still plays an important role in EVAR surveillance.

Endovascular repair of late type IIIb endoleak after endovascular aneurysm repair: a case report

Background

Type IIIb endoleak is a rare complication after endovascular aneurysm repair (EVAR) and the understanding of type IIIb endoleak is insufficient.

Case presentation

Three elderly patients with previously successfully performed EVARs were sent to our center due to abdominal pain and diagnosed with late type IIIb endoleak. The type IIIb endoleak fabric tears were closed with cuffs or stents by endovascular retreatment. The patients recovered adequately and were discharged from hospital.

Conclusions

Endovascular repair with empirical relining could be a good choice for treatment of late type IIIb endoleak with good prognosis.

Electronic supplementary material

The online version of this article (10.1186/s12872-019-1138-8) contains supplementary material, which is available to authorized users.

Type IIIb Endoleak After Endovascular Aneurysm Repair Using the Zenith Stent Graft

We present 3 cases of type IIIb endoleak after endovascular aneurysm repair (EVAR) using the Zenith stent graft system. Type III endoleak, like type I endoleak, is a high-pressure, high-risk leak that increases sac pressure up to or even above arterial pressure, and is associated with an increased frequency of open conversions or risk of aneurysm rupture. Type IIIb endoleak is rare but there is much concern that the incidence of type IIIb endoleak is likely to increase hereafter; the mechanism of type IIIb endoleak is deterioration of graft fabric in conjunction with stent sutures. Type IIIb endoleak is difficult to diagnose before rupture. The possibility of type IIIb endoleak should be highly suspected when the continued growth of an excluded aneurysm sac without direct radiologic evidence is observed during follow-up. Type IIIb endoleak can be repaired by relining of the stent graft with additional stent grafts.

Diagnosis and relining techniques for delayed type IIIB endoleaks with the second-generation AFX endograft

Type IIIB endoleaks resulting from endograft fabric tear are an uncommon but serious late complication of endovascular aortic aneurysm repair. The Strata fabric used in the earlier generation AFX endograft (updated to Duraply in October 2014) has been associated with an increased frequency of these events. Herein we report on two patients exhibiting delayed type IIIB endoleaks after AFX device insertion to treat an abdominal aortic aneurysm and discuss optimal relining techniques.

Type III B endoleak leading to aortic rupture after endovascular repair: analysis of errors in follow up and treatment

Background

The aim of this paper is to describe the case of a patient with a type III endoleak which was misdiagnosed and treated without success as a type I-II endoleak. An incorrect endoleak diagnosis lead to aortic rupture, which could be avoided with a correct diagnosis. Type III B endoleaks presents some diagnostic difficulties, in the case we describe, they were increased by late presentation and poor follow up.

Case presentation

We revised this 89 years old patient history, he underwent EVAR 11 years before, a control scan six month after surgery, showed a type I-II endoleak which was still present after first intervention. He was treated with proximal cuff positioning and embolization coils. Eight years after first intervention, a Computed Tomography Angiography (CTA) showed persisting type I-II endoleak so same problem was suspected and patient was treated with another proximal cuff and right iliac extension. A Magnetic Resonance Imaging (MRI) control, six months later, showed an increase of the aneurysm sac size of 12 mm. Two years later patient presented at emergency room at our hospital with malaise, sweating and abdominal pain. Computed Tomography (CT-scan) showed increased abdominal aortic diameter (140 × 130 mm) with rupture and hemoperitoneum. He was treated in urgent fashion with endograft removal and aortic-iliac Dacron graft reconstruction. During surgery three large tears on endograft fabric and a stent suture rupture were observed. After surgery patient was admitted in intensive care unit and died on second postoperative day due to multiorgan failure.

Conclusions

Type III endoleak is an uncommon complication: a correct and prompt diagnosis is mandatory for appropriate treatment After EVAR, and especially in those cases of known endoleak, a correct follow-up is mandatory and in case of diagnostic doubts correct imaging should be performed. Media contrast allergies should not be neglected and should not represent a CTA limitation.

Aneurysm sac enlargement 16 years after endovascular aortic aneurysm repair due to late type IIIb endoleak: A case report

INTRODUCTION

We report a case with delayed aneurysm sac enlargement 16 years after EVAR due to late type IIIb endoleak.

PRESENTATION OF CASE

An 84-year-old man was referred to our hospital with an aneurysm sac enlargement after endovascular aortic aneurysm repair (EVAR), which had been performed at another hospital 18 years earlier using the Zenith endograft. Computed tomography (CT), after EVAR had shown significant sac shrinkage. However, the patient presented with delayed aortic aneurysm enlargement due to an assumed endoleak. Duplex ultrasound showed a type IIIb and a type Ib endoleak. We performed a re-intervention with an AFX endograft, for relining due to persistent type IIIb endoleak.

DISCUSSION

Compared with the type IIIB endoleaks discussed in past reports, this case occurred with a much longer delay. Although CT could not identify the type of endoleak, duplex ultrasound led us to diagnose the type IIIb endoleak.

CONCLUSION

Relining using an ePTFE endograft may be considered an effective procedure for type IIIb endoleaks. Duplex ultrasound is useful for determining endoleak types.

Endovascular Repair for a Ruptured AAA due to a Combined Type IIIb and Ia Endoleak

We report a case of a ruptured abdominal aortic aneurysm (AAA) caused by a combined type IIIb and Ia endoleak. Also, we propose the mechanism that resulted in this combined endoleak. Specifically, a 71-year old-man, with a previous history of endovascular aneurysm repair (EVAR) for an AAA, was diagnosed with a contained rupture. CT scan depicted a type Ia endoleak and a migrated Talent endograft. A proximal aortic cuff sealed the endoleak, but intraoperative angiography revealed that a type IIIb endoleak coexisted due to fabric tear close to the Talent bifurcation. A second aortic cuff could not seal the fabric tear; so, in-lay parallel limbs were sequentially deployed as a “kissing endograft” technique inside the cuff. Simultaneous treatment of combined type IIIb and Ia endoleaks has not yet been described. Maybe the type IIIb endoleak is the primary entity causing sac enlargement, neck recontouring, proximal migration, and ultimately type Ia endoleak, which leads to huge enlargement and rupture. Placement of an aortic cuff to seal the proximal endoleak/migration and kissing endografts limbs for the fabric tear seems a safe option in such patients.

Type IIIb endoleak after elective endovascular aneurysm repair: a systematic review

INTRODUCTION

The aim of this article is to investigate the presentation, etiology, management and outcomes of type IIIb endoleak after endovascular aneurysm repair (EVAR).

EVIDENCE ACQUISITION

Electronic bibliographic databases were searched to identify published reports of type IIIb endoleak after EVAR, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards.

EVIDENCE SYNTHESIS

In total 33 articles were identified reporting on a total of 50 patients spanning 19 years of EVAR (1998-2017). Some 11 device-types were used. The median time from implantation to intervention was 27 months (0-168). There was a significant aneurysm sac expansion in 69% of reported cases. Thirteen patients (26%) presented with aneurysm rupture. A definitive diagnosis of type IIIb endoleak made on computed tomographic angiography (CTA) in only 20% of cases. Proposed failure modes included suture breakage, graft erosion by stents, iatrogenic, graft infection and presumed manufacturing faults. Endoleak location was in the main body in 81% of reported cases. Almost one third (31%) of patients were treated with open repair. The remaining patients were treated with endovascular techniques or hybrid procedures. Some novel off-label endovascular solutions were proposed to maintain a bifurcated configuration. Thirty-day mortality in patients treated for aneurysm rupture was 50%. The 30-day mortality rate in non- rupture cases was 2% (endovascular 0% treatment, open 2%).

CONCLUSIONS

Type IIIb endoleak is a serious condition associated with a significant risk of rupture. Definitive diagnosis is challenging and has been described in almost all conventional devices. Most patients can be treated successfully by endovascular means, though maintaining a bifurcated configuration may require non-standard techniques or off-label use.

Delayed Type III Endoleak Caused by Fabric Erosion after Endovascular Repair of an Abdominal Aortic Aneurysm

A 74-year-old patient presented with recurrent aneurysms in the infrarenal abdominal aorta and right common iliac artery 6 years after endovascular aortic repair using endografts in the same location. The patient underwent an aorto-bi-iliac replacement with removal of the stent graft. Two holes measuring 2 mm each were found in the removed graft, and they appeared to have been caused by wear from continuous friction between the endograft and the aortic wall.

Parallel placement of Excluder legs for treatment of type IIIb endoleaks caused by fabric tear after endovascular aneurysm repair

A total of 576 patients underwent endovascular aneurysm repair using main body devices for treatment of abdominal aortic aneurysms or iliac artery aneurysms. During follow-up, type IIIb endoleaks caused by fabric tear occurred in six patients (1.0% [6/576]). The device used was Zenith (Cook Medical, Bloomington, Ind) in five cases and Talent (Medtronic, Santa Rosa, Calif) in one case. All endoleaks were close to the flow divider of the main body devices. The distance between the lower renal artery and the top end of the contralateral leg was 53 ± 14 mm. Bell-bottom-shaped Excluder (W. L. Gore & Associates, Flagstaff, Ariz) legs were placed parallel from the top of the main body device through both legs to treat these endoleaks. In two patients, coil embolization was required to treat gutter endoleaks. Postoperative computed tomography showed the obliteration of type IIIb endoleaks in all patients. Our technique may be an acceptable method for treatment of type IIIb endoleaks, especially when they occur near the flow divider.

Late Type 3b Endoleak Mimicking Type 2 Endoleak after Endovascular Aortic Aneurysm Repair

Endovascular abdominal aortic aneurysm (AAA) repair has been widely used for the treatment of AAA as a safe and efficient method, but endoleaks causing persistent expansion of aneurysm sac may cause aneurysmal rupture and death. Type 3 endoleak is rare but a predominant cause of late rupture. Type 3b endoleak can be misdiagnosed as type 2 endoleak, which is more frequent. Here we report two cases of type 3b endoleak mimicking type 2 endoleak, which were successfully treated by open surgery of partial explantation of the stent-graft and endoaneurysmal interposition graft replacement.

Endovascular Management of Type I Endoleak with Fenestrated Aortic "Cuff" and Afterwards Treatment of Endoleak Type III

Endovascular aortic repair (EVAR) has become preferable treatment of abdominal aortic aneurysms because of proven mortality reduction as well as complications reduction compared with open surgery. Endoleak remains a primary complication of EVAR, however, and occurs in 20 to 25% of the patients. EVAR patients thus undergo lifelong surveillance for the presence of aneurysm expansion and endoleaks usually via computed tomographic angiography. We describe the endovascular management of an enlarged aneurysmal sac size 3 years after EVAR due to combined endoleak of types 1 and 3. We needed to use a fenestrated aortic cuff, a main body graft extension, and an aortouniiliac converter device to seal the leak. This case highlights the potential challenges in identifying and treating type III endoleaks.

Delayed Type IIIb endoleak secondary to graft fabric tear 7 years following implantation of a Medtronic Talent endovascular aortic device: A case report and review of the literature

Objectives:

To report a rare case of delayed Type IIIb endoleak secondary to fabric tear following implantation of a Medtronic Talent endovascular device.

Methods:

A 83-year old gentleman underwent elective endovascular aneurysm repair for infrarenal abdominal aortic aneurysm with a Medtronic bifurcated stent graft in 2008.

Results:

Seven years after the initial repair, imaging surveillance revealed significant endoleak and brisk aneurysm sac expansion due to Type IIIb endoleak secondary to endograft limb fabric tear.

Conclusions:

This case illustrates the imperative role of imaging surveillance in detection of long-term endovascular aneurysm repair complications. Furthermore, we discuss exclusion of the graft tear with aortouniiliac stent grafting as the treatment for this complication.

Type IIIb Endoleak and Relining

Purpose: To examine the changes in distraction force following relining of a conventional abdominal aortic stent-graft with a type IIIb endoleak using the Nellix endovascular sealing device compared to a unilateral stent-graft. Methods: Relining is often used to repair type IIIb endoleaks, but the consequences to graft stability are unknown. A mathematical model was constructed based on pressure and volume flow through the stent-grafts, incorporating recognized distraction force equations. Steady flow was presumed at peak systolic pressures to calculate the maximum distraction force, with gravity ignored. Distraction forces for 28- to 36-mm-diameter stent-graft bodies with 16-mm limbs were calculated and compared to forces following relining with single and double Nellix devices or the Renu unilateral device. Results: Distraction forces for the 28-, 32-, and 36-mm stent-grafts prior to relining were 5.99, 10.21, and 14.99 N, respectively. Similar forces were reported after relining with bilateral Nellix devices (5.86, 10.08, and 14.86 N, respectively). However, use of a unilateral Nellix increased the distraction forces to 9.92, 14.14, and 18.92 N, respectively. These were comparable to the increase observed after relining with a Renu unilateral stent-graft (9.87, 14.09, and 18.86 N, respectively). The proportional increase in distraction force for a unilateral relining ranged from 26% to 66%, with the greatest increase noted in the smaller diameter main bodies. Conclusion: Relining a stent-graft with a type IIIb endoleak using bilateral Nellix devices does not increase the distraction force. However, a unilateral Nellix device or the Renu system could theoretically increase the distraction force by up to 66%, potentially risking migration and type Ia endoleak. In clinical practice, these results suggest that a relining with bilateral Nellix may have benefits over the Renu unilateral stent-graft.

Late Type 3b Endoleak with an Endurant Endograft

Endovascular stent grafting with different commercially available stent graft systems is widely applied for the treatment of abdominal aortic aneurysms with high success rates in the current era. Various types of endoleaks are potential complications of the procedure. They usually occur in the early period. In this report, we present type 3b endoleak occurring 14 months after a successful endovascular abdominal aortic aneurysm repair with a Medtronic Endurant stent graft.

Hybrid repair of rare type IIIb endoleaks from an abdominal endograft: repeatedly undetected endoleaks

We report a rare case of massive type IIIb endoleaks from an abdominal endograft, which were difficult to diagnose and required hybrid repair (including open surgery). The patient had previously undergone three catheter interventions for type Ia and II endoleaks after abdominal endografting. However, the abdominal aortic aneurysm gradually enlarged and required hybrid treatment (including an open repair), to successfully perform aneurysmorrhaphy and additional endograft insertions for the massive type IIIb endoleaks.

Zenith Cook limb type IIIB endoleak causing aneurysm rupture five years after EVAR

Type III endoleaks are rare late complications of endovascular abdominal aortic aneurysm repair. The aneurysm sac is pressurised either through disconnection of modular components (type IIIA) or a defect in the graft fabric (type IIIB). We report the endovascular treatment of a ruptured infrarenal aortic aneurysm five years after elective endovascular abdominal aortic aneurysm repair caused by a type IIIB endoleak secondary to probable graft material erosion of the contralateral limb. This is the first report of a late aneurysm rupture caused by fabric defect in a Cook Zenith limb. The case highlights the potential serious consequences of minimal migration of the device and the importance of landing the proximal fixation in healthy aorta.

Type II endoleak after endovascular aneurysm repair (Br j surg 2013; 100: 1262-1270

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Repair of a complex post-EVAR type III endoleak using a chimney aortouniiliac stent graft and femorofemoral crossover bypass

Post-EVAR type III endoleaks present a particular challenge as they carry a significant risk of rupture. We present a case of an 81-year-old gentleman, 10 years post-EVAR, with complex type III endoleak with component separation that was successfully treated with a combination of left renal artery chimney, aortouniiliac stent grafting and femorofemoral crossover bypass.

A sutureless aortic stent-graft based on a nitinol scaffold bonded to a compliant nanocomposite polymer is durable for 10 years in a simulated in vitro model

PURPOSE

To physiologically test the durability of a sutureless aortic stent-graft based on nitinol bonded to polyhedral oligomeric silsesquioxane (POSS) and poly(carbonate-urea) urethane (PCU) for 10 years according to Food and Drug Administration guidelines.

METHODS

Aortic stent-grafts (n = 4) were tested in 37°C distilled water using simulated in vivo hydrodynamic pulse loading. After 400 million cycles, surface topography was assessed by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Dynamic compliance was measured using a pulsatile flow phantom. Mechanical and elastic properties were determined by stress-strain studies and elastic deformation tests. Dynamic scanning calorimetry (DSC) and thermomechanical analysis (TMA) were used to assess thermal resistance. Comparison was made with a zero-cycled control.

RESULTS

All stent-grafts successfully completed accelerated pulsatile fatigue at 94±14-mmHg pulse pressure. SEM images confirmed uniform surface topography without any fractures. FTIR showed increased intensity of -NHCO- bonds, but there was no significant sign of biodegradation. Tensile stress of fatigue-tested polymer compared favorably with the zero-cycled control at 50% to 500% strain (p = 0.69). At a mean pressure range of 60 to 120 mmHg, overall compliance of the fatigue-tested grafts was 3.48±1.27%mmHg(-1)×10(-2) with no significant difference compared to control (3.26±0.65%mmHg(-1)×10(-2); p = 0.47). DSC and TMA showed comparable thermotropic transition.

CONCLUSION

Simulated physiological in vivo hydrodynamic loading has no significant degradative effect on an innovative sutureless stent-graft made from POSS-PCU nanocomposite polymer. Sutureless technology incorporating nitinol stents proved to be robust, with no separation over an accelerated 10-year cycle, which may allow development of durable stent-grafts with better compliance.

Late type III endoleak from fabric tears of a zenith stent graft: report of a case

We report a case of late type III B endoleak from a fabric tear in the main body of a Zenith bifurcated stent-graft approximately 19 months after implantation. A follow-up computed tomography (CT) scan showed gradual growth in the size of the aneurysm, but no apparent endoleak was recognized. However, the CT scan had demonstrated a mosaic pattern in the aneurysm sac, which could indicate an endoleak from a fabric tear. The defect was repaired by implantation of body extensions, but the patient died 5 h after the procedure.

Early type III endoleak with an Endurant endograft

We report the case of an 81-year-old man who presented with an intraoperative type III endoleak after treatment with an Endurant endograft for a 60-mm abdominal aortic aneurysm. To our knowledge, this is the first case of a type III endoleak reported with this new device. It was most likely due to a tear in the polyester graft, the cause of which remains speculative. The tear was demonstrated by postoperative angiography, which was more informative than computed tomography. The endoleak was successfully treated by relining with an aorto-uni-iliac device.

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.

Endovascular device design in the future: transformation from trial and error to computational design

Endovascular devices have been designed by trial and error, with bench and animal testing followed by human clinical trials to determine whether the devices are safe and effective. Despite remarkable advances over the past 15 years, there are persistent concerns regarding the long-term durability of endovascular devices. This may be due to deficiencies in device design, which has lagged behind other industries in adopting computational methods that are now routinely used to design, develop, and test new aircraft and automobiles. Similar computational design and failure mode simulations that evaluate performance under stress conditions have not been widely applied in the development of endovascular devices. Advances in medical imaging and computational modeling now allow simulation of physiological conditions in patient-specific 3-dimensional vascular models, which can provide a framework to design and test the next generation of endovascular devices. This modeling will allow the prospective design of devices that can withstand the force variations in the cardiovascular system that occur during bending, coughing, and varying degrees of exercise, as well as the extremes encountered during sudden impact in contact sports. Utilization of computational design methodology that takes into consideration the physiology of the cardiovascular system will improve future endovascular devices so that they are safer and more effective and durable.