In-stent restenosis caused by a reprotruding calcified nodule and stent fracture in the hinged coronary artery.

Calcified nodules (CNs) cause in-stent restenosis (ISR) frequently. Although reprotrusion of CNs through stent struts is one of the mechanisms of ISR, the process of this phenomenon has not been understood. Furthermore, little is known about stent fracture (SF) occurring at the site of CNs. We are presenting a case of an 82-year-old male who developed early ISR due to the combination of an in-stent CN and SF in the hinged right coronary artery. The process of progression of the in-stent CN was recorded sequentially with angiography and intravascular ultrasound (IVUS). IVUS from the fulcrum of hinge motion revealed the repetitive protruding movement of the CN into the stent lumen.

Double-wire woven nitinol stent for treating dogs with refractory tracheal collapse: A case series.

This retrospective case series describes the signalments, clinical signs, diagnostic test results, and postoperative complications obtained from the medical records of 10 client-owned dogs that underwent treatment for grade IV tracheal collapse using double-wire woven nitinol stents between October 2017 and September 2021. Respiratory signs resolved in all dogs immediately after tracheal stent placement. Mild to moderate stent fractures were identified in five dogs, of which two showed concurrent respiratory distress necessitating re-stenting after several months. Minor complications, such as stent migration, were absent. The double-wire woven nitinol stent optimised for the canine trachea showed favourable outcomes and minimal complications.

Bare Stent Fracture After TEVAR With the Modified Restrictive Bare Stent (RBS) Technique in Type B Aortic Dissections.

PURPOSE: The aim was to assess the mid-term aortic remodeling and bare-metal stent (BMS) integrity of the restricted bare stent (RBS) technique reconstruction in aortic dissections. MATERIALS AND METHODS: This retrospective cohort study included prospectively collected patients treated with the modified RBS technique between 2017 and 2020. The preoperative, postoperative, and last follow-up computed tomographic (CT) scans were analyzed in the centerline at the mid-descending, celiac trunk (CeT), and the mid-abdominal levels for false lumen (FL) patency, aortic diameter, and true lumen (TL) diameter changes. Bare-metal stent integrity was assessed in the 3-dimensional multiplanar reformats. RESULTS: The median follow-up of the cohort (n=17) was 26 (11, 45) months. The procedure was mainly performed with the Relay NBS endograft (15/17; 88%) + E-XL BMS (17/17; 100%). Postoperative mortality, paraplegia, stroke, renovisceral vessel loss, and type I and III endoleaks were not observed. BMS fractured in 6 patients (6/17; 36%), damaged the dissection flap in 4/17 (24%), and led to the reperfusion of the FL and re-interventions with TEVAR (4/17; 24%). Two patients without FL reperfusion showed stable CT follow-ups 13 and 17 months after the fracture diagnosis. The TL expansion was seen at all landmarks and peaked in the thoracic aorta (+10; 6, 15; p<0.001). The FL thrombosis after modified RBS was only relevant in the thoracic aorta (p<0.001) and at CeT (p=0.003). The aortic diameter was stable in the thoracic aorta and increased at distal landmarks (CeT [+5; 1, 10; p=0.001]; mid-abdominal [+3; 1, 5; p=0.004]). CONCLUSION: The modified RBS technique could not stop aortic growth below the diaphragm and prevent new membrane rupture due to the fractures of the BMS and consecutive flap damage with the reperfusion of the FL. CLINICAL IMPACT: The treatment of complicated type B aortic dissections with TEVAR has become a standard. Particularly, patients with true lumen collapse and malperfusion may benefit from a more aggressive treatment strategy including proximal TEVAR and distal bare-metal stent implantation to re-open the true lumen and to prevent distal stent-induced new entry. However, this study reports the challenges of this approach with a high rate of bare-metal stent fractures during the follow-up. The fractures that occurred at the site of vertical nitinol bridges led to the dissection membrane ruptures and the reperfusion of the false lumen with consecutive dilatation. A close follow-up is mandatory to detect this complication and to treat the patients with TEVAR extension.

Fractured Sealing Rings in a Fenestrated Anaconda Stent-Graft.

An 81 year-old man presented with an asymptomatic juxtrarenal abdominal aortic aneurysm and was subsequently treated with a fenestrated endovascular Anaconda stent-graft. Surveillance imaging within the first postoperative year demonstrated a lower proximal sealing ring fracture. In the second postoperative surveillance year, the upper proximal sealing ring was also fractured with extension of the wire into the right paravertebral space. Despite these sealing ring fractures, there were no endoleak nor visceral stent complications and the patient continued on standard surveillance protocols. There are an increasing number of reports of fractured proximal sealing rings with the fenestrated Anaconda platform. Those analysing the surveillance scans of patients treated with this device should stay vigilant for the development of this complication.

Treatment of stent rupture after endovascular treatment of superior mesenteric aneurysm with open surgery.

BACKGROUND: The progress of visceral artery aneurysms (VAAs) after the endovascular repair of artery aneurysms is often accompanies by the potential risks of stent fracture. The clinical reported cases of VAAs stent fractures with stent displacement were extremely rare but severe complication, particularly for the superior mesenteric artery aneurysm (SMAA). METHOD: We here reported a 62-year-old female patient with recurrent symptoms of SMAA 2 years after the successful endovascular repair using coil embolization and two partial overlapping stent-grafts in SMAA. The open surgery was performed instead of secondary endovascular intervention. RESULT AND CONCLUSION: The patient experienced a good recovery. As one of the complications after endovascular repair, stent fracture maybe more dangerous than SMAA itself, the stent fracture after endovascular repair treated by open surgery with satisfactory results is alternative and feasible.

Bridging stent graft fracture after branched endovascular aortic repair in a dual-center retrospective cohort study.

OBJECTIVE: Target vessel instability is a relevant complication after thoracoabdominal aortic aneurysms branched endovascular aortic repair (BEVAR). Long-term bridging stent graft (BSG) durability has already been established, but the incidence of long-term complications as component fractures was not deeply investigated. This paper aims to assess BSG fracture incidence and risk factors after BEVAR. METHODS: This was a dual-center observational retrospective cohort study. Data of each patient treated with BEVAR between April 2008 and December 2019 were prospectively collected. The primary outcome was the incidence of BSG fracture during follow-up. A logistic regression analysis was performed, including preoperative and postoperative measurements as well as intraoperative details to identify potential risk factors. RESULTS: Two hundred ninety-five target visceral vessels in 91 patients were considered suitable for cannulation. Technical success was 96.9% (286/295 target visceral vessels). The median follow-up was 32.5 months (interquartile range, 14.3-50.1 months). Five BSG fractures (1.75%; 5/286) were detected. Four BSG fractures involved the superior mesenteric artery, and one the celiac trunk. Four different types of fractured stents were detected during follow-up: two Advanta, one BeGraft, one Fluency, and one Viabahn. The median time to BSG fracture was 28.2 months (interquartile range, 11.7-50.8 months). The use of multiple stents (P = .030) and different stent types on the same vessel (P = .004) were associated with BSG fracture at univariable analysis. Using bare-metal stents for distal relining (P = .045) was the only significant factor predisposing to BSG fracture at multiple logistic regression. CONCLUSIONS: BSG fracture is a rare but severe complication after BEVAR. It is not related to the stent type used as bridging stent, and it is hardly predictable based on preoperative anatomy. Using multiple and different stents on the same vessel and relining the bridging stents with bare-metal stents may increase BSG fracture risk. A strict computed tomography angiography follow-up remains the best strategy to detect target vessel instability.

Coronary Stent Fracture Causing Myocardial Infarction: Case Report and Review of Literature.

Coronary stent fracture (SF) is a potential cause of stent failure increasing the risk for in-stent restenosis, stent thrombosis, target lesion revascularization and major adverse cardiac events. Overall incidence of SF ranges from < 1.0% up to 18.6% and SF can be found in up to 60% of failed devices. Advanced imaging techniques have improved the detection of SF. However, defining the optimal therapeutic approach towards these complex lesions is challenging. This review summarizes the most important publications on the topic of SF and discusses current insights into pathophysiology, diagnostic tools, classification and therapeutic management. Furthermore, two illustrative cases of SF leading to myocardial infarction are presented, which demonstrate typical SF risk factors such as vessel angulation and hinge motion, stenting in the right coronary artery, use of long stents and multiple stent layers.

First Case of Nellix Stent Rupture in a Huge Symptomatic Abdominal Aortic Aneurysm Who Underwent Endovascular Aneurysm Sealing 7 Years Before.

PURPOSE: Despite encouraging early results, mid- and long-term follow-up of endovascular aneurysm sealing (EVAS) has shown increased rates of failure mainly associated with endoleak detection and progressive bag separation with aneurysm reperfusion. CASE REPORT: We present the first case of a Nellix endograft stent fracture detected in a 91-year-old male patient, presenting with widespread abdominal pain, 7 years after elective treatment of an abdominal aortic aneurysm by EVAS. Considering the sudden and unexpected nature of the event, an in-depth analysis of the possible causes of this structural failure has been performed. CONCLUSION: Material fatigue could be another significant cause of late EVAS failure and should be carefully assessed in addition to endoleak detection during follow-up. CLINICAL IMPACT: The case presented in this article further underlines the importance of a strict long term follow-up protocol in every patients who underwent EVAS.

Surgical treatment of a giant right coronary aneurysm following coronary stent fracture.

BACKGROUND: Coronary artery aneurysm represents a challenging and potentially fatal disease. AIM AND MATERIAL METHODS: We present the case of a giant right coronary artery aneurysm treated surgically after percutaneous intervention and fracture of the stent. RESULTS AND DISCUSSION: The aneurism was opened and the coronary ligated proximally and distally. It was not possible to re-established continuity of the coronary artery or perform a bypass graft. An early surgical strategy would have re-established blood flow in the involved coronary artery and avoided chronic ischemia of the supplied myocardial territory.

Fatigue Resistance of the Advanta V12/iCast and Viabahn Balloon-Expandable Stent-Graft as Bridging Stents in Experimental Fenestrated Endografting.

PURPOSE: Bridging stents undergo millions of cycles during respiratory movements of the kidneys throughout the patient's life. Thus, understanding the response of fabric and endoskeleton of the stent to cyclic loading over the time is crucial. In this study, we compare the fatigue resistance of the Viabahn Balloon-Expandable stent-graft (VBX) with the widely used Advanta V12/iCast under prolonged stress induction. MATERIALS AND METHODS: A polyester test sheet with 10 fenestrations was used simulating a fenestrated endograft. Five 6×59 mm VBX stent-grafts and five 6×58 mm Advanta stent-grafts were implanted into 6×6 mm fenestrations. The stents were flared with a 10×20 mm PTA (percutaneous transluminal angioplasty) catheter and connected with a fatigue stress machine. All stent-grafts were evaluated by microscopy and radiography at baseline and after regular intervals until 50,000,000 cycles were applied, simulating a life span of approximately 75 months. Freedom from fracture (FF), freedom from initial polytertafluoroethylene (PTFE) changes (FIC), and from PTFE breakpoint (FBP, all-layer defect) were calculated. RESULTS: Digital radiographic images did not show any stent fracture in both groups after 50,000,000 cycles. The VBX stent-graft was free from any all-layer defects at the conclusion of 50,000,00 cycles resulting in a significant higher FBP compared with Advanta V12 (50,000,000 vs 33,400,000; p<0.01). All-layer defects were observed only in the Advanta group. Two of 5 Advanta stents showed early penetration of the nitinol ring causing a defect of PTFE. Regarding FIC, there was no significant difference between the stents (3,400,000 in VBX vs 3,200,000 in Advanta). CONCLUSIONS: In fatigue tests simulating respiration movements, VBX and Advanta V12 performed equally well in terms of fracture resistance and freedom from initial PTFE changes. VBX maintained freedom from PTFE breakpoint throughout the full 50,000,000 cycles. All-layers defects were detected only in Advanta and were mainly caused by penetration of the nitinol ring through the PTFE.

Stent-Graft Relining Using the Altura Endograft for Type Ia and IIIb Endoleaks after Kissing Iliac Arteries Stent.

A 79 years old man, affected by serious comorbidities, occurred to the Emergency Room of our Hospital complaining abdominal pain. He was previously submitted to kissing iliac arteries stent for iliac aneurysms. An urgent CT scan showed a type Ia and a type IIIb endoleaks with left common iliac artery enlargement, occlusion of both hypogastric arteries and inferior mesenteric artery, and a severe stenosis of the right iliac external artery. We opted for a relining with a two-piece D-shaped Altura endograft for the aorta, with bilateral iliac components, landing at the level of the external iliac arteries. Postoperative course was uneventful with no endoleak or endograft migration on CT scan control at 6 months.

Treatment of complex atherosclerotic femoropopliteal artery disease with a self-expanding interwoven nitinol stent: Midterm results.

OBJECTIVE: To examine the efficacy and durability of an interwoven self-expanding nitinol stent for the treatment of superficial femoral and popliteal arteries. METHOD: Consecutive patients with severely diseased superficial femoral and popliteal arteries who received SUPERA® stents were retrospectively identified.The patients were followed for 12 months by Doppler ultrasound examinations, stent roentgenograms, and estimation of Rutherford-Becker class and ankle-brachial index. RESULTS: From July 2012 to May 2014, 42 limbs in 36 patients (mean age, 61.5 ± 7.5 years; 75% male) were treated with angioplasty and primary stenting. Total occlusions were present in 14 limbs, and 63.8% had either moderate or severe calcification. The mean (±SD) lesion length was 105 mm (±28). Primary patency was 91.4% at 6 months and 85.7% at 12 months. The ankle brachial index increased from 0.57 ± 0.19 preoperative to 0.91 ± 0.12 postoperative. There was no procedural or device-related morbidity or mortality after revascularization and only one major amputation was observed on follow-up. CONCLUSIONS: Our experience shows that, Supera stents are safe and effective in our cohort of patients, with acceptable patency rates. There were no stent fractures so far even with stenting of the femoropopliteal segments. Stent design provides a viable option for high-grade obstructive disease in the femoropopliteal artery.

The incidence and risk factors of stent fracture in patients treated for proximal common carotid artery stenosis.

OBJECTIVE: Our aim was to identify the incidence of and predictors for common carotid artery (CCA) stent fractures (SFs) and to examine the effect of SFs on the development of in-stent restenosis (ISR). METHODS: Seventy patients (37 women; median age, 60.9 years) who were stented for significant (≥60%) proximal CCA stenosis from 2006 to 2016 and revisited us to determine SF using fluoroscopy in 2018 were evaluated. Seventy stents were deployed; among them 87.1% were balloon-expandable and 12.9% were self-expandable. SFs were classified as type I (fracture of one strut), type II (fracture of multiple struts without stent deformity), type III (fracture of multiple struts with stent deformity), type IV (complete fracture of the stent without a gap), and type V (complete fracture of the stent with a gap). Duplex ultrasound examination was used for monitoring stent patency. Mann-Whitney U and Fisher's exact tests, Kaplan-Meier and logistic regression analyses, and a log-rank test and a gamma correlation analysis were applied as statistical methods. RESULTS: The patients were followed for 75.5 months (range, 47-109 months). Significant (≥70%) ISR was observed in eight patients (11.4%). Reintervention was performed in four cases (5.7%). Twenty-seven SFs (38.6%; type I, 8; type II, 10; type III, 4; type IV, 2; and type V, 3) were found. Calcification was shown to be a significant predictor for SF (odds ratio, 13.2; 95% confidence interval, 3.9-45.1; P < .001). There was no significant difference between the fractured and the nonfractured group regarding the number of patients with ISR and reintervention (P = .701 and P = .636, respectively). Neither did the primary patency rates differ significantly (P = .372) in patients with and without SF. CONCLUSIONS: Fractures frequently occur in a wide variety of stent devices deployed in the proximal CCA, but SFs seem to have no effect on ISR and reintervention.

A case of AndraStent® fracture in a patient with aortic coarctation: a review of the literature.

Percutaneous treatment of aortic coarctation is based on angioplasty and/or stenting of the isthmus. We report a case of a 28-year-old girl suffering from aortic coarctation syndrome (coarctation + ventricular septal defect + bicuspid aorta). She underwent coarctectomy with subclavian flap and pulmonary bandage followed by ventricular septal defect closure and bandage removal in her first year of life. When she was 27 years old, a follow-up echocardiography detected an isthmic pressure gradient and a demodulated Doppler in abdominal aorta. A cardiac catheterisation confirmed the diagnosis of aortic re-coarctation. An AndraStent® XL 48 mm was implanted with a resolution of the isthmic gradient. One year later, because of the reappearance of demodulated Doppler in abdominal aorta, a chest X-ray was performed, which showed a stent third-grade fracture. The fracture was corrected by positioning a covered stent cheatham platinum 45 mm through the fragments. The rarest complication after stenting procedures is the fracture of the device with an incidence between 0.01% and 0.08%. Pressure overload beyond the elastic threshold of the material and the pulsatile tension exerted by the blood flow on the walls of the stent are the main mechanisms at the base of the fracture, together with the compliance of the tissue. A vessel that underwent multiple surgical rearrangements could interfere with and complicate the physiopathology at the basis of the fracture. In conclusion, stenting is a safe technique to treat aortic coarctation; stent fracture is a rare event, and different anatomical and haemodynamic factors are related to this complication.

Carotid Stent Fractures Are Not Associated With Adverse Events: Results From the ACT-1 Multicenter Randomized Trial (Carotid Angioplasty and Stenting Versus Endarterectomy in Asymptomatic Subjects Who Are at Standard Risk for Carotid Endarterectomy With Significant Extracranial Carotid Stenotic Disease).

BACKGROUND: The impact of carotid artery stent fractures on the incidence of adverse clinical events remains unclear. The objective of this study is to report the stent fracture rate and its association with in-stent restenosis and adverse outcomes in the ACT-1 trial (Carotid Angioplasty and Stenting Versus Endarterectomy in Asymptomatic Subjects Who Are at Standard Risk for Carotid Endarterectomy With Significant Extracranial Carotid Stenotic Disease). METHODS: ACT-1 is a prospective multicenter trial of patients who have standard surgical risk with severe asymptomatic carotid artery stenosis randomly assigned to carotid artery stenting or carotid endarterectomy (Abbott Vascular). The primary end point was a composite of death, stroke, or myocardial infarction during the 30 days after the procedure or ipsilateral stroke during the 365 days after the procedure. After 771 patients were enrolled, successively randomly assigned patients were required to undergo annual radiographic (x-ray) analysis for stent fracture. Images were independently adjudicated by a core laboratory. RESULTS: Of 1021 patients treated with carotid artery stenting during a mean follow-up of 3.1±1.6 years, 939 had at least 1 x-ray during the follow-up period. Stent fracture was reported in 51 (5.4%) patients. With a maximum follow-up period of 5 years, adverse clinical outcomes occurred in 39 patients with at least 1 x-ray during the follow-up. Of 826 (80.9%) subjects who underwent both duplex ultrasound and x-ray, 822 (99.5%) were interpretable. There was no association between stent fracture and the primary end point (P=0.86) or with restenosis (P=0.53). CONCLUSIONS: In this large, independently adjudicated, multicenter study, the stent fracture rate was low and not associated with major adverse clinical events or in-stent restenosis. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00106938.

The presence of long and heavily calcified lesions predisposes for fracture in patients undergoing stenting of the first part of the subclavian artery.

OBJECTIVE: To determine the prevalence and risk factors of subclavian artery stent fractures and to investigate their impact on in-stent restenosis development. METHODS: One hundred eight patients (65 females; median age, 58.3 years [interquartile range, 53.4-65.5 years]) with steno-occlusive disease of the first part of the subclavian artery who underwent stenting (N = 108 stents; balloon-expandable, 83.3%; self-expandable, 16.7%) between 2005 and 2015 and returned for a fluoroscopic examination of the implanted stents in 2017 were included in our study. Fractures were type I (single strut fracture), type II (multiple strut fractures without deformation), type III (multiple strut fractures with deformation), type IV (multiple strut fractures with acquired transection but without gap), or type V (multiple strut fractures with acquired transection with gap in the stent body). Stent patency was monitored by duplex ultrasound imaging. The Mann-Whitney U and Fisher's exact tests; Kaplan-Meier, receiver operating characteristic, and logistic regression analyses; as well as a log-rank test were used as statistical methods. RESULTS: The median follow-up was 73.8 months (interquartile range, 35.6-104.2 months). Thirty-eight fractures (35.2%) were detected; fractures were type I in 13, type II in 12, type III in 6, type IV in 4, and type V in 3 cases. Multivariable logistic regression analysis revealed the presence of long (≥20 mm) lesions (odds ratio, 3.3; 95% confidence interval, 1.3-8.4; P = .012) and heavy calcification (odds ratio, 4.7; 95% confidence interval, 1.7-12.7; P = .002) to be significant independent predictors of stent fracture. The primary patency rates were significantly worse (P = .035) in patients with stent fracture compared with those without stent fracture. CONCLUSIONS: Stent fractures frequently occur. Patients with long and/or heavily calcified lesions require closer follow-up.

SAPIEN valve for percutaneous transcatheter pulmonary valve replacement without "pre-stenting": A multi-institutional experience.

OBJECTIVES: To describe a multicenter experience of percutaneous transcatheter pulmonary valve replacement (TPVR) using the Edwards SAPIEN S3 valve without the use of a prior stent ("pre-stenting"). BACKGROUND: The SAPIEN S3 and XT valves have durable cobalt-chromium stent frames which may allow for TPVR in large diameter dysfunctional right ventricular outflow tracts (RVOTs) without pre-stenting the landing zone. METHODS: A retrospective review was performed of all patients with Congenital Heart Disease and dysfunctional RVOT who underwent TPVR using the SAPIEN valve without the use of a pre-stent. Imaging data, procedural elements, and clinical follow-up data were collected to evaluate short and intermediate-term results. RESULTS: Fifty-seven patients underwent percutaneous placement of the SAPIEN valve in the pulmonary position without the use of pre-stenting. The anatomical substrate varied: native RVOTs (n = 41), conduits (n = 10), and bioprosthetic valves (n = 6). There were no cases in which the valve could not be implanted and no cases of valve embolization or misplacement. On follow-up (range 1 month to 2.2 years, median 5.3 months), no patients had significant obstruction or regurgitation around the valve. There were no frame fractures. There were no procedural deaths. Major complications included severe aortic compression (n = 1) requiring surgical explantation and tricuspid valve injury requiring surgical intervention (n = 2). CONCLUSIONS: This limited multi-institutional experience demonstrates that the SAPIEN valve can be used for TPVR without the use of a pre-stent without medium-term risk of frame fracture, paravalvar leak, or embolization. Longer term follow-up is required to fully assess this method.

An Animal Model of Human Peripheral Arterial Bending and Deformation.

BACKGROUND: Designing peripheral arterial stents has proved challenging, as implanted devices will repetitively and unpredictably deform and fatigue during movement. Preclinical testing is often inadequate, given the lack of relevant animal models. The purpose of this study was to test the hypothesis that deformation of the human peripheral vasculature could be qualitatively and quantitatively modeled using an experimental animal. METHODS: Anteroposterior contrast angiography was performed in domestic Landrace-Yorkshire farm pigs. Images were obtained with the hind limbs naturally extended then repeated, (1) flexed approximately 90° at the hip and knee, (2) overflexed in a nonphysiological fashion. Quantitative vascular angiographic analysis was utilized to measure arterial diameter, length, and deformation. Percent axial arterial compression and bending were assessed. RESULTS: Eight iliofemoral arteries in four animals were imaged. Mean luminal diameters of the iliac and femoral segments in the neutral position were 5.4 ± 0.5 mm and 4.6 ± 0.5 mm. Hind limb physiologic flexion induced profound arterial compression, 17 ± 8% and 29 ± 6% and bending, 36°±10° and 76° ± 13° within the iliac and femoral segments, respectively. With extreme flexion, the femoral artery could be reliably bent >90°. The observed findings exceeded the deformation observed historically within the human superficial femoral (∼5% compression and 10° bending) and popliteal artery (∼10% compression and 70° bending). CONCLUSIONS: Significant nonradial deformation of the porcine iliofemoral arteries was observed during manual hind limb flexion and exceeded that typically observed in humans. This model constitutes a "worst case" scenario for testing deformation and fatigue of intravascular devices indicated for the human peripheral vasculature.

In Vitro Evaluation of the Gore Viabahn Balloon-Expandable Stent-Graft for Fenestrated Endovascular Aortic Repair.

PURPOSE: To evaluate the safety and integrity of a new stent-graft as a potential bridging device in fenestrated stent-grafts using an in vitro fenestrated model. MATERIALS AND METHODS: Polyester test sheets with ten 6-mm- or 8-mm-diameter fenestrations were used to simulate a fenestrated main body endoprosthesis. In total, 50 Viabahn balloon-expandable (VBX) stent-grafts of varying lengths (29 and 39 mm) and diameters (6, 7, and 8 mm) were implanted in the fitting fenestrations. After release, the 6- and 7-mm-diameter stent-grafts were flared with a 10×20-mm angioplasty balloon; a 12×20-mm balloon was used in the 8-mm-diameter devices. Safety of the devices was defined as absence of fractures detected on radiography or computed tomography (CT), as well as material failure detected by microscopy and water permeability testing. The forces (in Newtons, N) needed for perpendicular dislocation (pullout force) and axial dislocation (shear stress force) were also evaluated. RESULTS: Forty VBX stent-grafts were subjected to digital radiographic imaging and multiplanar CT. None showed any stent fracture. Subsequent microscopy indicated no damage to the fabric or separation of the graft after flaring. Ten VBX stent-grafts underwent water permeability testing after flaring; no water passed through the graft wall during a 10-minute period under an intraluminal pressure at 120 mm Hg. Testing of 25 VBX stent-grafts revealed initial pullout forces between 11.3 and 31 N. Shear stress tests showed that the average force needed to dislocate the stent-grafts by 50% of their diameter ranged between 5.75 and 6.91 N (mean 6.1±0.5 N) for the 6-mm stents and between 3.31 and 5.4 N (mean 4.4±0.8) for the 8-mm stents. CONCLUSION: This preliminary study demonstrated the applicability of the VBX as a bridging stent-graft in a simulated fenestration model. A comparison with other stent-grafts and clinical assessment are required.