Self-expanding Device Research Articles

Fabrication of self-expandable NiTi thin film devices with micro-electrode array for bioelectric sensing, stimulation and ablation.

Self-expandable medical devices provide mechanical functionality at a specific location of the human body and are viable for minimal invasive procedures. Besides radiopaque markers and drug-eluting coatings, next generation self-expandable devices can be equipped with additional functionality, such as conductive and flexible electrodes, which enables chronic recording of bioelectrical signals, stimulating or ablating tissue. This promises new therapeutic options in various medical fields, among them in particular neuromodulation (e.g. deep brain stimulation), BioMEMS, radio frequency ablation, mapping or denervation. However, the fabrication of such multi-functional devices is challenging. For this study we have realized a 35μm thick, superelastic NiTi thin film stent structure with six isolated electrodes on the outer circumference, each electrode connected to a contact pad at the end of the stent structure, using magnetron sputtering, UV lithography and wet chemical etching. Mechanical and electrical properties of the device during typical loading conditions, i.e. crimping, simulated pulsatile and electrochemical testing, were characterized and reveal promising results. For the fabrication of future multifunctional, minimal invasive medical devices, such as electroceuticals or other intelligent implants, NiTi thin film technology is therefore a versatile alternative to conventional fabrication routes.

Efficacy of a Self-expanding Tract Sealant Device in the Reduction of Pneumothorax and Chest Tube Placement Rates After Percutaneous Lung Biopsy: A Matched Controlled Study Using Propensity Score Analysis.

To evaluate the use of a self-expanding tract sealant device (BioSentry™) on the rates of pneumothorax and chest tube insertion after percutaneous lung biopsy. In this retrospective study, we compared 318 patients who received BioSentry™ during percutaneous lung biopsy (treated group) with 1956 patients who did not (control group). Patient-, lesion-, and procedure-specific variables, and pneumothorax and chest tube insertion rates were recorded. To adjust for potential selection bias, patients in the treated group were matched 1:1 to patients in the control group using propensity score matching based on the above-mentioned variables. Patients were considered a match if the absolute difference in their propensity scores was ≤equal to 0.02. Before matching, the pneumothorax and chest tube rates were 24.5 and 13.1% in the control group, and 21.1 and 8.5% in the treated group, respectively. Using propensity scores, a match was found for 317 patients in the treatment group. Chi-square contingency matched pair analysis showed the treated group had significantly lower pneumothorax (20.8 vs. 32.8%; p=0.001) and chest tube (8.2 vs. 20.8%; p<0.0001) rates compared to the control group. Sub-analysis including only faculty who had >30 cases of both treatment and control cases demonstrated similar findings: the treated group had significantly lower pneumothorax (17.6 vs. 30.2%; p=0.002) and chest tube (7.2 vs. 18%; p=0.001) rates. The self-expanding tract sealant device significantly reduced the pneumothorax rate, and more importantly, the chest tube placement rate after percutaneous lung biopsy.

First Experiences with the New Enterprise2® Stent

Stent-assisted coiling of wide-necked intracranial aneurysms has become an established treatment and has significantly benefited from the introduction of compliant, self-expanding devices, such as the Enterprise VRD (EP-VRD). We report our experiences with the successor model, the Enterprise2 (EP2) stent in stent-assisted coiling as well as in the treatment of atherosclerotic stenosis. In 11 consecutive patients 12EP2 were used to treat 9 intracranial aneurysms and 2 stenoses. All stents could easily be delivered including partial or complete recapturing when necessary. In two cases with sharp angled curves in the carotid siphon there was kinking and flattening of the stent resulting in incomplete wall apposition of the stent. Moreover, when vascular anatomy showed curves with angles >50° it was regularly observed that the proximal stent markers were asymmetrically arranged along the vessel circumference without influence on the stent apposition. Both findings could be reproduced in asilicone flow model. The EP2 performed well in our small patient cohort; however, above acritical acute angle there may be incomplete wall apposition of the stent.

Spring-mediated distraction enterogenesis in-continuity

PurposeDistraction enterogenesis has been investigated as a novel treatment for patients with short bowel syndrome (SBS) but has been limited by loss of intestinal length during restoration and need for multiple bowel surgeries. The feasibility of in-continuity, spring-mediated intestinal lengthening has yet to be demonstrated. MethodsJuvenile mini-Yucatan pigs underwent in-continuity placement of polycaprolactone (PCL) degradable springs within jejunum. Methods used to anchor the spring ends to the intestine included full-thickness sutures and a high-friction surface spring. Spring constant (k) was 6–15N/m. Bowel was examined for length and presence of spring at 1 to 4weeks. ResultsAnimals tolerated in-continuity lengthening without bowel obstruction for up to 29days. In-continuity jejunum with springs demonstrated intestinal lengthening by 1.47-fold ±0.11. Five springs had detached prematurely, and lengthening could not be assessed. Histologically, in-continuity jejunum showed significantly increased crypt depth and muscularis thickness in comparison to normal jejunum. ConclusionSelf-expanding endoluminal springs placed in continuity could lengthen intestine without obstruction in a porcine model. This is the first study showing safety and efficacy of a self-expanding endoluminal device for distraction enterogenesis. This is proof-of-concept that in-continuity spring lengthening is feasible and demonstrates its therapeutic potential in SBS. Level of evidenceLevel 3.

Correlation of CoreValve implantation ‘true cover index’ with short and mid-term aortic regurgitation: A novel index

Background‘Cover index’ has been proposed to appraise the congruence between the aortic annulus and the device, with the assumption of not taking into account the actual device implantation depth. The aim of this study was to investigate whether the annulus–prosthesis mismatch, as expressed with the new proposed ‘true cover index’ according to actual implantation depth, can predict aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI). MethodsPatients who had undergone TAVI with the self-expandable CoreValve device, were retrospectively studied. All available prosthesis sizes were ex-vivo scanned and the precise diameter at 0.3mm intervals along each device was measured. The ‘true cover index’ was evaluated, as a ratio of the following: 100×([prosthesis actual diameter at implantation depth−annulus diameter]/prosthesis actual diameter at implantation depth). AR was echocardiographically evaluated at discharge and 30days and classified as prominent if moderate, or trivial if none or mild. ResultsOverall, 120 patients who had undergone TAVI, were considered eligible for the study. ‘True cover index’ was statistically significantly lower among patients with prominent AR in comparison with trivial AR at discharge (5.7±4.8mm vs 9±5.1, p=0.025), as well as at one month post-TAVI (5.4±5.1mm vs 9.0±5.1, p=0.023), indicating increased AR for smaller index. After adjustment for severe annulus calcification, impaired baseline LVEF and previous valvuloplasty, it remained an independent predictor of one month prominent AR (OR: 0.854, CI: 0.730–0.999; p=0.048). ‘True cover index’ of <4.3 was shown to predict one-month prominent AR with sensitivity =75% and specificity =82.5%. Conclusions‘True cover index’ is strongly and independently correlated with the short and mid-term AR after CoreValve implantation.

Comparative Outcomes of Balloon, Mechanical and Self-expanding Devices in Transcatheter Aortic Valve Replacement

Comparative Outcomes of Balloon, Mechanical and Self-expanding Devices in Transcatheter Aortic Valve Replacement

Mechanical behavior of peripheral stents and stent-vessel interaction: A computational study

ABSTRACTIn this paper stents employed to treat peripheral artery disease are analyzed through a three-dimensional finite-element approach, based on a large-strain and large-displacement formulation. Aiming to evaluate the influence of some stent design parameters on stent mechanics and on the biomechanical interaction between stent and arterial wall, quasi-static and dynamic numerical analyses are carried out by referring to computational models of commercially and noncommercially available versions of both braided self-expandable stents and balloon-expandable stents. Addressing isolated device models, opening mechanisms and flexibility of both opened and closed stent configurations are numerically experienced. Moreover, stent deployment into a stenotic peripheral artery and possible postdilatation angioplasty (the latter for the self-expandable device only) are simulated by considering different idealized vessel geometries and accounting for the presence of a stenotic plaque. Proposed results highlight important differences in the mechanical response of the two types of stents, as well as a significant influence of the vessel shape on the stress distributions arising upon the artery-plaque system. Finally, computational results are used to assess both the stent mechanical performance and the effectiveness of the stenting treatment, allowing also to identify possible critical conditions affecting the risk of stent fracture, tissue damage, and/or pathological tissue response.

Magnetic Resonance Imaging-Guided Transcatheter Cavopulmonary Shunt.

The aim of this study was to test the hypothesis that real-time magnetic resonance imaging (MRI) would enable closed-chest percutaneous cavopulmonary anastomosis and shunt by facilitating needle guidance along a curvilinear trajectory, around critical structures, and between a superior vena cava "donor" vessel and a pulmonary artery "target." Children with single-ventricle physiology require multiple open heart operations for palliation, including sternotomies and cardiopulmonary bypass. The reduced morbidity of a catheter-based approach would be attractive. Fifteen naive swine underwent transcatheter cavopulmonary anastomosis and shunt creation under 1.5-T MRI guidance. An MRI antenna-needle was advanced from the superior vena cava into the target pulmonary artery bifurcation using real-time MRI guidance. In 10 animals, balloon-expanded off-the-shelf endografts secured a proximal end-to-end caval anastomosis and a distal end-to-side pulmonary anastomosis that preserved blood flow to both branch pulmonary arteries. In 5 animals, this was achieved with a novel, purpose-built, self-expanding device. Real-time MRI needle access of target vessels (pulmonary artery), endograft delivery, and superior vena cava shunt to pulmonary arteries were successful in all animals. All survived the procedure without complications. Intraprocedural real-time MRI, post-procedural MRI, x-ray angiography, computed tomography, and necropsy showed patent shunts with bidirectional pulmonary artery blood flow. MRI guidance enabled a complex, closed-chest, beating-heart, pediatric, transcatheter structural heart procedure. In this study, MRI guided trajectory planning and reproducible, reliable bidirectional cavopulmonary shunt creation.

Transapical Transcatheter Aortic Valve Implantation in Pure Aortic Regurgitation: Midterm Outcomes

Objectives: Recently, we evaluated the self-expandable ACURATE-TA device (Symetis S.A., Ecublens, Switzerland) in patients with pure aortic regurgitation. As current experience with transcatheter aortic valve implantation (TAVI) in this specific entity is limited, we aimed to analyze the fate of the aortic annulus as well as the implanted self-expandable prosthesis in the mid-term.

Undescribed Anatomical Predictors of Vascular Injury after Fully-Percutaneous Trans Femoral Trans Catheter Aortic Valve Implantation

Abstract Background: Vascular injury (VI) remains frequent after trans catheter aortic valve implantation (TAVI). We aimed to assess the incidence, predictive factors, and the impact of early VI after fully-percutaneous (FP) TAVI. Method: We included a total of 139 consecutive patients who underwent FP transfemoral TAVI in our institution with 14 to 18Fr sheath systems, through right (119, 85.6%) or left (20, 14.4%) femoral arteries. VI was classified as mayor or minor according to VARC-2 definitions. In hospital data were prospectively collected. Follow-up was available for all patients. Reassessment of femoral artery anatomy as determined by computed tomography was performed including lumen diameters, calcification, tortuosity, height of femoral bifurcation and marked collateral circulation around common femoral artery. Results: Mean age was 81 ± 6.5, 54% were men, logEuroSCORE were 13.9 ± 7.9 and STS-score was 6.3 ± 4.9. Balloon-expandable and self-expandable devices were used in 14 (10.1%) and 125 patients (89.9%), respectively. Mayor and minor VI were observed in 25 (18%) and in 20 patients (14.3%) respectively, 20 of them due to suboptimal femoral closure (80% of major VI occurring in the first half of the learning curve). Lower platelet count (p=0.043), higher calcification of aortic valve (p=0.049), presence of femoral collaterals (OR=4.5, [95% CI: 1.6-12.9], p=0.005), height of femoral bifurcation (OR=14.5, [95% CI: 5.0-42.1], p<0.001), and failed femoral closure (OR=21.3, [95% CI: 4.5-101.4], p<0.001) were associated to higher rate of VI. The median length of hospitalization was 11.6 days [IQR: 7-14], (15.7 days [IQR: 8-19] in the VI cohort, p<0.001). VI was associated to higher in hospital mortality (13.3 vs. 2.1%, p=0.014). Conclusion: In patients who underwent FP TAVI, the rate of VI is still high and associated to worse outcomes. A high common femoral artery bifurcation and the presence of collaterals, especially if associated to other concomitant predisposing factors for VI, should be handled with special care and surgical access may be considered.

Optimization Of The Fatigue Resistance Of Nitinol Stents Through Shot Peening

“Nitinol” (NiTi) is an intermetallic alloy of approximately equal atomic percentages of nickel and titanium that is widely used in less invasive and self-expanding implantable medical devices such as cardiovascular stents, due to its superelastic, shape memory and biocompatibility properties. Most of its applications in the medical industry involve the application of repeated stresses or strain cycles that drive the need of increasing the fatigue and fracture resistance of this alloy. The Nitinol stent supporting a biological heart valve prosthesis is considered one such example and is the critical structural component in many of the heart valve prostheses. Continuous effort is made to increase the fatigue resistance of these cardiac devices through experimenting with various manufacturing and surface treatment techniques. This study proves that the shot peening (SP) process improves the fatigue resistance of Nitinol stents and also describes the effect of different peening intensities on the treated surfaces, through the application of the Almen test.

Prediction of patient-specific post-operative outcomes of TAVI procedure: The impact of the positioning strategy on valve performance

Prosthesis positioning in transcatheter aortic valve implantation procedures represents a crucial aspect for procedure success as demonstrated by many recent studies on this topic. Possible complications, device performance, and, consequently, also long-term durability are highly affected by the adopted prosthesis placement strategy. In the present work, we develop a computational finite element model able to predict device-specific and patient-specific replacement procedure outcomes, which may help medical operators to plan and choose the optimal implantation strategy. We focus in particular on the effects of prosthesis implantation depth and release angle. We start from a real clinical case undergoing Corevalve self-expanding device implantation. Our study confirms the crucial role of positioning in determining valve anchoring, replacement failure due to intra or para-valvular regurgitation, and post-operative device deformation.

PERCUTANEOUS LEFT ATRIAL APPENDAGE OCCLUSION : INITIAL EXPERIENCE WITH THE ARTICULATED ULTRASEPT LAA OCCLUDERTM

We report the first series of left atrial appendage (LAA) occlusion with the (USLO) UltraSeptTM LAA Occluder (Cardia Inc, Eagen, MN), a novel device specifically designed to mitigate implantation challenges such as acute angulation and misizing. The USLO is a self-expanding device made of connecting nitinol wires creating a bulb and a sail. The bulb features 6 pairs of hooks and serves as the anchor in the LAA neck; the sail is made of several polypropylene-covered overlapping petals designed to occlude the LAA ostium and promote endothelialization. The bulb and sail are connected through a flexible dual articulating joint designed to allow a significant sail-to-bulb angulation, hence coaxial implantation of both these structures despite significant angulation between the LAA neck and ostium. The device is fully retrievable and repositionable up to final release. Bulb sizes vary from 16 to 32 mm with low radial force allowing implantation of a giving bulb in large range of anatomies. The bioptome-like delivery cable connects to the device in ball-and-socket fashion. Patients with atrial fibrillation and an indication for anticoagulation were considered for LAA closure if they had a long-term contraindication to anticoagulation. From January to April 2015, 5 patients underwent LAA occlusion with the USLO device in our center. All patients underwent pre-intervention TEE to rule-out thrombus. Procedures were performed under local anesthesia and conscious sedation using angiographic and intracardiac echocardiographic guidance (Figure 1). After measurements of the LAA neck diameter, USLO size was selected using 2-3mm oversizing. If position and sealing were satisfactory, device stability was tested with a pull test prior final release. Successful LAA occlusion was defined as the absence of peri-device leak larger than 3 mm. Baseline patient characteristics and procedural data are in Table 1. In one patient, the initial USLO was changed for a larger one. LAA occlusion was successful in all cases - 3 patients had no residual leak while the other two had leaks of 2 and 3 mm respectively. One patient suffered tamponade, successfully treated with pericardial drainage. There were no other complications. Adequate device position was generally easy to achieve, however the bulb is implanted in a deeper position than that of the similar Amplatzer Cardiac Plug (St.Jude Medical Inc.)View Large Image Figure ViewerDownload (PPT)

Aortic neck evolution after endovascular repair with TriVascular Ovation stent graft

Aortic neck dilation has been reported after endovascular aneurysm repair (EVAR) with self-expanding devices. With a core laboratory analysis of morphologic changes, this study evaluated midterm results of aortic neck evolution after EVAR by endograft with no chronic outward force. This was a multicenter registry of all patients undergoing EVAR with the Ovation endograft (TriVascular, Santa Rosa, Calif). Inclusion criteria were at least 24 months of follow-up. Standard computed tomography (CT) scans were reviewed centrally using a dedicated software with multiplanar and volume reconstructions. Proximal aortic neck was segmented into zone A (suprarenal aorta/fixation area), zone B (infrarenal aorta, from lowest renal artery to the first polymer-filled ring), and zone C (infrarenal aorta, at level of the first polymer-filled ring/sealing zone). Images were analyzed for neck enlargement (≥2 mm), graft migration (≥3 mm), endoleak, barb detachment, neck bulging, and patency of the celiac trunk and superior mesenteric and renal arteries. Inclusion criteria were met in 161 patients (mean age, 75.2 years; 92% male). During a mean follow-up period of 32 months (range, 24-50), 17 patients died (no abdominal aortic aneurysm-related death). Primary clinical success at 2 years was 95.1% (defined as absence of aneurysm-related death, type I or type III endoleak, graft infection or thrombosis, aneurysm expansion >5 mm, aneurysm rupture, or conversion to open repair). Assisted primary clinical success was 100%. CT scan images at a minimum follow-up of 2 years were available in 89 cases. Patency of visceral arteries at the level of suprarenal fixation (zone A) was 100%. Neither graft migration nor barb detachment or neck bulging was observed. None of the patients had significant neck enlargement. The mean change in the diameter was 0.18 ± 0.22 mm at zone A, -0.32 ± 0.87 mm at zone B, and -0.06 ± 0.97 mm at zone C. Changes at zone B correlated significantly with changes at zone C (correlation coefficient, 0.183; P = .05), whereas no correlation was found with zone A (correlation coefficient, 0.000; P = 1.0). No aortic neck dilation occurred in this series at CT scan after a minimum 24-month follow-up. This may suggest that aortic neck evolution is not associated with EVAR at midterm follow-up when an endograft with no chronic outward radial force is implanted.

New Self-Expanding Transcatheter Valve for Off-Pump Transatrial Mitral Valve-In-Ring Implantation

Objectives: To validate a self-expanding transcatheter valve for off-pump transatrial mitral valve-in-ring (VIR) implantation via a left thoracotomy. Methods: Mitral valve annuloplasty was performed via sternotomy during cardiopulmonary bypass on 9 pigs. After successful weaning from extracorporal circulation, the custom-made, self-expanding transcatheter VIR device was deployed under fluoroscopic guidance within the annuloplasty ring via a left thoracotomy. Hemodynamic data before and after the implantation were recorded. Mitral annulus diameter and valve area were measured by echocardiography. Transvalvular and left-ventricular outflow-tract pressure gradient were measured invasively. Results: Eight successful implantations were performed. Implantation failed in 1 pig because of difficulty with technical delivery of the sheath. Mean transatrial procedure time was 12.6 ± 1.7 min. Hemodynamic status during transatrial implantation was stable, and differences were not statistically significant. Mean mitral annulus diameter and mean mitral orifice area were 2.32 ± 0.2 and 3.84 ± 0.55 cm², respectively. Mild regurgitation was detected in 7 animals and moderate regurgitation in 1. Mean gradients were 6.1 ± 5.0 mm Hg across the device. Postmortem examination confirmed adequate positioning of devices within the annuloplasty ring. Conclusions: This custom-made transcatheter device allows for safe and reproducible off-pump transatrial mitral VIR implantations. Transatrial access is a promising route to facilitate VIR implantations. Our custom-made stent-valve may be suitable for VIR procedures.

Two-Year Outcomes with Self-Expanding TAVR

Transcatheter aortic valve replacement (TAVR) has become the standard of care in patients who are at extreme risk for complications from surgery. Optimistically, a continuation of technology iteration and improvement might result in a survival advantage, as previously suggested by a study of a self-expanding TAVR device (NEJM JW Cardiol May 2014 and J Am Coll Cardiol …

Development of Off-Pump Mitral Valve Replacement in a Porcine Model

We describe our initial experience with on-bypass and off-bypass (off-pump) mitral valve replacement with the modified version of our novel catheter-based sutureless mitral valve (SMV) technology, which was developed to atraumatically anchor and seal in the mitral position. The SMV is a self-expanding device consisting of a custom designed nitinol framework and a pericardial leaflet valve mechanism. For the current studies, our original device was modified (SMV2) to reduce the delivery profile and to allow for controlled deployment while still maintaining the key principles necessary for atraumatic anchoring and sealing in the mitral valve position. Ten Yorkshire pigs underwent successful SMV2 device implantation through a left atriotomy (on-pump, n= 6; off-pump, n= 4). Echocardiography and angiography revealed excellent left ventricular systolic function, no significant perivalvular leak, no mitral valve stenosis, no left ventricular outflow tract obstruction, and no aortic valve insufficiency. Postmortem examination demonstrated that the SMV2 devices were anchored securely. This study demonstrates the feasibility and short-term success of off-pump mitral valve replacement using a novel, catheter-based device in a porcine model.

Intraperitoneal mesh devices for small midline hernias: mesh behavior in a porcine model.

Although clinical data on long-term efficacy are lacking, the use of self-expanding devices for intraperitoneal placement in the management of small midline hernias has been popularized. In the present experimental study, two different devices were investigated regarding tissue ingrowth, adhesion formation and solid mesh placement. Two devices of 4.3 cm diameter, one ePTFE-containing small pore polypropylene mesh (PP/ePTFE) and a multi-layered large-pore polypropylene patch with an oxidized cellulose anti-adhesive barrier (PP/ORC), both containing a self-deployment system, were placed intraperitoneally at the linea alba of 24 female pigs. A first laparoscopy was performed to evaluate mesh positioning against the abdominal wall. 1 (n = 6), 2 (n = 6), 4 (n = 6) and 12 weeks (n = 6) later, mesh appearance was inspected and adhesion formation was assessed. All meshes were excised for histological evaluation. Folding of the patch was more frequently observed at PP/ePTFE, yet no excessive cupping was noticed. Adhesions predominantly presented at short-term evaluation. Overall adhesion formation at all samples was significantly more extensive for PP/ORC (p = 0.048). Massive shrinkage was observed for PP/ORC: after a 12-week period 22% residual surface was preserved, compared to 83% for PP/ePTFE (p < 0.001). While at short-term inflammatory reaction was comparable, at long-term PP/ORC induced a significant more pronounced inflammatory and foreign body reaction. Although a strong deployment system provides adequate initial placement, shrinkage and excessive adhesion formation are much more prominent in the large-pore multi-layered restorbable devices compared to the ePTFE patch. This might influence long-term clinical outcome and caution seems warranted.

Valve-in-valve transcatheter aortic valve implantation for failing surgical aortic stentless bioprosthetic valves: A single-center experience

BackgroundValve-in-valve (ViV) transcatheter aortic implantation (TAVI) is an alternative to redo surgery for patients with a failing aortic bioprosthesis. A lack of anatomic markers may complicate the procedure. This study reports procedural and midterm outcomes of patients undergoing ViV-TAVI for failing stentless bioprostheses, at a single institution. MethodsA total of 22 consecutive patients with failing homograft (n = 17), stented porcine valve (n = 3), aortic root bioprosthesis (n = 1), or native resuspended aortic valve (n = 1) (aged 74 ± 12 years; Society of Thoracic Surgeons 30-day predicted risk of mortality score: 14% ± 8%) were treated with ViV-TAVI, between 2007 and 2014. All had severe aortic regurgitation and were highly symptomatic before TAVI: 41% had chronic kidney disease; 32% had undergone previous coronary bypass grafts; 27% had previous percutaneous coronary intervention; 14% had severe pulmonary disease; 14% had had a stroke. All underwent TAVI with a self-expanding device. ResultsThe 30-day mortality was 0%. No cases occurred of myocardial infarction, tamponade, stroke, severe bleeding, acute kidney injury, or major vascular complications. Three instances of device migration, and 1 of device embolization, occurred. Permanent pacing was required in 14%. Paravalvular aortic regurgitation was absent or mild in 19, and mild to moderate in 3. Average hospital stay was 8 ± 3 days; all patients were discharged home. Six-month and 1-year mortality was 4.8% and 14.3%, respectively. Aortic valve area and paravalvular aortic regurgitation were unchanged at 1 year. ConclusionsThe ViV-TAVI procedure may be performed in high-risk patients with a degenerate stentless bioprosthesis with low 30-day mortality, and 1-year mortality of 14.3%. Although technically challenging, owing to a lack of anatomic markers, satisfactory positioning is possible in most cases, with excellent clinical and echocardiographic outcomes.

Erratum.

Stent fracture and occlusion after treatment of symptomatic vertebral artery ostium stenosis with a self-expanding device: A case report by Jun Lu, Jiachun Liu, Daming Wang and Shuo Wang, Interventional Neuroradiology 2014 20: 755-760, DOI: 10.15274/INR-2014-10068. In the above article the author affiliations were listed incorrectly, the correct version is listed below: Jun Lu(1), Jiachun Liu(2), Daming Wang(2) and Shuo Wang(1) (1)Department of Neurosurgery, Beijing Tiantan Hospital, Capital Medical University, Beijing, China (2)Department of Neurosurgery, Beijing Hospital, Beijing, China.