Ian Mcdougall

A novel endovascular clip system for the treatment of intracranial aneurysms: technology, concept, and initial experimental results. Laboratory investigation.

OBJECT The authors describe a novel device for the endovascular treatment of intracranial aneurysms, the endovascular clip system (eCLIPs). Descriptions of the device and its delivery system as well as the results of flow model tests and the treatment of experimental aneurysms are provided. METHODS The eCLIPs comprises a flexible hybrid implantable device (an anchor and a covered leaf) and a balloon catheter delivery system, designed to be positioned and activated in the parent vessel in such a way that the covered portion will abut the aneurysm neck. The eCLIPs was subjected to testing in glass, elastomeric, and cadaveric flow models to determine its navigability, orientation, and activation compared with commercially available stents. In a second experiment, 8 carotid artery sidewall aneurysms in swine were treated using eCLIPs. The degree of occlusion was observed on angiography immediately following and 30 days after device activation, and a histological analysis was performed at 30 days. RESULTS The device could navigate tortuous glass models and human cadaveric vessels. Compared with commercially available stents, the eCLIPs performed well. It could be navigated, oriented, and activated easily and reliably. With regard to the 8 porcine experimental aneurysms, immediate postactivation angiograms confirmed complete occlusion of 4 lesions and near occlusion of the other 4. Angiographic follow-up at 30 days postactivation showed occlusion of all 8 aneurysms and patency of all parent vessels. Histopathological analysis revealed aneurysm healing, with smooth-muscle cells growing across the lesion neck to allow reendothelialization. CONCLUSIONS Aneurysm occlusion with a single extrasaccular endovascular device has potential advantages. The authors believe that eCLIPs may prove to be a useful tool in the endovascular treatment of cerebral aneurysms. The system should reduce risks associated with coiling, procedure time, costs, and radiation exposure. The device satisfactorily occluded 8 experimental sidewall aneurysms. The observed healing pattern is similar to that seen after microsurgical clipping.

Technical Development and Initial Animal Experience with a Novel, Uncovered, Self-Expanding, Highly Flexible Aortic Stent with Improved Side Branch Access

Purpose: To present a novel, uncovered, self-expanding aortic stent for use as a thoracoabdominal stent-graft extension to improve distal flow in aortic dissections complicated by malperfusion syndrome and to enhance the remodeling process in the abdominal aorta after thoracic endovascular aortic repair. Methods: This aortic prosthesis is a laser cut, self-expanding nitinol stent that is designed to provide an optimal balance between radial support and flexibility to negotiate tortuous arterial anatomy. Undulating circumferential rings provide radial force, while flexibility is achieved through the shape and configuration of the longitudinal connectors that extend from the valley of one ring to the offset peak of the next ring. Delivery and deployment characteristics, in vivo flexibility of the stent, and side branch accessibility through the bare stent struts were evaluated in 4 anesthetized domestic swine weighing 68 to 73 kg. Results: All 11 attempted stent implantations were successful in the 4 pigs using a retrograde transiliac access. The stents were positioned and deployed exactly at the intended target locations and conformed well to the aortic anatomy, even in the tortuous aortic arch, with no evidence of stent kinking or collapse. Overall, 21 major aortic side branches were intentionally covered with the bare stent struts; perfusion was not impaired in any branch vessel. Superselective catheterization of the side branches with coronary guiding catheters through the stent struts was possible for all vessels, as was side branch stenting in 3/3 attempts. Conclusion: This initial feasibility study demonstrates the ability to deploy this novel self-expanding aortic stent in pigs. The high flexibility of the stent allowed conformability with tortuous aortic anatomy. Access to side branches overstented with bare stent struts was excellent. Clinical evaluation of the device is planned for the near future.

CorrespondenceResearch CorrespondenceReal-Time Magnetic Resonance Imaging–Guided Transarterial Aortic Valve Implantation: In Vivo Evaluation in Swine

Real-time magnetic resonance imaging (rtMRI) is considered attractive for guiding transarterial aortic valve implantation (TAVI). Compared with X-ray fluoroscopy, rtMRI offers unrestricted scan plane orientation and an unsurpassed soft-tissue contrast with simultaneous device visualization,

The second-generation eCLIPs Endovascular Clip System: initial experience

OBJECTIVE Treatment of wide-necked intracranial aneurysms is associated with higher recanalization and complication rates; however, the most commonly used methods are not specifically designed to work in bifurcation lesions. To address these issues, the authors describe the evolution in the design and use of the eCLIPs (Endovascular Clip System) device, a novel hybrid stent-like assist device with flow diverter properties that was first described in 2008. METHODS A registry was established covering 13 international centers at which patients were treated with the second-generation eCLIPs device. Aneurysm morphology and rupture status, device neck coverage, coil retention, and procedural and late morbidity and mortality were recorded. For those patients who had undergone successful implantation more than 6 months earlier, the final imaging and clinical follow-up results and need for re-treatment were recorded. RESULTS Thirty-three patients were treated between June 2013 and September 2015. Twenty-five (76%) patients had successful placement of an eCLIPs device; 23 (92%) of these 25 patients had complete data. Eight cases of nondeployment occurred during the 1st year of use, consistent with a learning curve; no failures of deployment occurred thereafter. Two periprocedural transient ischemic attacks and 2 asymptomatic thrombotic events occurred. Twenty-one (91%) of 23 patients underwent follow-up at an average of 8 months (range 3-18 months); 9 (42.9%) of these 21 patients demonstrated an improvement in Raymond grade at follow-up; no cases of worsening Raymond grade were recorded, and 17 (81.0%) patients sustained a modified Raymond-Roy Classification class of I or II angiographic result at follow-up. Two delayed ruptures were recorded, both in previously coiled, symptomatic giant aneurysms where the device was used as a part of a salvage strategy. CONCLUSIONS The second-generation eCLIPs device is a viable treatment option for bifurcation aneurysms. The aneurysm occlusion rates in this initial clinical series are comparable to the initial experience with other bifurcation support devices.

Physiological remodeling of bifurcation aneurysms: preclinical results of the eCLIPs device

OBJECTIVE Intracranial bifurcation aneurysms are complex lesions for which current therapy, including simple coiling, balloon- or stent-assisted coiling, coil retention, or intrasaccular devices, is inadequate. Thromboembolic complications due to a large burden of intraluminal metal, impedance of access to side branches, and a high recurrence rate, due largely to the unmitigated high-pressure flow into the aneurysm (water hammer effect), are among the limitations imposed by current therapy. The authors describe herein a novel device, eCLIPs, and its use in a preclinical laboratory study that suggests the devices design and functional features may overcome many of these limitations. METHODS A preclinical model of wide-necked bifurcation aneurysms in rabbits was used to assess functional features and efficacy of aneurysm occlusion by the eCLIPs device. RESULTS The eCLIPs device, in bridging the aneurysm neck, allows coil retention, disrupts flow away from the aneurysm, leaves the main vessel and side branches unencumbered by intraluminal metal, and serves as a platform for endothelial growth across the neck, excluding the aneurysm from the circulation. CONCLUSIONS The eCLIPs device permits physiological remodeling of the bifurcation.

Real-time MR-guided transarterial aortic valve implantation (tavi): in vivo evaluation in swine

Transcatheter, transarterial aortic valve implantation (TAVI) is rapidly emerging as a promising new treatment option for patients with severe symptomatic aortic valve stenosis who are considered at high or prohibitive surgical risk [1,2]. Envisioning real-time MR guidance of the TAVI procedure, the objective of this study was the systematical