Geometric Study of Various Chimney Graft Configurations in an In Vitro Juxtarenal Aneurysm Model

The treatment of cerebral aneurysms is frequently accomplished via endovascular delivery of metal coils in order to occlude the aneurysm and prevent rupture. This procedure involves imprecise packing of large lengths of wire into the aneurysm and often results in high rates of aneurysm recanalization. Over time, this incomplete aneurysm occlusion can lead to aneurysm enlargement, which may have fatal consequences. This report describes the fabrication and preliminary testing of a novel aneurysm occlusion device composed of a single metal coil surrounded by a biocompatible polymer shell. These coil-in-shell devices were tested under flow conditions in synthetic in vitro models of saccular aneurysms and deployed in vivo in a short-term porcine aneurysm model to study occlusion efficacy. A single nickel titanium shape memory wire was used to deploy a biocompatible, elastic polymeric shell, leading to aneurysmal sac filling in both in vitro and in vivo aneurysm models. The deployment of this coil-in-shell device in synthetic aneurysm models in vitro resulted in varying degrees of aneurysm occlusion, with less than 2% of trials resulting in significant leakage of fluid into the aneurysm. Meanwhile, in vivo coil-in-shell device implantation in a porcine aneurysm model provided proof-of-concept for successful occlusion, as both aneurysms were completely occluded by the devices. Both in vitro and in vivo studies demonstrated that this coil-in-shell device may be attractive as an alternative to traditional coil embolization methods in some cases, allowing for a more precise and controlled aneurysm occlusion.

Download Full-text

A novel intracranial exchange guidewire improves the navigation of various endovascular devices: An in vitro study of challenging situations

Interventional Neuroradiology ◽

10.1177/15910199211057332 ◽

2021 ◽

pp. 159101992110573

Author(s):

Naoki Kaneko ◽

Ariel Takayanagi ◽

Hamidreza Saber ◽

Lea Guo ◽

Satoshi Tateshima

Keyword(s):

Giant Aneurysm ◽

In Vitro Study ◽

Target Vessel ◽

Success Rates ◽

Intracranial Stenting ◽

Aneurysm Neck ◽

Significant Difference ◽

Aneurysm Model ◽

Endovascular Devices

Objective Neuroendovascular procedures rely on successful navigation and stable access to the target vessel. The Stabilizer is a 300 cm long exchange wire with a 0.014 diameter and a soft, flexible stent at the distal end designed to assist with navigation and device delivery. This study aims to assess the efficacy of the Stabilizer for navigation in a variety of challenging environments. Methods The efficacy of the Stabilizer was evaluated using three challenging vascular models: a giant aneurysm model, a severe tortuosity model, and an M1 stenosis model. The Stabilizer was compared with a conventional wire during navigation in each model. Results In the giant aneurysm model, there was no significant difference of success during straightening of a looped wire and significantly higher success rates when advancing an intermediate catheter with the Stabilizer beyond the aneurysm neck compared to a conventional guidewire. The Stabilizer also significantly increased success rates when advancing an intermediate catheter through a model with severe tortuosity compared to a conventional guidewire, as well as exchange maneuver for intracranial stenting in a stenosis model compared to an exchange wire. Conclusions In our experimental model, the Stabilizer significantly improved navigation and device delivery in a variety of challenging settings compared to conventional wires.

Download Full-text

In Vitro Study of Near-Wall Flow in a Cerebral Aneurysm Model with and without Coils

American Journal of Neuroradiology ◽

10.3174/ajnr.a2121 ◽

2010 ◽

Vol 31 (8) ◽

pp. 1521-1528 ◽

Cited By ~ 21

Author(s):

L. Goubergrits ◽

B. Thamsen ◽

A. Berthe ◽

J. Poethke ◽

U. Kertzscher ◽

...

Keyword(s):

Cerebral Aneurysm ◽

In Vitro Study ◽

Vitro Study ◽

Wall Flow ◽

Aneurysm Model ◽

Near Wall

Download Full-text

Commentary: The Value of In Vitro Studies in Assessing Chimney Graft Behavior in Endovascular Aneurysm Repair

Journal of Endovascular Therapy ◽

10.1177/1526602818762465 ◽

2018 ◽

Vol 25 (3) ◽

pp. 395-396

Author(s):

Gaspar Mestres

Keyword(s):

Endovascular Aneurysm Repair ◽

In Vitro Studies ◽

Aneurysm Repair ◽

Chimney Graft

Download Full-text

The Cascade device – In vitro tests to assess coil protrusion into the parent vessel

Interventional Neuroradiology ◽

10.1177/1591019920925708 ◽

2020 ◽

Vol 26 (4) ◽

pp. 494-500 ◽

Cited By ~ 1

Author(s):

P Bhogal ◽

K Wong ◽

HLD Makalanda

Keyword(s):

Flow Velocity ◽

In Vitro Tests ◽

Parent Vessel ◽

Single Episode ◽

Average Flow Velocity ◽

Velocity Reduction ◽

Temporary Support ◽

Aneurysmal Neck ◽

Aneurysm Model

Background Balloon and stent-assisted coiling of aneurysms have increased the number of aneurysms available for endovascular treatment. Newer devices that allow flow within the parent vessel but coverage at the neck have recently entered the market. The Cascade is a new non-occlusive fully retrievable neck-bridging support device that has been designed to provide temporary support during coil embolisation of intracranial aneurysms. Methods Using a silicone aneurysm model three different aneurysms were catheterised with the coiling microcatheter placed in three different positions within each aneurysm – at the neck, centrally, and looped within the aneurysm. Multiple different coils were then deployed within each aneurysm with the Cascade device deployed across the neck to provide protection. In total 480 attempted coilings were performed. Aneurysm flow was used to calculate the change in intra-aneurysmal flow with the Cascade device deployed across the neck of the aneurysm. Results We did not observe a single episode of coil protrusion through the Cascade mesh nor did we observe any coil protrusion into the parent vessel when the Cascade was deployed across the neck. There was an average flow velocity reduction of 23% with the Cascade device deployed across the neck of the aneurysm. Conclusion The Cascade device offers robust protection of the aneurysmal neck and parent vessel as well as inducing significant intra-aneurysmal flow velocity reduction.

Download Full-text

Cellular responses to flow diverters in a tissue-engineered aneurysm model

Journal of NeuroInterventional Surgery ◽

10.1136/neurintsurg-2020-016593 ◽

2020 ◽

pp. neurintsurg-2020-016593

Author(s):

Wenjing Liu ◽

Daying Dai ◽

Yong-Hong Ding ◽

Yang Liu ◽

Kristen Temnyk ◽

...

Keyword(s):

Cellular Responses ◽

Parent Vessel ◽

Aortic Endothelial Cells ◽

Aneurysm Neck ◽

Aortic Smooth Muscle ◽

Cell Coverage ◽

Human Aortic Endothelial Cells ◽

Aneurysm Model ◽

Flow Diverters

BackgroundNotwithstanding the widespread implementation of flow diverters (FDs) in the treatment of intracranial aneurysms, the exact mechanism of action of these devices remains elusive. We aimed to advance the understanding of cellular responses to FD implantation using a 3D tissue-engineered in vitro aneurysm model.MethodsAneurysm-like blood vessel mimics (aBVMs) were constructed by electrospinning polycaprolactone nanofibers onto desired aneurysm-like geometries. aBVMs were seeded with human aortic smooth muscle cells (SMCs) followed by human aortic endothelial cells (ECs). FDs were then deployed in the parent vessel of aBVMs covering the aneurysm neck and were cultivated for 7, 14, or 28 days (n=3 for each time point). The EC and SMC coverage in the neck was measured semi-quantitatively.ResultsAt day 7, the device segment in contact with the parent vessel was partially endothelialized. Also, the majority of device struts, but not pores, at the parent vessel and neck interface were partially covered with ECs and SMCs, while device struts in the middle of the neck lacked cell coverage. At 14 days, histology verified a neointimal-like lining had formed, partially covering both the struts and pores in the center of the neck. At 28 days, the majority of the neck was covered with a translucent neointimal-like layer. A higher degree of cellular coverage was seen on the struts and pores at the neck at 28 days compared with both 7 and 14 days.ConclusionaBVMs can be a valuable alternative tool for evaluating the healing mechanisms of endovascular aneurysm devices.

Download Full-text

In Vitro Quantification of Gutter Formation and Chimney Graft Compression in Chimney EVAR Stent-Graft Configurations Using Electrocardiography-Gated Computed Tomography

Journal of Endovascular Therapy ◽

10.1177/1526602818762399 ◽

2018 ◽

Vol 25 (3) ◽

pp. 387-394 ◽

Cited By ~ 9

Author(s):

Simon P. Overeem ◽

Esmé J. Donselaar ◽

Jorrit T. Boersen ◽

Erik Groot Jebbink ◽

Cornelis H. Slump ◽

...

Keyword(s):

Computed Tomography ◽

Stent Graft ◽

Cardiac Cycle ◽

Intraclass Correlation ◽

Endovascular Aneurysm Repair ◽

Enhanced Computed Tomography ◽

Geometric Changes ◽

Aneurysm Repair ◽

Chimney Graft

Purpose: To assess the dynamic behavior of chimney grafts during the cardiac cycle. Methods: Three chimney endovascular aneurysm repair (EVAR) stent-graft configurations (Endurant and Advanta V12, Endurant and Viabahn, and Endurant and BeGraft) were placed in silicone aneurysm models and subjected to physiologic flow. Electrocardiography (ECG)-gated contrast-enhanced computed tomography was used to visualize geometric changes during the cardiac cycle. Endograft and chimney graft surface, gutter volume, chimney graft angulation over the center lumen line, and the D-ratio (the ratio between the lengths of the major and minor axes) were independently assessed by 2 observers at 10 time points in the cardiac cycle. Results: Both gutter volumes and chimney graft geometry changed significantly during the cardiac cycle in all 3 configurations (p<0.001). Gutters and endoleaks were observed in all configurations. The largest gutter volume (232.8 mm3) and change in volume (20.7 mm3) between systole and diastole were observed in the Endurant-Advanta configuration. These values were 2.7- and 3.0-fold higher, respectively, compared to the Endurant-Viabahn configuration and 1.7- and 1.6-fold higher as observed in the Endurant-BeGraft configuration. The Endurant-Viabahn configuration had the highest D-ratio (right, 1.26–1.35; left, 1.33–1.48), while the Endurant-BeGraft configuration had the lowest (right, 1.11–1.17; left, 1.08–1.15). Assessment of the interobserver variability showed a high correlation (intraclass correlation >0.935) between measurements. Conclusion: Gutter volumes and stent compression are dynamic phenomena that reshape during the cardiac cycle. Compelling differences were observed during the cardiac cycle in all configurations, with the self-expanding (Endurant–Viabahn) chimney EVAR configurations having smaller gutters and less variation in gutter volume during the cardiac cycle yet more stent compression without affecting the chimney graft surface.

Download Full-text

In Vitro Quantification of Stent-Graft Behaviour During ch-TEVAR

10.31224/osf.io/kcf3s ◽

2020 ◽

Author(s):

Jakub Kwiecinski ◽

Raman Uberoi ◽

Mohammed Hadi ◽

Christopher P. Cheng ◽

Zhong You

Keyword(s):

Cardiac Cycle ◽

Physiological Model ◽

Aortic Pressure ◽

Spatial And Temporal Variability ◽

Brachiocephalic Trunk ◽

Device Type ◽

Surface Deviation ◽

Substantial Change ◽

Chimney Graft

Purpose: To quantify dynamic gutter phenomena and endograft deformations during double chimney thoracic endovascular aortic repair (ch-TEVAR) in a physiological model of the thoracic aorta subjected to pulsatile haemodynamic conditions. Methods: Two in vitro procedures revascularizing the brachiocephalic trunk and left common carotid artery were performed representing both balloon-expandable (BE, Ankura-BeGraft) and self-expandable (SE, Ankura-Viabahn) double ch-TEVAR configurations. Retrospectively gated computed tomography (CT) was used to evaluate endograft behaviour. Device interactions were characterised according to gutter volume, gutter surface deviation, and endograft deformation (D-ratio) at end-diastolic and peak-systolic aortic pressure. Results: Use of BE chimney grafts resulted in three times total gutter volume compared to SE chimney grafts. Gutter volumes were observed to vary dynamically between the end-diastolic and peak-systolic phases of the cardiac cycle, with the most substantial change associated with the BE configuration. Chimney graft deformations were dependent on device type, with SE devices exhibiting up to twice the deformation as BE devices. When adjacent, SE chimney grafts were observed to support each other, and thus tended towards a more consistently circular shape. Conclusions: Gutter and chimney graft behaviour were dependent on device type, and exhibited both spatial and temporal variability. This study emphasizes notable differences between BE and SE double ch-TEVAR configurations which should be considered when evaluating risk of endoleak. The findings reported here also support the use of gated CT to better identify and predict device related complications in ch-TEVAR, and can be used in the design of next generation devices.

Download Full-text