scholarly journals Comparison of the In Vitro Hemodynamic Performance of New Flow Diverters for Bypass of Brain Aneurysms

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Asher L. Trager ◽  
Chander Sadasivan ◽  
Baruch B. Lieber
Keyword(s):  
Cerebral Aneurysms ◽  
Flow Diverter ◽  
Parent Artery ◽  
New Device ◽  
Design Changes ◽  
Hemodynamic Performance ◽  
Braiding Angle ◽  
Treatment For Cerebral Aneurysms

One possible treatment for cerebral aneurysms is a porous tubular structure, similar to a stent, called a flow diverter. A flow diverter can be placed across the neck of a cerebral aneurysm to induce the cessation of flow and initiate the formation of an intra-aneurysmal thrombus. This excludes the aneurysm from the parent artery and returns the flow of blood to normal. Previous flow diverting devices have been analyzed to determine optimal characteristics, such as braiding angle and wire diameter. From this information, a new optimized device was designed to achieve equivalent hemodynamic performance to the previous best device, but with better longitudinal flexibility to preserve physiological arterial configuration. The new device was tested in vitro in an elastomeric replica of the rabbit elastase induced aneurysm model and is now in the process of being tested in vivo. Particle image velocimetry was utilized to determine the velocity field in the plane of symmetry of the model under pulsatile flow conditions. Device hemodynamic performance indices such as the hydrodynamic circulation were evaluated from the velocity fields. Comparison of these indices with the previous best device and a control shows that the significant design changes of the device did not change its hemodynamic attributes (p > 0.05).

scholarly journals Thrombogenicity of flow diverters in an ex vivo shunt model: effect of phosphorylcholine surface modification

2016 ◽  
Vol 9 (10) ◽  
pp. 1006-1011 ◽  
Author(s):  
Matthew W Hagen ◽  
Gaurav Girdhar ◽  
John Wainwright ◽  
Monica T Hinds
Keyword(s):  
Surface Modification ◽  
Antiplatelet Therapy ◽  
Ex Vivo ◽  
Cerebral Aneurysms ◽  
Flow Diverter ◽  
Preclinical Model ◽  
Platelet Deposition ◽  
Treatment For Cerebral Aneurysms ◽  
Flow Diverters

BackgroundFlow diverters offer a promising treatment for cerebral aneurysms. However, they have associated thromboembolic risks, mandating chronic dual antiplatelet therapy (DAPT). Shield Technology is a phosphorylcholine surface modification of the Pipeline Embolization Device (PED) flow diverter, which has shown significant reductions in material thrombogenicity in vitro.ObjectiveTo compare the thrombogenicity of PED, PED with Shield Technology (PED+Shield), and the Flow-Redirection Endoluminal Device (FRED)—with and without single antiplatelet therapy and DAPT—under physiological flow.MethodsAn established non-human primate ex vivo arteriovenous shunt model of stent thrombosis was used. PED, PED+Shield, and FRED were tested without antiplatelet therapy, with acetylsalicylic acid (ASA) monotherapy, and with DAPT. Radiolabeled platelet deposition was quantified over 1 hour for each device and total fibrin deposition was also quantified.ResultsCumulative statistical analysis showed significantly lower platelet deposition on PED compared with FRED. The same statistical model showed significant decreases in platelet deposition when ASA, clopidogrel, or Shield Technology was used. Direct comparisons of device performances within antiplatelet conditions showed consistent significant decreases in platelet accumulation on PED+Shield relative to FRED. PED+Shield showed significant reductions in platelet deposition compared with unmodified PED without antiplatelet therapy and with DAPT. PED accumulated minimal fibrin with and without Shield Technology.ConclusionsIn this preclinical model, we have shown that the Shield Technology phosphorylcholine modification reduces the platelet-specific thrombogenicity of a flow diverter under physiologically relevant flow with and without DAPT. We have further identified increased fibrin-driven thrombogenicity associated with FRED relative to PED.

Modeling of Angiographic Dye Washout From Cerebral Aneurysms Before and After Stenting: An Index for Stent Efficacy

2001 ◽  
Author(s):  
C. Sadasivan ◽  
B. B. Lieber ◽  
D. K. Lopes ◽  
A. J. Ringer ◽  
L. N. Hopkins
Keyword(s):  
Thrombus Formation ◽  
Cerebral Aneurysms ◽  
Parent Artery ◽  
Clinical Tool ◽  
Before And After ◽  
Flow Stasis ◽  
Intracranial Circulation ◽  
Viable Treatment

Abstract The ultimate goal in the treatment of cerebral aneurysms is to exclude them from the intracranial circulation while preserving the parent artery. Recently, in vivo and in vitro experiments and clinical studies demonstrated that endovascular stenting is a significant and viable treatment option for cerebral aneurysms. Stents reduce the mass and momentum transport of blood from the parent artery into the aneurysm and alter both intra-aneurysmal flow and inflow-outflow patterns. The reduction of vorticity and flow stasis within the sac leads to thrombus formation and eventual exclusion of the aneurysm from the circulation. Digital subtraction angiography (DSA) has become an essential clinical tool for the diagnosis and treatment of aneurysms and is an important adjunct to stenting procedures.

Current status of training environments in neuro-interventional practice: are animal models still contemporary?

2018 ◽  
Vol 11 (3) ◽  
pp. 283-289 ◽  
Author(s):  
Marie Teresa Nawka ◽  
Jens Fiehler ◽  
Johanna Spallek ◽  
Jan-Hendrik Buhk ◽  
Andreas Maximilian Frölich
Keyword(s):  
Online Survey ◽  
Training Model ◽  
Flow Diverter ◽  
General Concept ◽  
Current Status ◽  
Training Models ◽  
New Device ◽  
Training Modalities

PurposeSeveral different training environments for practicing neurointerventional procedures have been realized in silico, in vitro, and in vivo. We seek to replace animal-based training with suitable alternatives. In an effort to determine present training model distribution and preferences, we interviewed interventional neuroradiologists from 25 different countries about their experience in distinct training environments.MethodsA voluntary online survey comprising 24 questions concerning the different training facilities was designed and electronically conducted with the members of the European Society for Minimally Invasive Neurological Therapy.ResultsSeventy-one physicians with an average experience of 11.8 (±8.7) years completed the survey. The majority of participants had experience with animal-based training (eg, stroke intervention: 36; 50.7%). Overall, animal-based training was rated as the most suitable environment to practice coil embolization (20 (±6)), flow diverter placement (13 (±7)), and stroke intervention (13.5 (±9)). In-vitro training before using a new device in patients was supported by most participants (35; 49.3%). Additionally, preference for certain training models was related to the years of experience.ConclusionThis survey discloses the preferred training modalities in European neurointerventional centers with the majority of physicians supporting the general concept of in-vitro training, concomitantly lacking a standardized curriculum for educating neurointerventional physicians. Most suitable training modalities appeared to be dependent on procedure and experience. As animal-based training is still common, alternate artificial environments meeting these demands must be further developed.

A Hybrid Coil/Polymer Device for Occlusion of Cerebral Aneurysms

2009 ◽  
Vol 3 (4) ◽  
Author(s):  
Fangmin Xu ◽  
Kevin Hart ◽  
Claire E. Flanagan ◽  
John C. Nacker ◽  
Roham Moftakhar ◽  
...  
Keyword(s):  
Cerebral Aneurysms ◽  
In Vitro Models ◽  
In Vivo Studies ◽  
Polymer Shell ◽  
Device Implantation ◽  
Occlusion Device ◽  
Aneurysm Occlusion ◽  
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.

Treatment of Cerebral Aneurysms With Flow Divertors: Long Term Results in an In Vivo Model

2007 ◽  
Author(s):  
Chander Sadasivan ◽  
Baruch B. Lieber ◽  
Liliana Cesar ◽  
Jaehoon Seong ◽  
Ajay K. Wakhloo
Keyword(s):  
Thrombus Formation ◽  
Cerebral Aneurysms ◽  
Long Term Results ◽  
In Vivo Model ◽  
Parent Artery ◽  
Momentum Exchange ◽  
Aneurysm Neck ◽  
Flow Stasis

Subarachnoid hemorrhagic stroke is a devastating illness with a 30-day mortality rate of 45% and is mostly caused due to the rupture of an intracranial aneurysm. Although these aneurysms are currently treated surgically by clipping, or, endovascularly by coiling and stent-assisted coiling, the feasibility of successfully treating aneurysms solely by the placement of an intravascular flow-diverting mesh across the aneurysm neck was established more than a decade ago [1]. Flow divertors disrupt the momentum exchange between the parent artery and aneurysm and significantly reduce intraaneurysmal hydrodynamic vorticity. The resultant flow stasis promotes thrombus formation within the aneurysm sac, which eventually matures into fibrotic tissue, leading to the exclusion of the aneurysm from the circulation. With the increased use of stents in the intracranial circulation, cases where coiling is not feasible, or is staged as a secondary procedure, are providing clinical evidence of the successful treatment of aneurysms with stents alone [2,3]. Such reports are sporadic and, moreover, the devices used are not designed to be flow divertors. Methodological evidence of the performance of appropriately designed flow divertors in treating cerebral aneurysms is currently unavailable.

Simulation of the Role of Oscillatory Shear Stress on Mesenchymal Stem Cell Proliferation and Extracellular Matrix Production in Engineered Heart Valve Tissue Formation

2013 ◽  
Author(s):  
João S. Soares ◽  
Trung B. Le ◽  
Fotis Sotiropoulos ◽  
Michael S. Sacks
Keyword(s):  
Extracellular Matrix ◽  
Heart Valves ◽  
Structural Evolution ◽  
Biodegradable Scaffolds ◽  
Cell Sources ◽  
Hemodynamic Performance ◽  
Tissue Engineered Heart Valves ◽  
Oscillatory Shear Stress

Living tissue engineered heart valves (TEHV) may circumvent ongoing problems in pediatric valve replacements, offering optimum hemodynamic performance and the potential for growth, remodeling, and self-repair [1]. TEHV have been constructed by seeding vascular-derived autologous cells onto biodegradable scaffolds and exhibited enhanced extracellular matrix (ECM) development when cultured under pulsatile flow conditions in-vitro [2]. After functioning successfully for up to 8 months in the pulmonary circulation of growing lambs, TEHV underwent extensive in vivo remodeling and structural evolution and have demonstrated the feasibility of engineering living heart valves in vitro [3]. The employment of novel cell sources, which are clinically obtainable in principle such as bone marrow-derived mesenchymal stem cells (MSCs), is key to achieve viable clinical application [4].

The Filtragometer: A New Device for Measuring Platelet Aggregation in Venous Blood of Man

1975 ◽  
Vol 34 (02) ◽  
pp. 531-544 ◽  
Author(s):  
G Hornstra ◽  
F ten Hoor
Keyword(s):  
Platelet Aggregation ◽  
Pressure Difference ◽  
Venous Blood ◽  
New Device ◽  
Platelet Aggregates ◽  
Spontaneous Platelet Aggregation ◽  
Short Time ◽  
Forearm Vein

SummaryA new device for the direct assessment of spontaneous platelet aggregation in human venous blood is described: the Filtragometer. The principle of the method is based on measurement of the pressure difference across a filter with pores of 20 μπι diameter through which blood from a forearm vein is drawn. Platelet aggregates, obstructing the filter, cause a change in the pressure difference which is proportional to the degree of platelet aggregation. The measurement takes only a short time and a small amount (5-10 ml) of blood.Platelet aggregation as measured with the Filtragometer depends on the type of anticoagulant used. The Filtragometer response decreases on inhibition of platelet stickiness in vitro by prostaglandin E1 and in vivo by aspirin ingestion. Moreover it appeared to be higher in a group with a high thrombosis tendency than in a group less susceptible to fatal arterial thrombosis.The Filtragometer seems especially useful in monitoring the results of diet and/or drug therapy.

scholarly journals Testing the Medina embolization device in experimental aneurysms

2019 ◽  
Vol 131 (5) ◽  
pp. 1485-1493 ◽  
Author(s):  
Robert Fahed ◽  
Tim E. Darsaut ◽  
Igor Salazkin ◽  
Guylaine Gevry ◽  
Jean Raymond
Keyword(s):  
Flow Diverter ◽  
Group 3 ◽  
Group 2 ◽  
Aneurysmal Neck ◽  
Near Occlusion ◽  
Platinum Coils ◽  
Group 1

OBJECTIVEThe Medina embolization device (MED) is a novel, braided self-expanding endovascular device designed to occlude aneurysms by constructing an in situ intrasaccular flow diverter. Although a single device can be positioned at the neck of simple spherical in vitro aneurysms, the best way to occlude more complex in vivo aneurysms (using multiple MEDs or a combination of MEDs and platinum coils) is currently unknown.METHODSFifty-two aneurysms of 3 different types were created in 31 canines, yielding 48 patent aneurysms. Treatments were randomly allocated by drawing lots: group 1, MEDs alone (n = 16); group 2, MEDs plus standard platinum coils (n = 16); and group 3, control aneurysms treated with coils alone (n = 16). Angiographic results were scored and compared immediately following treatment completion and at 3 months. Specimens were photographed and the extent of neointimal closure of the aneurysmal neck scored, followed by histopathological analyses.RESULTSAngiographic scores of 0 or 1 (occlusion or near occlusion) were initially obtained in 2 of 16 (12.5%, 95% CI 1.6%–38.3%) group 1 (MEDs alone), 3 of 16 (18.7%, 95% CI 4%–45.6%) group 2 (MEDs plus coils), and 10 of 16 (62.5%, 95% CI 35.4%–84.8%) group 3 (coils alone) aneurysms (p = 0.005). At 3 months, scores of 0 or 1 were found in 11 of 16 (68.7%, 95% CI 41.3%–89.0%) group 1, 9 of 16 (56.2%, 95% CI 29.9%–80.2%) group 2, and 8 of 16 (50%, 95% CI 24.7%–75.3%) group 3 aneurysms (p = 0.82). Neointimal scores were similar for the 3 treated groups (p = 0.66).CONCLUSIONEndovascular treatment of experimental aneurysms with MEDs or MEDs and coils showed angiographic occlusion and neointimal scores at 3 months that were similar to those achieved with standard platinum coiling.

PHARMACOLOGICAL STUDIES OF PLATELET ANTIAGGREGANTS USING AN IN VITRO MODEL OF PRIMARY HEMOSTASIS.

1987 ◽  
Author(s):  
S Bellucci ◽  
E Cambau ◽  
B Candalot ◽  
J P Caen
Keyword(s):  
Ex Vivo ◽  
Repeated Measurements ◽  
New Drugs ◽  
Type Iii Collagen ◽  
Type I ◽  
Glass Capillary ◽  
New Device ◽  
Primary Hemostasis

We used a new device simulating in vitro primary haemostasis : more precisely the reactivity of blood to collagen and ADP. Thus an artificial vessel was created consisting of two main parts : a glass capillary (ID 140 um, length 16 mm, siliconized) simulating the haemodynamic resistance of an arteriole and an aperture (ID 150 um) reflecting the injured part of a cut arteriole. This aperture was performed in a cellulose acetate filter covered with collagen type I (3 mg/ml) to provide a defined surface for the adhesion of platelets and soaked with ADP in a concentration similar to that of injured endothelial cells (2 x 10-2 M). The mean - sd control values were 110 ± 24 s, 156 -± 40 ul (n = 25) and correlated well with in vivo bleeding time values (p< 0.01). We studied the effect on this test of classical antiaggregant drugs which act on primary hemostasis by different mechanisms of action. Acetylsalycilic acid (Egic laboratories) prolonged this test for concentrations above 10−5 M, ticlopidine (Millot-Solac laboratories) above 3 × 10−4 M, prostacyclin (Wellcome laboratories) above 5 Õ 10−9 M, the synthetic octapeptide LYS-PRO-GLY-GLU-PRO-GLY-PR0-LYS derived from type III collagen (gift from Y. Legrand) above 5 × 10−4 M. We evidenced a synergistic action between collagen octapeptide and ticlopidine. Thus this device permits the screening of new drugs for their effects on primary hemostasis and the study of ex vivo repeated measurements for the monitoring of antiaggregant therapy.

scholarly journals Analysis of Supplemental Surgical or Endovascular Treatment for Cerebral Aneurysms in the Endovascular Performed Cases

2006 ◽  
Vol 12 (1_suppl) ◽  
pp. 73-76
Author(s):  
K. Fukui ◽  
M. Watanabe ◽  
N. Inoue ◽  
K. Wakabayashi ◽  
T. Kato ◽  
...  
Keyword(s):  
Clinical Outcome ◽  
Bypass Surgery ◽  
Cerebral Aneurysms ◽  
Artery Occlusion ◽  
Parent Artery ◽  
Modified Rankin Scale ◽  
Surgical Clipping ◽  
Parent Artery Occlusion ◽  
Treatment For Cerebral Aneurysms ◽  
Surgical Treatments

In the 150 endovascular performed cases from May 1997 to Dec 2004, supplemental combination of endovascular and surgical treatments were performed in 46 cases. Characteristics of the treatments were combination for multiple aneurysms, surgical clipping for failed endovascular attempt, embolization for recurrence after clipping, bypass surgery before endovascular parent artery occlusion, surgery for recurrent aneurysms after embolization, and embolization for failed surgical attempt. Sixty seven percent of ruptured and 87% of unruptured cases showed satisfactory clinical outcome (modified Rankin scale = 0 to 2). Supplemental combination of each treatment will support the disadvantage of another treatment, and which improve the clinical outcome of cerebral aneurysm.

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