We report a novel model of arterial tortuosity in the porcine brachial artery for testing of endovascular devices in the flexed forelimb position. This provides an ideal vascular territory for an in vivo assessment of guidewires, microcatheters, and endovascular implants because it closely mimics the challenging curvature at the carotid siphon

Carniato, S.

Gounis, Matthew J.

King, R. M.

Mehra, M.

Wakhloo, Ajay K.

English

eScholarship@UMMS

University of Massachusetts Medical School eScholarship@UMMS Radiology Publications and Presentations Radiology 2013-04-01 Porcine brachial artery tortuosity for in vivo evaluation of neuroendovascular devices S. Carniato Stryker Neurovascular Et al. Let us know how access to this document benefits you. Follow this and additional works at: https://escholarship.umassmed.edu/radiology_pubs  Part of the Neurology Commons, and the Radiology Commons Repository Citation Carniato S, Mehra M, King RM, Wakhloo AK, Gounis MJ. (2013). Porcine brachial artery tortuosity for in vivo evaluation of neuroendovascular devices. Radiology Publications and Presentations. https://doi.org/10.3174/ajnr.A2778. Retrieved from https://escholarship.umassmed.edu/radiology_pubs/278 This material is brought to you by eScholarship@UMMS. It has been accepted for inclusion in Radiology Publications and Presentations by an authorized administrator of eScholarship@UMMS. For more information, please contact Lisa.Palmer@umassmed.edu. TECHNICAL NOTEINTERVENTIONALPorcine Brachial Artery Tortuosity for In Vivo Evaluation ofNeuroendovascular DevicesS. Carniato, M. Mehra, R.M. King, A.K. Wakhloo, and M.J. GounisSUMMARY: We report a novel model of arterial tortuosity in the porcine brachial artery for testing of endovascular devices in the ﬂexedforelimb position. This provides an ideal vascular territory for an in vivo assessment of guidewires, microcatheters, and endovascularimplants because it closely mimics the challenging curvature at the carotid siphon.ABBREVIATIONS AC average curvature; 3DRA 3D rotational angiography; CCA common carotid arteryAdvances in interventional neuroradiology are reshaping thetreatment paradigms and have facilitated the development ofa wide array of endoluminal techniques for vascular lesions thatwere earlier only approachable neurosurgically. The ICA siphon isextremely relevant for intracranial access, because its tortuosityand bony encasement can be a significant impediment for guide-wires and microcatheters to gain intracranial access and may alsopreclude the delivery of devices like intracranial stents.As newer devices are developed, they are first evaluated in vitroand in cadaveric models. Although indispensible, these can onlyassess themechanical and structural responses. For a realistic sim-ulation of the critical vessel viscoelastic andphysiologic responses,an in vivo assessment of endovascular devices is crucial. We de-scribe a porcine brachial artery tortuositymodel to provide a chal-lenging vascular territory for endovascular device testing.TECHNIQUEThree Yorkshire swine (male; mean weight, 47 kg) were used forthe purposes of our study. All procedures were conducted in ac-cordance with the protocol approved by the Institutional AnimalCare and Use Committee of University of Massachusetts MedicalSchool. The animals were premedicated with glycopyrrolate (0.01mg/kg). Anesthesia was induced by an intramuscular injection oftiletamine (Telazol, 5mg/kg), ketamine (2.5mg/kg), and xylazine(2.5 mg/kg) and maintained with mechanical ventilation of oxy-gen containing 1%–3% isoflurane. Continuousmonitoring of theheart rate, respiration, oxygen saturation level (pulse oximetry),end-tidal carbon dioxide, and temperature allowed real-time as-sessment of the physiologic status of the animal. A 6F hemostaticintroducer was placed in the right femoral artery by using a mod-ified Seldinger technique following a cut-down. The introducerwas secured in place, with the distal aspect of the femoral arteryligated. A 6F catheter was then advanced over the guidewire underx-ray fluoroscopy.Animal PositioningSelective intra-arterial digital subtraction angiography of the rightand left subclavian arteries was performed in both the extendedand the flexed forelimb position of the swine by using table re-strainers, as illustrated in Fig 1A, -B. The guide catheter was selec-tively positioned in the brachial branch of the subclavian artery. Aselective intra-arterial injection of the contrast agent (Iopamidol,Isovue; Bristol Myers Squibb, Princeton, New Jersey) was admin-istered with a power injector at an injection rate of 2.5 mL/s for11.2 seconds with a 7-second delay to acquire a 3DRA dataset (Fig1C, -D).Image ProcessingAC (the parameter used to describe the vessel tortuosity), pathlength, and the vessel diameters were determined by using amethod previously described.1 Briefly, the 3DRA dataset was im-ported to Mimics (Materialize, Leuven, Belgium). The target tis-sue was extracted from the neighboring tissue through threshold-ing. To generate a segmentation mask, we set maximum andminimum threshold values, and the segmentation was furtherrestricted by cropping the mask. The selected pixels in each sec-Received May 2, 2011; accepted after revision June 10.From Research and Development (S.C.), Stryker Neurovascular, Fremont, California;and Department of Radiology (M.M., R.M.K., A.K.W., M.J.G.), New England Centerfor Stroke Research, University of Massachusetts Medical School, Worcester,Massachusetts.This work was supported by Stryker Neurovascular.Please address correspondence to Matthew J. Gounis, PhD, Department of Radiol-ogy, University of Massachusetts, New England Center for Stroke Research, 55Lake Ave N, SA-107R, Worcester, MA 01655; e-mail: matt.gounis@umassmed.eduIndicates open access to non-subscribers at www.ajnr.orgIndicates article with supplemental on-line video.http://dx.doi.org/10.3174/ajnr.A2778E36 Carniato Apr 2013 www.ajnr.orgtion were connected; this step resulted in a clean mask for the useof 3Dmodel construction. The resulting centerlinewas composedof control points equally spaced on a constant 0.4-mm interval.The path length of the extracted centerline and the diameter of thebest-fit circle to the vessel cross-section at each control point wererecorded and averaged.Statistical AnalysisThe AC, path length, and the vessel diameter of the porcine bra-chial artery vasculature in the flexed and extended position werecompared with a realistic human ICA dataset previously de-scribed.1 Data normality were tested by using the method de-scribed by Kolmogorov and Smirnov. Nonparametric data anal-ysis of the AC and the path length was performed by using theKruskal-Wallis test, and a parametric analysis for vascular diam-eters was performed by using a 2-tailed unpaired t test by usingGraphPad Prism 5.04 software (GraphPad, San Diego,California).RESULTSThe AC, path length, and vascular diameter calculated for thearterial segments (average  standard error of the mean) in theextended (0.28 0.06 mm1, 13.99 1.66 mm, and 2.60 0.19mm) and the flexed (0.29  0.02 mm1, 17.59  0.77 mm, and2.59  0.12 mm) positions in swine are similar (Fig 2). In com-parison, the values calculated for the population-representativehuman carotid siphon are 0.34 0.02 mm1, 22.60 0.79 mm,and 4.15 0.09 mm, respectively.1The nonparametric Kruskal-Wallistest was performed to compare the meansof the AC of the human carotid siphonand the tortuous bends of the porcinebrachial artery both in the flexed and theextended position. There was no statisti-cal difference between the groups (P .44). Also, there was no statistical differ-ence between the path lengths among the3 groups (P  .45). The vascular diame-ters between the human and the porcinearteries were, however, significantly dif-ferent (P .0001).The positioning of the forelimb in theflexed position increased the number oftortuous bends in comparison with theextended position (Fig 1, On-line Video)and emphasized the complexity of thecurvatures. This arterial territory allows asuccessful navigation and testing of an ar-ray of endovascular devices like guide-wires, microcatheters, endovascularstents, and delivery systems.DISCUSSIONForceful catheterization of the carotid si-phon can result in thrombosis and vaso-spasm as a result of endothelial injury.The growing availability of endovasculardevices for delivery to the intracranialspace creates the need for a more realistic approximation of thetortuosity of the human intracranial vessels. Themodel describedprovides a robust environment to challenge the delivery and de-ployment of neuroendovascular devices.Although some physical properties of microcatheters andguidewires like radio-opacity and handling can be evaluated in invitro models, other parameters like steerability/torquability, lu-bricity, stiffness, and durability are better analyzed in an in vivoenvironment. Also, the ability to evaluate the consequences ofendovascularmanipulation like vessel straightening and displace-ment, vessel vasospasm, endothelial injury, secondary platelet ad-hesion, fibrin polymerization, and vessel perforation makes invivo assessment indispensible.Models simulating the carotid tortuosity have previously beendescribed. Some researchers have described complex vascularsurgical maneuvers like encasement of the canine CCA in carotidsiphon replicas.2,3 Also methods for generating tortuosity havebeen described by surgical interposition of the Dacron vasculargraft (E.I. du Pont de Nemours and Company, Wilmington, Del-aware) between the common trunk and the CCA, creating a vas-cular redundancy, which can be positioned and sutured in placeto create tortuosity simulating the siphon.4 These vascular proce-dures are considerably challenging technically, requiring a skilledsurgical team and a recovery period before device testing. Animalmodels with siphon anatomy resembling humans exist in thenonhuman primates; however, ethical and financial consider-ations preclude their use for endovascular device testing.5FIG 1. Images depicting the positioning of the swine forelimb and the 3DRA acquired throughthe guide catheter in the subclavian artery in the extended (A and C ) and the ﬂexed (B and D )position, revealing their arterial tortuosity (arrows ). The number of bends and the tortuosity ofthe path are accentuated in the ﬂexed position.AJNR Am J Neuroradiol 34:E36–E38 Apr 2013 www.ajnr.org E37Ourmodel allows a rigorous testing of endovascular devices ina challenging tortuous vascular environment, in a model that iseasily reproducible and technically much less challenging. Deviceperformance can be evaluated on the basis of both the qualitativeexperience of the device while negotiating the tortuous vascula-ture and the angiographic response secondary to navigation. Thetechnique for inducing the tortuosity is very feasible and repro-ducible and requires no prior surgical preparation. We have suc-cessfully used this vascular territory to evaluate commerciallyavailable versions of guidewires, microcatheters, endovascularstents, and their delivery systems. Further validation of themodel was provided by an evaluation of the safety and perfor-mance profile of final device prototypes, before their incorpo-ration as commercially available products for clinical use, byan experienced neuroradiologist.Although this model is appropriate for an acute assessment,the tortuous vascular path is positional; repositioning andmanip-ulating the forelimbmay likely alter the geometry of the endovas-cular implants over the bends. The caliber of the target vessel doesnot replicate the human ICA. The porcine arteries also have ahigher propensity for vasospasm. We cannot replicate the bonyencasement and the level of immobility experienced at the humancarotid siphon. Nevertheless, despite these limitations, endovas-cular device testing in this territory provides a robust environ-ment for a rigorous assessment of the delivery and deployment ofendovascular devices in a technically less demanding and repro-ducible in vivo model.Disclosures: Sarena Carniato—UNRELATED: Employment: Stryker, Comments: em-ployed full-time. Ajay Wakhloo—RELATED: Consulting Fee or Honorarium: Stryker,Comments: serve as a consultant on a per-hour basis; UNRELATED: Consultancy:Codman, Stryker, Soteira, Comments: consultation fee on per-hour basis; Grants/Grants Pending: Philips; Stock/Stock Options: Surpass Medical. Matthew Gounis—UNRELATED: Consultancy: Codman, Micrus, Soteira, Comments: fee per-hour con-sultation; Grants/Grants Pending: Boston Scientiﬁc, Concentric, Codman, Geurbet,ev3, Micrus, Neurointerventional Therapeutics, Neuravi, Stryker, Sanoﬁ-Aventis,Thrombolytic Scientiﬁc.REFERENCES1. Chueh JY, Wakhloo AK, Gounis MJ. Neurovascular modeling:small-batchmanufacturingof silicone vascular replicas.AJNRAmJNeuroradiol 2009;30:1159–642. Tan HQ, Li MH, Zhu YQ, et al. Surgical construction of a novelsimulated carotid siphon in dogs. J Neurosurg 2008;109:1173–783. Xie J, Li MH, Tan HQ, et al. Establishment of an experimental in-tracranial internal carotid arterymodel and the application in cov-ered-stent navigability testing. AJNR Am J Neuroradiol2009;30:1041–454. Georganos SA, Guilbert F, Salazkin I, et al. Surgical construction ofan in vivo carotid siphonmodel to test neurovascular devices.Neu-rosurgery 2004;54:1239–43, discussion 435. TenjinH, Fushiki S,Nakahara Y, et al.Effect ofGuglielmi detachablecoils on experimental carotid artery aneurysms in primates. Stroke1995;26:2075–80FIG 2. Box andwhiskers plots showing themedian, maximum,minimum, and upper and lower quartiles of the average curvature (A), path length(B), and the vascular diameters (C) of the human carotid siphon and the porcine brachial artery in the ﬂexed and extended position.E38 Carniato Apr 2013 www.ajnr.org

Porcine brachial artery tortuosity for in vivo evaluation of neuroendovascular devices

https://escholarship.umassmed.edu/cgi/viewcontent.cgi?article=1288&amp;context=radiology_pubs

Porcine brachial artery tortuosity for in vivo evaluation of neuroendovascular devices

Abstract

Similar works

Full text

Available Versions

eScholarship@UMMS