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Research Papers

Smart Guidewires for Smooth Navigation in Neurovascular Intervention

[+] Author and Article Information
Matthew M. Barry

Department of Mechanical Engineering
and Materials Science,
University of Pittsburgh,
Pittsburgh, PA 15261
e-mail: mmb49@pitt.edu

Mahdis Shayan

Department of Industrial Engineering,
University of Pittsburgh,
Pittsburgh, PA 15261
e-mail: mas461@pitt.edu

Brian T. Jankowitz

Department of Neurological Surgery,
University of Pittsburgh Medical Center,
Pittsburgh, PA 15261
e-mail: jankbt@upmc.edu

Yanfei Chen

Department of Industrial Engineering,
University of Pittsburgh,
Pittsburgh, PA 15261
e-mail: yac33@pitt.edu

Xinjie Duan

Department of Mechanical Engineering
and Materials Science,
University of Pittsburgh,
Pittsburgh, PA 15261
e-mail: xid14@pitt.edu

Anne M. Robertson

Department of Mechanical Engineering
and Materials Science,
University of Pittsburgh,
Pittsburgh, PA 15261;
Department of Bioengineering,
University of Pittsburgh,
Pittsburgh, PA 15261
e-mail: rbertson@pitt.edu

Minking K. Chyu

Department of Mechanical Engineering
and Materials Science,
University of Pittsburgh,
Pittsburgh, PA 15261
e-mail: mkchyu@pitt.edu

Youngjae Chun

Department of Industrial Engineering,
University of Pittsburgh,
Pittsburgh, PA 15261;
Department of Bioengineering,
University of Pittsburgh,
Pittsburgh, PA 15261
e-mail: yjchun@pitt.edu

1Corresponding author.

Manuscript received August 11, 2014; final manuscript received January 7, 2015; published online January 27, 2015. Assoc. Editor: John LaDisa.

J. Med. Devices 9(1), 011011 (Mar 01, 2015) (9 pages) Paper No: MED-14-1222; doi: 10.1115/1.4029558 History: Received August 11, 2014; Revised January 07, 2015; Online January 27, 2015

Smart nitinol guidewires have been proposed to improve trackability, facilitating the advancement of catheters through complex vascular anatomies during neurovascular interventions. A smart 0.015 in. diameter nitinol guidewire was actualized through Joule heating of one-way and two-way shape memory alloys (SMA). The device functionalities in terms of bending performance were analyzed: (1) trackability of a 4 Fr catheter as determined in an anatomically correct in vitro environment; (2) time and spatial response of the smart guidewire as a function of material temperature and applied current; and (3) thrombogenic effects as a function of temperature and applied voltage. The results suggest that smart guidewires have substantially improved trackability (i.e., deflection of 15 deg) to overcome the “ledge effect” with the absence of thrombogenicity via a smart guidewire–catheter combined transcatheter based procedure which keeps the catheter surface temperature at 30–33 °C.

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References

Figures

Grahic Jump Location
Fig. 1

Illustration of the ledge effect commonly encountered in neurovascular vessels. The guidewire is able to bridge the branch of the vessel, whereas upon advancement of the catheter, the distal end impinges the far edge of the branch, preventing further advancement.

Grahic Jump Location
Fig. 2

Coaxial technique overcomes the ledge effect. (a) The 3.4 French distal outer diameter of the 032 reperfusion catheter results in a 0.2 mm ledge which facilitates tracking around the ophthalmic bend. (b) By applying gentle traction on the Merci Retriever, the course of the wire straightens, approximating the inner curve of the vasculature, pulling the catheter complex away from the opening of the branching vessel [16].

Grahic Jump Location
Fig. 3

(a) Ledge effect in the cerebrovascular system and (b) proposed design

Grahic Jump Location
Fig. 4

(a) Schematic of 1 W- and 2 W-SMA smart guidewire design. The hollow 1 W- or 2 W-SMA tube is mechanically attached to a hollow NiTi superelastic alloy tube. Thin, electrically insulated copper wires are then passed through the proximal end of the NiTi guidewire up to and through the SMA tube. One electrical connection is made on the distal end of the SMA tube via one copper wire and the other on the proximal end of the SMA tube via the remaining copper wire, thus creating a complete electrical circuit. The copper wires ex vivo are connected to an electrical power supply. (b) Prototype of a 1 W-SME guidewire, in which the angle changes by applying voltage (i.e., generating electrical heating) on the wire: (i) prototype device, (ii) before applying voltage, and (iii) the changed angle of the guidewire. The deflection angle was measured as the acute angle between the longitudinal axes of the fixed proximal and distal ends of the guidewire. (c) Prototype of 2 W-SME guidewire.

Grahic Jump Location
Fig. 5

Reversible behavior of the two-way shape memory effect (2 W-SME) in a nitinol wire

Grahic Jump Location
Fig. 6

Time-lapsed imaging of two-way SMA nitinol guidewire. The wire starts at a bent angle (a) at and upon the introduction of a voltage potential, experiences Joule heating, in which the increase in temperature causes the wire to straighten (b)–(e). Upon the removal of the voltage potential, the wire returns to its initial state (g)–(j).

Grahic Jump Location
Fig. 7

(a) Deflection angle versus maximum temperature and (b) maximum temperature and deflection versus time

Grahic Jump Location
Fig. 8

(a) Catheter-combined smart guidewire, (b) bare nitino wire, (c) covered with a 3.0 Fr RENEGADE microcatheter (Boston Scientific), and (d) covered with a 2.5 Fr Cantata Superselective Microcatheter (Cook Medical)

Grahic Jump Location
Fig. 9

(a) Blood coagulation induced by heat on the surface of a nitinol guidewire and (b) the surface of the microdelivery catheter covering the heated guidewire. Both experiments were conducted with a voltage potential of 6.5 V.

Grahic Jump Location
Fig. 10

(a-1)–(a-3) The ledge effect with a 4 Fr catheter over a conventional 0.015 in. diameter guidewire. (b-1)–(b-3) The ledge effect of a 4 Fr catheter over a nonheated smart guidewire. (c-1)–(c-6) Illustrates how a deployed smart guidewire is able to change its angle and allow the 4 Fr catheter to overcome the ledge effect.

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