Research Papers: Therapeutic

Thulium fiber laser recanalization of occluded ventricular catheters in an ex vivo tissue model

[+] Author Affiliations
Thomas C. Hutchens, David A. Gonzalez, Luke A. Hardy, Nathaniel M. Fried

University of North Carolina at Charlotte, Department of Physics and Optical Science, North Carolina, United States

C. Scott McLanahan

Carolinas Medical Center, Adult Hydrocephalus Specialty Clinic, Charlotte, North Carolina, United States

J. Biomed. Opt. 22(4), 048001 (Apr 21, 2017). doi:10.1117/1.JBO.22.4.048001
History: Received February 14, 2017; Accepted April 7, 2017
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Abstract.  Hydrocephalus is a chronic medical condition that occurs in individuals who are unable to reabsorb cerebrospinal fluid (CSF) created within the ventricles of the brain. Treatment requires excess CSF to be diverted from the ventricles to another part of the body, where it can be returned to the vascular system via a shunt system beginning with a catheter within the ventricle. Catheter failures due to occlusion by brain tissues commonly occur and require surgical replacement of the catheter. In this preliminary study, minimally invasive clearance of occlusions is explored using an experimental thulium fiber laser (TFL), with comparison to a conventional holmium: yttrium aluminium garnet (YAG) laser. The TFL utilizes smaller optical fibers (<200-μm OD) compared with holmium laser (>450-μm OD), providing critical extra cross-sectional space within the 1.2-mm-inner-diameter ventricular catheter for simultaneous application of an endoscope for image guidance and a saline irrigation tube for visibility and safety. TFL ablation rates using 100-μm core fiber, 33-mJ pulse energy, 500-μs pulse duration, and 20- to 200-Hz pulse rates were compared to holmium laser using a 270-μm core fiber, 325-mJ, 300-μs, and 10 Hz. A tissue occluded catheter model was prepared using coagulated egg white within clear silicone tubing. An optimal TFL pulse rate of 50 Hz was determined, with an ablation rate of 150  μm/s and temperature rise outside the catheter of 10°C. High-speed camera images were used to explore the mechanism for removal of occlusions. Image guidance using a miniature, 0.7-mm outer diameter, 10,000 pixel endoscope was explored to improve procedure safety. With further development, simultaneous application of TFL with small fibers, miniature endoscope for image guidance, and irrigation tube for removal of tissue debris may provide a safe, efficient, and minimally invasive method of clearing occluded catheters in the treatment of hydrocephalus.

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© 2017 Society of Photo-Optical Instrumentation Engineers

Citation

Thomas C. Hutchens ; David A. Gonzalez ; Luke A. Hardy ; C. Scott McLanahan and Nathaniel M. Fried
"Thulium fiber laser recanalization of occluded ventricular catheters in an ex vivo tissue model", J. Biomed. Opt. 22(4), 048001 (Apr 21, 2017). ; http://dx.doi.org/10.1117/1.JBO.22.4.048001


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