Enhanced laser thrombolysis with photomechanical drug delivery: An in vitro study

Abstract

Background and Objective: Current techniques for laser thrombolysis are limited because they can not completely clear thrombotic occlusions in arteries, typically leaving residual thrombus on the walls of the artery. The objective of this study was to investigate the possibility of using photomechanical drug delivery to enhance laser thrombolysis by delivering drugs into mural thrombus during laser thrombolysis. Study Design/Materials and Methods: Three experimental protocols were performed in vitro to quantitatively compare the effectiveness of thrombolysis by 1) constant infusion of drug, 2) laser thrombolysis, and 3) photomechanical drug delivery. A fiber‐optic flushing catheter delivered drug (a solution of 1 μm fluorescent microspheres) and light ( a 1 μs pulsed dye laser) into a gelatin‐based thrombus model. The process of laser‐thrombus interaction was visualized using flash photography and the laser‐induced pressure waves were measured using an acoustic transducer. Results Lumen sizes generated by mechanically manipulating the catheter through the thrombus were smaller than those generated by laser ablation. The microspheres could be driven several hundred microns into the mural thrombus. Conclusion Photomechanical drug delivery has potential for enhancement of laser thrombolysis. Two mechanisms seem to be involved in photomechanical drug delivery: 1) mural deposition of the drug at the ablation site and 2) increased exposure of the thrombus surface area to the drug. Lasers Surg. Med. 23:151–160, 1998. © 1998 Wiley‐Liss, Inc.

Interaction of radiation with microparticles for enhancement of drug delivery in tumors

“…Laser radiation can potentially be used to deliver drugs into thrombus or increase permeability of cell membranes. It was demonstrated that drugs can potentially be delivered photomechanically into thrombus on the walls oflarge arteries with the use ofmicrosecond laser pulses [28,29]. The laser pulses can be delivered into the arteries through fiber-optic catheters and induce millimeter-sized bubble expansion and collapse.…”

Shear-, Sound-, and Light-Sensitive Nanoparticles for Thrombolytic Drug Delivery

“…A localized drug delivery, termed photomechanical drug delivery, has been reported by Shangguan et al 59 They demonstrated that hydrodynamic flow and pressures resulting from formation, expansion, and collapse of laser induced bubbles can be the driving force for facilitating drug delivery. 59 Apart from bubbles, a liquid jet can also be formed via laser irradiation. For example, Hirano et al reported that a liquid jet formed through Ho:YAG laser irradiation within a water-filled catheter could promote fibrinolysis by means of delivering fibrinolytic agents into the thrombus.…”

Acute Interventions for Ischemic Stroke: Present Status and Future Directions

“…21 This effect may be due to the increased surface area of clot exposed to the thrombolytic agent. 22 However, the inability to navigate mechanical devices through small blood vessels to the target areas limits this approach. Furthermore, large fragmented particles of clot may lead to undesirable occlusion of distal branches.…”