ENHANCED LASER THROMBOLYSIS WITH PHOTOMECHANICAL DRUG-DELIVERY - AN IN-VITRO STUDY

Background and Objective: Current techniques for laser thrombolysis ar e limited because they can not completely clear thrombotic occlusions in arteries, typically leaving residual thrombus on the walls of the a rtery. The objective of this study was to investigate the possibility of using photomechanical drug delivery to enhance laser thrombolysis b y delivering drugs into mural thrombus during laser thrombolysis. Stud y Design/Materials and Methods: Three experimental protocols were perf ormed in vitro to quantitatively compare the effectiveness of thrombol ysis by 1) constant infusion of drug, 2) laser thrombolysis, and 3) ph otomechanical drug delivery. A fiber-optic flushing catheter delivered drug (a solution of 1 mu m fluorescent microspheres) and light (a 1 m u s 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 t ransducer. Results: Lumen sizes generated by mechanically manipulating the catheter through the thrombus were smaller than those generated b y laser ablation. The microspheres could be driven several hundred mic rons into the mural thrombus. Conclusion: Photomechanical drug deliver y has potential for enhancement of laser thrombolysis. Two mechanisms seem to be involved in photomechanical drug delivery: 1) mural deposit ion of the drug at the ablation site and 2) increased exposure of the thrombus surface area to the drug. (C) 1998 Wiley-Liss, Inc.