The use of pulsed laser energy to clear arteries obstructed by thrombus (blood clot) and plaque has emerged as a promising method for the treatment of cardiovascular diseases such as myocardial infarction and stroke. The laser energy is well absorbed by the thrombus and poorly absorbed by the adjacent arterial tissue. However, current techniques are limited because they cannot completely clear the clot in arteries, especially where a large volume clot is presented. Mural clot is a potent stimulus for reocclusion.
We hypothesize that the combination of laser thrombolysis and localized intramural delivery of clot-dissolving drugs during the procedure may be a solution to the limitation, i.e., the majority of clots can be removed by laser pulses, whereas the mural clot is dissolved by the drugs. This study was motivated by this hypothesis. 90 pulses of 30-70mJ were delivered onto gelatin-based thrombus model with a flushing catheter. A solution of fluorescent particles as a drug model was injected at a rate of 4mL/min in coincident with laser delivery. The controls were performed by injecting drug after laser thrombolysis. We measured the penetration of the particles in gel and the sizes of lumen and stained areas. The results of this study demonstrated the possibility of enhancing laser thrombolysis by delivering drugs into thrombus since the particles could be driven several hundred micron in gel, so that the lumen areas increased up to ~130% by accounting the areas that may be potentially dissolved by the drugs.
H. Shangguan, L. W. Casperson, K. W. Gregory, and S. A. Prahl. Penetration of Fluorescent Particles in Gelatin during Laser Thrombolysis. SPIE Proceedings of Diagnostic and Therapeutic Cardiovascular Interventions VII, Feb. 8-14, 1997.