Penetration of fluorescent particles in gelatin during laser thrombolysis

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. Current techniques for laser thrombolysis 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 suggest that the combination of laser thrombolysis and localized intramural delivery of clot-dissolving drugs during the procedure may be a solution to this limitation. Ninety pulses of 30 - 70 mJ were delivered onto gelatin-based thrombus model with a flushing catheter. A solution of 1 micrometer fluorescent particles as a drug model was injected at a rate of 4 mL/min in coincidence with the laser delivery. The controls were performed by injecting drug after laser thrombolysis. We measured the penetration of the particles in gelatin and the sizes of the lumen and stained areas. The results of this study demonstrated the possibility of enhancing laser thrombolysis by delivering drugs into thrombus. It was found that the particles could be driven several hundred micron in gelatin, and the lumen areas would be increased up to 25% if the areas were dissolved by the drugs.