Laser thrombolysis is a procedure for removing blood clots in occluded arteries using pulsed laser energy. The laser light is delivered through an optical fiber to the thrombus. The ablation process is profoundly affected by whether the optical fiber tip is inside a catheter or in contact with the thrombus. This study measured ablation efficiency of one microsecond laser pulses to remove porcine clot confined in a silicone tube. The cavitation effects were investigated through visualization of laser-induced bubble formation with flash photography and acoustic transient measurements with an acoustic transducer. These experiments were performed on gelatin-based thrombus models. The effect of using these two methods on drug delivery during laser thrombolysis was also investigated.
The efficiency of the contact ablation was about three times greater than that of the non-contact ablation. A 200µm fiber could remove almost the same amount of the clot as a 400µm fiber at the same energy. Additionally, a similar localized drug delivery could be achieved with contact delivery at a lower laser energy to that possible with non-contact delivery at a higher energy.
H. Shangguan, L. W. Casperson, and S. A. Prahl. Microsecond Laser Ablation of Thrombus and Gelatin under Clear Liquids: Contact vs Non-contact IEEE Journal of Quantum Electronics, accepted, 1996.