Laser thrombolysis in an in vitro model

Stroke is the leading cause of disability and is the third leading cause of morbidity in the United States. Approved therapies are limited. A novel therapy utilizing laser energy delivered through a fluid core catheter in the ablation of embolic thrombus in acute stroke is currently being tested in a clinical trial. In order to optimize the efficiency of clot removal by this system, an in vitro method to measure the effects of varying the laser parameters on the efficiency of clot removal was developed. Included in this model is a new reconstituted clot target that has reproducible mechanical and optical properties which allow reliable spectrophotometric measurement of the mass ablated. In this study the parameters of energy and repetition rate were adjusted while the average power remained constant at approximately 100 mW. The energy levels and repetition rates tested were 36 mJ at 3 Hz, 25 mJ at 4 Hz, 20 mJ at 5 Hz, 15 mJ at 7 Hz, and 12.4 mJ at 8 Hz. We demonstrate that the efficiency of clot removal achieved at higher pulse energies and low repetition rates can be maintained at a lower energy and higher repetition rate. These results are in agreement with previous studies using gel phantoms. This study demonstrates the reproducibility of the reconstituted clot and supports the use of this model as a clinically relevant method to investigate the efficiency of laser thrombolysis.