The effect of 220 kHz insonation scheme on rt-PA thrombolytic efficacy < i > in vitro < /i > .

The effect of 220 kHz insonation scheme on rt-PA thrombolytic efficacy <i>in vitro</i>. Phys Med Biol. 2019 Jun 12;: Authors: Kleven RT, Karani KB, Salido NG, Shekhar H, Haworth KJ, Mast TD, Tadesse DG, Holland CK Abstract Ultrasound-enhanced recombinant tissue plasminogen activator (rt-PA) thrombolysis is under development as an adjuvant to ischemic stroke therapy. The goal of this study was to design a pulsed ultrasound (US) exposure scheme that reduced intracranial constructive interference and tissue heating, and maintained thrombolytic efficacy relative to continuous wave (CW) insonation. Three 220-kHz US schemes were evaluated, two pulsed insonation schemes (15 cycles, 68 µs pulse duration, 33% or 62.5% duty cycle) and an intermittent CW insonation scheme (50 s active, 30 s quiescent) over a 30-min treatment period. An in silico study using a finite-difference model of transcranial US propagation was performed to estimate the intracranial acoustic field and temperature rise in the skull for each insonation scheme. In vitro measurements with flow were performed to assess thrombolysis using time-lapse microscopy. Intracranial constructive interference was not reduced with pulsed US using a pulse length of 15 cycles compared to intermittent CW US. The 33.3% duty cycle pulsed US scheme reduced heating in the temporal bone as much as 60% relative to the intermittent CW scheme. All insonation schemes promoted sustained s...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research