Laser-activated shape memory polymer intravascular thrombectomy device

Abstract

A blood clot (thrombus) that becomes lodged in the arterial network supplying the brain can cause an ischemic stroke, depriving the brain of oxygen and often resulting in permanent disability. As an alternative to conventional clot-dissolving drug treatment, we are developing an intravascular laser-activated therapeutic device using shape memory polymer (SMP) to mechanically retrieve the thrombus and restore blood flow to the brain. Thermal imaging and computer simulation were used to characterize the optical and photothermal behavior of the SMP microactuator. Deployment of the SMP device in an in vitro thrombotic vascular occlusion model demonstrated the clinical treatment concept.

Polyurethane: A Shape Memory Polymer (SMP)

“…Various approaches are developed to overcome this problem. One route is the use of noncontact triggering stimulus such as infrared (IR), lasers, and so on [34,35]. These can heat SMP inside the body at the accurate location.…”

Shape memory polymer therapeutic devices for stroke

“…In prior work [20] coils were made from commercially available SMPs MM5520 (nominal Tg=55 °C) and MM6520 (nominal Tg=65 C) purchased from Diaplex (a subsidiary of Mitsubishi Heavy Industries Ltd., Tokyo, Japan). The Diaplex SMPs are segmented polyurethanes based on poly(ether-urethane) chemistry [41].…”

“…In the case of the commercial thermoplastic SMP, the coil must still be coupled to a 240 micron optical fiber, which is done by predrilling a coaxial hole in the proximal end of the SMP, inserting optically transparent epoxy (EPO-TEK ® OG603, Epoxy Technology, Inc., Billerica, MA), and then the optical fiber. The benchtop characterization of the photothermal actuation of SMP coil devices was previously described by Small [20] in detail. The temperature of the SMP device was monitored during laser-activation in air using a cooled infrared video camera (Thermacam PM250, Inframetrics, Billerica, MA) fitted with a close-up lens.…”

“…SMPs have been identified as materials suitable for therapeutic microactuator fabrication [2][3][19][20]. In previous work [3,[19][20], commercial SMPs based on segmented thermoplastic polyurethanes were used to fabricate a mechanical thrombectomy coil device used treat ischemic stroke (Fig.…”

“…In previous work [3,[19][20], commercial SMPs based on segmented thermoplastic polyurethanes were used to fabricate a mechanical thrombectomy coil device used treat ischemic stroke (Fig. 1).…”