Prototype Fabrication and Preliminary In Vitro Testing of a Shape Memory Endovascular Thrombectomy Device
- Resource Type
- Periodical
- Authors
- Small, W.; Wilson, T. S.; Buckley, P. R.; Benett, W. J.; Loge, J. M.; Hartman, J.; Maitland, D. J.
- Source
- IEEE Transactions on Biomedical Engineering IEEE Trans. Biomed. Eng. Biomedical Engineering, IEEE Transactions on. 54(9):1657-1666 Sep, 2007
- Subject
- Bioengineering
Computing and Processing
Components, Circuits, Devices and Systems
Communication, Networking and Broadcast Technologies
Prototypes
Fabrication
In vitro
Microactuators
Shape memory alloys
Heating
Coagulation
Temperature
Arteries
Polymers
Nitinol
shape memory alloy
shape memory polymer (SMP)
stroke
thrombectomy
- Language
- ISSN
- 0018-9294
1558-2531
An electromechanical microactuator comprised of shape memory polymer (SMP) and shape memory nickel-titanium alloy (nitinol) was developed and used in an endovascular thrombectomy device prototype. The microactuator maintains a straight rod shape until an applied current induces electro-resistive (Joule) heating, causing the microactuator to transform into a corkscrew shape. The straight-to-corkscrew transformation geometry was chosen to permit endovascular delivery through (straight form) and retrieval of (corkscrew form) a stroke-causing thrombus (blood clot) in the brain. Thermal imaging of the microactuator during actuation in air indicated that the steady-state temperature rise caused by Joule heating varied quadratically with applied current and that actuation occurred near the glass transition temperature of the SMP (86 $^{\circ}$C). To demonstrate clinical application, the device was used to retrieve a blood clot in a water-filled silicone neurovascular model. Numerical modeling of the heat transfer to the surrounding blood and associated thermal effects on the adjacent artery potentially encountered during clinical use suggested that any thermal damage would likely be confined to localized areas where the microactuator was touching the artery wall. This shape memory mechanical thrombectomy device is a promising tool for treating ischemic stroke without the need for infusion of clot-dissolving drugs.