Preclinical testing platforms for mechanical thrombectomy in stroke: a review on phantoms, in-vivo animal, and cadaveric models

Abstract

Preclinical testing platforms have been instrumental in the research and development of thrombectomy devices. However, there is no single model which fully captures the complexity of cerebrovascular anatomy, physiology, and the dynamic artery-clot-device interaction. This article provides a critical review of phantoms, in-vivo animal, and human cadaveric models used for thrombectomy testing and provides insights into the strengths and limitations of each platform. Articles published in the past 10 years that reported thrombectomy testing platforms were identified. Characteristics of each test platform, such as intracranial anatomy, artery tortuosity, vessel friction, flow conditions, device-vessel interaction, and visualization, were captured and benchmarked against human cerebral vessels involved in large-vessel occlusion stroke. Thrombectomy phantoms have been constructed from silicone, direct 3D-printed polymers, and glass. These phantoms represent oversimplified patient-specific cerebrovascular geometry but enable adequate visualization of devices and clots under appropriate flow conditions. They do not realistically mimic the artery-clot interaction. For the animal models, arteries from swine, canines, and rabbits have been reported. These models can reasonably replicate the artery-clot-device interaction and have the unique value of evaluating the safety of thrombectomy devices. However, the vasculature geometries are substantially less complex and flow conditions are different from human cerebral arteries. Cadaveric models are the most accurate vascular representations but with limited access and challenges in reproducibility of testing conditions. Multiple test platforms should be likely used for comprehensive evaluation of thrombectomy devices. Interpretation of the testing results should take into consideration platform-specific limitations.

Keywords: blood flow; device; intervention; stroke; thrombectomy.

Figure 1. Optical visualization of thrombectomy of clots in the anterior circulation inside a silicone phantom (A), direct 3D-printed phantom (B), glass phantom (C), and whole human brain model (D).

All the test platforms can enable high-definition and radiation-free observation of device-clot interaction and the glass phantom provides the best clarity.

Figure 2. Lumen diameter of the target vessels in animal models for thrombectomy and comparison to human cerebral arteries involved in large vessel occlusion.

Included arteries: human M2, M1, D-ICA, and P-ICA, swine SCA,^, renal arteries, APA, IMA, SFA,^, and CCA; canine MCA, IMA, and VA; rabbit CCA. APA: ascending pharyngeal artery, CCA: common carotid artery, C-ICA: cavernous ICA, ICA: internal carotid artery, IMA: internal maxillary artery, MCA: middle cerebral artery, SCA: superficial cervical artery, SFA: superficial femoral artery, T-ICA: terminal ICA, VA: vertebral artery.