Ranking Human Arterial Pathways Using Metrics of Curvature and Tortuosity for Simulated Use Bench Testing of Neurovascular Interventional Devices
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Contributing OfficeCenter for Devices and Radiological Health
Abstract
Catheters and guidewires can have different polymer coatings, as well as metals, that can reduce the coefficient of friction, making it easier for these catheters and guidewires to slide easily past tortuous anatomies. As a result, these devices are used in a variety of surgical procedures, but there is a concern that the polymer coatings applied to guidewires and catheters can separate during surgery, causing complications. In this study, the goal is to therefore determine how coating integrity and durability will vary with pre-clinical bench testing. Metrics such as curvature and tortuosity are measured quantitatively to help determine what arterial pathway within the body is the most difficult to traverse. Consequently, these metrics can be used to rank pathways by providing manufacturers with a worst-case scenario model that can be used for testing future coating materials. The pathway used for this study originates at the right femoral artery, moving from there to the abdominal and thoracic aorta before reaching the four defining arterial branches, and finishing at the Circle of Willis. The four defining arterial branches, which are the left and right vertebral and left and right carotid, are therefore the focus of the curvature and tortuosity rankings. As a form of data validation, the curvature and tortuosity calculations were applied to the ASTM standard F2394-07 pathway, which is very commonly used in simulated use testing of medical devices, e.g. for catheter or guidewire tracking, device deployment, and particulates evaluation. Since the known curvature values of the standard are provided, the values calculated from our equations can be compared to the standard for validation. The final calculated values for both curvature and tortuosity of the four arterial pathways were then ranked from most to least difficult for device tracking. As shown, the ranking of pathways from most to least difficult for both metrics was the same: right vertebral, left vertebral, left carotid, and right carotid, respectively. Therefore, it can be recommended that curvatures more commonly seen in the right vertebral pathway be used in simulated use bench testing for rigorous evaluation of coating integrity and durability during design and development of neurovascular interventional devices.