Pre-clinical evaluation of surface coating performance in guidewire surrogates: Potential implications for coated interventional surgical devices

Purpose Polymer fragments have been identified from autopsy reports of patients who had at some point undergone intravascular procedures with medical devices (such as guidewires and catheters) with lubricious coatings. Coating separation on these devices may cause a range of adverse events, the most severe being patient death associated with undesired embolization of blood vessels by coating particles. The objective of the present study is to identify bench test methods for evaluation of hydrophobic and hydrophilic coatings to better understand the relationships between coating formulation and coating behavior, which in turn helps to determine safety and effectiveness of the coating on the device. Methods Hydrophilic or hydrophobic coatings were applied on prepared 304 V stainless steel guidewire surrogates. Coating integrity was assessed after exposing the surrogates to extended periods of soaking and rotary bend fatigue testing. Additionally, coating durability was evaluated by abrasion testing. Results Soaking tests showed deionized water can cause more changes to the microscopic appearance of the coating on the guidewire surrogates as compared to 0.9% saline at both room temperature and 37°C; however, soaking tests in either medium did not alter coating integrity after 11 hours. Rotary bend fatigue, which subjects the coatings to both tension and compression, did not affect coating integrity on the guidewire surrogates after three hours. The pad material used in abrasion testing can lead to markedly different performance predictions. Conclusion Soaking, bend fatigue test, and abrasion tests can provide valuable information on coating performance. Coating integrity and durability were affected during abrasion testing, a test method that can provide more useful information for evaluating bench coating performance. It remains to correlate these findings with clinical performance, but emphasis should be placed on comprehensive characterization. Further investigation is needed by multidisciplinary stakeholders: materials scientists, engineers, and clinicians, to properly inform next steps.