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This report is being sent as follow-up no.1 to update section d9, section h3, and to provide the completed investigation results.The actual device has been returned for evaluation.A visual inspection of the actual sample was conducted.The distal end of the guidewire was found to be fractured.The length of the main body of the guidewire measured approximately 1485 mm.Considering that the specified length of this product is 1500 mm, it is likely that approximately 15 mm is missing.The appearance of the actual sample was examined using a digital microscope.No exposure of the core wire was observed at the fracture site.However, stretching in the outer layer was noted near the fracture.Additionally, no anomalies such as scratches were found in other areas.Electron microscopic inspection of the actual sample revealed scratches, wrinkles, and torn shapes on the outer layer of the fractured area.Dimensional inspection of the outer diameter of the undamaged parts near the fracture was confirmed to meet the factory's specifications.No anomalies were detected.The outer layer of the actual sample was removed to examine the appearance of the core wire using an electron microscope.No tapering was observed on the side of the core wire, while a radial pattern was visible on the top surface of the core wire.X-ray fluoroscopic inspection inside the actual sample revealed that the fractured end of the core wire was located approximately 3 mm from the fractured end of the outer layer.The historical investigation of the product code and lot number involved revealed no anomalies in the manufacturing record or the shipping inspection record.Additionally, no similar cases have been reported from other facilities.Based on our previous experiences, we conducted a simulation test to examine the fracture of the guidewire.When a continuous one-way torque load was applied to a curved guidewire, no tapering was observed on the side of the core wire at the fractured section, and a radial pattern was noted on the fracture surface of the core wire.Additionally, when a continuous one-way torque load was applied to a curved guidewire until the core wire fractured, and then torque load and tensile load were simultaneously applied, the outer layer of the guidewire fractured, resulting in a stretched end and wrinkled surface.This condition was found to resemble that of the actual sample.Based on the investigation results, no anomalies were found in the manufacturing record and the product inspection record.As a possible cause of the occurrence, it is likely that continuous torque load was applied to the actual sample in a curved state, leading to metal fatigue and subsequent fracture of the core wire.Additionally, when a torque load and a tensile load were applied simultaneously, the outer layer of the guidewire experienced stretching and fracture.The estimated missing length of the actual sample is approximately 15 mm.The quality of this product is assured by the factory through several inspections and control measures.Eddy current flaw detection is used to confirm that there are no cracks in the core wire along its entire length.The outer diameter of the core wire is controlled to ensure the strength of the wire.Before the product packaging process, a 100% visual inspection is performed to confirm that there are no anomalies such as kinks or scratches.Eddy current flaw detection: when an alternating current is passed through a coil, a magnetic field is generated in the direction perpendicular to the current.When the coil is brought close to the conductor (core), an eddy current is generated on the surface of the conductor.If any anomaly, including a crack, is present in the conductor, the eddy current avoids the crack and flows around the conductor, causing a change in flow compared to when there is no crack.This method of detecting changes in the flow of eddy currents to search for cracks is called eddy current flaw detection.The instructions for use (ifu) of this product indicates as follows.If any resistance is felt or if the tip's behavior and/or location seems improper, stop manipulating the glidewire and/or the catheter and determine the cause by fluoroscopy.Failure to exercise proper caution may result in bending, kinking, separation of the guide wire's tip, damage to the catheter, or damage to the vessel.
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