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Author Topic: Short Circuit  (Read 79905 times)
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dennis100
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« Reply #270 on: June 18, 2019, 12:25:50 AM »

Model Number 304-20
Device Problems Corroded ; Fracture; Low impedance
Event Date 11/21/2017
Event Type  Malfunction   
Manufacturer Narrative
 
Event Description
Low impedance was observed on a patient's device during a clinic visit. Three weeks earlier, impedance values near the bottom of the normal range had been observed on the patient's device. The impedance was otherwise normal throughout the remainder of the available programming history. The patient was scheduled for revision surgery due to the low impedance. X-rays images of the patient's lead and generator were reviewed by the manufacturer. The lead appeared wavy in several portions. A portion of the lead was not visible in the x-ray images, indicating the likelihood of a larger lead break. A sharp angle was observed at the center of three tie-downs used to secure the top of the lead, indicating the presence of a lead discontinuity or short circuit condition. The patient underwent lead and generator replacement surgery. The lead had reportedly become disconnected inside the patient. The physician reported that the patient did not manipulate the device or experience any trauma that may have led to the low impedance or broken lead. The explanted devices have not been received by the manufacturer to date. No additional relevant information has been received to date.
 
Event Description
The distributor and physician believed that low lead impedance was observed on the generator because the lead was short-circuited at the lead break. The explanted lead and generator were received by the manufacturer for analysis, but analysis has not been approved for the explanted devices to date.
 
Manufacturer Narrative
(b)(4).
 
Event Description
Analysis was approved for the lead and generator. When received, the data was downloaded from the pulse generator and reviewed. The last significant change in impedance value registered on the generator was observed the day before explant surgery. And both impedance values were below 1000 ohms. The pulse generator performed according to functional specifications. There were no performance or any other type of adverse conditions found with the pulse generator. The lead was returned in two portions. Note that since the electrode array portion was not returned for analysis, an evaluation and resulting commentary could not be made on that portion of the lead. Set screw marks were observed on the connector pin, providing evidence that proper contact existed between the lead and generator at least once. Microscopy identified a stress-induced fracture at the lead break location, and secondary stress-induced fissures were also noted in two strands of the positive coil. A portion of the positive coil is exposed and stretched at a lead break location. An intermittent contact was identified between the lead coils. Pitting and wear were identified near the break location on the negative and positive coils. Abraded openings were identified along the outer and inner tubing of the lead and were points of entry for dried fluid observed in both layers of tubing. The appearance of the lead suggested patient manipulation of the implanted device. Identification of portions of the lead coils being exposed may confirm this to be a contributing factor for the reported low lead impedance. Other than the above mentioned observations and typical wear and explant related observations, no other anomalies were identified in the returned lead portion.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=7123169
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