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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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dennis100
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« Reply #271 on: August 09, 2019, 10:00:48 PM »

Model Number 304-20
Device Problem Low impedance
Event Date 06/27/2019
Event Type  Malfunction   
Event Description
It was reported that a patient's device has low impedance and that there are no complaints from the patient. Anteroposterior and lateral chest x-rays were received and reviewed. Per the images received, the connector pin insertion cannot be assessed due to the quality and angle of the image. The placement of the generator is normal. The feed thru wires do not seem intact at the connector pin and appeared bent. The lead was located behind the generator and the lead wires at the connector pins could not be assessed due to the quality and angle of the image. The lead was observed in the patient¿s neck and appeared to be routed toward the patient¿s left chest. There is no strain relief loop or bend present. One tie-down was visualized and not placed per labeling - tie down and lead were not located parallel to the electrodes. No gross fractures were visualized however a sharp angle was seen, directly below the electrodes, and appears to be looped over itself. Based on the x-rays received, the cause of the low impedance cannot be determined, as no obvious short circuit condition could be visualized. The sharp angle below the electrode and the bent feed through wires cannot be ruled out as possible causes, however, cannot be confirmed to be reasons for the low impedance. A possible fracture or short circuit in the part of the lead that was not able to be visualized in the x-ray images and also cannot be ruled out. No surgical intervention has been reported to date. No additional relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8798633
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dennis100
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« Reply #272 on: September 06, 2019, 09:57:37 PM »

Device Problem Low impedance
Event Date 07/17/2019
Event Type  Malfunction   
Event Description
It was reported that low impedance <600 ohms was observed on the patients generator in (b)(6) 2019. In (b)(6) 2019, impedance was within normal limits. The physician said he believed it was a short circuit condition, and he reported that the patient occasionally stretches his neck, so it's possible something happened to the lead during that. No adverse events associated with the low impedance were reported. No further relevant information has been received to date. No known surgical intervention has occurred to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8880514
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