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Author Topic: Low Impedance  (Read 28385 times)
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dennis100
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« Reply #270 on: April 15, 2019, 12:28:46 AM »

Model Number 300-20
Event Date 07/13/2016
Event Type  Malfunction   
Event Description
It was reported that a patient had a low impedance message when diagnostics were performed. It was later reported that the patient was also experiencing discomfort when the vns device fired. No further 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=5848174
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dennis100
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« Reply #271 on: April 16, 2019, 12:42:29 AM »

Model Number 304-20
Event Date 07/15/2016
Event Type  Malfunction   
Event Description
It was reported that a patient had low impedance found during system diagnostics on a follow-up visit. X-rays were taken and provided to the manufacturer for review. The x-rays were reviewed by the manufacturer. The lead appeared intact, the electrodes appeared to be aligned on the left vagus nerve. The condition of the feedthru wires, pin insertion, and connector pin could not be assessed due to the clarity of the provided x-ray images. The generator was also found to be placed abnormally high in the left chest, adjacent to the clavicle. No obvious cause for the reported low impedance was found through review of the x-rays. No further relevant information has been received to date. No surgical intervention has occurred to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5858271
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dennis100
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« Reply #272 on: April 16, 2019, 12:43:16 AM »

Model Number 302-20
Event Date 08/25/2016
Event Type  Malfunction   
Event Description
During a prophylactic generator replacement surgery, the surgeon saw the lead was tied in a knot. When he straightened the lead out, he noticed the insulation of the lead was degraded. Impedance on the previous device was less than 600ohms. Therefore the surgeon performed a full revision surgery. The explanted devices were received on 09/20/2016. Analysis is underway but has not been completed to date.
 
Event Description
An analysis was performed on the returned lead portions and the reported "mechanical problem / abraded insulation" (lead section) allegation was verified. The electrodes were not returned for analysis; therefore, a complete evaluation could not be performed on the entire lead product. During the visual analysis the outer silicone tubing appeared to be compressed, twisted with abraded openings, in several areas. During the visual analysis, multiple lead portions appeared to be melted. What appeared to be spatter and pitting was found on the surface of the quadfilar coil strands. Based on the obvious signs of melting on the coil surfaces, it is possible the thermally-damaged coils were exposed to a high temperature device such as a cauterizing tool (electrosurgical unit) during the explant of this lead. The abraded openings and melted appearance found on the outer silicone tubing, most likely provided the leakage path for the dried remnants of what appeared to have once been body fluids inside the outer silicone tubing. For the observed inner tubing fluid remnants, there was no obvious path for fluid ingress other than the melted / torn ends that were made during the explanted process. The condition of the returned lead portions is consistent with conditions that typically exist following an explant procedure. No other obvious anomalies were noted. The setscrew marks found on the lead connector pin provide evidence that, at one point in time, a good mechanical and electrical connection was present. Continuity checks of the returned lead portions were performed, during the visual analysis, with no discontinuities identified. Various electrical loads were attached to the pulse generator and results of diagnostic tests demonstrate that accurate resistance measurements were obtained in all instances. A comprehensive automated electrical evaluation showed that the pulse generator performed according to functional specifications. The battery, 2. 813 volts, shows an ifi=no condition. There were no performance or any other type of adverse conditions found with the pulse generator.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5966266
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dennis100
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« Reply #273 on: April 24, 2019, 01:09:25 AM »

Model Number 302-20
Event Date 11/23/2016
Event Type  Malfunction   
Event Description
Clinic notes were received on (b)(6) 2016 and dated (b)(6) 2016. It was stated there was a warning message that there was low impedance < 600 ohms. The patient denies any unusual stimulation or shock-like sensations. The device was interrogated again on (b)(6) 2016 and it was stated impedances were fine. No surgical intervention has occurred to date. No additional information has been received to date.
 
Event Description
The patient was seen again in the physician's office, and the diagnostics showed that impedance was within normal limits. The patient refused surgery at that time because the impedance was within normal limits, even though low impedance was seen at a previous office visit. No surgical intervention has occurred to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6178919
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dennis100
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« Reply #274 on: April 24, 2019, 01:10:21 AM »

Model Number 304-20
Event Date 01/01/2015
Event Type  Malfunction   
Event Description
The patient was referred for a prophylactic generator replacement when it reported that low impedance had been observed for quite some time on the generator, the exact date of first observance was not known. X-rays had been performed and the results were reviewed by the physician. Since no lead discontinuity was observed by the physician he decided to leave the lead implanted and only replace the generator. After the new generator was implanted the low impedance continued to be observed. Further follow-up with the physician found the patient felt stimulation at higher settings and the patient's seizure condition were under good control. Additionally, the physician noted that the x-rays did not show any signs of a short circuit condition in the lead. Therefore the physician felt that it was reasonable to leave the system implanted and to only replace the generator when the battery expired. The x-rays have not been reviewed by the manufacturer to date. No additional relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6176718
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dennis100
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« Reply #275 on: April 24, 2019, 01:11:12 AM »

Model Number 303-20
Device Problems Fracture; Low impedance
Event Date 11/23/2016
Event Type  Malfunction   
Event Description
It was reported that a vns patient¿s device showed low impedance. Additional relevant information has not been received to-date.
 
Event Description
Follow-up to the physician provided the device has had increasing impedances values since (b)(6) 2016, resulting in high impedance. The patient reported that she has not had a seizure in two months but she has had a mild shock near the generator site. The patient has denied any trauma or manipulation. No known surgery has occurred to-date.
 
Manufacturer Narrative
(b)(6).
 
Event Description
The physician later provided the patient had high lead impedance still and was referred for lead revision. The patient states she has been having pain on the left side of the neck by the lead for the vns and has heard a cracking noise. She states that she is having pain on the left side of the chest where the magnet is and states there is swelling on that side, and feels like little knots. The patient states that when she lay on the left side of the neck it hurts and feels like it crackles. The patient states that she start having tingling like feeling 2 weeks ago, states that feels like having electric shocking.
 
Event Description
Follow-up from the physician¿s office provided that the swelling was not related to vns, even though the lead impedance is high.
 
Event Description
Follow-up was received indicating the patient does not want to go through with the revision due to her age and other health issues.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6191236
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dennis100
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« Reply #276 on: April 29, 2019, 05:21:33 AM »

Model Number 304-20
Device Problems Fluid Leak; Low impedance
Event Date 01/27/2017
Event Type  Malfunction   
Event Description
A physician reported that a patient had low impedance identified on a system diagnostic test. The patient had not been seen for 6 months when the low impedance message was observed. There were no patient symptoms reportedly occurring after the low impedance message was identified. The patient's physician opted not to program the device off because the patient was not having any pain. The child was reportedly very active and fell quite a bit, but there was no specific trauma thought to be related to the low impedance. No known surgical intervention has occurred to date.
 
Event Description
Additional information was received via clinic notes stating that the patient had been reportedly pulling at her lead and the physician believed she had pulled the lead from the generator, causing the low impedance.
 
Event Description
The patient underwent a full replacement due to the low impedance and the post-op impedance values were within normal limits. The explanted lead and generator were both returned to the manufacturer for product analysis. Analysis has not been completed to date.
 
Manufacturer Narrative
(b)(4).
 
Event Description
The explanted generator and lead both had product analysis completed. The analysis of the generator verified its ability to accurately measure impedance values in all instances. A comprehensive electrical evaluation showed that the device performed according to all functional specifications. A review of the generator data showed evidence that low impedance was present prior to explant. The returned lead portions had a visual analysis performed which identified abraded openings in the outer and inner silicone tubing, which provided leakage paths for what appeared to have once been body fluids inside the silicone tubes. A condition was created by this abraded insulation where the exposed coils could have come into contact with each other. The set screw marks on the lead pin provided evidence that at one point in time a good mechanical connection existed between the lead and the generator. Other than the abraded openings and the resulting exposed quadfilar coils, no anomalies were identified with the returned lead portions.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6344969
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dennis100
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« Reply #277 on: May 01, 2019, 12:09:32 AM »

Model Number 302-20
Device Problem Low impedance
Event Date 01/06/2017
Event Type  Malfunction   
Event Description
It was reported that low impedance was identified on a patient's device. There was no known trauma or manipulation of the device. No further relevant information has been received to date.
 
Event Description
The patient had no clinical symptoms associated with the low impedance. The patient had surgery to correct the low impedance. Low impedance was seen during pre-op and initially during surgery. The surgeon replaced the generator and attached it to the existing lead. The impedance was 766ohms, which is not considered low impedance, but the second impedance value came back at 661ohms. The surgeon felt that the impedance was too close to "low" impedance (600ohms), so the surgeon did a full revision. The explanted products have not been received to date.
 
Event Description
The explanted products were discarded by the hospital. Therefore, no analysis could be performed.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6294913
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dennis100
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« Reply #278 on: May 01, 2019, 12:10:21 AM »

Model Number 304-20
Device Problem Low impedance
Event Date 01/11/2017
Event Type  Malfunction   
Event Description
It was reported that during a follow-up appointment a diagnostic test resulted in a low impedance warning message. The physician stated that the family would likely prefer to have the device disabled and then to monitor the seizure frequency before considering replacement surgery. No surgical interventions are known to have occurred to date. No additional relevant information has been received to date.
 
Event Description
It was reported that the device had been disabled and the physician did not suspect that patient manipulation or trauma contributed to the low impedance. It was also reported x-rays had not been performed since the low impedance warning. No surgical interventions are known to have been scheduled or taken to date. No additional relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6302591
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dennis100
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« Reply #279 on: May 01, 2019, 12:11:01 AM »

Model Number 302-20
Device Problem Low impedance
Event Date 01/12/2017
Event Type  Malfunction   
Event Description
It was reported that low impedance was identified during the second follow-up after surgery. The impedance values after surgery and during the first clinic visit were reportedly within normal limits. X-rays were provided for review and did not provide a definitive cause for the high impedance.
 
Manufacturer Narrative
Device evaluated by manufacturer, corrected data: the initial report inadvertently did not select "device not returned to manufacturer".
 
Event Description
Additional information was received providing the patient's information. No known surgical intervention has occurred to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6303303
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dennis100
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« Reply #280 on: May 03, 2019, 12:40:50 AM »

Model Number 300-20
Device Problem Low impedance
Event Date 03/07/2017
Event Type  Malfunction   
Event Description
Information was received indicating that a low impedance message had been observed with the patient's generator. The patient who has developmental delays was not able to communicate whether there was an altered perception of stimulation. The physician elected to keep the patient's generator programmed on because the benefit would outweigh the risk. It was reported that the patient was experiencing isolated seizures but better than before. No surgical intervention has occurred to date. No additional relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6451422
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dennis100
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« Reply #281 on: May 03, 2019, 12:41:35 AM »

Model Number 302-20
Device Problems Corroded ; Fluid Leak; Fracture
Event Date 12/28/2016
Event Type  Malfunction   
Event Description
A patient reportedly had low impedance identified on a system diagnostic test. A diagnostic test was performed immediately afterwards and high impedance was found. There was no report of trauma, but the patient was reportedly extremely active. The patient's device was reportedly working as intended during the previous office visit.
 
Event Description
The patient underwent a full replacement surgery due to the high impedance. The post-op impedance values were within normal limits. The explanted lead and generator were both sent to the manufacturer for analysis, which has not been completed to date.
 
Event Description
The returned generator and lead had analyses completed one each respective device. The analysis of the generator confirmed in its ability to accurately measure impedance values and showed that the device performed according to all functional specifications. The generator was monitored for a greater than 24 hour period while placed in a simulated body temperature environment and the results confirmed in the generator's ability to accurately provide the intended output. The review of the generator data confirmed that the high impedance first occurred in (b)(6) 2016. A portion of the lead, including the electrodes, were not returned for analysis so a complete evaluation could not be performed. During the visual analysis, the connector ring quadfilar coil was broken approximately 355mm from the end of the connector boot and scanning electron microscopy was performed and showed evidence of extensive pitting which prevented identification of the coil fracture type. Pitting and residual matter were observed on the coil surface. An abraded opening was also identified on the outer silicone tubing and likely provided a leakage path for what appeared to be dried remnants of body fluid inside the outer silicone tubing. The setscrew marks identified on the lead connector pin provided evidence that a good mechanical and electrical connection was present and one point in time between the generator and the lead.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6446912
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dennis100
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« Reply #282 on: May 05, 2019, 12:20:00 AM »

Model Number 300-20
Device Problem Low impedance
Event Date 02/22/2017
Event Type  Malfunction   
Event Description
Clinic notes were originally received in regards to a prophylactic vns generator replacement referral. However, during surgery, a low impedance warning message was observed. Due to the low impedance observed, the patient underwent a full vns revision. Attempts for product return have been made; however, the products has not been received to date. It is unknown if the product will be returned to the manufacturer for analysis.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6424884
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dennis100
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« Reply #283 on: May 05, 2019, 12:20:52 AM »

Model Number 304-20
Device Problems Fluid Leak; Low impedance
Event Date 09/02/2016
Event Type  Malfunction   
Manufacturer Narrative
(b)(4).
 
Event Description
The manufacturer received the patient¿s explanted generator and lead for product analysis. Product analysis was completed on the explanted generator. Review of the internal device data showed record of an impedance change from 182 to 280 ohms, both meeting the criteria of low lead impedance, experienced prior to device explant. Low impedance was also registered on the last recorded automatic impedance measurement. Visual examination of the generator showed only observations consistent with the explant process; no surface abnormalities were noted on this device. The pulse generator diagnostics were as expected for the programmed parameters. A comprehensive automated electrical evaluation showed that the pulse generator performed according to functional specifications. The battery measured at 2. 935 volts during the functional testing. The internal device data revealed that 16. 474% of the battery had been consumed. Besides the identified low impedance condition believed to relate to the explanted lead, there were no performance or any other type of adverse conditions found in the analysis of the pulse generator. Product analysis results for the returned lead were reviewed. A large portion of the lead assembly - including the electrodes - was not returned for analysis, and therefore could not be evaluated. Visual and functional tests were performed on the portion of the lead that was returned. Abraded openings were found in the outer silicone tubing that were determined to be due to wear. Dried remnants of what appeared to have once been body fluids were found inside the outer silicone tubing. No discontinuities in the returned lead portion were identified. The condition of the returned lead portion is otherwise consistent with conditions that typically exist following an explant procedure. No other obvious anomalies or evidence to suggest an anomaly were noted. The lead's device history record was reviewed, and it was found all specifications were met prior to distribution. No additional pertinent information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6421802
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dennis100
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« Reply #284 on: May 08, 2019, 10:06:08 AM »

Model Number 304-20
Device Problem Low impedance
Event Date 02/08/2017
Event Type  Malfunction   
Event Description
It was reported that during an office visit, system diagnostics on the patient's generator resulted in a low impedance warning. No patient adverse events were reported. The physician planned on ordering x-rays to attempt to determine the cause of the low impedance. However, x-rays have not been reviewed by the manufacturer to date. No surgical interventions are known to have occurred to date. No additional relevant information has been received to date.
 
Event Description
X-rays were received and reviewed by the manufacturer. However, due to the quality of the images received, the lead was difficult to evaluate and the cause of the low impedance could not be determined.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6373640
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dennis100
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« Reply #285 on: May 11, 2019, 12:49:01 AM »

Model Number 302-20
Device Problem Low impedance
Event Date 01/30/2019
Event Type  Malfunction   
Event Description
It was reported to a company representative that a patient was "having some trouble" and vns is "going out". The physician saw the patient and stated that the vns was "failing". Follow up with the physician clarified that the "trouble" was the patient not feeling stimulation and experiencing an increase in seizures. The device was suspected to be "failing" due to the patient's breakthrough increased seizures. The physician did not have an assessment of the cause of the reported events. It was further indicated that no intervention was planned or taken for the events to date. Diagnostics were reported to be showing low output status and low impedance. No additional, relevant information was received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8476666
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dennis100
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« Reply #286 on: May 11, 2019, 12:50:04 AM »

Model Number 304-20
Device Problem Low impedance
Event Date 03/20/2019
Event Type  Malfunction   
Event Description
It was reported that low lead impedance of less than 600 ohms resulted from multiple system diagnostics tests although output current was ok and was successfully delivered at 1. 5ma. Additionally, the patient does have painful stimulation sometimes as well. The patient was referred for surgery. Follow up was performed with the patient's physician regarding the low impedance. It was reported that there is known trauma or manipulation of the vns area, the patient does not manipulate the lead themselves, and there is no change in stimulation perception reported by the patient. No known surgery has occurred to date. No additional or relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8515263
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dennis100
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« Reply #287 on: May 11, 2019, 12:50:50 AM »

Model Number 300-20
Device Problem Low impedance
Event Date 02/26/2019
Event Type  Malfunction   
Event Description
Patient underwent generator and lead replacement surgery, due to prophylactic replacement. The generator and lead were returned to the manufacturer for product analysis. The generator performed according to functional specifications; however, low impedance was detected on the generator. Based on the information known to date, low impedance prior to device explant cannot be ruled out. Product analysis was performed on the returned lead, which was received in 10 portions. Set screw marks found on the connector pin provide evidence that at one point in time a good mechanical and electrical connection was present. The product analysis lab did not confirm a low impedance short circuit condition on the portion of the lead returned. Other than typical wear and explant related observations, no anomalies were identified in the returned lead portions. No further relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8557391
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dennis100
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« Reply #288 on: May 11, 2019, 12:51:29 AM »

Model Number 302-20
Device Problems Fracture; Mechanical Problem; Low impedance
Event Date 03/11/2019
Event Type  Malfunction   
Event Description
It was reported that the patient had low impedance during battery replacement. Upon inspection of the lead, the surgeon reported that the lead was completely cut which appeared to indicate a visible lead fracture. The lead was replaced and impedance was within normal limits. Additionally, burn marks were reportedly visible on the patient's tissue near the lead. The lead has been received and product analysis is underway. No additional or relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8486810
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dennis100
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« Reply #289 on: May 14, 2019, 12:34:10 AM »

Model Number 302-20
Device Problem Low impedance
Event Date 03/17/2010
Event Type  Malfunction   
Event Description
It was initially reported from social media post that a patient¿s son did not see any benefit from the vns device. At this point patient information was unknown. Additional information was received from the patient¿s mother which identified the patient whose vns was said to be ineffective. She said that the generator was dead and that vns had "failed" and did not help her son enough to agree to have the generator replaced. She said that the patient's physician had told her that explant would run the risk of infection and that it would be safer to keep the system implanted. The programming history database was reviewed and showed a possible short circuit condition. It appears that there was a dramatic drop in impedance from (b)(6) 2009 dcdc 2 to (b)(6) 2010 showing dcdc 0. Along with the allegation that the device was ineffective, this shows there may have been a short circuit condition present. No additional information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8491506
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« Reply #290 on: May 18, 2019, 12:24:40 AM »

Model Number 303-20
Device Problem Low impedance
Event Date 10/29/2015
Event Type  Malfunction   
Event Description
A low impedance event was found through a periodic review of the programming history database. System diagnostics were performed and showed the impedance value was low at 60;600 ohms. The device had not been programmed off at that time. It was confirmed the physician was informed of the low impedance observed and the manufacturer's recommendations. No known surgical interventions have occurred to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6585754
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« Reply #291 on: May 18, 2019, 12:25:21 AM »

Model Number 302-30
Device Problem Low impedance
Event Date 05/03/2017
Event Type  Malfunction   
Event Description
It was reported that a vns patient¿s device was interrogated and showed low lead impedance, less than 600 ohms. The battery did not show an end-of-service condition. Additional relevant information has not been received to-date. No known surgery has occurred to-date.
 
Event Description
Clinic notes were received providing that the impedance value was low at 600 ohms and stated to be unusual and they didn¿t feel they usually see that.
 
Event Description
An implant card was received indicating that the patient underwent a full revision surgery due to the low impedance. Historically, the facility does not return explanted products to the manufacturer. The products have not been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6591791
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« Reply #292 on: May 18, 2019, 12:25:59 AM »

Model Number 304-30
Device Problems Fluid Leak; Low impedance
Event Date 04/24/2017
Event Type  Malfunction   
Event Description
It was reported on the date of the patient¿s generator replacement surgery that low lead impedance was registered on the patient¿s vns. This was the lead that was found to be attached to the generator. During troubleshooting with this lead, low impedance messages were observed with repeated pin insertion attempts. The test resistor was also used on the generator to verify that impedance on the generator itself was within normal limits. The lead was observed to have a section on it with no tubing and exposed wires. This lead and the previous vns generator were explanted. The explanted devices were reported to have been discarded. No additional pertinent information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6572209
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« Reply #293 on: May 20, 2019, 08:58:23 PM »

Model Number 302-30
Device Problems High impedance; Mechanical Problem; Low impedance
Event Type  Malfunction   
Event Description
It was reported that when the patient was seen in the physician's office a high impedance message was observed. It was also stated that the generator had migrated to under the patient's arm which was causing discomfort. The migration and discomfort have been reported in mfg report # 1644487-2017-03742. The patient was recommended for surgery due to the high impedance. High impedance was again observed during pre operation diagnostics. Once in the operating room, the pin was re-inserted in the generator and low impedance was observed during a diagnostic test. It was also noted that abrasions were observed in the insulation of the lead. The lead and generator were replaced during the surgery. Both the lead and generator were discarded of after the surgery. No additional relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6554061
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dennis100
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« Reply #294 on: May 20, 2019, 08:59:09 PM »

Model Number 304-20
Device Problem Low impedance
Event Date 04/12/2017
Event Type  Malfunction   
Event Description
It was reported that a diagnostic test during an office visit resulted in low impedance. It was noted that patient had not seen a recent change in seizure frequency. X-rays were ordered by the physician and the images were reviewed by the manufacturer. No anomalies or fractures were noted in the x-ray images. However, due to the quality of the images provided the lead¿s integrity was difficult to assess in some locations. There was a portion of the lead that appeared to potentially be a sharp angle however this could not be confirmed in the other x-rays images. It was noted that the lead pin appeared to be fully inserted however due to the angle of the generator the lead pin's position could not be fully assessed. No additional relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6563232
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dennis100
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« Reply #295 on: May 20, 2019, 09:00:06 PM »

Model Number 304-20
Device Problems Corroded ; Fracture; Mechanical Problem; Low impedance
Event Date 04/11/2017
Event Type  Malfunction   
Event Description
It was reported that during an office visit a diagnostic test was performed and resulted in low impedance. It was also reported that the patient had been experiencing an increase in seizures and a change in behavior which both appeared to be related to the low impedance. X-rays were performed and reviewed by the manufacturer. However due to the poor quality of the images provided the integrity of the lead was difficult to assess. Therefore the cause of the low impedance could not be determined. The patient was then referred for surgery where the lead and generator were replaced. The explanted products have not been received to date.
 
Event Description
The generator and lead were received by the manufacturer. The generator product analysis was completed. Visual analysis noted signs consistent with generator manipulation during explantation. The device was noted to be at ifi = no. The results were expected for all diagnostic tests in which various impedance loads were applied to the generator. The output signal of the generator was monitored for a 24 hour period and there were no variations in the output. The device performed to specification. The lead is pending product analysis.
 
Event Description
Analysis was completed on the lead. The lead was received in two portions of tubing with 3 loose quadfilar coils. Set screw marks confirmed that at one time there was adequate connection between the lead pin and generator. Visual analysis observed several abraded openings in the inner & outer tubing that appeared to be caused by wear. These confirmed openings were in adjacent areas and the exposed conductive quadfilar coils created a potential short-circuit condition thus confirming the report of low impedance. Additionally, lead fractures were observed in various locations. Some fractures appeared to be caused by the explant procedure while others appeared to have been caused by mechanical fatigue. Pitting was observed at some fracture sites, indicating that the stimulation was still be provided after the fracture occurred. It was noted that the three loose strands of coil each had melted ends indicating they were exposed to electrocautery during the explant procedure.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6563365
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dennis100
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« Reply #296 on: May 23, 2019, 10:47:27 PM »

Model Number 304-20
Device Problems Detachment Of Device Component; Mechanical Problem; Low impedance
Event Date 04/10/2017
Event Type  Malfunction   
Event Description
It was reported that the patient's device was interrogated and a low impedance warning was observed. X-rays were reviewed by the physician and there was no issues found on them. The x-rays have not been reviewed by the manufacturer to date. The patient is being referred for a surgical consultation due to the low impedance. No surgical intervention is known to have occurred to date. No additional relevant information has been received to date.
 
Event Description
X-rays were received and a review was performed. The cause of the low lead impedance could not be found. The visible portions of the lead were assessed and no fractures or discontinuities could be observed. There were portions of the lead that could not be seen so the entire lead could not be assessed. The patient's lead was replaced and the lead impedance was noted as ok after the replacement. After the explant, the lead was noted to look like the lead body had pulled away from the pin and it is unclear if this is the cause of the low impedance or if this was damage that occurred during the explant surgery. The lead has not been received by the manufacturer to date.
 
Manufacturer Narrative
Describe event or problem - corrected information: in supplemental report #01, it was stated that the device had not been received by the manufacturer to date however the device had been received at that point. Device available for evaluation - corrected information: supplemental report #01 needed to state the device had been returned to the manufacturer on 06/02/2017. Evaluation codes - corrected data: the conclusion coding in supplemental report #01 did not have code (b)(4) to indicate the device had been received and that evaluation was in progress.
 
Event Description
The lead was returned to the manufacturer and analysis was completed. The lead was returned in two portions which contained the lead pin and the electrodes. There were abrasions noted in the outer and inner tubing of the silicone most likely caused by wear. The connector boot wiring appeared to have been cut or torn at the end of the connector ring. This is most likely related to manipulation from the explant procedure. There was also melting of the wiring due to exposure to a high temperature device, most likely cautery during the explant procedure. The lead pin had a set screw mark which confirmed that it was fully inserted at one point in time. Continuity checks were performed on the returned lead portions and no discontinuities were identified. Analysis was unable to confirm the cause of the low impedance event.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6546620
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dennis100
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« Reply #297 on: May 27, 2019, 10:39:19 PM »

Model Number 302-20
Device Problem Low impedance
Event Date 05/20/2017
Event Type  Malfunction   
Event Description
Information was received that the patient had an approximately 3 minute seizure. The staff at the facility used the magnet twice to abort the seizure with no success. The device was checked and the lead impedance was marked ok but the impedance was 228 ohms, which is indicative of low impedance. The output status was low with 3. 25 ma delivery. The device was not at near end of service. Clinic notes were received indicating that the patient is experiencing an increase in seizures due to "suboptimal output current on vns device". The notes also state that the patient's epilepsy is still not controlled with "maximum vns parameters". No additional relevant information has been received to date.
 
Event Description
Patient was referred for low lead impedance issues but the surgeon only replaced the vns generator prophylactically. Surgeon was made aware of the low impedance issues as documented in the neurologist's clinical notes. But the surgeon chose to only replace the battery and not the lead. The lead impedance after replacement per implant card is within normal limits. No additional relevant information has been received.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6649013
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dennis100
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« Reply #298 on: May 27, 2019, 10:40:09 PM »

Model Number 304-20
Device Problem Low impedance
Event Date 05/30/2017
Event Type  Malfunction   
Event Description
A neurologist observed a low impedance error message when she interrogated the patient's device. The patient underwent full revision surgery. The surgeon believed that the original lead may have slipped off the patient's nerve, resulting in the low impedance. The explanted lead and generator were not returned for analysis. No additional relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6663167
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dennis100
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« Reply #299 on: May 30, 2019, 05:30:52 AM »

Model Number 302-20
Device Problem Low impedance
Event Date 05/11/2017
Event Type  Malfunction   
Event Description
It was reported that during an office visit the patient's vns device was checked and a low impedance warning message was observed. The device was checked twice and the low impedance message presented after each test. The patient was then referred for surgery to possibly replace both the vns generator and lead. No surgical interventions are known to have occurred to date.
 
Event Description
The patient underwent generator and lead replacement surgery. The explanted lead and generator have not been received to date. Historically, the explanting facility does not return explanted products therefore product return is not expected.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=6614709
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