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Author Topic: Low Impedance  (Read 28382 times)
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dennis100
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« Reply #240 on: March 09, 2019, 01:46:17 AM »

Model Number 302-20
Device Problem Low impedance
Event Date 06/20/2011
Event Type  Malfunction   
Event Description
During an internal programming history review it was discovered that the generator showed a drastic decrease in its lead impedance, which is an indication of a potential low impedance event. No other relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8362498
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dennis100
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« Reply #241 on: March 09, 2019, 01:47:07 AM »

Model Number 302-20
Device Problem Low impedance
Event Type  Malfunction   
Event Description
A generator was received for analysis for an unknown reason. Attempts were made for the reason for explant, however no information was received. Product analysis was completed for the generator and found that the generator performed according to functional specifications. Data from the generator was reviewed and noted low impedance. Product analysis was completed for the returned lead. Note that a comprehensive evaluation could not be completed as a large portion of the lead was not returned for analysis. Of the portion that was returned, no obvious anomalies were present and evidence suggests that the lead was properly connected to the generator and functioned as intended. No performance or any other type of adverse conditions were found. No additional, relevant information was received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8364088
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dennis100
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« Reply #242 on: March 10, 2019, 01:53:28 AM »

Model Number 303-20
Device Problem Low impedance
Event Date 01/07/2019
Event Type  Malfunction   
Event Description
It was reported that a patient was involved with a burn unrelated to vns and needed to be operated on to treat the burn wounds. The company representative was called in to interrogate the vns and assist with surgery precautions as needed. Upon interrogating the device, a low impedance error message was received. It was noted that the patient's x-rays appeared fine, and that the patient's mother mentioned that the device had previously shown low impedance, and that the neurologist had been monitoring it. An update was received from after the surgery to treat the burn wound, located on the neck and chest. It was noted that the surgery involved bovie, a form of electrocautery. The surgeon was advised about use of electrocautery around the vns, but it was stated that the surgery could not be completed otherwise. Post-operatively, the device was turned back on and the impedance was noted to be >600ohms. No further relevant information was received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8296859
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dennis100
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« Reply #243 on: March 11, 2019, 07:29:27 AM »

Model Number 304-30
Device Problem Low impedance
Event Date 08/25/2015
Event Type  Malfunction   
Event Description
Analysis was performed on the returned lead portion. The lead was returned intact. During the visual analysis the (+) white and (-) green electrode ribbons appeared to be stretched and the helices misshaped. This most likely occurred due to manipulation of the lead during the attempted implant procedure while attempting to place the electrodes on the vagus nerve. The condition of the lead assembly returned is consistent with conditions that typically exist following an attempted implant procedure; therefore the absence of abrasions on the connector boot and outer silicone tubing is evidence that the lead assembly was not fully implanted. Continuity checks of the returned lead assembly were performed with no discontinuities identified. Overall length and resistance measurements of the complete returned lead were determined to be in compliance with those defined in the manufacturing specifications. Based on the findings from product analysis, there is no evidence to suggest an anomaly with the returned device which may have contributed to the stated complaint. A review of device history records for the lead shows that no unresolved non-conformances were found.
 
Event Description
During an implant surgery, the surgeon reported that the electrodes seemed to be "straighter" and that the electrode coils didn't have the normal turns so it was more difficult to wrap around the nerve. Diagnostics performed with this lead were recorded the impedance to be 748 ohms and 800 ohms. Due to the lower impedance value, the surgeon opted to replace the lead. The explanted lead was received on (b)(6) 2015. Analysis is underway but has not been completed to date. An impedance value greater than 600 ohms and less than 5300 ohms is considered to be within normal limits.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5085587
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dennis100
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« Reply #244 on: March 15, 2019, 01:29:25 AM »

Device Problem Low impedance
Event Date 09/22/2015
Event Type  Malfunction   
Event Description
It was reported that the patient has low impedance seen on a system diagnostics test on (b)(6) 2015. Good faith attempts for further information from the physician were unsuccessful. Although surgery is likely, it has not occurred to date. The lead product information cannot be obtained as the implanting hospital will not give out this information.
 
Event Description
On 10/12/15 it was reported that the patient underwent a full revision that day. During surgery, the surgeon noticed the lead wire insulation had pulled away from the lead wire immediately next to the generator header. This resulted with the lead wire being in direct contact with body tissue. The surgeon stated that he could not remove the lead pin from the header of the generator. The explanted lead and generator were returned for product analysis on 10/14/15. Product analysis is still underway and has not yet been completed.
 
Event Description
On (b)(6) 2015 the physician reported that the low impedance was first observed on (b)(6) 2015. There was no reported patient manipulation or trauma and the patient has not experienced clinical symptoms that are believed to be related to the low impedance. X-rays were taken but have not been sent to the manufacturer for review to date.
 
Event Description
Product analysis was completed on the generator on (b)(4) 2015. Various electrical loads were attached to the generator and results of diagnostic tests demonstrate that accurate resistance measurements were obtained in all instances. In the product analysis lab, the device output signal was monitored for more than 24-hrs, while the generator was placed in a simulated body temperature environment. Results showed no signs of variation in the pulse generator铠output signal and demonstrated that the device provided the expected level of output current for the entire monitoring period. Magnet activations performed during output monitoring (at a distance of one-inch, spacer block, from the generator), demonstrate the appropriate magnet output for the programmed settings. In addition, a comprehensive automated electrical evaluation showed that the pulse generator performed according to functional specifications; there were no performance or any other type of adverse conditions found with the pulse generator. Product analysis was completed on the leads on (b)(4) 2015. An analysis was performed on the returned lead portions and bare and exposed conductive coils may be a contributing factor condition that could potentially contribute to the reported low impedance. During the visual analysis of the returned 389mm portion the connector boot / inner silicone tubes appeared to be torn / pulled apart in half (at the end of the connector ring) with the quadfilar coils bare, exposed and stretched in between. During the visual analysis of the returned 56mm portion the (+) white electrode inner silicone tubing appeared have been melted through and the quadfilar coil appeared to be slightly melted. Additional melted areas were observed on both of the inner silicone tubes. Based on the obvious signs of mechanical damage on the inner silicone tubes and quadfilar coil, it is possible the thermally-damaged coil was exposed to a high temperature device such as a cauterizing tool (electrosurgical unit) during the explant of this lead (damaged coil, not a break). The abraded opening found on the outer silicone and the cut ends that were made during the explanted process, 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 cut ends that were made during the explanted process and the torn ends of the connector boot / outer / inner silicone tubes at the end of the connector ring. With the exception of the abraded opening and torn / pulled apart connector boot / inner silicone tubes, the condition of the returned lead portions is consistent with those 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, and no discontinuities were identified.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5144333
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dennis100
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« Reply #245 on: March 16, 2019, 01:20:31 AM »

Model Number 303-20
Device Problems Circuit Failure; Loss of Power
Event Date 09/07/2015
Event Type  Malfunction   
Event Description
It was reported that a vns patient had pain in the neck and throat, and swollen spot in the neck. It was reported that short circuit was suspected, as the dcdc value dropped from 6 to 5, to 3, to 2 and now 0. The generator was switched off. It was reported that the x-rays will be taken then sent to the manufacturer for review. Review of the available programming and diagnostic history showed normal diagnostic results through (b)(6) 2012. Review of manufacturing records confirmed that both lead and generator passed all functional tests prior to distribution. No known surgical interventions have occurred to date.
 
Event Description
It was later reported that the vns patient had eating disorder, hoarseness, dysphagia and protrusion. Review of the available programming and diagnostic history received from the nurse showed normal diagnostic results through (b)(6) 2012. The x-rays were taken and sent to the manufacturer for review. The generator appears in the upper left chest in a normal placement. The filter feed-through wires appeared to be intact. The lead connector pin seems to be fully inserted into the generator connector block. The electrodes placement seems to be normal. One tie-down, strain relief bend were used to secure the implanted lead but not as indicated in the labeling. Part of the lead was behind the generator. No lead breaks or sharpe angles were visible on the assessed lead parts.
 
Event Description
Further information received indicating that the patient underwent a full revision. The lead was replaced due to lead function issue (low impedance) and the generator was replaced likely due to battery depletion. No explanted devices return is expected at ths time.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5123049
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dennis100
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« Reply #246 on: March 18, 2019, 01:52:01 AM »

Model Number 304-20
Device Problems Low impedance; Component Missing ; Material Protrusion / Extrusion; Lead
Event Date 11/04/2015
Event Type  Malfunction   
Event Description
It was reported that a low impedance warning was received during diagnostic testing of a patient's generator. The patient had a bandage over his generator incision site. The patient underwent exploratory surgery to determine the cause of the low impedance. When the bandage was removed from the generator incision site, a portion of the lead was sticking out of the generator incision. Two surgeons spent 1. 5 hours searching for the rest of the lead, but they were unable to find it other than a small portion of one of the coils in the neck. There was an infection present at the generator site, so the surgeons decided to remove the generator and remaining portion of the lead that was attached to the generator. X-rays and ultrasound confirmed that no lead was present. The surgeons believed that the patient pulled the lead out of his body through the generator incision site. The device history record for the lead was reviewed, and the lead was sterilized prior to release. Attempts for further information regarding the infection were unsuccessful to date. The explanted generator and remaining portion of the lead have not been received to date. The patient has not had a new vns system implanted to date.
 
Event Description
Analysis was completed on the generator on 01/11/2016. The generator performed according to functional specifications. There were no performance or any other type of adverse condition found with the pulse generator.
 
Event Description
The explanted generator and remaining portion of lead were received on 12/14/2015. Analysis on the lead was completed on 01/05/2016. The portion of the lead containing the manufacturing id tag was not returned, thus the model and the serial number of the returned lead portion could not be verified. Since a significant portion of the lead (including the electrode array) was not returned for analysis, an evaluation could not be made on that portion of the lead. Other than typical wear and explant related observations, no anomalies were identified in the returned lead portion. Analysis has not been completed on the generator to date.
 
Event Description
The cause of the infection was the patient picking at the incision site until it opened up and exposed the lead. It has been planned to replace the vns system in the future with the generator implanted on the patient's back. The patient has not had re-implant surgery to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5252502
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dennis100
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« Reply #247 on: March 18, 2019, 01:52:54 AM »

Model Number 302-30
Device Problems Low impedance; Device Displays Incorrect Message
Event Date 11/06/2015
Event Type  Malfunction   
Event Description
It was reported by the physician that the patient no longer feels stimulation. It was also reported the physician received the low impedance <600 ohms warning when interrogating the device. The patient was referred to a consultation for a full revision and replacement of the vns system. It was also reported the patient is severely mentally retarded and developmentally delayed. The patient is also prone to violent outbursts.
 
Event Description
It was reported the patient is a poor historian and the date of initial onset for the inability of the patient to perceive stimulation is not known. Additionally, it was reported there was no known trauma or incident suspected that could have caused or contributed to the reported event. No additional relevant information has been received to date.
 
Event Description
It was reported the patient underwent lead and generator revision surgery on (b)(6) 2016. Pre-operative testing of the vns verified the low impedance previously observed. The physician put a new generator on the existing lead and found 615 ohms. The decision was made to removed and replace the lead. It was found during surgery the electrodes were not on the nerve and there was no strain relief loop or anchor tethers present. The new lead was placed on the nerve, tethered and connected to the new generator. Diagnostics were performed and showed 2155 ohms. There was no known trauma or manipulation that could have caused the lead to come off of the nerve; however, the patient is autistic and combative. No additional relevant information has been received to date.
 
Event Description
Product analysis for the returned generator was completed. The generator output signal was monitored for more than 24 hours while in a simulated body temperature environment. Results showed no signs of variation in the generator's output signal and demonstrated the device provided the expected level of output current for the entire monitoring period. In addition, a comprehensive automated electrical evaluation showed the generator performed according to functional specifications. The battery voltage measured during analysis showed an ifi = yes (intensified follow-up indicator) condition. There were no performance or any other type of adverse conditions found with the generator.
 
Event Description
Pa for the returned lead portion was approved on (b)(6) 2016. The lead was found to have abraded openings on the outer and inner silicone tubing of the lead coils. Also, the positive and negative lead coils have what appear to be wear (flat surfaces) at the exposed portions located past the electrode bifurcation. The reported ¿low impedance¿ allegation was not verified. Though it was difficult to state conclusively, the identified exposed coil portions at the silicone tubing abraded openings may confirm this to be a contributing factor for the reported low impedance/short circuit condition. However, the exact point in time when the short occurred is unknown. Note that since the electrode array portion was not returned for analysis, an evaluation and resulting commentary cannot be made on that portion of the lead. Other than the above mentioned observations and typical wear and explant related observations, no other anomalies were identified in the returned lead portion.
 
Event Description
It was also observed, during lead product analysis, that the lead connector boot had partial detachment at the ring/backfill interface. The reason for this condition was unknown.
 
Manufacturer Narrative
Describe event or problem; corrected data: this information was inadvertently left off of the supplemental #04 mfr. Report.
 
Event Description
The lead assembly had dried remnant of what appeared to have once been body fluids inside the inner and the outer silicone tubing. No obvious point of entrance was noted other than the identified tubing openings and the end of the returned lead portion.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5257603
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dennis100
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« Reply #248 on: March 20, 2019, 10:39:51 AM »

Model Number 302-20
Device Problems Retraction Problem; Low impedance
Event Date 10/28/2015
Event Type  Malfunction   
Event Description
It was reported that during generator replacement surgery for end of service the surgeon disconnected the generator from the lead and then attempted to pull the lead from the patient's back side to re-tunnel the lead to the chest area. When the surgeon pulled the lead it got hung up in the patient's body and when the surgeon pulled on it the lead wires started retracting in the tubing. A new generator was attached to the lead and device diagnostics showed low impedance (<600 ohms). The surgeon did not obtain consent for lead replacement, so the lead was cut and explanted and a new generator was not placed. The patient was closed and rescheduled for lead replacement. No known surgical interventions have been performed to date.
 
Event Description
It was reported that the explanted devices were discarded; therefore, no product analysis can be performed. An implant card was received indicating that the patient underwent generator and lead reimplant on (b)(6) 2015. The surgeon indicated that he believed the lead electrodes were not on the nerve which he identified while dissecting the lead electrodes off of the nerve to reimplant the new lead. The surgeon indicated that the patient's anatomy was a little different than normally seen and an ultrasound was used to help determine the lead placement. The new generator was placed at the patient's chest. Device diagnostics were within normal limits.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5220659
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dennis100
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« Reply #249 on: March 21, 2019, 12:42:54 AM »

Event Date 10/09/2015
Event Type  Malfunction   
Event Description
It was reported that low impedance was identified inside and outside the chest pocket during a generator replacement surgery. Generator diagnostics were performed with the test resistor, which resulted in normal impedance. The lead pins were fully inserted two different times, but the low impedance was still present. The patient was closed up, and no known lead revision surgery has occurred to date.
 
Event Description
Programming history was reviewed for the patient's generator and confirmed the low impedance. Low impedance was also observed during a recent clinic visit. No additional relevant information has been received to date. No surgical intervention has occurred to date.
 
Event Description
The patient underwent lead and generator replacement surgery. The explanting facility did not return the explanted devices to the manufacturer for analysis. No additional relevant information has been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5198143
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« Reply #250 on: March 23, 2019, 01:04:39 AM »

Model Number 300-20
Event Date 11/18/2015
Event Type  Malfunction   
Event Description
It was reported that low impedance was found during system diagnostics at a patient's first follow-up visit since her generator replacement surgery. X-rays were ordered. The physician reviewed the x-rays and determined that a lead fracture was present. The patient was referred for full revision surgery. No surgical intervention has occurred to date.
 
Event Description
The patient had full revision surgery on (b)(6) 2016 due to lead discontinuity. The explanted generator and lead were received on (b)(6) 2016. Analysis of the generator was approved on (b)(6) 2016. There were no performance or any other type of adverse conditions found with the pulse generator. Analysis of the lead has not been completed to date.
 
Event Description
During analysis of the returned portion of the lead, a break was identified at the end of the positive coil. Scanning electron microscopy images of the positive coil showed that pitting or electro-etching conditions had occurred at the break location. However, due to pitting and mechanical distortion (smoothed surfaces) the fracture mechanism of the coil could not be ascertained. Note that since a significant portion of the outer and the inner silicone tubing and the electrode array portion was not returned for analysis, an evaluation and resulting commentary cannot be made on that portion of the lead. Other than the above mentioned observations and typical wear and explant related observations, no other anomalies were identified in the returned lead portions.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5291318
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« Reply #251 on: March 24, 2019, 02:10:50 AM »

Model Number 302-20
Device Problems Insulation; Hole In Material; Low impedance; Scratched Material
Event Date 12/10/2006
Event Type  Malfunction   
Event Description
Information was received indicating that low lead impedance was repeatedly observed via system diagnostics with a new pulse generator and a prior implanted lead during a generator replacement surgery. The surgeon verbally reported that the lead looked odd. It is unknown if generator diagnostics were performed with a test resister to test the generator's ability to accurately measure impedance. The physician did not replace the lead and the patient is being referred for a revision surgery. Subsequently received operative notes indicate that the physician observed a significant gap (opening) in the silicone insulation of the lead and attributed the low impedance to this condition. Pictures were taken of the lead and submitted and show possible, but inconclusive, insulation abrasion. A review of programming history with the prior device indicates system diagnostics lead impedances ranging from 0 to 2 with a decrease from 2 to 0 for the last several years of the available date. System diagnostic data from the date of replacement surgery with the prior pulse generator indicates dcdc 0, a warning of low lead impedance and impedance value <600 ohms. Attempts for additional relevant information have been unsuccessful to date and no known surgical interventions have occurred to date.
 
Event Description
The patient underwent lead explant and replacement on (b)(6) 2015. The surgeon left the electrode portion of the lead implanted and the new lead electrodes were placed above the former electrodes. It was observed that the lead insulation was broken down. No pre-operative device check was performed. The explanted lead has not been received by the manufacturer to date.
 
Event Description
The explanted lead was returned to the manufacturer. Product analysis confirmed abraded openings of the outer and inner silicone tubes in adjacent areas, exposing the conductive quadfilar coils and creating a potential short-circuit condition. A break of the positive coil in the electrode region of the returned lead was also observed. It is unknown if the break occurred while stimulation was present due to the absence of metal pitting on the broken coil wire surfaces. With the exception of the discontinuity and abraded openings, the condition of the returned lead portions is consistent with those that typically exist following an explant procedure. No other obvious anomalies were noted. Note that since a portion of the lead assembly (body), including the electrode array section was not returned for analysis, an evaluation and resulting commentary cannot be made on that portion of the lead.
 
Manufacturer Narrative
(b)(4).

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5275057
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« Reply #252 on: March 25, 2019, 01:24:06 AM »

Model Number 304-20
Device Problems Disconnection; Low impedance; Lead
Event Date 12/21/2015
Event Type  Malfunction   
Event Description
Low impedance was reported to be observed on the patient's vns device. The patient was referred for revision surgery due to the observed decrease in impedance. There was no trauma reported that could have caused or contributed to the low impedance and there were no reported adverse events. The patient underwent revision surgery on (b)(6) 2016. During the surgery, the surgeon observed a lead discontinuity near the generator site. Attempts for additional relevant information were unsuccessful to date.
 
Event Description
Product analysis for the returned generator demonstrated that accurate resistance measurements were obtained in all instance using various electrical loads. A comprehensive automated electrical evaluation showed that the vns generator performed according to functional specifications. The final electrical test showed an ifi = no condition. There were no performance or any other type of adverse conditions found with the vns generator. Product analysis for the returned lead found abraded an opening on the inner silicone tube, in one locations, and abraded openings on the outer silicone tube. The abraded opening on the outer tubing and the cut ends made during the explant process most likely provided the leakage path for the dried remnants of what appeared to have been body fluids found inside the outer tubing. What appeared to be white deposits were observed in various locations. Energy dispersion spectroscopy was performed on the deposits observed on the connector boot and identified the deposit as containing silicon and sodium. With the exception of the abraded openings, the condition of the returned lead portions is consistent with those that typically exist following an explant procedure. No other obvious anomalies were noted. The setscrew marks found on the lead connector pin provide the 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 visual analysis and no discontinuities were identified. Based on these findings in the product analysis lab, there was no evidence to support the low impedance, short circuit, or fractured lead allegations. It should be noted that a portion of the lead assembly, including the electrodes, was not returned for analysis; therefore, a complete evaluation could not be performed on the entire lead product.
 
Event Description
It was also reported the patient had an increase in seizures, above pre-vns baseline levels, which began after the lead fracture occurred. The increased seizures continued once the new devices were implanted and was reported, and will continue to be investigated, in mfr. Report 1644487-2016-01782.

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« Reply #253 on: April 02, 2019, 12:18:40 AM »

Model Number 302-20
Event Date 06/03/2015
Event Type  Malfunction   
Event Description
It was reported that a patient had low impedance that was observed during generator replacement surgery on (b)(6) 2015 and again on a follow-up visit on (b)(6) 2016. The surgeon who performed generator replacement on (b)(6) 2015 noted that there was a stitch piercing the lead. The surgeon assessed that the 4-0 prolene stitch was presumably placed at the time of implant. The surgeon cut the stitch and opted not to replace the lead as a result of the low impedance and closed the patient. Clinic notes from (b)(6) 2016 stated that the patient had received good results from the vns device. On (b)(6) 2016, the physician noted the low lead impedance was observed and the patient was experiencing an increase in seizures. The patient's device was programmed "off" as a result of the low impedance. The patient also reported that he hits his chest when he feels the generator on or when he believes it is time for the generator to come on and he does not feel stimulation. It was communicated that those actions would not affect the device providing stimulation and was informed of how to provide "on-demand" stimulation. A review of the programming history was performed on the device that was implanted on (b)(6) 2015 and showed that the diagnostic test performed after surgery showed a low impedance value. There were no allegations of low impedance with the previous generator (the generator explanted on (b)(6) 2015). Clinic notes reported that the patient thought he had a panic attach and was unsure if vns helped. The patient underwent full revision surgery on (b)(6) 2016 and had acceptable impedance values after the surgery was completed. The explanted generator and lead were discarded; therefore, no product analysis will be completed.
 
Event Description
It was reported that the generator and lead had not been discarded as previously stated. The explanted product has not been received by the manufacturer to date.
 
Event Description
An analysis was performed on the returned portion of the lead on (b)(6) 2016. A portion of the lead assembly, including the electrodes, was not returned and an evaluation could not be performed on this portion of the device. During the visual analysis, the end of the connector pin quadfilar coil appeared to be melted. Scanning electron microscopy (sem) was performed on the melted area and identified the area as having the appearance of being melted, with re-solidified material, giving evidence that it was melted at one time. This was identified in 3 total portions of the returned lead. 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 area on the remaining coil strand appeared to be mechanically damaged which prevented identification of the coil fracture type. What appeared to be spatter, flat spot and pitting was observed on the coil surface. The abraded opening found on the outer silicone tubing and the cut ends that were made during the explanted process, most likely provided the leakage path for the dried remnants of what appeared to have once been body fluids inside the outer silicone tubing. The condition of the returned lead portions was consistent with conditions that typically exist following an explant procedure. No other obvious anomalies were noted. Continuity checks of the returned lead portions were performed, during the visual analysis, with no discontinuities identified. An analysis was performed and approved for the generator on (b)(6) 2016. An end-of-service warning message was verified in the pa lab and found to be associated with the output being disabled by the pulse generator. Burn marks were observed on the pulse generator case. Review of the ram/flash data downloaded from the pulse generator shows an indication of low impedance. Various electrical loads were attached to the pulse generator and results of diagnostic tests demonstrate that accurate resistance measurements were obtained in all instances. The functionality and ability of the generator to provide appropriate programmed output current was verified in the pa lab.

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« Reply #254 on: April 02, 2019, 12:19:27 AM »

Model Number 304-20
Device Problems Fracture; High impedance; Low impedance
Event Date 04/17/2016
Event Type  Malfunction   
Manufacturer Narrative
(b)(4).
 
Event Description
A physician reported to an international distributor that low lead impedance had been observed in a patient's vns system at a device follow-up. X-rays were taken and provided to the manufacturer for review. The x-rays showed no obvious anomalies but did reveal a possible sharp bend in the lead just above the generator and a possible pin insertion issue. The entire lead body could not be evaluated based on the x-ray images submitted. Submitted diagnostic data shows three low impedance (<600 ohms) measurements on (b)(6) 2016 along with 7 normal impedance measurements on that same date. A decrease in impedance is observed in the data over the last seven months. No patient adverse events have been reported. The physician intends to monitor the patient's condition and continue normal patient following. No specific intervention is planned and no surgical interventions have occurred to date.
 
Event Description
Follow-up on this event was provided indicating that the patient's impedance values were fluctuating. The patient had low impedance values that fluctuated to high impedance on (b)(6) 2016. Then, on (b)(6) 2016 the impedance values were all within normal limits. Then, the patient was visited on (b)(6) 2016 and the impedance values were high on multiple system diagnostic tests. The system diagnostic test on (b)(6) 2016 was also high. Then, the patient was seen on (b)(6) 2017 and the impedance was within normal limits. A new set of x-rays was provided for review and there was no indication of a sharp angle on this x-ray and the lead pin did not appear fully inserted into the connector block. No know surgical intervention has occurred to date.
 
Event Description
The patient was seen for a clinic visit on (b)(6) 2018, and high lead impedance was observed on her device. The distributor noted that the patient's device had previously shown both high and low lead impedance, but the impedance values had recently been within the normal range. Diagnostics performed at the clinic visit indicated an output current of only 0. 50 ma was being delivered, although the generator was programmed to 1. 5 ma. The distributor planned to send x-rays to the manufacturer for review. The x-rays were received by the manufacturer but have not been reviewed to date. The full programming history was reviewed for the patient's generator. Fluctuating impedance values were observed throughout a significant portion of the programming history, including the aforementioned low and high impedance, along with several internal impedance changes not observed in previous diagnostic tests. Low impedance was internally detected between multiple interrogations when impedance appeared to be normal in system diagnostic testing, indicating several quick fluctuations in impedance value. On (b)(6) 2017 impedance values were within the normal limits and remained so through multiple clinic visits until (b)(6) 2018; however, the high impedance was internally detected three days prior. No additional relevant information has been received to date. No surgical intervention has occurred to date.
 
Event Description
The x-ray images were reviewed by the manufacturer. Due to the angle of the generator in the image, lead pin insertion into the generator could not be assessed. The filter feedthrough wires appeared intact, and the lead wire appeared intact at the lead pins. The lead was observed in the neck and chest. Due to the exclusion of the patient¿s upper neck from the provided images, the presence of strain relief could not be assessed in its entirety; however, a strain relief bend did appear to be present, and a strain relief loop appeared to be complete. Two tie-downs secured the lead at the strain relief bend, and one tie-down secured the lead at the strain relief loop. A portion of the lead appeared to be routed behind the generator. No gross fractures or lead discontinuities were observed in the provided images as visibility of the lead was lost near the collarbone. 3d-ct images were also included with the provided x-ray images. The presence and completeness of the lead strain relief was confirmed in the 3d-ct images. The portion of the lead routed behind the generator was also visible in the images, and a gross fracture was visualized in the portion of the lead that was not visible in the x-ray image. The thickness of the lead was minimal at the fracture location compared to the remainder of the lead body, signaling the potential for a short circuit condition to have existed. No additional relevant information has been received to date. No surgical intervention has occurred to date.

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« Reply #255 on: April 02, 2019, 12:20:06 AM »

Model Number 303-20
Event Date 04/25/2016
Event Type  Malfunction   
Event Description
It was reported that during generator replacement the lead showed uninsulated spot just after the connection to the generator. Furthermore, the lead was bent 180 degrees at this spot. The lead was disconnected from the old generator with some difficulties. Then, it was plugged in the new generator. The lead impedance at this time was 1400 ohms. Generator was placed into the pocket, and the wound was closed. System diagnostics was performed again and it showed impedance below 600 ohms. New generator has been left in place. Follow up indicated that no explanted generator return is possible as this was discarded after the replacement surgery. It was also reported that the physician did not suspect a lead manipulation. The device manufacturing records were reviewed. The review of manufacturing records confirmed that the lead passed all functional tests prior to distribution. Further follow up with nurse indicated that the patient underwent a lead and generator replacement; during the lead replacement on (b)(6) 2016 no hex screwdriver was available in the or to disconnect the lead from the generator. That was the reason of the replacement of the generator as well. The facility will not return the explanted devices to the manufacturer for analysis; therefore, no analysis can be performed.

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« Reply #256 on: April 03, 2019, 01:07:31 AM »

Model Number 304-20
Event Date 04/12/2016
Event Type  Malfunction   
Event Description
Low impedance (=600 ohms) was observed for patient's device. In house programming history database contained programming history from date of implant, (b)(6) 2013 through (b)(6) 2015. The last diagnostics were performed on (b)(6) 2015, which showed normal impedance of 1092 ohms. On the day of initial implant, (b)(6) 2013, the impedance was 1118 ohms. Based on the diagnostic history, the device impedance value since implant has not exceeded 1200 ohms and were within normal limits. Patient was referred for a full revision surgery but no known surgical interventions have occurred to date.
 
Event Description
Patient underwent full revision surgery on (b)(6) 2016. The explanted devices have not been received to date. Additional information was received that the low impedance message was seen on (b)(6) 2016. It is unknown if there has been any change in patient's perception of stimulation since implant of the vns because the patient is non-verbal.

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« Reply #257 on: April 04, 2019, 12:57:17 AM »

Model Number 302-20
Event Date 05/23/2016
Event Type  Malfunction   
Event Description
It was reported by a physician that diagnostics for a patient showed low impedance. The physician stated the device still seems to be working and the patient is not having seizures. Follow-up by the company representative to the physician revealed there was no trauma or manipulation around the lead or generator. No adverse events have been experienced. There were no previously recorded issues with the device diagnostics. X-rays were planned to be taken, but have not been received by the manufacturer for review. Additional relevant information has not been received to-date.
 
Event Description
Follow-up by the company representative who attended the patient's follow-up visit revealed that the patient's generator is low in the back area below the ribcage which was requested due to cosmetic reasons. The patient reported it felt like it would "catch or feel funny, like it was caught on something". Two diagnostics at the time indicated high lead impedance. The output current was lowered to 1. 0 (from 1. 75ma the lead impedance upon diagnostics registered as high. Diagnostics performed after output current reduction to 0. 5ma resulted in high lead impedance. The patient was reprogrammed to 1. 0ma and was referred for revision surgery. No known surgery has occurred to-date.
 
Event Description
Revision surgery occurred on (b)(6) 2016. Prior to surgery, system diagnostics showed high impedance. An incision was made to remove the generator, the pin was removed and reinserted three times which showed high impedance each time. The test resistor was inserted and generator diagnostics were performed showing impedance values were within normal limits with the resistor in place. Lead revision was performed. The generator was not replaced. Lead impedance was tested out of the pocket and inside the pocket and was within normal limits. The lead was discarded by the explant facility.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5735989
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« Reply #258 on: April 04, 2019, 01:00:55 AM »

Model Number 302-30
Event Date 03/13/2015
Event Type  Malfunction   
Manufacturer Narrative

Event Description
It was reported on 05/25/2016 that the patient reports having a shocking feeling in her chest area. The neurologist will consult with the surgeon about a possible lead or full revision. The patient went to the er (b)(6) 2016 and the vns was programmed off which resolved the issue. It was stating the diagnostics showed dcdc-0 at (b)(6) 2016 so at the time of the call it was not clear if there was a short circuit. She said that the pocket stimulation never completely went away after his generator was replaced in 2013. It did get significantly better after surgery but it has gotten progressively more bothersome over time. This seems to support the theory about an abraded opening in the lead. No additional information has been received to date.
 
Event Description
Device diagnostics were ran and there was no lead impedance and everything seemed fine, however patient experienced pain near generator. Full revision is planned but has not been completed to date.
 
Event Description
An implant card was received indicating that the patient had replacement surgery on (b)(6) 2016 due to prophylactic replacement and lead discontinuity. The explanted devices have not been received for analysis to date.
 
Event Description
The generator and lead were received for analysis on 10/26/2016. Product analysis for the generator was completed and approved on 11/03/2016. The device performed according to functional specifications. Analysis of the generator in the pa lab concluded that no abnormal performance or any other type of adverse condition was found. Analysis for the lead is currently underway but has not been completed to date.
 
Event Description
Product analysis for the lead was completed and approved on (b)(6) 2016. The condition of the returned lead portions is consistent with conditions that typically exist following an explant procedure. No 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, and no discontinuities were identified. Based on the findings in the product analysis lab, there is no evidence to suggest discontinuities in the returned portions of the device which may have contributed to the low impedance.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5733663

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« Reply #259 on: April 05, 2019, 09:33:42 PM »

Model Number 1000
Device Problem Mechanical Problem
Event Date 10/12/2018
Event Type  Malfunction   
Event Description
It was reported that the physician was unable to take the patient out of guided/scheduled programming mode. The physician received a programming error message repeatedly. Two different programmers were used but this did not resolve the issue. Later it was indicated that an error code associated with reed switch failure was observed. The internal data of the generator was reviewed. Battery voltages and impedances from up to implant date were within normal limits and there was no evidence of reboot. The run state for all programming operations on (b)(6) 2019, the date when the physician was unable to take the patient out of guided programming, was "stimulation inhibited". It was found that the generator had last checked voltage and impedance on (b)(6) 2018, which indicates that the generator had been disabled/inhibited since that time. There were a large number of magnet swipes the following day. This behavior is consistent with what occurs when the generator's reed switch is stuck closed. At the patient's follow-up, the patient's generator was reset. Diagnostics indicated low impedance, which evidences that the reed switch was closed. The patient's family reported that they had placed the patient's magnet on the generator for a few days on (b)(6) 2018. The patient's parents also said that the magnet may have been less effective at aborting seizures than it was at the beginning. Session reports from this follow-up appointment indicate that autostimulation and normal mode stimulation had occurred since the last visit, which indicates that the reed switch was unstuck for some amount of time. The manufacturer's device history records were reviewed. The generator passed final quality and functional specifications prior to release no further relevant information has been received to date.

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« Reply #260 on: April 05, 2019, 09:34:22 PM »

Device Problem Low impedance
Event Date 02/26/2019
Event Type  Malfunction   
Event Description
It was reported that the patient's device showed low impedance during their last diagnostic test. A review of the device history records indicated that the patient's generator passed all functional specifications prior to distribution. No known relevant surgical intervention has occurred to date. Attempts were made to the neurologist to obtain additionally information regarding the low impedance. No further relevant information has been received to date.

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« Reply #261 on: April 06, 2019, 12:26:55 AM »

Device Problem Low impedance
Event Date 02/28/2019
Event Type  Malfunction   
Event Description
It was reported that the patient had low impedance. The patient had x-rays taken and there were no visible fractures per the radiologist. The x-rays have not been received by livanova. Surgery is likely but has not 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=8426044
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« Reply #262 on: April 07, 2019, 01:54:12 AM »

Model Number 1000
Device Problem Mechanical Problem
Event Date 02/20/2019
Event Type  Malfunction   
Event Description
It was reported that the when diagnostics were attempted on the patient's vns, error code 254 was observed. The patient was later seen at a different appointment and the same 254 error code was observed. The generator would interrogate, but system diagnostics could not be performed. A cable connection between the wand and vns programming tablet was attempted and error code 43 was seen. A tablet and wand hard reset were performed. Error code 254 was seen again during system diagnostic attempts. The programmer was verified to not be plugged into the wall. Both the company representative's and physician's programmer showed the error message. Emi sources were removed and the wand was rotated 45 degrees. The magnet was swiped for 30 seconds consistently and re-interrogation/system diagnostics were performed. The error code appeared again. The programming tablet data was received and reviewed by the manufacturer. The findings were indicative that the issue was due to a stuck magnet reed switch. A generator reset was performed and low impedance was observed following the reset. The low impedance was a result of the output current not being delivered, which was related to the stuck reed switch. The patient was referred for generator replacement surgery. No relevant surgery is known to have occurred to date. No additional relevant information has been received to date.

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« Reply #263 on: April 07, 2019, 01:54:50 AM »

Model Number 304-20
Device Problem Low impedance
Event Date 02/22/2019
Event Type  Malfunction   
Event Description
It was reported that during the patient¿s replacement that the new generator had high impedance, seen on a system diagnostic test. The surgeon undid the leads, cleaned the insertion point in the generator and reinserted, then ran system diagnostics again which returned low impedance. They ran the diagnostics two or three times. After removing the lead from the generator, the test resistor was put into the generator and the diagnostic results were fine. The test resistor was removed, the leads were reinserted into the generator, and low impedance was seen again. The patient was closed and system diagnostics were performed with low impedance as a result. Programming history was reviewed for the patient¿s previous generator. No anomalies were seen, and the impedance was within normal limits throughout the device history. Programming history was reviewed for the generator. On the day of implant, the generator had 1 high impedance reading followed by 3 low impedance readings, followed by a good impedance (4050 ohms) followed by 3 low impedance readings. Then, one generator diagnostics had low impedance as well, but the timeline of the event reported indicates that the good impedance may have been seen with the test resistor and not on the lead, and the generator diagnostic most likely occurred following the patient being closed. No anomalies were seen. No additional information has been received to date.

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« Reply #264 on: April 08, 2019, 02:23:47 AM »

Model Number 304-20
Device Problem Low impedance
Event Date 08/30/2017
Event Type  Malfunction   
Event Description
It was found in programming history that there was evidence of fluctuating lead impedance levels, indicating a short circuit or low impedance condition. No additional information has been received.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=8392232
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« Reply #265 on: April 08, 2019, 02:24:29 AM »

Model Number 302-20
Device Problems High impedance; Low impedance
Event Date 10/09/2018
Event Type  Malfunction   
Event Description
An implant card was received which noted that high/low lead impedance was observed during the patient's vns generator replacement due to battery depletion. Lead impedance was also marked to be normal on the implant card. Ap neck x-rays of the patient were previously reviewed. The connector pin appeared to be fully inserted inside the connector block, and feedthru wires appeared intact. There appeared to be a portion of the lead wire located behind the generator which was unable to be assessed. No obvious gross lead discontinuities or sharp angles were observed in the visible portion of the lead. Due to the image quality and angles, the lead and generator could not be completely assessed. Note that the presence of a micro-fracture and/or a lead discontinuity could not be ruled out in the portion of the lead that is not visible in the provided images. No additional or relevant information has been received to date.

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« Reply #266 on: April 10, 2019, 01:00:49 AM »

Model Number 304-20
Device Problem Fracture
Event Date 06/22/2016
Event Type  Malfunction   
Event Description
Device diagnostics were performed which showed low impedance (<= 600 ohms). X-rays were taken; however, the review by a company representative did not indicate any discontinuities. The device was programmed off. The patient's father wants to see if the patient's seizures return prior to surgical intervention to ensure that vns has been helpful. There was no trauma or patient manipulation that may have caused or contributed to the low impedance. Subsequent device diagnostics were within normal limits at 606 ohms. No known surgical interventions have been performed to date. No additional relevant information has been received to date.
 
Event Description
It was reported that the patient's neurologist interrogated the generator and high impedance was found and the patient is having discomfort. The neurologist disabled the generator due to the high impedance. X-rays were reportedly viewed and found no discontinuity of the leads. Also, the neurologist stated that the vns system was programmed back on at some point and the previously reported issues with low impedance (reported as an initial report with the same mfr report number) had resolved. No known surgical interventions have been performed to date. No additional relevant information has been received to date.
 
Event Description
It was reported that the high impedance was found to have resolved and the patient's discomfort was not related to vns. There was no known physical trauma that may have contributed to the high impedance. No known surgical intervention 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=5806196
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« Reply #267 on: April 12, 2019, 12:45:38 AM »

Model Number 304-20
Event Date 05/01/2016
Event Type  Malfunction   
Manufacturer Narrative

Event Description
It was reported that a vns patient's device showed low impedance at 600 ohms. No injuries, falls, or trauma were reported. It was stated by the patient's mother that they get efficacy from the magnet. The patient has been referred for full revision. Clinic notes were received indicating that the vns magnet was initially effective, but is now no longer effective. An increase in seizures since may 2016 was documented and was attributed to "vns dysfunction resulting in low impedance value on interrogation. " the device had been programmed off on (b)(6) 2016. Lead and generator revision surgery occurred on (b)(6) 2016. A lead break was visualized approximately one-third of the distance from the generator. The explanted devices have not been received to-date. Additional relevant information has not been received to-date.
 
Manufacturer Narrative
Relevant tests/laboratory data, corrected data: the relevant test data was inadvertently not included in the initial report.
 
Event Description
The explanted devices were received for analysis on 10/05/2016. Analysis was performed on the returned lead portion 10/24/2016. The electrodes were not returned for analysis and therefore a complete evaluation could not be performed on the entire lead product. The outer silicone tubing appeared to be twisted and abraded openings were observed on the outer and inner silicone tubes. The coils were bare and exposed in the areas of the abraded openings. The abraded openings found on the outer and inner silicone tubes, most likely provided the leakage path for the dried remnants of what appeared to have once been body fluids found inside the outer and inner silicone tubes. What appeared to be white deposits were observed in various locations. Eds (energy dispersion spectroscopy was performed on the deposit observed on the outer silicone tubing and identified the deposit as containing silicon, sulphur and calcium. With the exception of the twisted appearance and abraded openings, the condition of the returned lead portions is consistent with those 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 portion were performed, during the visual analysis, and no discontinuities were identified. Analysis was completed for the returned generator 10/27/2016. The downloaded from the generator shows an indication of decreased impedance, as the last >25% change in impedance value showed the pre-change impedance value was 63 ohms and the post-change value was 257 ohms, with a time of change detection on (b)(6) 2016. The device was explanted later on (b)(6) 2016. Review of the manufacturer's programming history database shows the last known diagnostic test was performed on (b)(6) 2016 with an impedance value of 1812 ohms. Various electrical loads were attached to the pulse generator and results of diagnostic tests demonstrate that accurate resistance measurements were obtained in all instances. The device output signal was monitored for more than 24-hrs, while the pulse generator was placed in a simulated body temperature environment. Results showed no signs of variation in the pulse generator output signal and demonstrated that the device provided the expected level of output current for the entire monitoring period. Magnet activations performed during output monitoring demonstrate the appropriate magnet output for the programmed settings. 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 3. 055 volts and shows an intensified follow-up indicator was not set. 18. 519% of the battery had been consumed. There were no performance or any other type of adverse conditions found with the pulse generator. Review of the downloaded generator data revealed no anomalies.

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« Reply #268 on: April 13, 2019, 04:11:04 AM »

Model Number 303-20
Event Date 07/28/2016
Event Type  Malfunction  
Manufacturer Narrative
(b)(4).
 
Event Description
It was reported that low impedance was observed on vns patient's system implanted on (b)(6) 2015. The impedance was already found to be low some times before, but when the patient's device was checked in (b)(6) 2016, 3 system diagnostic tests were performed which showed impedance values of 600 ohms, 3000 ohms and again less than 600 ohms. X-ray was taken and sent to the manufacturer for review. The generator appears on the x-ray to be placed in upper chest in normal arrangement. The filter feed-through wires appears to be intact. The pin connector appears to be fully inserted. The electrodes appeared to be placed in normal arrangement. It is unable to assess the presence of the strain-relief bend and loop and if they were placed as specified by labeling. One tie-down is visible to secure the implanted lead. A portion of lead behind the generator could not be assessed. A clear lead discontinuity is visible, near the clavicle. A sharp angle is visible in the chest near the generator block connection and in that area, the lead appears to be twiddled. Based on the x-ray image, the cause for low impedance could be a short circuit in the lead part that appears to be twiddled. Further information was received from the nurse, indicating that no loss of efficacy yet but the patient recently could not perceive stimulation in magnet or normal mode. It was reported that no trauma was noted. The nurse indicated that it's unlikely that twiddling occurred as the generator is fairly deep and under a large breast. It was reported that the patient suffers from anxiety. Review of manufacturing records confirmed that both, the generator and the lead, passed all functional tests prior to distribution. No known surgical interventions have been performed to date.
 
Manufacturer Narrative
(b)(4).
 
Event Description
An implant card was received which indicated that the patient underwent lead revision surgery. The explanted lead has not been received to date.

https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfmaude/detail.cfm?mdrfoi__id=5892846
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« Reply #269 on: April 13, 2019, 04:13:01 AM »

Model Number 304-20
Event Date 06/30/2015
Event Type  Malfunction   
Manufacturer Narrative

Event Description
During review of the in-house programming/diagnostic history database, it was observed that low impedance was observed at office visit on (b)(6) 2015. A subsequent diagnostic test was performed during the same visit and resulted with normal impedance levels. It is unknown if any patient manipulation or trauma occurred that could have caused or contributed to the low impedance reading. Review of the programming data that captured the low impedance found that when the low impedance message presented the actual impedance value was measured as 384 ohms. Further follow-up found that the generator was still presenting with a low impedance message during a visit on (b)(6) 2016. No surgical interventions are known to have occurred to date.
 
Event Description
It was reported that the patient was experiencing a funny sensation in the neck and throat; which was attributed to vns stimulation. This change in perception was noted at the same time that the low impedance was observed and therefore appears to be related. The patient was referred for a lead and generator replacement however no surgical interventions are known to have occurred to date.
 
Event Description
The patient underwent vns lead and generator replacement surgery. In pre-op, diagnostic testing resulted within normal limits. During surgery the surgeon observed approximately 1 inch of the lead insulation was stripped off of the lead. The missing piece of the lead insulation could not be located. The lead and generator were then explanted and later received by the manufacturer. Both products are currently pending product analysis.
 
Event Description
Product analysis on the generator was completed. During analysis the output signal of the generator was monitored for more than 24-hrs and no variations in the output signal or expected level of output current were observed. The generator performed to functional specification.
 
Event Description
Product analysis was completed on the received lead portions. It was noted that the portion of the lead with the electrodes was not received therefore a complete evaluation could not be performed on the entire lead. The lead was received in 4 portions with the segment containing the lead connector pin still inserted into the generator. A continuity measurement verified electrical and mechanical contact between the generator and the lead pin. X-rays were taken and revealed that the canted spring of the generator was making contact with the connector ring of the lead. The continuity of the lead portions were evaluated and no discontinuities were identified within each portion. During analysis it was observed that the outer and inner silicone tubing had abrasions which would have made it possible for the quadfilar coils to come in contact with each other which would have caused a short circuit condition that would result in low impedance. Bodily fluids were observed inside the inner and outer tubing and coil fractures were observed in multiple areas however pitting was not observed. Analysis determined that the mechanism for some of the fractures appeared to be stress induced. However the mechanism for all of the fractures could not be determined. Based on the results of analysis it appears that the cause of the low impedance is related to a short circuit condition in the lead.
 
Event Description
It was reported that the patient experienced discomfort when the lead and generator were implanted.

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