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Related to report # 3001845648-2017-00302.The image review for report # 3001845648-2017-00302 observed stent shortening.An additional complaint was opened to record this failure mode.190647 complaint details: right leg angio gram for a claudication.A g38482 from lot number c1334468 was the first stent deployed in the patients sfa.Then the facility deployed a second stent, a g38481 from lot number c1262496.While attempting to withdrawal the deployment system; the zilver ptx deployment system got caught on the amplatz.Thsf-35-260-aes wire from lot number 7455253.To maintain access, the g11638 was parked at the upper end of the proximal stent.The physician had pull the deployment system and the wire out together at the same time.They inserted a new amplatz wire.They post dilated the stent with a mustang balloon and the run looked good.However, a clot was revealed in the proximal stent.They de-thrombosed with tpa using the angiodynamics unifuse catheter system.Then, the doctor used an angio jet machine in the proximal stent.Then the doctor did another run and it showed the proximal stent was not clear, but the clot had moved down thru both stents beyond the end of the distal stent and down to the of the trifurcation.Also, thrombus was seen in the popliteal vessel.Patient is now being sent for fem-pop bypass.Patient received 3 units of heparin prior to the intervention reference also report 3001845648-2017-00302 ((b)(4)).
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Cook ireland ltd (manufacturer) is submitting this report on behalf of (b)(4).Exemption number: e2016031.(b)(4).Pma/510(k) # p100022/s014.This follow up report is being submitted due to the completion of the investigation and an update to the conclusion of this investigation.The zisv6-35-125-6-100-ptx device of lot number c1262496 involved in this complaint was returned for evaluation, with the original packaging.The packaging was open on receipt.With the information provided, a physical examination and document based investigation was conducted.There are two failure modes related to this device and event.Reference also report 3001845648-2017-00302 (b)(b)(4).From customer testimony, it is known that the complaint device was advanced over a cook amplatz wire guide, of 0.035¿ diameter (part number thsf-35-260-aes).The wire guide was non hydrophilic, was used prior to this occurrence and was wiped between uses.The complaint device was flushed prior to use, as per the ifu.The sales representative stated it was likely that pre-stenting poba (plain old balloon angioplasty) was not performed prior to stent deployment.The physician stated that an inadequate heparin dose or leaving the sheath in place while exchanging devices may have been risk factors for the blood clot.The length of the procedure, between advancing the device and the attempted withdrawal, was seconds.Clinical input was requested, prior to images of the procedure being evaluated.The following information was provided: ¿blood clot forms almost directly after a blood vessel (endothelium) has been damaged or disrupted.Within twenty seconds of an injury in which the blood vessel's epithelial wall is disrupted, coagulation is initiated.It takes approximately sixty seconds until the first fibrin strands begin to intersperse among the wound.After several minutes, the platelet plug is completely formed by fibrin.Clot could¿ve been formed if the inner layer of vessel was damaged duo to withdrawal of the deployment system.Another possibility was the clot could have been formed while placing the stent or dilation procedure? or this clot could be a pre-existing condition?¿ images were provided to support the complaint investigation.They were reviewed through cook research inc.(cri) and the following comments were provided by the independent reviewer: findings: three photographs of an angiography monitor are provided along with the complaint report.Given the event description in the complaint report, the first image demonstrated two zilver stents implanted from the mid sfa through the distal sfa.Filling defects in the proximal stent were consistent with acute clot.A filling defect in the distal stent did not have the characteristic appearance of acute clot.Its appearance was more consistent with atheroma cheese grating through the stent interstices with possibly some surface thrombus.Two images of a later angiogram but at slightly different times demonstrated the distal sfa through proximal calf after the described distal embolization.The subtracted and unsubtracted images demonstrated the distal popliteal artery (pa) embolism.The embolism was smooth and convex on its superior surface, indicative of at least some residual acute clot.The moderately stenotic above knee pa with a residual lumen diameter of 2.8mm over a 10mm length starkly contrasted with more distal pa ectasia to 6.8mm.The distal stent was implanted to a length of approximately 96mm although it was likely closer to its design length of 100mm given some foreshortening produced by the angle at which photograph was taken.The second stent was implanted to a length of approximately 90mm.This stent may have been slightly foreshortened but not enough to account for 10mm.Stent overlap was 15mm.The proximal stent expansion ranged between 5mm and 6mm.The distal stent expansion ranged between 4.5mm and 5.5mm with some mild curvature and constraint occurring through the adductor canal segment from atherosclerotic plaque.The tip of the access sheath was observed in the proximal sfa.This typically is the deepest a 45cm sheath can reach down an sfa from a contralateral approach.The suggestion that the sheath was advanced into the stents to maintain access was likely impossible unless a 65cm sheath was used.Use of a 65cm sheath would be highly unusual for this procedure.The three units of heparin mentioned in the complaint report were likely 3000 units.The patient still would have been inadequately anti-coagulated.An adequate heparin bolus requires between 50 and 100 units per kg.This 95 kg patient would have required a 4750 unit heparin bolus at a minimum to prevent in situ thrombosis.Typically, adequacy of anticoagulation is checked with an act measurement prior to intervention.There is no mention of this being performed.Impression: the imaging cannot confirm or explain the complaint of zilver ptx and amplatz wire binding.No imaging of the event was provided.The sfa and pa were straight.It is very unlikely the binding caused the embolic event as other more likely causes were evident.First, no mention of pre-stent implantation preparatory angioplasty was provided.When the artery is not aggressively prepped, the opportunity for plaque cheese grating through the stent interstices is greater.The distal stent appearance is more consistent with cheese grated atheroma coated with thrombus.Second, the decision to perform fem-pop bypass also strongly suggests the operator suspected the same otherwise a thrombolytic infusion would have likely resolved the distal embolism.Third, outflow was limited by the 50% above knee pa stenosis.This would have slowed flow increasing thrombosis risk.Finally, the patient was not fully heparinized.Significant findings relative to the patient's anatomy were not observed.Significant findings relative to the disease state were not observed.Significant findings relative to the use of the device were observed.The artery was likely not aggressively prepped or not prepped at all with angioplasty prior to stent implantation, leading to distal embolization of atheroma.The patient was not fully heparinized despite significant untreated pa outflow limitation.Significant findings relative to the design or performance of the device were not observed.Cause of adverse events was not observed.Additional comments were received from cook research inc.(cri): "the stent was implanted in mild longitudinal compression.No stent failure or abnormality was observed.I am confident the stent was its labeled length.The stent appeared normal although perhaps a little crowded.That is what caught my eye to begin with.The compression was likely secondary to the implantation technique(forward pressure and poor vessel prep) and possibly within normal limits, since it is only 90% of the overall length.I measure my own stent lengths and they can vary up to 5%; so i know this happens but we all aggressively prep the artery with angioplasty.Perhaps this is why i do not observe greater than 5% discrepancy.I only measure out of curiosity.I know my partners do not measure unless they felt something went wrong.They aggressively prep as well and we have not had a stent deployment issue in recent memory.So what i do not know is how much is too much and what is the range of normal variation or how much is related to poor vessel prep.I mention this because it could be useful information in the future.Currently, the compression is innocuous." cook research confirmed that the stent shortening was not linked to the blood clot and the bypass reported by the customer.The device related to this occurrence underwent a laboratory evaluation on the 28th july 2017.On evaluation of the returned device, it was observed that the device was returned with the wire guide still in the device lumen.The wire guide was measured as 0.035¿ diameter, and 24.2cm of the wire guide was seen exiting the distal end of the device.An unsuccessful attempt was made to remove the wire guide.The distance between the end of the strain relief to the end of the stent retraction sheath (srs) was 106.Cm.The distance between the end of the strain relief to the distal white tip was 124.7cm, which was within specification of 125.0cm +1/-2cm (reference: dwg1512 version 5).There was no evidence of kinking damage on the outer sheath.Some surface damage was noted on the distal end of the srs.Congealed blood was observed on the overlap between the stability sheath and the srs.The evaluating engineer tested the function of the thumbwheel mechanism, but caused the retraction wire to separate from the srs.The distal inner was cut, but it was still not possible to remove the wire guide by hand.Congealed blood was observed at the end of the proximal inner, next to the distal inner.The engineer made another attempt to remove the wire guide, which was successful.Congealed blood was observed on the wire guide.A new 0.035¿ diameter wire guide was advanced through the delivery system, with no resistance encountered (ref att.¿images¿).The evaluating engineers also stated that the thrombosis was likely due to patient condition.Complaint is confirmed as the failure was verified in the image(s).The image review showed apparent stent shortening from 100mm to 90mm.Possible causes for the stent shortening could include the procedural method.From the image review, the patient was not aggressively prepped with angioplasty prior to stent implantation.From the image review and the additional comments, it is possible that the physician applied forward pressure to the delivery system during deployment.This could have cause or contributed to the foreshortening of the stent on deployment.There was no evidence to suggest a malfunction of defect with the stent.However, as the circumstances of use cannot be replicated in a laboratory environment, a definitive root cause cannot be determined.Prior to distribution, all zisv6 (zilver ptx thumbwheel) devices are subject to visual inspection and functional checks to ensure device integrity.A review of the relevant manufacturing records did not reveal any discrepancies which could have contributed to this complaint issue.Upon review of complaints, this failure mode has not occurred previously with this lot number.Based on the information available to date, there is no evidence to suggest that there are any manufacturing issues associated with lot number c1262496.According to the initial reporter, the patient required bypass surgery as a result of the blood clot.Complaints of this nature will continue to be monitored for potential emerging trends.
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This follow up report is being submitted due to the completion of the investigation and an update to the conclusion of this investigation.Initial report details: related to report # 3001845648-2017-00302.The image review for report # 3001845648-2017-00302 observed stent shortening.An additional complaint was opened to record this failure mode.(b)(4) complaint details: right leg angio gram for a claudication.A g38482 from lot number c1334468 was the first stent deployed in the patients sfa.Then the facility deployed a second stent, a g38481 from lot number c1262496.While attempting to withdrawal the deployment system; the zilver ptx deployment system got caught on the amplatz.Thsf-35-260-aes wire from lot number 7455253.To maintain access, the g11638 was parked at the upper end of the proximal stent.The physician had pull the deployment system and the wire out together at the same time.They inserted a new amplatz wire.They post dilated the stent with a mustang balloon and the run looked good.However, a clot was revealed in the proximal stent.They de-thrombosed with tpa using the angiodynamics unifuse catheter system.Then, the doctor used an angio jet machine in the proximal stent.Then the doctor did another run and it showed the proximal stent was not clear, but the clot had moved down thru both stents beyond the end of the distal stent and down to the of the trifurcation.Also, thrombus was seen in the popliteal vessel.Patient is now being sent for fem-pop bypass.Patient received 3 units of heparin prior to the intervention reference also report 3001845648-2017-00302 (b)(4).
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