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Pma/510(k) # s001.(b)(4).Device evaluation: it may be noted that this complaint file was opened as a result of imaging review receive for mdr ref # 3001845648-2017-00255.The independent reviewer could not definitely determine if the occlusion was as a result of restenosis or thrombosis, "the occlusion would be a combination of both.There is no imaging to determine what was primarily the cause.If only the stent was involved, a year after implant it would be more likely neointimal hyperplasia; however more artery than just the stent was occluded so progressive atherosclerotic occlusion adjacent the stent with stent thrombosis is just as likely.I did not comment on it because it is impossible to know." therefore two complaint files were required.This complaint file, mdr ref # 3001845648-2017-00319 was opened to address thrombosis.For the investigation of restenosis refer to mdr ref # 3001845648-2017-00255.The ziv6-35-125-6-100-ptx stent was implanted in the patient and is therefore unavailable for evaluation.With the information provided a document based investigation was carried out.It may be noted that the patient had the following pre-existing conditions: this (b)(6) male presented at the time of enrollment with a history of hypertension, chronic obstructive pulmonary disease, hypercholesterolemia, and smoking (current).The lesion morphology revealed a tasc i type d lesion and a tasc ii type b lesion with moderate calcification and no thrombus.There was no previous intervention in the study lesion.There was no inflow tract stenosis greater than 50% and one patent runoff vessel.Baseline angiographic lesion measurements revealed a proximal and distal reference vessel diameter (rvd) of 6.0 mm and 100% diameter stenosis.The lesion length was 82.0 mm.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: implantation angiography and an ultrasound and x-rays performed one year post implantation and one month post the reported occlusion and bypass are provided along with the complaint report.The lesion was a distal right sfa occlusion spanning the adductor canal to the above knee popliteal artery.The occlusion length was 40 mm and was flanked by moderately stenotic equal length shoulders for a total lesion length of 85 mm.The lesion was moderately calcified.The mid sfa proximal to the stent was diffusely narrowed 40%.Iliac inflow was normal.Distal runoff was limited to the anterior tibial artery.The popliteal artery was diffusely narrowed 50% above and below the knee except for at the knee where a relatively normal caliber lumen was present.The anterior tibial artery was diffusely narrowed and further stenosed 75% just distal to the origin.Both the proximal peroneal and the entire posterior tibial arteries were occluded.The zilver ptx, 6 mm x 100 mm stent, was implanted in mild longitudinal compression at 95 mm and angioplastied to 5 mm with a greater than 5 mm expansion, except for mild constraint to 4.5 mm through the proximal third of the stent and to 4.7 mm through the distal third of the stent.The one year ultrasound was performed a month after the reported bypass.The sfa occluded approximately 2 cm proximal to the stent.The stent was occluded.The occlusion extended distal to the stent an undetermined distance.One year x-ray demonstrates complete stent expansion.The original constraint had resolved.The stent was not fractured.Impression: stent occlusion after bypass was confirmed.Presumably it was occluded prior to bypass for the bypass to have been performed.If patent, the flow siphoned off by the bypass would have insured stent occlusion.Patency was challenged primarily by the severely limited single vessel runoff as well as the reported continued tobacco abuse.Significant findings relative to the patient's anatomy were observed.The anterior tibial artery was the only patent runoff vessel and it was moderately, diffusely narrowed with an additional severe proximal stenosis.The popliteal artery was diffusely, moderately narrowed.The mid sfa was narrowed 40%, proximal to the stent.Significant findings relative to the disease state were observed.Continued tobacco abuse was reported.Significant findings relative to the use of the device were not observed.Significant findings relative to the design or performance of the device were observed.The stent occluded between implantation and 11 months post.Cause of adverse events was not observed.The customer complaint is confirmed as stent occlusion was observed in the image review.The following question was sent to the originator: ¿did the patient experience restenosis or thrombosis of the stents, resulting in the worsened claudication and rest pain?¿ and the following response was received: ¿developed return of claudication sx, angio revealed stent occluded not amenable to endovascular treatment right fem -pop above knee bypass performed on (b)(6) 2016 developed return of right leg claudication in (b)(6) 2016, not amenable to percutaneous/endovascular intervention, underwent open right fem-pop above knee bypass using vein graft on (b)(6) 2016- thrombus formation during case in popliteal artery treated with open thrombectomy¿ the independent reviewer was contacted to determine the thrombosis if present be as a result of the stent? or would it be linked to patient conditions, the following was received: "because adjacent superficial femoral artery, both proximal and distal, was included it is possible that the stent was an innocent bystander.However there is no information to determine whether the stent, the adjacent artery, or both caused the occlusion." as stated previously, as the image reviewer was not able to determine if the stent occlusion was due to restenosis or thrombosis, two complaint files were opened to address restenosis and thrombosis independently.The below list indicates potential risk factors that can generally contribute to the thrombosis event: - patient factors: history of coagulopathy/prior thrombosis (e.G., dvt), diabetes, especially if poorly controlled, cancer/chemotherapy, advanced age, obesity, hyperlipidemia, hypertension, smoking.- lesion factors: long lesion, small vessel diameter, severe calcification, lesion totally occluded prior to stent placement, placement for in stent restenosis.- procedure factors: residual inflow, outflow, or in-segment stenosis or dissection, poor run off (i.E., beyond trifurcation).- medication factors: inadequate procedural heparinization, inadequate loading dose of antiplatelet (ticlopidine or clopidogrel), inadequate dapt prescribed, non-responder to the apt, or non-compliant with prescribe regimen.Possible root causes for this occurrence could include the patient anatomy and pre-existing conditions.The image review noted that the vessel patency was severely limited by a single vessel runoff as well as the reported continued tobacco abuse and hypertension.These factors could have caused or contributed to this occurrence.However, as the circumstances of use cannot be replicated in a laboratory environment, a definitive root cause cannot be determined.As per the instructions for use, thrombosis is a known potential adverse event associated with placement of this device.Worsened claudication/rest pains are also known potential adverse event associated with the placement of this device as per the instructions for use.Document review: the ziv6-35-125-6-100-ptx stent contains zilver ptx drug eluting stent zvsp6-125-6-100-is.Prior to distribution all zilver ptx devices are subject to visual inspection and functional checks to ensure device integrity.A review of the relevant manufacturing records revealed no discrepancies that could have contributed to this complaint.Based on the information available to date, there is no evidence to suggest that there are any manufacturing issues associated with the lot number.Summary: the customer complaint is confirmed as stent occlusion was observed in the image review.A right above-the-knee femoral popliteal bypass procedure and thrombectomy were performed as a result of this occurrence.No other device related adverse events have been reported.Complaints of this nature will continue to be monitored for any potential emerging trends.
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This initial mdr is being submitted to capture a second failure mode from the image review [reference: mdr3001845648-2017-00255].(b)(6) ¿ worsened claudication/rest pain possible related to study product.On (b)(6) 2015, the patient received one 6.0 mm x 100 mm zilver ptx study stent in the right distal sfa.On (b)(6) 2015, the patient underwent pre-dilatation of study lesion with one inflation of a 5.0 mm x 80 mm balloon at 8 seconds.One 6.0 mm x 100 mm (lot # c1123550) was placed in the right distal sfa via contralateral access.The implanting physician noted that ease of device deployment was easy.No non-study stents were used to treat the study lesion.Post-stent dilatation was performed with one inflation of a 5.0 mm x 80 mm dilatation balloon for 8 seconds.At the conclusion of the case, no thrombus or dissection was noted by the site, and the entire length of the study stent was apposed to the vessel wall.There was no residual stenosis remaining in the study lesion and the proximal and distal rvds were 6.0 mm.The post-procedural abi was not performed for the study leg.On the same day, the patient was discharged from the hospital taking plavix and aspirin.On (b)(6) 2016 (292 days post-procedure), the patient experienced worsened claudication and rest pain in the study leg.The patient continued to take plavix and aspirin.On (b)(6) 2016 (336 days post-procedure), a right above-the-knee femoral popliteal bypass procedure and thrombectomy was performed.The physician determined that the event was possibly related to the study product and the patient¿s pre-existing peripheral vascular disease caused or contributed to this event.The device did not malfunction or deteriorate in characteristics or performance.No other device related adverse events have been reported.
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