The complaint instrument was not returned to biotronik.Therefore, no technical investigation on the subject could be performed.The corresponding production documentation was reviewed to establish whether a deviation from the manufacturing process could be the cause for this event.In addition, screenshots taken from the angiographic material were reviewed.The screenshots taken from the angiographic material show the implantation of the complaint stent by direct stenting.Before post dilatation the outer surface of the stent does not seem to be smoothly open with a visible step in the stent outer contour.Finite element analysis was used to investigate further local material distribution effects, and a very similar step in the stent outer contour could be reproduced.After post-dilatation of the stent, the appearance of the outer contour seems to be much smoother.The presence of a stent fracture could not be confirmed.Review of the production documentation verified that the instrument was manufactured according to specifications and fulfilled all the requirements of in-process and final inspection.Based on the conducted investigations of the device being subject to this complaint, no material or manufacturing related root cause was determined.It might have been beneficial to have had the artery prepared with a non-compliant balloon before stenting.It should be noted that the corresponding ifu clearly advises the user that pre-dilatation of the lesion is mandatory.
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