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Upon receipt, the lead under complaint was found cut 5.5 cm distal to the is-1 connector pin (into two segments).All fragments were received for analysis.An extraction aid was found on the distal fragment, it is reasonable to assume that the lead was cut during the surgery.The analysis showed abrasion marks in the distal end region, which is assumed to be the root cause of the reported oversensing.Based on the characteristics of this damage, it is reasonable to assume that the lead had been subject to severe mechanical stress in the implanted state.Significant lead motion in the area of the tricuspid valve and interaction with atypical tissues should be taken into consideration.Further analysis showed that the lead tip and ring electrode were found covered in fibrotic growth.Calcifications are known to cause high impedances and is thus assumed to be the root cause of the observed high stimulation impedance.Prior to the analysis of the device, the quality documents accompanying the manufacturing process for this device were re-investigated.All production steps were performed accordingly, and in particular the final acceptance test proved the device functions to be as specified.In conclusion, the analysis did not reveal any sign of a material or manufacturing problem.
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