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During investigation, two breaks were detected at the transition to the pump connector and close to the cable tie.The two cracks look different, which indicates different types of stress on the driving tube.At this region of the driving tube, there is a transition from smaller diameter to larger diameter.This transition area of the driving tube is where the most stress is applied by external forces when in use by a patient.Torsional stresses can occur in the area of the cable tie when the driving tube is turned.It is very likely that high stress from the patient's mobility may have caused the fractures in the driving tube, and the presence of a small surface damages indicate that high degree of movement must have occurred at this region and contributed to the fracture.The exact cause of the defect cannot be detected in this case.In the current instructions for use (ifu), the user is advised that the cannula and driving tubes must not be bent, since this could lead to the damage of the cannula and driving tube.Furthermore, the user is advised to ensure that the cannulae and driving tubes are not subjected to any tension, torsion, pressure, or traction.And further on, in the manual the user of excor is instructed to inspect the blood pumps, cannulae and driving tubes regularly.
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