Quantitative, low cycle, crack initiation fatigue testing of fine wires and CENELEC standard pacing coil

Uniaxial fatigue testing was performed on different diameters of fine wires made from MP35N, The fatigue limits of the wires differed from each other based on the diameter of the wire. Multiaxial (shear) fatigue testing was a lso performed on a benchmark toil used to evaluate the fatigue life of all modern pacemaker leads (the CENELEC standard coil), A computer algorithm wa s used to quantify the maximum shear stress and strain on the coil. The ben d radius, coil diameter, wire diameter, and pitch of the coil all affect th e shear stress and strain and therefore the fatigue properties of conductor coils, Based on the analysis presented, it was determined that the portion of the CENELEC standard dealing with fatigue, when used in its present for mat, is not a valid fatigue test for pacemaker leads. (C) 1999 John Wiley & Sons, Inc.