chest wires

Has anyone in the group had trouble with setting off metal detectors? I have gone through only two airport checks in the 20 months since my operation and did not set off any alarm either time. These were just the walk through detectors. However, I think that the wand detectors might be more sensitive. One time I was surprised to hear one go off when it was passed under my arm. It turned out that it was the zipper for an underarm vent in the travel shirt that I was wearing. Since my sternum wires are so close to the suface that I can easily feel them with my fingers under the skin, I am concerned that a wand passed over my chest might detect them. Any comments? regards, Bob S.