On 7/19/97, a 69 y/o male pt was implanted with a bipolar single-chamber pacemaker and another mfr's lead. On 7/20/97, pt presented with loss of capture. Physician said he obtained good lead thresholds but was unsure if the pacemaker had paced adequately from initial hook-up. Physician attempted to reprogram the device but was unsuccessful. Physician elected to explant the pacemaker and lead and replace it with another pacemaker and lead from the mfr. Complication was resolved. A device explant/event report form was received which indicated battery depletion.

Visual exam: unaided eye-the pacemaker presented a normal appearance when viewed with no magnification. Microscopic eval-the pacemaker presented a normal appearance when viewed at 10x. Electrical eval: 1. All data printout-a normal all data printout was obtained upon receipt of the pacemaker on 7/22/97. The following values were reported: mode-vvi, rate-72ppm, pulse width-0. 6 msec, amplitude-3. 5 volts, refractory period-280 msec, sensitivity-l2. 5 m volts: current-0. 3mamp, impedance-9999kohm, and cell voltage-2. 74 volts. These are nominal vvi pacemaker settings and expected lead current and impedance readings (no lead attached) and battery voltage readings (fresh battery). 2. Electrical test-a complete quality assurance console electrical test was performed on 7/22/97. All values were within specification and when compared to previous tests as a hybrid and as a pacemaker final test there were no significant changes (deltas) in the tested values. At electrical test the tech was unable to engage the setscrews. The author's attempts to assist were unsuccessful. Under a microscope one setscrew hole plug was carved away with a scalpel permitting a more aggressive insertion of the setscrew hex wrench. This allowed enough insertion to engage the setscrew against the electrical test lead connector pin. A more aggressive insertion of the hex wrench into the collar setscrew was also successful in electrically connecting the bipolar test lead sleeve. The wrench was difficult to remove from the setscrew slot indicating stripped hex flats within the setscrew hex slot. Electrical test of the pacemaker was completely successful but the test lead was difficult to remove afterwards due to add'l problems engaging the setscrew. Microscope photos were taken of the setscrews. Both had cavities filled with what appeared to be medical adhesive. This adhesive is used to seal the perimeter of the setscrew hole plug in place during final assembly of the pacemaker but is not allowed in the setscrew cavity. Also, note worthy are three setscrew cone point indentations on both the lead connector pin and bipolar collar. This indicates that both setscrews were sufficienty tightened against both the lead pin and collar to distort their metals. Both setscrews' hex wrench slots were stripped. A comparison photo was taken with a uncompromised setscrew to demonstrate the amount of stripping. It should be pointed out that, by design, the setscrew metal is about twice as hard as the metal of the hex wrench supplied with the pulse generator. This design is intended so that the hex wrench shaft will strip its flats before the setscrew slot flats get stripped. The fact that setscrew slot flats were stripped indicates something other than the pulse generator supplied hex wrench was used. Conversations with the implant physician revealed he has his own tools for pacemaker setscrews. Conclusions: there are no indications that the pacemaker or lead would not capture or pace.