Apparent pacemaker failure due to reversion circuitry within the programming device

While being evaluated for a recurrent tachyarrhythmia, a patient with a permanent pacemaker underwent reprogramming of the unit from the DVI to the VVI mode for assessment of the underlying rhythm. Subsequent reprogramming of the pacemaker to the DVI or DDD mode was impossible despite multiple attempts and the use of multiple programmers. The problem was considered to be a malfunction of the pacemaker circuitry, and plans were made for the pacemaker to be explanted and a replacement unit implanted. Before the procedure, the pacemaker company was notified of the explantation. We subsequently learned that a special programming sequence had to be carried out because of reversion circuitry present in the pacemaker but not described in the available literature. This report emphasizes the need for familiarity with each of the individual pacemakers being implanted and the need for the manufacturer to be as specific as possible given the complexity of current units.