The managed ventricular pacing algorithm can be misinterpreted as pacemaker malfunction

Some pacing algorithms developed to minimize right ventricular pacing have made the interpretation of electrocardiogram sometimes difficult and challenging. We report a case of a 76-year-old man admitted to our Cardiology Department for apparent pacemaker malfunction. Four months before, he had undergone dual-chamber pacemaker implantation for episodes of asymptomatic prolonged sinus pauses. The Managed Ventricular Pacing (MVP) algorithm provides an atrial-based pacing (AAI/R) with ventricular backup and can operate both in AAI/R and DDD/R modes. As the picture shows, atrial pacing spikes initially were followed by spontaneous ventricular depolarization. Then, the fifth atrial paced beat was not followed by ventricular depolarization (*) and so a ventricular backup stimulation was delivered 80 ms after the further programmed atrial beat (**). After a further loss of spontaneous ventricular depolarizations (*), an additional ventricular rescue pacing stimulus was delivered 80 ms after the following atrial beat (**). Since atrioventricular (AV) conduction did not occur over two of the last four A–A cycles, the device perceived persistent loss of conduction and switched to DDD/R mode. The presence of a very short AV interval of 80 ms following the loss of ventricular output is the essential clue and should alert the physician to MVP algorithm. The full-length version of this report can be viewed at: http://www.escardio.org/communities/EHRA/publications/ep-case-reports/Documents/non-invasive-electrophysiological.pdf