[Pacemaker syndrome with AV-synchronized stimulation of the heart]

Characteristic signs of the pacemaker syndrome occurred in a 69-year-old woman with intermittent 3 degrees atrioventricular (AV) block after implantation of a dual-chamber AV-synchronized pacemaker. Cannon beats due to inappropriate atrial timing were the main haemodynamic finding. Their development and size depended on the programmed AV interval and AV-synchronized mode of stimulation. Very long AV intervals in the DDD mode at a heart rate of 100/min caused very unpleasant palpitations and pulsations in the upper thorax. The symptoms due to the cannon beats were avoided by changing to a short AV interval. The clinical and haemodynamic events were thus the consequence of preserved sinus node function with subsequent atrial triggering.