Mechanism of pacemaker induced cough.

Single chamber ventricular pacing (VVI) may be associated with a group of adverse symptoms known as the pacemaker syndrome. Cough is an unusual but recognised feature of the pacemaker syndrome. A patient with a VVI permanent pacemaker experienced a disturbing cough during VVI pacing. There were no other symptoms associated with the pacemaker syndrome. The effects of short-term ventricular pacing on the cough were examined while the subject was standing and lying. After control recordings, the pulse generator was programmed to either VVI 50 beats/min or 90 beats/min and recordings made over 60 seconds. There was an interval of 60s between recordings. Overall, five recording periods at VVI of 50 beats/min and VVI of 90 beats/min were made in random order. The patient was blinded to the order of programming. The recordings were repeated with the subject lying. Cough was not found during normal sinus rhythm. During VVI pacing the patient experienced a tickling sensation in the throat associated with intermittent coughing. The number of coughs decreased during each successive recording period. The pacing cough reflex was enhanced when the patient was lying down. The mechanism of cough during VVI pacing is uncertain. The findings suggest a possible role for afferent vagal receptors from the airways.