Potential adverse effect of cardiac pacemakers in PD

A case report in Neurology describes how a man with Parkinson disease developed symptomatic tachycardia and reversible hallucinations due to rate response of a cardiac pacemaker to his tremor. The authors of the report explain, "Rate response (rate adaptive) pacing is available in most newer pacemakers and is designed to allow patients to increase their heart rates in response to exercise, which is sensed by movement or increased respiratory rate. Inappropriate tachycardia has been reported going over bumpy roads, but has not been previously reported from tremor?Of interest is the fact that the patient's tachycardia appeared to cause reversible hallucinations."The 76-year-old man had been implanted with a pacemaker two-and-a-half months before presenting with tachycardia. Over the next few months after implantation, he experienced increasing confusion, hallucinations, and weight loss and became wheelchair bound. His hallucinations dramatically increased on the day before his admission.On admission, the patient had a regular heart rate of 88 beats/minute and no active hallucinations. His PD symptoms fluctuated between an off state (UPDRS 3) and on state with a rating of mild to moderate rigidity in the extremities (UPDRS 2) and absent tremor. Head CT demonstrated microangiopathic changes, but no interval changes to explain his hallucinations and decreased mobility.However, the patient was in an off state during a routine echocardiogram the next day, with significant tremor, including tremor of the pectoralis muscles. The nurse noted increasing agitation, mild diaphoresis, and the onset of vivid hallucinations, and his echocardiogram recorded tachycardia (133 beats/minute). After his next dose of PD medications about two hours after the onset of tachycardia, he became less tremulous and his heart rate normalised. His hallucinations also resolved and his mental state improved around the same time. After the patient's cardiac pacemaker's rate response mode was disabled, his tachycardia did not recur.Reference...