72-year-old nursing home resident sent to ER for evaluation of fever. Why is his pacemaker firing at a rate of 125/minute?
The pacemaker is firing at a ventricular rate of 125/minute. There is a PVC approximately half-way across the rhythm strip with a compensatory pause which allows you to notice a P wave – and the ventricular pacer follows the atrial activity. This is a dual chamber pacer, which is more physiologic than a single lead ventricular pacemaker. The pacer allows the ventricle to follow the sinus rate during exercise or other situations of appropriate increased heart rate.
This elder man is febrile and dehydrated – both good reasons for sinus tachycardia at 125/minute. Appropriate treatment of this pacemaker-mediated tachycardia is fluid resuscitation and acetaminophen!