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Challenges in Clinical Electrocardiography
March 14, 2011

Tachycardia in a Patient With a Dual-Chamber Pacemaker—Discussion

Author Affiliations


Arch Intern Med. 2011;171(5):380-381. doi:10.1001/archinternmed.2011.60

The patient was evaluated and diagnosed as having pacemaker-mediated tachycardia (PMT). A magnet was placed over the pulse generator, which terminated the PMT. The pacemaker was reprogrammed, and after a short course of observation without further rapidly paced ventricular episodes, the patient was discharged home.

Two common causes of rapid paced ventricular rates on a resting electrocardiogram include (1) tracking of rapid atrial rates and (2) PMT. Other causes include programmed overdrive pacing to terminate tachyarrhythmias, “runaway” pacemaker due to a malfunctioning pulse generator, and tracking of oversensed signals in the atrial channel. Given the myriad of possible programmed functions and differing devices, it can be challenging for the untrained professional to distinguish normal from abnormal function. Therefore, the most important lesson about apparent pacemaker malfunction is that it is often appropriate. Occasionally, a rapid paced ventricular rate may represent an undesirable response that requires treatment of an underlying atrial arrhythmia or pacemaker reprogramming. It is valuable for the clinician to have a basic understanding of the mechanisms that result in inappropriate rapid paced ventricular rates and of indications that intervention is required.

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