Author + information
- Received March 31, 2015
- Revision received April 24, 2015
- Accepted May 6, 2015
- Published online August 1, 2015.
- Dinesh Sharma, MD,
- Marc A. Miller, MD,
- Chandrasekar Palaniswamy, MD,
- Jacob S. Koruth, MD,
- Srinivas R. Dukkipati, MD and
- Vivek Y. Reddy, MD∗ ()
- ↵∗Reprint requests and correspondence:
Dr. Vivek Y. Reddy, Helmsley Electrophysiology Center, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1030, New York, New York 10029.
A 67-year-old man underwent implantation of a single-chamber leadless cardiac pacemaker (Nanostim, St. Jude Medical, St. Paul, Minnesota) for recurrent syncope and paroxysmal complete heart block (Figure 1). At routine follow-up (4 weeks post-implantation), the patient underwent simultaneous device interrogation and 12-lead electrocardiogram analysis. High-frequency signals were noted after each sensed and paced QRS complex (Figures 2A and 2B, respectively), which is consistent with the unique communication mechanism of the leadless pacemaker. The high-frequency signals disappeared (Figure 2C) after communication between the leadless pacemaker and external programmer was turned off, and the signals were reproducible on resuming communication.
Historically, most pacemakers use inductive (short-range, wanded) or radiofrequency (long-distance, wandless) telemetry for communication between the pulse generator and the programmer. However, the leadless cardiac pacemaker uses conductive telemetry, whereby signals are exchanged between electrodes on the skin and the implanted device in the ventricle. The programmer transmits signals to an implanted leadless cardiac pacemaker with subliminal 250-kHz pulses applied to the skin electrodes. Data are encoded in 5 high-frequency pulses (per heart beat), sent by the leadless cardiac pacemaker during the absolute ventricular refractory period. Conductive telemetry is highly energy efficient and miniaturize-able because it obviates the need for any additional component (e.g., coil for electromagnetic coupling), but high-frequency pulses can distort the surface electrocardiogram (1). The number of patients with leadless pacemakers is increasing; thus it is important for physicians and health care workers to recognize this mechanism of communication by its characteristic manifestation on the surface electrocardiogram (2).
Dr. Reddy has received grant support from St. Jude Medical (the manufacturer of the leadless cardiac pacemaker). All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received March 31, 2015.
- Revision received April 24, 2015.
- Accepted May 6, 2015.
- American College of Cardiology Foundation