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IMAGES IN ELECTROPHYSIOLOGY

The Leadless Cardiac PacemakerConductive Communication

Dinesh Sharma, MD, Marc A. Miller, MD, Chandrasekar Palaniswamy, MD, Jacob S. Koruth, MD,Srinivas R. Dukkipati, MD, Vivek Y. Reddy, MD

A 67-year-old man underwent implantationof a single-chamber leadless cardiac pace-maker (Nanostim, St. Jude Medical, St. Paul,

Minnesota) for recurrent syncope and paroxysmalcomplete heart block (Figure 1). At routine follow-up(4 weeks post-implantation), the patient underwentsimultaneous device interrogation and 12-lead elec-trocardiogram analysis. High-frequency signals were

FIGURE 1 Chest X-Ray (Posterior-Anterior and Lateral) After LCP Im

LCP = leadless cardiac pacemaker.

From the Helmsley Electrophysiology Center, Mount Sinai School of Medicin

support from St. Jude Medical (the manufacturer of the leadless cardiac pa

have no relationships relevant to the contents of this paper to disclose.

Manuscript received March 31, 2015; revised manuscript received April 24, 2

noted after each sensed and paced QRS complex(Figures 2A and 2B, respectively), which is consis-tent with the unique communication mechanism ofthe leadless pacemaker. The high-frequency signalsdisappeared (Figure 2C) after communication be-tween the leadless pacemaker and external program-mer was turned off, and the signals were reproducibleon resuming communication.

plant

e, New York, New York. Dr. Reddy has received grant

cemaker). All other authors have reported that they

015, accepted May 6, 2015.

FIGURE 2 Conductive Communication

High-frequency pulses are visible on surface electrocardiogram, when the leadless cardiac pacemaker (LCP) and programmer are actively

communicating.

Sharma et al. J A C C : C L I N I C A L E L E C T R O P H Y S I O L O G Y V O L . 1 , N O . 4 , 2 0 1 5

Leadless Pacing Communication A U G U S T 2 0 1 5 : 3 3 5 – 6

336

Historically, most pacemakers use inductive (short-range, wanded) or radiofrequency (long-distance,wandless) telemetry for communication between thepulse generator and the programmer. However, theleadless cardiac pacemaker uses conductive telem-etry, whereby signals are exchanged between elec-trodes on the skin and the implanted device in theventricle. The programmer transmits signals to animplanted leadless cardiac pacemaker with subliminal250-kHz pulses applied to the skin electrodes. Data areencoded in 5 high-frequency pulses (per heart beat),sent by the leadless cardiac pacemaker during theabsolute ventricular refractory period. Conductivetelemetry is highly energy efficient and miniaturize-

able because it obviates the need for any additionalcomponent (e.g., coil for electromagnetic coupling),but high-frequency pulses can distort the surfaceelectrocardiogram (1). The number of patients withleadless pacemakers is increasing; thus it is importantfor physicians and health care workers to recognizethis mechanism of communication by its characteristicmanifestation on the surface electrocardiogram (2).

REPRINT REQUESTS AND CORRESPONDENCE: Dr.Vivek Y. Reddy, Helmsley Electrophysiology Center,Mount Sinai School of Medicine, One Gustave L. LevyPlace, Box 1030, New York, New York 10029. E-mail:vivek.reddy@mountsinai.org.

RE F E RENCE S

1. Ferguson JE, Redish AD. Wireless communica-tion with implanted medical devices using theconductive properties of the body. Expert RevMed Devices 2011;8:427–33.

2. Reddy VY, Knops RE, Sperzel J, et al. Permanentleadless cardiac pacing: results of the LEADLESStrial. Circulation 2014;129:1466–71.

KEY WORDS bradycardia, conductive,leadless cardiac pacemaker, telemetry