Pacemaker in the Pericardial Space with Excessive Sensor Response to Cardiac Motion

DOI: 10.19102/icrm.2014.050206

¹AMY SIMS, MD, ²VICKI FREEDENBERG, PhD, RN and ²CHARLES I. BERUL, MD

¹Baylor College of Medicine/Texas Children's Hospital, Houston, TX

²Children's National Medical Center, Washington, DC

KEYWORDS. pacemaker, pediatric cardiology, sensor response.

Charles Berul discloses he is a consultant for Medtronic, Inc.
Manuscript received December 3, 2013, final version accepted January 20, 2014.

Address correspondence to: Amy Sims, MD, Pediatric Cardiology, Baylor College of Medicine/Texas Children's Hospital, 6621 Fannin St, Houston, TX 77030.
E-mail: aesims@bcm.edu

In this case report, we describe a child with a pacemaker generator implanted in the pericardial space that appeared to exhibit an excessive sensor response in response to cardiac motion.

Our patient was born with congenital complete heart block and pulmonary stenosis. At 2 days old, he underwent placement of a Microny (St. Jude Medical, St Paul, MN) epicardial unipolar ventricular pacemaker in the pericardial space (Figure 1).

Figure 1: Chest X-ray in the anterior-posterior projection, showing pacemaker generator in pericardial space under the right ventricle, with a unipolar pacing lead sutured onto the anterior right ventricular outflow tract.

At 4.5 years of age our patient was asymptomatic, on no cardiac medications, and had no activity restrictions. At his clinic visit, his mother noted that his heart seemed to be beating fast even at rest.

Pacemaker interrogation revealed the device to be in the VVIR mode with lower to upper rate range from 80 to 160 bpm. There appeared to be an excessive sensor response, leading to resting heart rates of 120 bpm and the sensor indicated rates from 100 to 140 bpm (Figure 2).

Figure 2: Pacemaker interrogation showing excessive sensor response, leading to resting heart rates of 120 bpm and the sensor indicated rates from 100 to 140 bpm.

We initially decreased the slope from 8 to 4, which permitted a resting heart rate of 80 bpm; however, there was no sensor response to limited exercise in the office. A slope of 6 gave an appropriate heart rate response to a short period of exercise along with a resting heart rate of 80.

Our patient likely exhibited excessive sensor reaction in response to cardiac motion, due to the placement of the pacemaker in the pericardial space. Although generators placed in the pericardial space are rare, this is an interesting and clinically relevant phenomenon that should be evaluated when these patients present for pacer interrogation.