Inhibition of the Oversensing of Cardiac Pacemakers in Chest CT

Norihiko Akiba,Yasuo Okuyama,Kyoichi Ito,Osamu Nakamura,Mika Tsuboi,Kohki Yoshikawa,Morio Shimada,Masashi Takeda,Joel Matsumoto,Giichiro Nakaya

doi:10.4236/ojmi.2012.24022

Abstract

Objectives: The purpose of this study is to identify how to manage oversensing of pacemakers in chest CT. Methods: Four different models of pacemakers were examined to select the pacemaker generating oversensing. To the pacemaker with oversensing, intermittent switching X-ray was exposed using ECG-gated CT helical scan system at prospective CTA mode. IVY Model was used to synchronize the ECG. Only during in the alert period that is non-refractory and sensing is available, intermittent switching X-ray (300 msec/sec) was exposed in chest CT. For comparison, the same intermittent switching X-ray (300 msec/sec) was exposed in the refractory period when sensing was not available. Results: Oversensing was detected only in one of the four pacemakers tested. In this pacemaker, oversensing was generated by exposure of the intermittent switching X-ray in the alert (non-refractory) period, but oversensing was not observed in the refractory period. Conclusion: A pacemaker has alert and refractory periods. Oversensing of a pacemaker was found to be inhibited by selective ECG-synchronized exposure in the refractory period. Since all pacemakers have the refractory period, the results of this study can be widely applied to the patients with pacemakers in chest CT, and their chest CT can be operated safely.

Highlights

In 2005, the first case of the pacemaker-related defect was reported in Japan claiming that a pacemaker induced a partial electric oversensing in X-ray CT [1,2,3,4,5,6,7,8,11,12]
In the pacemaker which showed oversensing, atrial pacing (AP) and ventricular pacing (VP) were changed to atrial oversensing (AS) and ventricular oversensing (VS), respectively (Figure 4)
These results show that oversensing suppressed the changes of AP and VP (AP→AS and VP→VS)

Summary

Introduction

In 2005, the first case of the pacemaker-related defect was reported in Japan claiming that a pacemaker induced a partial electric oversensing in X-ray CT [1,2,3,4,5,6,7,8,11,12]. Ministry of Health, Labor and Welfare issued the reminder to medical institutions titling “Precautions for the use of X-ray CT and implantable cardiac pacemakers with regard to their interactions” [11,12]. As of 2011, the reports of oversensing and reset of the cardiac pacemaker still have been observed [7]. In this article we investigated the way to inhibit the oversensing in X-ray CT

Objectives

Methods

Results

Conclusion