Response by Elagha and Weissman Regarding Article, “Pacemaker Malfunction Attributed to Multidetector Cardiac Computed Tomography”
We thank Verheyen et al for their thoughtful comments on the case we published1 concerning pacemaker inhibition during the performance of cardiac computed tomography. We would like to add some of the details requested so that the context of this event can be better understood, and therefore, its broader implications can be considered.
The patient had Intermedics (model 479-01) dedicated unipolar leads placed in 1988. The sensing mode for both the atrial and ventricular leads was unipolar with a set sensitivity of 0.50 mV for the atrial lead and 2.80 mV for the ventricular lead. It is important to state that on the basis of the settings of the device, no intracardiac electrograms were recorded because the preset threshold to obtain a recording was not met. Therefore, the tracing shows only that the device interpreted the input it received during the performance of the computed tomography as a rhythm with a cycle length of 273 milliseconds lasting 6 beats. This was sensed equally in the atrial lead and the ventricular lead.
We agree with Verheyen et al that these findings should raise the awareness of potential pacemaker interactions, particularly in those with electrodes programmed in unipolar mode, and that further study is necessary to understand the likelihood of interactions with computed tomography in modern devices. Finally, it is difficult to suggest precautionary measures at this time because there is not a comprehensive understanding of the true event rate and risks.
Abdalla A. Elagha MD, PhD
Gaby Weissman, MD
Circulation is available at http://circ.ahajournals.org.
- © 2016 American Heart Association, Inc.