Cross‐Stimulation: The Unexpected Stimulation of the Unpaced Chamber

The ability to stimulate one chamber through a lead or output circuit to the opposite cardiac chamber is termed cross‐stimulation. Three examples of this phenomenon are presented. The first involves the close proximity of the atrial lead to the ventricular myocardium with ventricular capture occurring at sufficiently high outputs; the second is due to the basic design of dual unipolar pacing systems which have output circuits that share a common anode; the third is a self‐limited eccentricity of one device that occurs only during the first phase of magnet‐induced asynchronous pacing. The mechanism and clinical significance of these observations are discussed.