Failure of Demand Pacemaker From Low-Voltage Bipolar Ventricular Electrograms

Abstract

The recording of high voltage unipolar electrograms during bipolar demand ventricular pacing does not always guarantee delivery of an adequate QRS signal to the pacemaker as illustrated in two cases described in this report. In a bipolar system the actual QRS signal delivered to the pacemaker is the potential difference between the two intracardiac electrodes and may be measured by recording bipolar electrograms on a standard electrocardiograph.