Pacemaker spike
Also calledPacing spike · Pacer spike · Pacing artifact · Pacing artefact · Stimulus artifact · Pacemaker stimulus artifact
Definition
A narrow, sharp deflection on the ECG (a stimulus artifact) marking the instant the pacemaker delivers its pulse, followed by depolarization of the chamber when the pulse captures. The pulse itself is very brief, generally shorter than 0.5 ms. Spike size depends on the pacing configuration: unipolar pacing (between the generator and the lead tip) produces large spikes, whereas bipolar pacing (between two electrodes at the lead tip) produces small spikes that are sometimes almost imperceptible. The spike is the device's output, not myocardial activity.
Clinical noteBipolar spikes are often too small to recognize on the standard ECG; an unexpectedly large bipolar spike has been linked to a breach in lead insulation.
Sources
- Lloyd MS, Pelling M, Ibrahim R, El-Chami MF, Iravanian S. Accurate detection of lead malfunction from ECG-derived bipolar pacing stimulus amplitude. Heart Rhythm. 2024;21(11):2226-2231. doi.org/10.1016/j.hrthm.2024.03.1814
- Kligfield P, Gettes LS, Bailey JJ, et al. Recommendations for the standardization and interpretation of the electrocardiogram: part I: the electrocardiogram and its technology. Circulation. 2007;115(10):1306-1324. doi.org/10.1161/CIRCULATIONAHA.106.180200
- Samesima N, God EG, Kruse JCL, et al. Brazilian Society of Cardiology guidelines on the analysis and issuance of electrocardiographic reports - 2022. Arq Bras Cardiol. 2022;119(4):638-680. doi.org/10.36660/abc.20220623
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.