Impact of recording technologies on cardiac electrogram morphology: implications for mapping and interpretation

Cardiac electrograms form the foundation of contemporary clinical electrophysiology and are essential for activation mapping, substrate characterization and catheter ablation of cardiac arrhythmias. Electrogram morphology, however, is not solely determined by myocardial electrophysiology, but also by multiple technological factors related to signal acquisition and processing. Electrode size, interelectrode spacing, electrode orientation, tissue coupling, filtering settings and annotation algorithms all influence electrogram morphology, voltage and activation timing. Consequently, identical myocardial activation patterns may generate markedly different electrograms depending on the recording configuration used. Recent advances in high-density mapping technologies, multi-electrode electrogram reconstruction and advanced signal-processing techniques have further expanded the possibilities and complexity of electrogram interpretation. This review discusses the biophysical principles underlying cardiac electrogram formation and examines the technological determinants that influence electrogram characteristics. In addition, the properties, advantages and limitations of different electrogram types, including unipolar, bipolar, multipolar, omnipolar and Laplacian electrograms, are reviewed together with their implications for voltage and activation mapping. A comprehensive understanding of both the physiological basis and technological limitations of electrogram acquisition remains essential for accurate electrogram interpretation and responsible advancement of cardiac arrhythmia mapping and ablation strategies.