Characterization of radiofrequency ablation lesions by high-density unipolar, bipolar and omnipolar voltage mapping

Radiofrequency (RF) energy is the most commonly used technique to create ablation lesions as treatment strategy for various arrhythmias. To have long-term freedom of arrhythmias, each lesion must be transmural and continuous throughout its entirety.

This study aimed to evaluate changes in unipolar, bipolar, and omnipolar potential voltages during various stages of linear RF ablation applications to define the most suitable technique to assess lesion transmurality and continuity.

Epicardial mapping of porcine hearts (N = 5) was performed during 3 stages of lesion application: non-transmural-discontinuous, transmural-discontinuous, and transmural-continuous. Unipolar electrograms were recorded, and bipolar and omnipolar electrograms were obtained. Potential voltage was defined as the peak-to-peak amplitude of the steepest deflection (unipolar) or highest peak (bipolar/omnipolar). Low-voltage areas were defined as bipolar/omnipolar voltage ≤0.5 mV and unipolar voltage ≤1.0 mV.

Both unipolar and omnipolar voltages at the lesion site decreased during stage 1 compared to baseline (27.5%-67.5% and 59.4%-92.8%, respectively). Using omnipolar electrograms, clear isolated areas of higher potential voltages reflecting a gap could be identified within the lesion area. However, no clear patterns could be identified using unipolar electrograms. The lowest unipolar and omnipolar potential voltages were found during ablation stage 3 (1.6-2.8 and 0.4-2.2 mV, respectively).

Omnipolar voltage mapping is the most effective technique to assess ablation lesion continuity and transmurality. Unipolar voltage mapping of the lesion area is highly variable and not suitable to detect a gap in the lesion. Future studies should investigate whether omnipolar voltage mapping could aid in long-term arrhythmia free survival.