Moving from voltage mapping to scar mapping using novel "near-field" metrics.

Background: In ventricular arrhythmia ablation procedures, traditional voltage mapping calculates overall peak-to-peak measurements. However, this methodology incorporates multiple signal components that do not distinguish near-field vs far-field components.

Objective: This study aimed to determine how the use of local bipolar measurements as identified by the first derivative of voltage over time (dV/dT) affects traditional voltage mapping characteristics.

Methods: Percutaneous endocardial and epicardial electroanatomic mapping was performed in a porcine myocardial infarction model (n = 5) with a multipolar and a point-by-point catheter. Electrograms were examined offline based on standard bipolar and unipolar voltage values and then reanalyzed by a novel algorithm that measures only the voltage magnitude pertaining to the maximum absolute dV/dT within a given electrogram. Computed tomography, gross pathology, and histopathology features were examined.

Results: There were 25,114 bipolar mapping points across multipolar catheter maps and 6317 mapping points across point-by-point catheter maps. A difference in calculated voltage occurred in >80% of all mapping points, with all changes using dV/dT methodology resulting in lower bipolar voltage values compared with traditional methods. There was a categorical change in standard voltage (scar, border zone, normal) in >7% of all points. Unipolar voltage calculated by local dV/dT also resulted in a lower value in >90% of all mapping points. Histologic examination of discrepant regions revealed patterns of diffuse fibrosis.

Conclusion: In a porcine infarct model, the use of dV/dT to identify bipolar voltage results in lower measured values in >80% of all mapping points compared with traditional peak-to-peak measurement. This methodology may more accurately identify local tissue properties by selection of near-field components within substrates implicated in ventricular arrhythmias.