The derivative of tissue activation as a marker of arrhythmogenic myocardium

Mapping techniques to identify diseased myocardial substrate during ventricular tachycardia ablation procedures remain limited.

We hypothesized that tissue derivative of the voltage with respect to time (dV/dt), the slope of the unipolar ventricular electrogram registered by local ventricular activation, represents a unique parameter for identifying potential arrhythmogenic tissue in the ischemic scar border zone.

Using high-resolution electrical mapping, we examined dV/dt characteristics in the border zone of animals after chronic myocardial infarction (MI).

Minimum dV/dt (dV/dt_min) in MI animals was less than that in control animals (-344.7 ± 68.7 in controls vs -174.2 ± 104.5 in MI; P < .001) and related to ventricular fibrosis. In MI animals, dV/dt_min values were divided into high (≤-200 μV/ms) and low (>-200 μV/ms) dV/dt_min. Low dV/dt_min regions harbored arrhythmogenic substrates that were characterized by (1) high responsiveness to sympathetic stimulation, (2) presence of late potentials, and (3) lower unipolar and bipolar voltage amplitudes.

Our data indicate that dV/dt_min is a unique parameter for identifying arrhythmogenic myocardium and may add a useful metric to conventional mapping strategies.