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

Area of Science:

• Cardiovascular Electrophysiology
• Medical Imaging and Mapping
• Cardiac Arrhythmia Research

Background:

• Traditional voltage mapping in ventricular arrhythmia ablation uses peak-to-peak measurements.
• This method conflates near-field and far-field signals, limiting precision.

Purpose of the Study:

• To evaluate the impact of local bipolar measurements, identified by the first derivative of voltage over time (dV/dT), on traditional voltage mapping.
• To determine if dV/dT improves the characterization of arrhythmogenic substrates.

Main Methods:

• Performed electroanatomic mapping in a porcine myocardial infarction model using multipolar and point-by-point catheters.
• Analyzed electrograms using standard bipolar/unipolar voltages and a novel dV/dT algorithm.
• Correlated mapping data with computed tomography, gross pathology, and histopathology.

Main Results:

• The dV/dT method altered voltage calculations in over 80% of bipolar mapping points, consistently yielding lower values.
• A significant categorical change in voltage classification (scar, border zone, normal) occurred in over 7% of points.
• Histopathology of discrepant areas revealed diffuse fibrosis, suggesting improved identification of tissue characteristics.

Conclusions:

• Using dV/dT for bipolar voltage measurement significantly reduces values compared to traditional methods in a porcine infarct model.
• This dV/dT approach may enhance the identification of local tissue properties by isolating near-field components relevant to ventricular arrhythmias.