Isochronal difference mapping: an approach for mapping dynamic changes during reentrant ventricular tachycardia.

Area of Science:

• Cardiac Electrophysiology
• Medical Imaging and Signal Processing

Background:

• Interpreting activation maps during reentrant ventricular tachycardia is challenging due to dynamic circuit changes.
• Existing methods struggle to reduce complexity and highlight distinct conduction patterns in electrophysiological data.

Purpose of the Study:

• To introduce and evaluate a novel technical method, isochronal difference mapping (IDM), for simplifying complex electrophysiological data.
• To enhance the visualization of distinctive conduction patterns in reentrant ventricular tachycardia circuits.

Main Methods:

• Acquired electrograms from 196 sites in a canine model of reentrant ventricular tachycardia with a figure-eight pattern.
• Constructed activation maps for each cardiac cycle during tachycardia episodes.
• Created IDM maps by subtractively comparing activation maps from consecutive cardiac cycles to highlight cycle-to-cycle differences.

Main Results:

• IDM maps readily revealed areas of conduction velocity changes, wavefront breakthrough, and regions of coherent or irregular activation.
• Demonstrated that as tachycardia cycle length prolonged due to slowed conduction, conduction velocity increased in other parts of the circuit.
• IDM effectively accentuates cycle-to-cycle variations in multi-channel electrophysiological data.

Conclusions:

• Isochronal difference mapping (IDM) is a valuable technique for reducing complexity in electrophysiological studies of reentrant ventricular tachycardia.
• IDM enhances the identification of dynamic conduction patterns, aiding in the interpretation of changing reentrant circuits.
• This method offers improved insights into the electrophysiological substrate of ventricular tachycardia.