Ventricular Tachycardia Substrate Mechanisms Revealed by Local Repolarization and Conduction Parameters

Ventricular tachycardia (VT) ablation remains the cornerstone treatment for drug refractory VT. Previous studies have reported success rate of VT ablation ranging from 23 to 49%. Despite improvements in mapping and catheter technology, there is a high recurrence rate and numerous patients who fail VT ablation.

Reasons for failure in VT ablation include the inability to identify critical areas of myocardium responsible for VT and hemodynamic instability of VT during mapping. Several studies have attempted to study electrical properties of cardiac tissues to identify potential circuits in sinus rhythm avoid mapping during unstable VT. This includes mapping fractionated electrical potentials, isochronal late activation mapping (ILAM), and ablation of low voltage regions. However, these techniques have yielded modest improvement in success rates with poor specificity of identifying important regions.

Monophasic action potentials (MAP) demonstrate cellular action potential of the myocardium. Recent evidence suggests that changes in MAP morphology can predict sudden cardiac death by ventricular arrhythmias. However, cellular activation has not been studied in VT. The researchers of this study propose that MAP signals can better elucidate electrophysiological characteristics of the myocardium, and thus identify sites critical to VT.

During a standard of care VT ablation, the researchers will use the MAP catheter to study cellular action potential of the ventricular myocardium, which cannot be done on traditional catheters. The design of this catheter is similar to other diagnostic catheters that are currently used for VT ablation. The MAP catheter is a bipolar catheter, two with electrical poles at the distal tip. The catheter is placed on the myocardium (similar to other traditional catheters) and a recording signal is transmitted to the workstation. Using the MAP catheter the will not interrupt or distort any of the standard treatment procedures.