Understanding the Significance and Approach to Ventricular Tachycardia Ablation of Scar-related Border Zones

Purpose of ReviewVentricular arrhythmias in non-ischemic cardiomyopathies can be uniquely challenging to manage with a higher rate of unsuccessful procedures and recurrent arrhythmia. This review focuses on ventricular tachycardia (VT) mapping and the utility of bipolar and unipolar substrate mapping to guide successful ablation.Recent FindingsBipolar voltage mapping can be used to identify potential channels of healthy tissue surrounded by myocardial scar and provide a target for ablation along isthmuses within scar or border zones. However, bipolar voltage is limited in field of view and unipolar electrograms can provide greater insight into the deeper myocardial tissue in both ischemic and non-ischemic cardiomyopathies. Endocardial unipolar voltage mapping may detect scar beyond the endocardium in regions of normal bipolar voltage, which could be critical for VT circuits. Thus, it may provide a better understanding of intramyocardial or epicardial components of VT circuits. In our experience, we have observed a series of patients with critical components of the VT circuit located in unipolar scar border zones in regions with normal bipolar endocardial voltage, suggesting that unipolar mapping with modern high density mapping catheters may be beneficial in identifying targets for VT ablation in those with mid-myocardial or epicardial scar.SummaryUnipolar voltage mapping with modern high density mapping catheters can identify mid-myocardial or epicardial substrate that might not otherwise be recognized using bipolar endocardial mapping alone. The use of current high density mapping catheters to create unipolar voltage maps and identify critical VT circuits may be beneficial to improve VT ablation outcomes in patients with mid-myocardial or epicardial scar.Trial RegistrationNot applicable.