Ventricular Tachycardia Isthmus Characteristics: Insights from High-density Mapping

Abstract

In the context of structural heart disease, ventricular tachycardia (VT) is related to surviving fibres in incomplete scar. New technologies which allow electroanatomic mapping at higher density and with smaller, more closely spaced electrodes have allowed new insights into the characteristics of VT circuits. VT isthmuses are complex structures, with multiple entrances, exits and dead ends of activation. The isthmus is frequently defined by regions of functional block and several VT circuits can be possible in a VT “critical zone”. In this review, we discuss these new insights and how they may improve VT ablation strategies, as well as discussing emerging technologies which may further develop our understanding.

Complete Electroanatomic Imaging of the Diastolic Pathway Is Associated With Improved Freedom From Ventricular Tachycardia Recurrence

“…However, this shortcoming may be somewhat mitigated by the fact that multiple VTs frequently share the same VT isthmus in patients. 15 The rate of epicardial access in our series was 27%. While this rate is comparable to contemporary VT series, 9 given the nature of our study, a higher number of combined endo-epicardial access may have provided additional information regarding potential intramural substrate.…”

Dynamic High-density Functional Substrate Mapping Improves Outcomes in Ischaemic Ventricular Tachycardia Ablation: Sense Protocol Functional Substrate Mapping and Other Functional Mapping Techniques

“…This may be achieved through the use of newer high-density mapping techniques that enable clearer characterisation of the substrate, and through new novel techniques of assessing dynamic substrate changes, aided by the advances in computing power of modern mapping systems. [ 26 , 43 , 44 ] The majority of centres worldwide perform substrate mapping in a static state either during SR or paced rhythm. As a consequence of this, mortality improvements from VT ablation have not been demonstrated in large-scale randomised trials incorporating standard mapping techniques.…”

Catheter Ablation of Ventricular Tachycardia in LMNA Cardiomyopathy: Out of Sight but not Out of Mind

“…11 This phenomenon likely explains the variable VT morphologies and cycle lengths in this patient. 12 Not unexpectedly, clinically there is a higher incidence of catheter ablation failure, arrhythmia recurrence and poor prognosis of VT in patients with LMNA cardiomyopathy due to complex intramural substrate. 4,5 Complete substrate elimination may not be effective or possible with standard ablation approaches in intramyocardial substrate cases.…”