Catheter Ablation of Ventricular Tachycardia After Myocardial Infarction: Relation of Endocardial Sinus Rhythm Late Potentials to the Reentry Circuit

Abstract

Although sites with sinus rhythm late potentials often participate in VT reentry circuits, many reentry circuit sites do not have late potentials. Late potentials can also arise from bystander regions. Late potentials may help identify abnormal regions in sinus rhythm but cannot replace mapping during induced VT to guide ablation.

Relationship Between Sinus Rhythm Activation and the Reentrant Ventricular Tachycardia Isthmus

“…1,2,5,14 There are several similarities between clinical observations and the measurements of electrical activation during sinus rhythm in dog hearts with and without inducible reentry. Clinical studies suggest that the extent of abnormal activation and number of fractionated sinus rhythm electrograms tend to be greater in patients with sustained reentry than with unsustained reentry, 14 in accord with the result of this study that mean sinus rhythm electrogram duration throughout the border zone was significantly greater for experiments with long runs of reentry versus short runs of reentry (PϽ0.05).…”

“…The time of latest depolarization during sinus rhythm has been partially correlated to the location of the reentry isthmus; however, the relationship is inexact. 2,3 At the border zone, both normal and abnormal (low-amplitude, fractionated, or wide-deflection) electrograms are present [2][3][4][5] ; these abnormal electrograms, however, can be present both within and away from the reentry circuit location and are therefore not a specific predictor of its position in the border zone. Therefore, methods for detection and measurement of abnormal sinus rhythm activation characteristics are not currently sufficient for targeting reentry circuits for catheter ablation, although the presence of abnormality suggests the proximity of an arrhythmogenic substrate.…”

Parasympathetic dysfunction and antiarrhythmic effect of vagal nerve stimulation following myocardial infarction

“…These values have been previously validated in the clinical setting to delineate scar, border zone, and viable regions during catheter ablation procedures (49,50). Border zone and scar regions are characterized by low-voltage electrograms that often have prolonged duration or fractionation ( Figure 2A) and represent targets of catheter ablation in patients (51). Samples (3-mm punch-biopsies) from the LV anterior wall were obtained from 15 normal animals and from scar, border zone, and viable regions in 14 infarcted animals.…”

Sustained ventricular tachycardia in structural heart disease

“…Sites where pacing produces a long S-QRS but matches the VT morphology are seen at some reentry circuit isthmus sites and can also be targeted for ablation [75]. However, pacemapping is more useful in cases of focal VT, and can be confusing in reentrant VT. Abnormal potentials recorded during sinus or paced rhythm allow the identification of potential channels within the dense scar and have been targeted for ablation with good results [76][77][78].…”