Effect of the Restitution Properties of Cardiac Tissue on the Repeatability of Entrainment Mapping Response

Abstract

This prospective study comprised 30 patients (26 males, mean age = 55±16 years) referred for ablation of either atrial or ventricular © 2014 American Heart Association, Inc. Original Article Background-The difference between the postpacing interval (PPI) and the tachycardia cycle length (TCL; PPI−TCL) is a useful tool in mapping macro-reentrant tachycardias. However, entrainment pacing causes some perturbation of the conduction velocity within the tachycardia circuit, which may affect the repeatability and consequently the accuracy of the measurement of PPI−TCL. The aim of this study was to assess PPI−TCL repeatability both in vivo and in silico. Methods and Results-In the experimental part, entrainment pacing was performed twice at each of the 124 tested sites for 30 patients undergoing radiofrequency ablation of atrial and ventricular re-entrant arrhythmias. A similar protocol was used in a simplified computer model of the cardiac tachycardia circuit in a 2-dimensional tissue strip using a Fenton-Karma model of cardiac tissue. In vivo, in the case of fast tachycardias (<350 ms), PPI−TCL variability observed was doubled compared with slow tachycardias (>350 ms; 95% Limits of Agreement ranged from −21.4 to 21.6 ms for TCL<350 ms and from −10.8 to 11.5 ms for TCL>350 ms). Simulations show that this increase of variability may be because of the oscillations of the conduction velocity inside the tachycardia circuits. The effect of the restitution properties of cardiac tissue on the outcome of entrainment pacing is discussed. Conclusions-PPI−TCL is characterized by a high repeatability with the differences between the results for individual stimulations of ≤20 ms. The variability of this parameter is significantly lower in the case of slow tachycardias.(Circ Arrhythm Electrophysiol. 2014;7:497-504.)

Effect of stimulation parameters on entrainment

“…When the stimulation intensity increases, more of the far-field tissue may be captured because of the virtual electrode and the downstream wavefront forming will be farther from the pacing site and will then return to the pacing site earlier and as a result, the PPI is shortened. Despite the existence of variability in PPI [3], we can clearly see the J o u r n a l P r e -p r o o f 3 tendency. Although the difference observed when the entrainment parameters are changed can consist in only a few ms, it could lead to misclassification of an entrained site when the PPI-TCL interval is close to the threshold of 30 ms.…”

“…As a result, PPI is shortened. Despite the existence of variability in PPI, 3 we can clearly see this tendency. Although the difference observed when the entrainment parameters are changed can consist of only a few milliseconds, it could lead to misclassification of an entrained site when the PPI–TCL interval is close to the threshold of 30 ms.…”

High-density automated mapping and entrainment pacing for successful atypical flutter ablation with one RF application.

“…Thus, the presumed isthmus should be confirmed by entrainment mapping. However it must be kept in mind that the response to entrainment pacing can also be misleading, especially when the pacing cycle is short [8] .…”