The Efficacy of Isochronal 3D Mapping-Based Ablation of Ventricular Arrhythmia

Abstract

SummaryTreatment of ventricular arrhythmias (VAs) commonly involves ablating sites showing electrograms with the earliest activity relative to the VA, but there is no threshold value for prematurity guaranteeing success. Ablation of sites with great prematurity can still result in failure.We hypothesized that isochronal map area (ISCA), derived from isochrones indicating electrogram prematurity, could help identify ablation targets in VA patients, as well as predict outcome. Specifically, we hypothesized that smaller ICSA for a given prematurity value would indicate a shallower arrhythmogenic focus leading to a higher likelihood of successful ablation.We studied ICSA in 29 patients (12 males, 57 [17-65] 1,2) Thus, frequent idiopathic ventricular arrhythmias (VAs) are a target for catheter ablation. Ablation of sites with electrograms preceding the PVC on the 12-lead surface ECG by the longest period of time is expected to maximize the chances of successful elimination of PVCs, since they are likely to be closest to the ectopic focus. For purposes of this article, we will define the duration between a PVC and electrograms preceding it as prematurity. It would be useful if there were a threshold value of prematurity over which successful ablation was assured. Unfortunately, the range of prematurity values resulting in successful ablation overlaps with values for unsuccessful ablation sites, [3][4][5] and therefore, better or additional criteria are needed.We hypothesized that part of the reason that ablation of a site with great prematurity does not necessarily result in successful elimination of a focus is that intramural depth of the focus plays a role. A deeper focus may be more difficult to ablate, not only because of the ablative energy failing to reach the focus effectively, but because excitation reaching the endocardium will arrive at a larger area at the same precocity, so that the site ablated might not be directly above the focus. In contrast, a more superficial focus would produce a smaller excited area at the same precocity. We therefore tested whether what is called isochronal map area (ISCA) measurement could provide a new predictor for eliminating VAs, and whether more superficial sites of origin would have smaller ISCA (Figure 1). ISCA has been analyzed previously in patients with RVOT VAs, [6][7][8] but no one has ever evaluated its ability to discriminate between multiple sites of VA origin as we have attempted to do here.From the

Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Using a Slow Pathway Extending to the Superoanterior Right Atrium

“…An apparently fixed VA interval during the tachycardia accompanied by the alternans of the tachycardia cycle length was consistent with the AVNRT diagnosis ( Figure 1A). 8) These variabilities in the tachycardia cycle length may be attributable to the decremental properties of AV nodal pathways. 9) Furthermore, retrograde conduction via the SP variant and decremental properties were reproducibly unmasked via ventricular double extrastimulation ( Figure 1A and B).…”

Comparison of Outcomes of Mitral Valve Repair for Leaflet Prolapse with Advanced versus Mild/Moderate Myxomatous Degeneration

“…Ventricular arrhythmia was defined as the presence of any of the following: premature ventricular contractions, couplets, and ventricular tachycardia. 15) Follow-up information was collected from clinic or telephone contact with patients by an investigator blinded to the degree of myxomatous degeneration. Echocardiograms were obtained at least every second year in most patients after discharge from our institution and others.…”

A Steam Pop Detected by Intracardiac Echocardiography During Catheter Ablation of the Left Ventricular Papillary Muscle

“…2,3) More recently, intracardiac echocardiography (ICE) has gained recognition as a very helpful technique in evaluation of cardiac anatomical structure during RFCA procedures, facilitating threedimensional (3D) electroanatomic mapping. [4][5][6] We report a case with steam popping and subsequent myocardial destruction detected by ICE during RFCA of the left ventricular papillary muscle (LVPM).…”