Excellent Pace Map Research Articles

Characterization of the right ventricular substrate participating in postinfarction ventricular tachycardia.

The right ventricle (RV) is uncommonly implicated in postinfarction ventricular tachycardia (VT). The prevalence and features of the RV substrate participating in postinfarction VT are undefined. The purpose of this study was to characterize critical right ventricular substrate (CRVS) involvement in patients with postinfarction VT. We retrospectively reviewed 1279 patients with postinfarction VT undergoing catheter ablation at our center from January 2000 through May 2020. Cases with CRVS defined by conclusive demonstration of participation in VT with activation, entrainment, and/or pacemapping during sinus rhythm were identified. CRVS was identified in 27 of 1279 patients (2.1%): age 65± 13 years, 96% male, median left ventricular (LV) ejection fraction 25%, and 93% with left bundle branch block (LBBB) morphology VT. CRVS was identified by RV activation and/or entrainment mapping (n = 19) or by the presence of low-voltage abnormal electrograms with excellent pacemap for the targeted VT and noninducibility after ablation (n = 8). VT termination during RV ablation occurred in 15 patients. After median follow-up of 20 months (interquartile range 9-53 months) and median of 2 procedures (interquartile range 1-3), 22 of 27 patients (80%) had no VT recurrence and 11 (41%) died. The RV contains critical substrate elements of postinfarction VT in at least 2.1% of cases. RV mapping should be considered in cases in which LV mapping fails to demonstrate adequate targets, particularly in patients with LBBB morphology VT.

Radiofrequency ablation on the right ventricular septum changed a bundle branch block pattern of a ventricular tachycardia: What is the mechanism?

A ventricular tachycardia (VT) with a left bundle branch block (BBB) pattern exhibited the earliest activation (EA) at the left ventricular basal septum near the His bundle with no excellent pace map (PM). Radiofrequency ablation at the right ventricular basal septum (opposite site of the EA site) changed the QRS morphology of VT to a right BBB pattern that matched a PM at the opposite site in the left ventricle. VT ablation was successful at the earliest activation site. The VT should have originated from an intramural origin with preferential pathways to the endocardial breakout sites in the right and left ventricular septum.

Left coronary cusp ablation to eliminate epicardial substrates – a novel strategy for left ventricular summit ventricular tachycardia ablation

Abstract Background Catheter ablation of LV summit VT can be challenging due to possible subepicardial or intramural site of origin and its close proximity to the major coronary vessels. Objective Local electrograms monitoring inside LV summit communicating vein potentially defines arrhythmogenic substrates and facilitates ablation from the adjacent anatomical structures. Results We experienced two cases of LV summit VT with epicardial local abnormal ventricular activities (Epi-LAVA) recorded from distal bipolar electrode of the 2F microcatheter in communicating vein close to the superior portion of LV summit. During sinus rhythm, Epi-LAVA displayed isolated late fractionated potentials in the first case but had initial fractionated potentials fused with terminal portion of far-field ventricular signals and late isolated potentials exhibiting 2:1 conduction in the second case. Epi-LAVA represented earliest ventricular signals during VT in both cases. Pace mapping at Epi-LAVA sites yielded single QRS morphology with excellent pacemap score and induced VT. Our strategy was to perform ablation at the facing site of Epi-LAVA aiming to eliminate the potentials transmurally. Radiofrequency (RF) energy was applied above and under the left coronary cusp opposite to Epi-LAVA sites using 3.5-mm tip open-irrigation catheter with a power of 30–35 W for 60 seconds under real-time intracardiac echocardiograhic guidance. VT was slowed and terminated in 1 second. Repeat ablation delayed and completely abolished Epi-LAVA followed by noninducibility of VT. Anatomical proximity of the left coronary cusp semilunar insertion and subepicardial or intramural site of origin possibly dictates successful ablation. Epi-LAVA from coronary vein mapping serve as a new landmark of the ablation target with a measurable procedural endpoint. Conclusion Elimination of epicardial substrates with RF energy application at the left coronary cusp can be a novel strategy for LV summit VT ablation. Funding Acknowledgement Type of funding source: None

Idiopathic Ventricular Arrhythmias Originating From the Vicinity of the Communicating Vein of Cardiac Venous Systems at the Left Ventricular Summit

The communicating vein (CV) between the great cardiac vein and small cardiac venous systems passes between the aortic and pulmonary annulus and is located in close association with the left ventricular summit (summit CV). Thirty-one patients with idiopathic ventricular arrhythmias (VAs) underwent mapping of the left ventricular summit by using a 2F microcatheter introduced into the summit CV with coronary sinus venographic guidance. Of these, 14 patients were found to have summit-CV VAs. The remaining 17 patients (control group) had VAs originating from the right ventricular outflow tract and the aortic cusps. In patients with summit-CV VAs, the earliest activation during VAs in the summit CV preceded QRS onset by 34.1±5.3 ms. The summit-CV VAs exhibited inferior axis, negative polarity in lead I, deeper QS wave in lead aVL than aVR, and nonspecific bundle branch block morphology with an R/S ratio in lead V1 of 0.67±0.33, which could be distinguishable from VAs originating from the right ventricular outflow tract and the right coronary cusp. Because of the inaccessibility of the summit CV to ablation catheter, ablation of summit-CV VAs was attempted at adjacent structures where an excellent pacemap was rarely obtained. Overall ablation success was achieved in 10 (71%) patients with summit VAs and 15 (88%) patients in control group (P=0.24). The myocardium near the summit CV can be the source of idiopathic VAs. Direct monitoring of the summit CV is helpful for identifying the site of origin and provides a landmark of the ablation target, which may facilitate ablation through adjacent structures.

A case of atrial tachycardia originating from pulmonary vein invaded by lung cancer

A 59-year-old man during chemotherapy for squamous cell carcinoma of the lung, underwent catheter ablation of drug-refractory atrial tachycardia. Pulmonary venography and chest computed tomography revealed presence of stenotic, carcinomatous lesion of the left superior pulmonary vein. Excellent pace map and elimination of inducibility of atrial tachyarrhythmias after left pulmonary isolation suggested that the atrial tachycardia originated from the metastatic region.

Idiopathic epicardial ventricular tachycardia with origin remote from vascular structures

We report a case of a patient with idiopathic left ventricular tachycardia (VT) successfully ablated from the epicardial aspect of the left ventricle, after a previous failed endocardial ablation. The VT appeared to be catecholamine sensitive. An excellent epicardial pacemap was found in the midlateral region of the left ventricle, remote from vascular structures. Following ablation, the patient discontinued antiarrhythmic drug use and has not experienced any recurrence of VT for more than 2 1/2 years.

Idiopathic Ventricular Tachycardia Originating from the Left Ventricle Near the His Bundle

A 62-year-old man with idiopathic ventricular tachycardia (VT) exhibiting left bundle branch block and left inferior axis QRS morphology with a Qr in lead III underwent electrophysiological testing. Successful ablation was achieved in the left ventricle (LV) at a site with an excellent pace map, adjacent to the His bundle electrogram recording site. At that site, the sequence of the ventricular electrogram and late potential recorded during sinus rhythm reversed during spontaneous premature ventricular contractions with the same QRS morphology as the VT. This case shows that VT can arise from the LV ostium adjacent to the membranous septum.

A Couplet of PVCs with Different QRS Morphologies Arising from a Single Origin in the Left Ventricular Outflow Tract

A 59-year-old man with two different premature ventricular contractions (PVCs) forming a couplet underwent electrophysiological testing. Although pacing from the aorto-mitral continuity (AMC) produced an excellent pace map of one type of PVCs, a radiofrequency application within the right coronary cusp (RCC) eliminated all the PVCs. This case demonstrates that a single origin with two breakout sites in the left ventricular ostium (LVos) may result in a couplet consisting of different PVCs and preferential conduction from the RCC to AMC may also occur. These possibilities should be kept in our mind when predicting sites of origin of LVos ventricular arrhythmias.

Electrocardiographic and Electrophysiological Characteristics in Idiopathic Ventricular Arrhythmias Originating From the Papillary Muscles in the Left Ventricle

Background— Idiopathic ventricular arrhythmias (VAs) can originate from the left ventricular papillary muscles (PAMs). This study investigated the electrophysiological characteristics of these VAs and their relevance for the results of catheter ablation. Methods and Results— We studied 19 patients who underwent successful catheter ablation of idiopathic VAs originating from the anterior (n=7) and posterior PAMs (n=12). Although an excellent pace map was obtained at the first ablation site in 17 patients, radiofrequency ablation at that site failed to eliminate the VAs, and radiofrequency lesions in a relatively wide area around that site were required to completely eliminate the VAs in all patients. Radiofrequency current with an irrigated or nonirrigated 8-mm-tip ablation catheter was required to achieve a lasting ablation of the PAM VA origins. During 42% of the PAM VAs, a sharp ventricular prepotential was recorded at the successful ablation site. In 9 (47%) patients, PAM VAs exhibited multiple QRS morphologies, with subtle, but distinguishable differences occurring spontaneously and after the ablation. In 7 (78%) of those patients, radiofrequency lesions on both sides of the PAMs where pacing could reproduce an excellent match to the 2 different QRS morphologies of the VAs were required to completely eliminate the VAs. Conclusions— Radiofrequency catheter ablation of idiopathic PAM VAs is challenging probably because the VA origin is located relatively deep beneath the endocardium of the PAMs. PAM VAs often exhibit multiple QRS morphologies, which may be caused by a single origin with preferential conduction resulting from the complex structure of the PAMs.

Evidence for an Intramural Origin of Idiopathic Premature Ventricular Contractions Successfully Ablated within the Great Cardiac Vein

A 37-year-old woman with idiopathic premature ventricular contractions (PVCs), exhibiting a right bundle branch block and inferior axis QRS morphology, underwent electrophysiological testing. The earliest ventricular activation with an isolated prepotential was observed within the great cardiac vein during the PVCs. Pacing from this site with an output of 10 mA produced an excellent pace map, whereas that with an output of 2 mA produced a wider QRS with notches in the early phase. A radiofrequency application delivered at this site eliminated the PVCs. These findings suggested that the PVC origin might have been intramural rather than epicardial.

Idiopathic Left Ventricular Arrhythmias Originating Adjacent to the Left Aortic Sinus of Valsalva: Electrophysiological Rationale for the Surface Electrocardiogram

Idiopathic ventricular arrhythmias (VAs) may be amenable to catheter ablation within or adjacent to the left sinus of Valsalva (LSOV). However, features that discriminate these sites have not been defined. The purpose of this study was to determine the electrocardiographic and electrophysiological features of VAs originating within or adjacent to the LSOV. We studied 48 consecutive patients undergoing successful catheter ablation of idiopathic VAs originating from the left coronary cusp (LCC, n = 29), aortomitral continuity (AMC, n = 10) and great cardiac vein or anterior interventricular cardiac vein (Epi, n = 9). A small r wave, or rarely an R wave, was typically observed in lead I during the VAs and pacing in these regions. An S wave in lead V5 or V6 occurred significantly more often during both the VAs and pacing from the AMC than during that from the LCC and Epi (p < 0.05 to 0.0001). For discriminating whether VA origins can be ablated endocardially or epicardially, the maximum deflection index (MDI = the shortest time to the maximum deflection in any precordial lead/QRS duration) was reliable for VAs arising from the AMC (100%), but was less reliable for LCC (73%) and Epi (67%) VAs. In 3 (33%) of the Epi VAs, the site of an excellent pace map was located transmurally opposite to the successful ablation site (LCC = 1 and AMC = 2). The MDI has limited value for discriminating endocardial from epicardial VA origins in sites adjacent to the LSOV probably due to preferential conduction, intramural VA origins or myocardium in contact with the LCC.

QRS alternans during idiopathic ventricular tachycardia originating from the right coronary cusp of the aorta

A 77-year-old man underwent electrophysiological testing for idiopathic ventricular tachycardia (VT) with QRS alternans exhibiting a left bundle branch block and left inferior axis QRS morphology. Successful radiofrequency catheter ablation was achieved at the site of the earliest ventricular activation in the right coronary cusp. Pacing at this site reproduced an excellent pace map with QRS alternans. Pacing from other sites in the ventricular outflow tracts reproduced neither an excellent pace map nor QRS alternans. This case demonstrates that VT with a single origin and multiple exits in the aortic root may exhibit QRS alternans.

Idiopathic Premature Ventricular Contractions Exhibiting Preferential Conduction within the Aortic Root

A 65-year-old man with frequent premature ventricular contractions (PVCs) underwent electrophysiological testing. Although an excellent pace map was obtained from the right coronary cusp (RCC), radiofrequency ablation at that site interrupted the PVCs transiently. Successful ablation was achieved in the left coronary cusp with earlier local ventricular activation during the PVCs than that in the RCC. These findings suggest that preferential conduction within the aortic root may exist and cause ventricular arrhythmias (VAs) arising from this region to exhibit variable electrocardiographic features, thereby limiting the reliability of electrocardiographic algorithms and pace mapping to predict the site of the VA origin.

Ventricular tachycardia with a myocardial fibre travelling from the origin in the right aortic sinus cusp to the epicardial breakout site of the right ventricular outflow tract

A 74-year-old man with idiopathic ventricular tachycardia (VT) with a QRS morphology with a left bundle branch block and right inferior axis underwent electrophysiologic testing. Successful ablation was achieved at the right coronary cusp (RCC) where an excellent pace map with long stimulus-to-QRS interval (St-QRS) (85 ms) was obtained. An excellent pace map was also obtained on the epicardial surface approximately 1 cm away from the successful ablation site and the St-QRS was shorter (40 ms). These findings suggested that a myocardial fibre travelling from the origin in the RCC to the epicardium of the right ventricular outflow tract might exist.

Ventricular Tachycardia With an Outflow Tract Septal Origin After Repair of Double Outlet Right Ventricle

A 12-year-old boy born with double outlet right ventricle (RV) developed sustained ventricular tachycardia (VT) 6 years after the corrective surgery and underwent electrophysiologic testing and catheter ablation. Electroanatomic mapping of the right and left ventricles during the VT revealed a centrifugal activation from the outflow tract septum. Though an excellent pace map was obtained in the RV, successful ablation was achieved on the left side. These findings suggested that the VT origin might have been located in the intramural region of the ventricular outflow tract septum with a preferential breakout site in the RV outflow tract.

Preferential Conduction Across the Ventricular Outflow Septum in Ventricular Arrhythmias Originating From the Aortic Sinus Cusp

The purpose of this study was to examine the relationship between the origin and breakout site of idiopathic ventricular tachycardia (VT) or premature ventricular contractions (PVCs) originating from the myocardium around the ventricular outflow tract. The myocardial network around the ventricular outflow tract is not well known. We studied 70 patients with idiopathic VT (n = 23) or PVCs (n = 47) with a left bundle branch block and inferior QRS axis morphology. Electroanatomical mapping was performed in both the right ventricular outflow tract (RVOT) and aortic sinus cusp (ASC) during VT or PVCs. The earliest ventricular activation (EVA) was recorded in the RVOT in 55 patients (group R) and in the ASC in 15 (group A). In all group R patients, the closest pace map and successful ablation were achieved at the EVA site. Although a successful ablation was achieved at the EVA site in all group A patients, the closest pace map was obtained at the EVA site in 8 and RVOT in 7 (with an excellent pace map in 4). The stimulus to QRS interval was 0 ms during pacing from the RVOT and 36 +/- 8 ms from the ASC. The distance between the EVA and perfect pace map sites in those 4 patients was 11.9 +/- 3.0 mm. Ventricular arrhythmias originating from the ASC often show preferential conduction to the RVOT, which may render pace mapping or some algorithms using the electrocardiographic characteristics less reliable. In some of those cases, an insulated myocardial fiber across the ventricular outflow septum may exist.