Septal Right Ventricular Outflow Tract Research Articles

Permanent Cardiac Pacing of the Right Ventricular Outflow Tract Guided by Real-time Assessment of Electromechanical Synchrony.

Permanent right ventricular apical pacing deteriorates cardiac systolic function in some patients. We investigated an alternative site for permanent pacemaker (PPM) lead positioning with the goal of achieving more physiological pacing. A total of 132 patients with bradyarrhythmias underwent PPM implantation at the right ventricular outflow tract (RVOT) with conventional active-fixation leads. A real-time cross-correlation analysis (CCA) was performed using the Synchromax® software (EXO Health, Seattle, WA, USA) to determine the optimal site for ventricular lead implantation based on the cardiac synchrony index. The follow-up period ranged from 6-36 months, and the following parameters were assessed: pacing capture threshold, lead stability, and the need for lead repositioning. Adequate parameters were achieved in 129 patients (98%), and there were no procedure-related complications. At follow-up, no leads were dislodged, pacing thresholds remained stable, and no lead required repositioning. Using real-time CCA as an intraoperative parameter during PPM implantation at the septal RVOT helps to achieve cardiac synchrony in the vast majority of cases. This technique is a simple, effective, and safe way to simplify and standardize PPM implantation at the RVOT.

Similarly high success and low complication rates of catheter ablation for idiopathic premature ventricular contractions from the left and right ventricular outflow tract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Catheter ablation is the first line treatment for idiopathic premature ventricular contractions (PVCs) from the right ventricular outflow tract (RVOT) but not from the left ventricular outflow tract (LVOT), due to presumed lower success and higher complication rates in the LVOT. In this observational single center study we analyzed success rates and complication rates in patients undergoing catheter ablation for idiopathic PVCs with an inferior axis. Methods Patients undergoing catheter ablation for idiopathic PVCs with an inferior axis at Hannover Heart Rhythm Center between 2012 and 2020 were included. Patients were excluded if no activation mapping could be performed because of low PVC activity. Ablation success was defined as complete suppression of the index PVC at the end of the procedure. Results 108 patients (53% male, age 53 ± 17 years) with predominantly symptomatic (94%) PVCs with one (72%), two (20%) or more (8%) morphologies and a PVC count of 22063 ± 14426 /24h were included. 47 PVCs (44%) were located in the RVOT (21 anterior RVOT and 26 septal RVOT) and 39 PVCs (36%) in the LVOT (11 lateral LVOT, 5 septal LVOT, 8 RCC, 2 ACC, 13 LCC). 14 PVCs (13%) had the origin close to the CS/LV summit and 8 PVCs (7%) in the parahisian region. Overall success rate was 82%. Success rates for RVOT and LVOT origin were 98% (46/47 cases) and 97% (38/39 cases) respectively. No significant differences in procedure time (145 ± 68 vs. 158 ± 72 min), ablation time (441 ± 328 vs. 462 ± 307 sec), fluoroscopy time (496 ± 521 vs. 519 ± 473 sec) or minor complications (5 vs. 8) were observed for outflow tract PVCs, and no major complications occurred in this group. However, 3 major complications and significantly lower success rates were observed for non-outflow tract PVCs (0/8 for parahisian origin, 4/14 (29%) for CS/LV summit origin). 2 patients with a parahisian focus experienced higher degree AV block and 1 patient with an LV summit focus had a pericardial tamponade. Conclusion Catheter ablation of PVCs with LVOT origin can be performed with similarly high success and low complication rates compared to PVCs with RVOT origin, and therefore could be considered as first-line therapy like RVOT PVCs. On the other hand, identification of PVCs with a parahisian or CS/LV summit focus should be aspired before an ablation procedure, as these localizations are associated with poorer ablation outcome and higher complication rates.

PO-04-061 A RARE CASE OF FOCAL LEFT VENTRICULAR OUTFLOW TRACT VENTRICULAR TACHYCARDIA LATE AFTER TRANSCATHETER AORTIC VALVE REPLACEMENT

Transcatheter aortic valve replacement (TAVR) is commonly used to treat severe aortic stenosis (AS). To date there is only one reported case of post-TAVR, new onset, left ventricular outflow tract (LVOT) ventricular tachycardia (VT) which was ablated above the TAVR valve. We report a case of late presenting symptomatic LVOT VT, which was successfully ablated via a trans-septal approach, without fluoroscopy, using intracardiac echocardiography (ICE) and electroanatomic mapping (EAM), thereby, avoiding catheter manipulation in the aorta above the valve. N/A A 68-year-old man underwent TAVR for severe AS with Sapien 3 valve (Edwards Lifescience). Nine months later, the patient developed worsening dyspnea. Echocardiogram showed well seated TAVR valve, and exercise nuclear stress revealed no ischemia. During the stress test, he had slow monomorphic VT at rest, during exercise, and recovery (100-120 bpm). A 24-hour Holter monitor revealed a ventricular arrhythmia burden of 55% with rates between 85 and 112 bpm. The 12-lead ECG of VT had an initial positive deflection in lead I, QS in V1 and V2, and an initial R wave in V3 taller than the sinus QRS, suggesting a septal right ventricular outflow tract (RVOT) vs. LVOT origin. There was no improvement with beta-blocker therapy. An electrophysiology study was performed using ICE and CARTO (Biosense Webster, Diamond Bar, CA). Activation mapping in the septal RVOT revealed a 20ms presystolic electrogram (far field) and an 80% pace map, despite the unipolar signal with QS complex. Radiofrequency ablation performed at this site only mildly suppressed the arrhythmia. The decision was made to map from the LVOT via transseptal access using EAM and real-time markers from Cartosound real time images to accurately visualize the ablation catheter below the TAVR. Earliest activation was beneath the left coronary cusp directly across the RVOT lesions with a sharp 22ms pre-systolic electrogram, unipolar QS, and 90% pace map match. Ablation performed here successfully eliminated the VT even after isoproterenol infusion and programmed stimulation. The patient’s symptoms have resolved, and he remains arrhythmia free. LVOT VA’s may rarely occur post TAVR, although a direct cause cannot be ascertained. This is the first report of successfully ablating the arrhythmia in a TAVR patient using a transeptal, subvalvular approach without fluoroscopy, and avoiding any risks associated with the aortic approach.

The QRS-right ventricular apex interval as acut-off value to differentiate the origin of outflow tract premature ventricular complexes.

Many electrocardiography (ECG) criteria have been proposed for the localization of outflow tract premature ventricular contractions (PVCs); however, in some cases, it is difficult to accurately localize the origin of PVCs using the surface ECG. The authors aimed to study the QRS-right ventricular apex (RVA) interval measured during electrophysiological study and its role in the differentiation between different sites of origin of outflow tract PVCs. The study included 90patients (81females, mean age 37.20 ± 7.87) referred for outflow tract PVC ablation. The authors measured the interval from the onset of the earliest QRS complex of the PVCs to the distal RVA intracardiac signal (the QRS-RVA interval) during the electrophysiological study and correlated this interval with the origin of outflow tract PVCs as identified by successful ablation during the procedure. The QRS-RVA interval was significantly longer in PVCs originating from the left ventricular outflow tract (LVOT) compared to the right ventricular outflow tract (RVOT) (67.33 ± 7.56 for LVOT PVCs vs. 37.11 ± 4.34 for RVOT PVCs, p < 0.001). Receiver operating characteristic (ROC) analysis showed that aQRS-RVA interval ≥ 48 ms predicted an LVOT origin of PVCs. Ashorter interval was noted in PVCs originating from the RVOT free wall rather than the septal RVOT wall, and ashorter interval was also noted in LVOT PVCs originating from the right coronary cusp as compared to other LVOT PVCs, although these differences did not reach statistical significance. Measuring the QRS-RVA interval is asimple and accurate method for differentiating the origin of outflow tract PVCs during an electrophysiological study. AQRS-RVA interval ≥ 48 ms predicts an LVOT origin of PVCs rather than an RVOT origin.

Electrocardiographic characteristics for successful radiofrequency ablation of right coronary cusp premature ventricular contractions.

Electrocardiographic (ECG) criteria identifying right- and left-sided outflow tract origins have been established. The purpose of this study was to define the criteria for premature ventricular contractions (PVCs) originating from the right coronary cusp (RCC) adequately.We analyzed ECG and electrophysiologic study data from patients who underwent successful ablation of PVCs originating from the RCC and right ventricular outflow tract (RVOT). Eighteen RCC and 28 septal RVOT PVCs were studied. Among these 18 successful RCC PVCs, a predominantly positive QRS in lead I in 18/18 (100%), longer V1–2 R-wave duration (81.4 ± 31.1 vs 44.8 ± 7.0 ms, P = .02), V1–2 R wave duration index (RWDI) (51.3 ± 22.0 vs 31.2 ± 7.5%, P = .06) were observed compared to those with posteroseptal RVOT. Local ventricular activation time preceding QRS onset was significantly earlier (−38 ± 12 ms) at the successful RCC ablation site compared to the failed ablation site of the septal RVOT (−22 ± 8 ms), even without good pace mapping at the RVOT (P < .001). The receiver operating characteristic curve showed that a pre-QRS time of ≥−31 ms predicted successful RCC ablation with 67% sensitivity and 94% specificity. A predominantly positive QRS in lead I, longer R-wave duration and RWDI in lead V1 or V2 with a local ventricular activation preceding QRS onset by an average of −31 ms suggests an effective RCC ablation site.

Transvenous dual-chamber pacemaker implantation in patients with persistent left superior vena cava

BackgroundPersistent left superior vena cava (PLSVC) is a rare congenital vascular anomaly. Permanent pacemaker implantation (PPI) in patients with PLSVC can be challenging because of the venous anomalies. We reported a case series of patients with PLSVC who underwent PPI with double active fixation leads.MethodsFrom January 2012 to July 2016, 9 patients (three male and six females, mean age 68 ± 11 years) with PLSVC who received a dual-chamber pacemaker with double active fixation leads were enrolled retrospectively in this observational study. The indications for pacemaker implantation were symptomatic third-degree atrioventricular block in one and sick sinus syndrome in eight patients.ResultsPPI were implanted successfully in all 9 patients. Successful positioning of the ventricular leads at the right ventricular outflow tract (RVOT) septum with a “C” shaped stylet was achieved in 7 patients (77.8%). In the remaining two cases, the ventricular leads were placed in the right ventricular apex and the inferior free wall of the sub-tricuspid annulus. The atrial leads were placed at the lateral wall of the right atrium in all patients. Procedure time and fluoroscopy time were 85.3 ± 11.3 min and 4.5 ± 1.1 min respectively. During a mean follow-up of 4 years, no complications were observed and pacing parameters did not change significantly.ConclusionPPI through PLSVC may be technically feasible, safe, and effective. Double active fixation leads may be standard for patients with PLSVC and most of the ventricular leads could be placed at the RVOT septum.

Conduction patterns of idiopathic arrhythmias from the endocardium and epicardium of outflow tracts: New insights with noninvasive electroanatomic mapping

Idiopathic arrhythmias commonly arise from the septal right ventricular outflow tract (RVOT), sinuses of Valsalva (SoV), and great cardiac vein (GCV). Predicting the exact site of origin is important for preparation for catheter ablation. The purpose of this study was to examine the diagnostic value of noninvasive electroanatomic mapping (NIEAM) to differentiate between septal RVOT, SoV, and GCV origin and compare it to that of 12-lead electrocardiography (ECG). NIEAM maps (CardioInsight, Medtronic) were generated during spontaneous ventricular premature depolarizations (VPDs) and threshold pacing from septal RVOT, SoV, and GCV. Origin prediction using NIEAM was compared to algorithmic ECG criteria (maximal deflection index; V2 transition ratio) and subjective ECG evaluation. Sixty NIEAMs (18 spontaneous VPDs and 42 pace-maps) from 31 patients (age 56 ± 16 years) were analyzed. NIEAM showed distinct conduction patterns, best visualized at the base of the heart: septal RVOT VPDs propagate toward the tricuspid annulus, depolarizing the septum from inferior to superior; SoV VPDs engage the superior septum early; and GCV VPDs move laterally along the mitral annulus, depolarizing the heart from left to right. Activation of the lateral mitral annulus >60.50 ms and the superior basal septum <22.5 ms from onset predicts RVOT and SoV origin, respectively, in 100% of cases. NIEAM was superior to maximum deflection index in predicting GCV origin (100% vs 42.2% accuracy) and superior to V2 transition ratio in predicting SoV origin (100% vs 75.9% accuracy). Arrhythmias arising from the outflow tracts follow distinct propagation patterns depending on the origin. A 2-step algorithm using activation timing by NIEAM yields 100% diagnostic accuracy in predicting origin.

Abstract 264: A Complement Pathway is Responsible for Degeneration of Right Ventricular Outflow Tract

Backgrounds: Right ventricular outflow tract (RVOT) has a unique role in the pathogenesis of inherited cardiac diseases such as Brugada syndrome and arrhythmogenic right ventricular cardiomyopathy. However, it remains elusive how RVOT plays a role in the pathogenesis. We hypothesized that RVOT would have different character from other parts of the heart and those phenotypes would be regulated by key factors. Methods: Microarray analysis of several parts of adult murine hearts was performed and differentially expressed genes (DEGs) in RVOT were extracted. Pathway analysis was performed using Ingenuity Pathway Analysis (IPA). Potential upstream candidate genes were examined using rat cardiomyocytes in vitro and adult mouse in vivo. Results: As a result of microarray analysis for RVOT, right ventricle, left ventricle and ventricular septum, 995 genes were statistically extracted as DEG in RVOT. IPA analysis revealed that an alternative complement pathway was significantly activated in RVOT. Additionally, complement factor, C3a was shown as a potential upstream gene attributable to these features. Administration of C3a protein to cardiomyocytes resulted in activation of several MAP kinases including ERK via C3a receptor and suppression of oncostatin M signaling. Furthermore, in vivo analysis, administration of C3a receptor antagonist dramatically improved right ventricular function in mouse model of right ventricular overload, pulmonary artery constriction. There results indicated that C3a would regulate the unique phenotypes in RVOT and would be the potent effector to right ventricular heart failure. Conclusion: We revealed that an activated alternative complement pathway has a crucial role in the unique features of RVOT and the pathogenesis of right ventricular heart failure. The blockade of the pathway would be a therapeutic target of RVOT-related diseases.

Electrocardiographic predictors of validated right ventricular outflow tract septal pacing for correct localization of transthoracic echocardiography.

Electrocardiographic (ECG) characteristics of true right ventricular outflow tract (RVOT) septal pacing have not been clearly demonstrated. We hypothesized that ECG parameters would help operators differentiate true RVOT septum from non-septal septum. We analyzed 151 patients who underwent pacemaker implantation with a ventricular lead in the RVOT. Transthoracic echocardiographic (TTE) determination of pacing sites was applied in all patients after implantation. A 12-lead ECG was recorded during forced ventricular pacing. According to TTE orientation, pacing at the RVOT septum was achieved in 94 patients (62.3%). Compared with nonseptal pacing, septal pacing had significantly shorter QRS duration (139.2 ± 18.5 ms vs 155.5 ± 14.7 ms; P < 0.001). More frequent negative or isoelectric QRS vector in lead I (76% vs 32%; P < 0.001), lead II/III R-wave amplitude ratio < 1 (52% vs 25%; P = 0.001), and aVR/aVL QS-wave amplitude ratio < 1 (59% vs 32%; P = 0.001) were observed in septal pacing. Transitional zone (TZ) score (3.8 ± 0.96 vs 4.2 ± 0.90; P = 0.004) and TZ index (0.3 ± 0.5 vs 0.6 ± 0.7; P = 0.008) were significantly lower in septal pacing than in nonseptal pacing, respectively. In multivariate analysis, paced QRS duration and negative or isoelectric QRS vector in lead I independently predicted RVOT septal pacing (P < 0.001). At ROC curve analysis, paced QRS duration ≤145 ms identified RVOT septal pacing with 85.1% sensitivity and 78.9% specificity. This study reveals the heterogeneity of lead placement within the RVOT. Narrower paced QRS duration and negative or isoelectric QRS vector in lead I independently predict RVOT septal pacing.

Pacing lead is more easily located at RVOT septum in patients with severe tricuspid regurgitation

Objective The optimal right ventricular (RV) pacing site in patients referred for permanent cardiac pacing remains controversial. The present study aims to evaluate at which pacing site the electrode is more easily and steadily located in patients with severe tricuspid regurgitation (TR).Methods and results We prospectively enrolled 50 patients with severe TR for permanent pacemaker implantation and randomly divided them into two groups to receive either RV apex (group A) or RV outflow tract (RVOT) pacing (group B). Time of X-ray exposure for ventricular lead deployment, incidence of intra-procedural dislodgement and post-procedural cTnT level were compared between the two groups. Lead performance and echocardiographic parameters were evaluated during follow-up. Fractional shortening (FS) of both RV body and RVOT were assessed so as to analyse the wall motion of the two RV components. As a result, RV body demonstrated a significantly higher FS than RVOT (36.7 ± 5.0% vs30.0 ± 4.6%, P< 0.01) among all TR cases. Compared with group A, less X-ray time was needed for ventricular lead implantation in group B (114.2 ± 28.9 s vs147.2 ± 55.6 s, P= 0.011) with a lower incidence of intra-procedural dislodgement (4% vs24%, P= 0.042). RVOT pacing was also associated with a lower cTnT level 6 and 24 hours after procedure (P <0.01). Lead performance and echocardiographic parameters during follow-up revealed no difference between RV apex and RVOT pacing.Conclusion In patients with severe TR, the ventricular lead is more easily and steadily located at RVOT septum than at the RV apex with shorter fluoroscopy time, lower incidence of intra-procedural dislodgement and less myocardial injury.

Assessment of left ventricular electromechanical activation during right ventricular apical and outflow tract pacing

Abstract Background Right ventricular (RV) apical pacing, induces asynchronous ventricular contraction and impairs cardiac function. Alternative sites of pacing particularly right ventricular outflow tract (RVOT) may have a more favorable hemodynamic profile, physiological left ventricular (LV) activation and normal ventricular contraction pattern. The Aim of the study was to find out the best alternative sites to RV apex for permanent pacemaker (PM) lead fixation in the RVOT, based on the width of the QRS in the surface ECG. Patients and methods The study included 69 patients with pacemaker-dependent complete heart block; 35 with active pacemaker lead fixation in the site which achieved narrowest max. QRS duration in the RVOT (group 1) and 34 with active pacemaker lead fixation in RV apex (group 2). Results High RVOT septum was the site which achieved the narrowest QRS duration on surface ECG (117.86 ± 8.43 ms) when compared with RV apex (140.29 ± 13.14) ( p p p Conclusion High RVOT septum is the ideal site for PM lead implantation. Compared with RV apical pacing, it is associated with improvement in functional and hemodynamic parameters over medium-term follow-up.

Right ventricular outflow tract septal pacing versus apical pacing: A prospective, randomized, single-blind 5-years follow-up study of ventricular lead performance and safety

Lead placement for ventricular pacing variably impacts the physiological benefit of the patient. This study evaluated the ventricular lead performance and safety of right ventricular outflow tract septal pacing in patients with bradyarrhythmia in South China over 60-month follow-up. Totally, 192 patients (108 males, and 84 females, 63±21 years old) with bradyarrhythmia were randomly divided into two groups. The right ventricular outflow tract septum (RVOTs) group had lead placement near the septum (n=97), while the right ventricular apex (RVA) group had a traditional apical placement (n=95). RV septal lead positioning was achieved with a specialized stylet and confirmed using fluoroscopic projection. All patients were followed up for 60 months. Follow-up assessment included stimulation threshold, R-wave sensing, lead impedance and lead complications. The time of electrode implantation in both the ROVTs and RVA groups were significantly different (4.29±0.61 vs. 2.16±0.22 min; P=0.009). No differences were identified in threshold, impedance or R-wave sensing between the two groups at 1st, 12th, 36th and 60th month during the follow-up period. No occurrence of electrode displacement, increased pacing threshold or inadequate sensing was found. The long-term active fixation ventricular electrode performance in RVOTs group was similar to that in RVA group. RVOTs pacing near the septum using active fixation electrodes may provide stability during long-term follow-up period.

Inadequacy of fluoroscopy and electrocardiogram in predicting septal position in RVOT pacing – Validation with cardiac computed tomography

BackgroundElectrocardiographic (ECG) and fluoroscopic criteria, which are the only available guides to achieve a true septal position during right ventricular outflow tract (RVOT) pacing, have been infrequently validated. We sought to validate these using cardiac computed tomographic angiography (CTA) to confirm lead position within the RVOT septum. MethodsForty-four patients with permanent pacemaker leads in the RVOT position underwent CTA. Lead positions in RVOT were classified as anterior, free wall, or septal location. Fluoroscopic images were obtained in 4 standard views. ResultsOnly 19 (43%) patients had lead in true septal position within the RVOT in CTA while 25 patients (57%) were found to have an anterior lead location. Mean QRS axis, QRS duration, negative QRS in lead I, and notching in inferior leads were not significantly different between the two groups. The standard fluoroscopic LAO view showed a rightward-directed lead not only in all 19 patients with septal location, but also in 14/25 patients in the anterior location (p=0.22), and thus had a sensitivity of 100% but specificity of only 16% in predicting true septal position. The posteriorly directed lead in left lateral view was more accurate in predicting true septal position with good sensitivity (73.7%) and excellent specificity (80%). ConclusionsThis study, using validation with CTA, showed that conventional ECG criteria and fluoroscopy are inaccurate in differentiating septal from anterior RVOT pacing. The fluoroscopic lateral view, as corroborated by CTA, is more reliable than the LAO view in predicting septal lead placement.

Non-contact mapping-guided ablation of ventricular arrhythmias originating from the pulmonary artery.

To identify unique electrophysiological characteristics of pulmonary artery (PA) ventricular arrhythmias (VA) and determine long-term clinical outcomes following non-contact mapping (NCM)-guided ablation. The NCM array was deployed in consecutive patients undergoing clinically indicated ablation of outflow tract (OT) VA with left bundle branch block morphology, inferior axis and the precordial lead transition zone ≥ V3. Activation, pace and NCM mapping parameters, and electrocardiogram analysis of PA VA patients were compared with 50 patients with right ventricular OT (RVOT) or aortic coronary cusps (ACC) foci. Of 170 consecutive patients, 20 (12%) patients (8 male, 39.7 ± 12.8 years old) with PA VA were identified. Electrocardiogram morphologies of PA ventricular tachycardia (VT) (located 10.8 ± 15.1 mm above the PV) were indistinguishable from RVOT VT, particularly those arising from the septal RVOT. Pulmonary artery VT can be mapped and ablated by targeting the site of earliest activation on NCM maps, with success rates of 90% after a single procedure, without anti-arrhythmics and mean follow-up of >5 years. Pace-mapping in the PA is complicated by frequent inability to capture (P < 0.01). Small far-field atrial potentials and smaller ventricular electrograms were more frequently recorded at successful sites of ablation in the PA (P < 0.05). Non-contact mapping is a useful technique to map PA VT and ablation at sites of earliest activation above the pulmonary valve is associated with excellent long-term clinical success.

Impact of earliest activation site location in the septal right ventricular outflow tract for identification of left vs right outflow tract origin of idiopathic ventricular arrhythmias.

The earliest activation site (EAS) location in the septal right ventricular outflow tract (RVOT) could be an additional mapping data predictor of left ventricular outflow tract (LVOT) vs RVOT origin of idiopathic ventricular arrhythmias (VAs). The purpose of this study was to assess the impact of EAS location in predicting LVOT vs RVOT origin. Macroscopic and histologic study was performed in 12 postmortem hearts. Electroanatomic maps (EAMs) from 37 patients with outflow tract (OT) VA with the EAS in the septal RVOT were analyzed. Pulmonary valve (PV) was defined by voltage scanning after validation of voltage thresholds by image integration. EAM measurements were correlated with those of macroscopic/histologic study. A cutoff value of 1.9 mV discriminated between subvalvular and supravalvular positions (90% sensitivity, 96% specificity). EAS ≥1 cm below PV excluded RVOT site of origin (SOO). According to anatomic findings (distance PV-left coronary cusp = 5 ± 3 vs PV-right coronary cusp = 11 ± 5 mm), EAS-PV distance was significantly shorter in VAs arising from left coronary cusp than from the other LVOT locations (4.2 ± 5.4 mm vs 9.2 ± 7 mm; P = .034). The 10-ms isochronal longitudinal/perpendicular diameter ratio was higher in the RVOT vs the LVOT SOO group (1.97 ± 1.2 vs 0.79 ± 0.49; P = .001). An algorithm based on EAS-PV distance and the 10-ms isochronal longitudinal/perpendicular diameter ratio predicted LVOT SOO with 91% sensitivity and 100% specificity. An algorithm based on the EAS-PV distance and the 10-ms isochronal longitudinal/perpendicular diameter ratio accurately predicts LVOT vs RVOT SOO in outflow tract VAs with EAS in the septal RVOT.

ASSA13-02-19 Identification of the Breakout and Origin Site in Idiopathic Ventricular Arrhythmias Arising from the Right Ventricular Outflow Tract

<h3>Background</h3> Multiple breakouts may present challenges during catheter ablation of ventricular arrhythmias (VAs, premature ventricular contractions, PVCs and/or nonsustained ventricular tachycardia, NSVT) arising from the right ventricular outflow tract septum (RVOT). <h3>Objective</h3> The purpose of this study was to clarify the breakout sites and origin site and investigate their electrophysiological characteristics in idiopathic VAs arising from the RVOT. <h3>Methods</h3> Nine patients occurred second PVCs with a different morphology after ablation of target PVCs were studied. Electroanatomical mapping (EAM) was performed in RVOT during sinus rhythm. Intracardiac electrograms of successful ablation site were evaluated by local activation time (LAT) and pace mapping (PM). Electroanatomical voltage mapping (EVM) was analysed after procedure. <h3>Results</h3> In all patients, target PVCs had narrower QRS duration than the second one (P = 0.001), the successful target site (Ts) had later LAT and worse template-matching (TM) score than the target site (Tt) of target PVCs which determined by LAT and PM (P &lt; 0.000, P = 0.030, respectively), and the stimulus to QRS interval was slightly longer during pacing at target than EVA site (P = 0.053). The distance between the Ts site and Tt site was 19 ± 8 mm and the target site always located at the transitional-voltage zone (TVZ, 0.5–1.5mV). <h3>Conclusions</h3> RVOT-VAs often shows multiple or deformation of QRS morphologies caused by multiple breakouts and a single origin, which may be explained by anisotropic conduction of the TVZ resulting from the complex histology characteristics of the RVOT.

Experience in the application of active fixation spiral leads in 48 patients with right ventricular outflow tract septum pacing

ObjectiveTo introduce experience in the application of active fixation spiral leads in right ventricular outflow tract (RVOT) septum pacing.MethodNinety eight patients needed to be implanted with pacemaker were divided into...

Alternate Site Right Ventricular Pacing: Defining Template Scoring

Prolonged right ventricular (RV) apical pacing produces dysynchronous ventricular contraction, which may result in left ventricular (LV) dysfunction, whereas septal pacing sites might reflect a more synchronous LV activation. This study examined a method of evaluating alternate RV pacing sites using a template scoring system based on measuring the angle of lead attachment in the 40° left anterior oblique (LAO) fluoroscopic view and its effect on altering the loop of lead in the RV. Twenty-three consecutive patients for RV pacing were enrolled. Conventional active fixation leads were positioned in either the RV outflow tract (RVOT) or mid RV using a stylet designed for septal placement (Model 4140, St. Jude Medical, St. Paul, MN, USA). Using LAO cine fluoroscopy, a generous loop of lead was inserted into the RV chamber and the change in angle of attachment determined. Successful positioning of pacing leads at the RVOT septum (18 patients) and mid-RV septum (five patients) was achieved. With introduction of more lead into the RV chamber, the angle of attachment in the LAO projection altered over a range of 6°-32° for all patients with a mean of 14.6 ± 6.6°. In 87% of patients, the range was predominantly within the same template score with only minor overlap into another zone. This study shows that the angle of lead attachment in the RV is altered by introducing more lead, but in most cases, the template score remains the same. Further studies are required to determine the accuracy and efficacy of the templates.

A Case of Ventricular Tachycardia Originated above the Pulmonary Artery Valve and Treated by the Catheter Ablation in the Separated Two Exits

A 24-year-old female was seen our hospital because of frequent palpitation. Twelve-leads ECG showed the ventricular tachycardia with left bundle branch block and inferior axis (VT1) with stable hemodynamic, and catheter ablation was performed. VT1 was provoked easily by the infusion of the isoproterenol, and it incessantly appeared. VT1 showed the near-perfect pacemap at the right ventricular outflow tract (RVOT) septum at first, it naturally changed to another VT (VT2) which had larger R wave in the inferior leads, and transitional zone shifted from V2-3 to V3-4. Appearance of the VT2 indicated the existence of the two different exits of the VT. After the termination of the VT1 by the application at the RVOT septum, VT2 began to appear continuously. Pacemap above the pulmonary artery valve showed the same morphologies as VT2, and clear discrete prepotential was identified at this site. Application at this site terminated the VT2, and all of the VTs become impossible to be provoked. We report a case of VT which had separated two exits, and was treated by the applications at each of the two exits.

Ablation of the Right Ventricular Outflow Tract Ventricular Tachycardia Guided by Ensite Velocity System: Case Report

Aims: We investigated whether the new contact mapping system, EnSite velocity system, is safe and effective for ablation of non-sustained ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT). Methods: A 42 year-old women who was old handball player presented with palpitation and dyspnea. Holter and treadmill test showed non-sustained VT with left bundle branch block pattern. Results: In electrophysiology study, non-sustained VT was easily induced by isoproterenol infusion at more than 140 beat per min of heart rate. Voltage and activation mapping were performed with EnSite velocity system. After the ablation at anterior septum of RVOT, non-sustained VT was not induced. Conclusion: The new contact mapping system, EnSite velocity system, is effective and helpful for mapping and ablation of RVOT VT.