Earliest Ventricular Activation Research Articles

Improving localization accuracy for non-invasive automated early left ventricular origin localization approach.

Background: We previously developed a non-invasive approach to localize the site of early left ventricular activation origin in real time using 12-lead ECG, and to project the predicted site onto a generic LV endocardial surface using the smallest angle between two vectors algorithm (SA). Objectives: To improve the localization accuracy of the non-invasive approach by utilizing the K-nearest neighbors algorithm (KNN) to reduce projection errors. Methods: Two datasets were used. Dataset #1 had 1012 LV endocardial pacing sites with known coordinates on the generic LV surface and corresponding ECGs, while dataset #2 included 25 clinically-identified VT exit sites and corresponding ECGs. The non-invasive approach used "population" regression coefficients to predict the target coordinates of a pacing site or VT exit site from the initial 120-m QRS integrals of the pacing site/VT ECG. The predicted site coordinates were then projected onto the generic LV surface using either the KNN or SA projection algorithm. Results: The non-invasive approach using the KNN had a significantly lower mean localization error than the SA in both dataset #1 (9.4 vs. 12.5mm, p < 0.05) and dataset #2 (7.2 vs. 9.5mm, p < 0.05). The bootstrap method with 1,000 trials confirmed that using KNN had significantly higher predictive accuracy than using the SA in the bootstrap assessment with the left-out sample (p < 0.05). Conclusion: The KNN significantly reduces the projection error and improves the localization accuracy of the non-invasive approach, which shows promise as a tool to identify the site of origin of ventricular arrhythmia in non-invasive clinical modalities.

Reappraisal and New Observations on Idiopathic Ventricular Arrhythmias Ablated From the Noncoronary Aortic Sinus

BackgroundThe electrophysiological characteristics of idiopathic ventricular arrhythmias (VAs) from the noncoronary sinus (NCS) have not been fully described. ObjectivesThis study sought to investigate electrophysiological characteristics and catheter ablation in patients with idiopathic NCS-VA. MethodsThis study comprised 11 patients undergoing radiofrequency (RF) catheter ablation for idiopathic NCS-VA. Angiography was performed to confirm the origin in the aortic sinus before RF ablation. ResultsClinical arrhythmias presented left bundle block/inferior axis morphology in all patients. QRS morphology of R’ and R/s’ pattern was dominantly found in lead III. Mapping in the right ventricle demonstrated the earliest ventricular activation (EVA) site at the His Bundle region, whereas mapping in the NCS demonstrated that the EVA preceded the activation at the His Bundle region by 12.1 ± 7.9 milliseconds. All VAs were successfully ablated in <2.5 seconds within the NCS with 1 RF application. The successful ablation site was at the nadir of NCS in 10 patients, and near the junction of NCS and the right coronary sinus in the remaining one. A discrete potential can be observed at the EVA site within the NCS in 10 patients (91%); however, an excellent pace mapping at the EVA site was obtained in only 2 patients. Junctional beats did not occur during RF application in all 11 patients. There were no complications or clinical recurrence during a mean follow-up of 26.0 ± 9.8 months. ConclusionsNCS-VA presents a peculiar electrocardiogram. A discrete potential can be mapped within the NCS during VA and sinus rhythm, and can be used in guiding ablation.

PO-657-04 OPEN-WINDOW MAPPING DURING INCESSANT ATRIAL FIBRILLATION MAY FACILITATE ACCESSORY PATHWAY ABLATION

Mapping accessory pathways (AP) via earliest ventricular activation during atrial fibrillation (AF) is challenging. Open-window mapping (OWM) is a well-known approach by which the sharpest local bipolar electrogram (EGM) deflections (absolute dV/dt) are annotated without regard to their chamber of origin; therefore, the need for an operator to decipher point-by-point whether a signal arises from the atrium, AP, or ventricle is obviated. OWM in incessant AF has not been described.

Left ventricular activation time and pattern are preserved with both selective and nonselective His bundle pacing.

BackgroundHis bundle pacing (HBP) can be achieved in 2 ways: selective HBP (S-HBP), where the His bundle is captured alone, and nonselective HBP (NS-HBP), where local myocardium is also captured, resulting a pre-excited electrocardiogram appearance.ObjectiveWe assessed the impact of this ventricular pre-excitation on left and right ventricular dyssynchrony.MethodsWe recruited patients who displayed both S-HBP and NS-HBP. We performed noninvasive epicardial electrical mapping for left and right ventricular activation time (LVAT and RVAT) and pattern.ResultsTwenty patients were recruited. In the primary analysis, the mean within-patient change in LVAT from S-HBP to NS-HBP was -5.5 ms (95% confidence interval: -0.6 to -10.4, noninferiority P < .0001). NS-HBP did not prolong RVAT (4.3 ms, -4.0 to 12.8, P = .296) but did prolong QRS duration (QRSd, 22.1 ms, 11.8 to 32.4, P = .0003). In patients with narrow intrinsic QRS (n = 6), NS-HBP preserved LVAT (-2.9 ms, -9.7 to 4.0, P = .331) but prolonged QRS duration (31.4 ms, 22.0 to 40.7, P = .0003) and mean RVAT (16.8 ms, -5.3 to 38.9, P = .108) compared to S-HBP. Activation pattern of the left ventricular surface was unchanged between S-HBP and NS-HBP, but NS-HBP produced early basal right ventricular activation that was not seen in S-HBP.ConclusionCompared to S-HBP, local myocardial capture during NS-HBP produces pre-excitation of the basal right ventricle resulting in QRS duration prolongation. However, NS-HBP preserves the left ventricular activation time and pattern of S-HBP. Left ventricular dyssynchrony is not an important factor when choosing between S-HBP and NS-HBP in most patients.

Three-dimensional mapping for His-bundle pacing in pediatric patients, a case series

IntroductionPediatric patients who receive pacemakers may have a lifetime of repeat exposure to fluoroscopy. His bundle pacing may provide better long-term pacing for these patients. To minimize fluoroscopy and for improved localization of the His bundle, we utilized three-dimensional mapping to guide His bundle pacing and we follow-up short-term results. MethodsAn Octapolar Livewire catheter (Abbott, Minneapolis, USA) was used for mapping and location of the His bundle while 3-dimensional mapping via the EnSite Precision system (Abbott Medical, Abbott Park, IL) was utilized to create a 3-dimensional geometry. The EnSite Precision system also mapped and recorded His bundle signal strengths and earliest ventricular activation or retrograde His bundle activation. ResultsThree patients are presented and followed for 4–5 months. The ages ranged from 10 to 15 years with 1 male patient. Diagnoses including progressive atrioventricular block, alternating bundle branch block and atrioventricular canal defect with complete heart block. All patients received selective His-bundle pacing systems. The range in fluoroscopy time was 6.4 to 9.9 min with 5.64 mGy to 10.18 mGy. Stable lead thresholds, impedances and sensing were present at last follow-up. ConclusionsHis bundle pacing in our 3 pediatric patients including one with altered His-bundle physiology (case 3 with atrioventricular canal defect) was successful with good short-term follow-up results.

Non-selective and selective His bundle pacing both preserve left ventricular activation time and pattern

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): British Heart Foundation Background: His bundle pacing can be achieved in two ways selective His bundle pacing, where the His bundle is captured alone, and non-selective His bundle pacing, where local myocardium is also captured resulting a pre-excited ECG appearance. We assessed the impact of this ventricular pre-excitation on left and right ventricular dys-synchrony. Methods We recruited patients who displayed both selective and non-selective His bundle pacing. We performed non-invasive epicardial electrical mapping to determine left and right ventricular activation times and patterns. Results In the primary analysis (n = 20, all patients), non-selective His bundle pacing did not prolong LVAT compared to select His bundle pacing by a pre-specified non-inferiority margin of 10ms (LVAT prolongation: -5.5ms, 95% confidence interval (CI): -0.6 to -10.4, non-inferiority p &amp;lt; 0.0001). Non-selective His bundle pacing did not prolong right ventricular activation time (4.3ms, 95%CI: -4.0 to 12.8, p = 0.296) but did prolong QRS duration (22.1ms, 95%CI: 11.8 to 32.4, p = 0.0003). In patients with narrow intrinsic QRS (n = 6), non-selective His bundle pacing preserved left ventricular activation time (-2.9ms, 95%CI: -9.7 to 4.0, p = 0.331) but prolonged QRS duration (31.4ms, 95%CI: 22.0 to 40.7, p = 0.0003) and mean right ventricular activation time (16.8ms, 95%CI: -5.3 to 38.9, p = 0.108) compared to selective His bundle pacing. Activation pattern of the left ventricular surface was unchanged between selective and non-selective His bundle pacing. Non-selective His bundle pacing produced early basal right ventricular activation, which was not observed with selective His bundle pacing. Conclusions Compared to selective His bundle pacing, local myocardial capture during non-selective His bundle pacing produces right ventricular pre-excitation resulting in prolongation of QRS duration. However, non-selective His bundle pacing preserves the left ventricular activation time and pattern of selective His bundle pacing. When choosing between selective and non-selective His bundle pacing, left ventricular dyssynchrony is not an important factor. Abstract Figure: Selective vs Non-Selective HBP

Prospective Multicenter Assessment of a New Intraprocedural Automated System for Localizing Idiopathic Ventricular Arrhythmia Origins.

The objective of this study was to present a new system, the Automatic Arrhythmia Origin Localization (AAOL) system, which used incomplete electroanatomic mapping (EAM) for localization of idiopathic ventricular arrhythmia (IVA) origin on the patient-specific geometry of left ventricular, right ventricular, and neighboring vessels. The study assessed the accuracy of the system in localizing IVA source sites on cardiac structures where pace mapping is challenging. An intraprocedural automated site of origin localization system was previously developed to identify the origin of early left ventricular activation by using 12-lead electrocardiograms (ECGs). However, it has limitations, as it could not identify the site of origin in the right ventricle and relied on acquiring a complete EAM. Twenty patients undergoing IVA catheter ablation had a 12-lead ECG recorded during clinical arrhythmia and during pacing at various locations identified on EAM geometries. The new system combined 3-lead (III, V2, and V6) 120-ms QRS integrals and patient-specific EAM geometry with pace mapping to predict the site of earliest ventricular activation. The predicted site was projected onto EAM geometry. Twenty-three IVA origin sites were clinically identified by activation mapping and/or pace mapping (8, right ventricle; 15, left ventricle, including 8 from the posteromedial papillary muscle, 2 from the aortic root, and 1 from the distal coronary sinus). The new system achieved a mean localization accuracy of 3.6mm for the 23 mapped IVAs. The new intraprocedural AAOL system achieved accurate localization of IVA origin in ventricles and neighboring vessels, which could facilitate ablation procedures for patients with IVAs.

Abstract 13184: A New Intraprocedural Automated System for Localizing Idiopathic Ventricular Arrhythmia Origin Sites

Introduction: Few intraprocedural localization systems have been developed to predict idiopathic ventricular arrhythmia (IVA) source sites. However, an accurate and bi-ventricular patient-specific automated site of origin localization system remains elusive. To address this issue, we have developed a new automatic arrhythmia origin localization (AAOL) system that determines the sites of earliest activation in both ventricles and provides superior accuracy. Hypothesis: We hypothesized that the AAOL system can use electroanatomic mapping (EAM) geometry and accurately localize IVA source sites on patient-specific geometry of LV, RV and neighboring vessels using 3-lead ECGs. Methods: Twenty patients undergoing IVA catheter ablation had a 12-lead ECG recorded during clinical arrhythmia and during pacing at various locations identified on EAM geometries. The AAOL system combined 3-lead (III, V2, V6) 120-ms QRS integrals and patient-specific EAM geometry with intracardiac pacing to predict the site of earliest ventricular activation. The predicted site was projected onto the EAM geometry using the EAM triangular-mesh site nearest to the tip of the predicted site. Results: Twenty-three IVA source sites were clinically identified by activation mapping and/or pace mapping (8 RV, 15 LV, including 8 from the posteromedial papillary muscle; 2 from the aortic root; and 1 from the distal coronary sinus). The new system achieved a mean localization accuracy of 3.6 mm for the 23 mapped IVAs (Figure 1D), better than that achieved by previous systems. Conclusions: The new AAOL system offers highly accurate localization of IVA source sites in both ventricles and neighboring vessels, which could facilitate ablation procedures for patients with IVAs.

QRS complex axis deviation changing in catheter ablation of left fascicular ventricular tachycardia.

The mechanisms of the QRS complex axis deviation changing of idiopathic left fascicular ventricular tachycardia (FVT) during or after radiofrequency catheter ablation were investigated in this study, which were still not well defined. In the index procedure, FVTs characterized by right bundle branch block configuration and left-axis deviation (LAD-FVT) were ablated at the VT exit site guided by the earliest ventricular activation with fused presystolic Purkinje potential (PP) in 234 consecutive patients. A new type of FVT characterized by right-axis deviation (RAD-FVT) was identified after successful elimination of the LAD-FVT in 12 patients, including 9 patients during the index procedure and 3 patients during follow-up. The QRS duration of RAD-FVT was shorter than that of LAD-FVT (115.3 ± 15.2 vs. 125.3 ± 16.4 ms, P = 0.006). The RAD-FVTs showed an earliest ventricle activation site localized at anterior fascicle area in 11 patients and anterior-median fascicle area in 1. However, the earliest PP during the RAD-FVT was still identified within the posterior fascicular network. Elimination of the RAD-FVTs was successfully achieved by applying radiofrequency current at a more proximal site within the left posterior fascicular network guided by the earliest PP. After a mean of 1.6 ± 0.8 ablation procedures and median follow-up of 132 (range 19-216) months since the last procedure, no recurrence was observed in any patients. The axis deviation changing of QRS complex in FVT may be attributed to the different exit sites of the reentry.

Prospective Assessment of an Automated Intraprocedural 12-Lead ECG-Based System for Localization of Early Left Ventricular Activation.

To facilitate ablation of ventricular tachycardia (VT), an automated localization system to identify the site of origin of left ventricular activation in real time using the 12-lead ECG was developed. The objective of this study was to prospectively assess its accuracy. The automated site of origin localization system consists of 3 steps: (1) localization of ventricular segment based on population templates, (2) population-based localization within a segment, and (3) patient-specific site localization. Localization error was assessed by the distance between the known reference site and the estimated site. In 19 patients undergoing 21 catheter ablation procedures of scar-related VT, site of origin localization accuracy was estimated using 552 left ventricular endocardial pacing sites pooled together and 25 VT-exit sites identified by contact mapping. For the 25 VT-exit sites, localization error of the population-based localization steps was within 10 mm. Patient-specific site localization achieved accuracy of within 3.5 mm after including up to 11 pacing (training) sites. Using 3 remotes (67.8±17.0 mm from the reference VT-exit site), and then 5 close pacing sites, resulted in localization error of 7.2±4.1 mm for the 25 identified VT-exit sites. In 2 emulated clinical procedure with 2 induced VTs, the site of origin localization system achieved accuracy within 4 mm. In this prospective validation study, the automated localization system achieved estimated accuracy within 10 mm and could thus provide clinical utility.

Eccentric Activation Patterns in the Left Ventricular Outflow Tract during Idiopathic Ventricular Arrhythmias Originating From the Left Ventricular Summit: A Pitfall for Predicting the Sites of Ventricular Arrhythmia Origins.

Idiopathic ventricular arrhythmias (VAs) originating from the left ventricular summit (LVS) can be ablated from the great cardiac vein and remote endocardial sites. The ablation sites are determined by mapping in the great cardiac vein and left ventricular outflow tract. This study investigated whether that mapping could accurately predict the sites of LVS-VA origins. We studied 26 consecutive patients with idiopathic LVS-VA origins that were identified in the basal and apical LVS in 15 and 11 patients, respectively. Radiofrequency catheter ablation of the apical LVS-VAs was successful in the great cardiac vein in 9 patients and in the apical LV outflow tract in 2. That of the basal LVS-VAs was successful in the aortomitral continuity in 9 patients, at the junction of the left and right coronary cusps in 4, and in the left coronary cusp in 2. Three apical LVS-VAs exhibited an eccentric endocardial activation pattern that was from the basal to apical LV outflow tract. In 11 basal LVS-VAs, the activation pattern was eccentric because the ventricular activation within the great cardiac vein in the apical LVS was earlier than that in the basal LV outflow tract. In 2 basal LVS-VAs, the activation pattern was eccentric because a relatively early ventricular activation was recorded at multiple sites away from the successful ablation site. Eccentric activation patterns often occurred during idiopathic LVS-VAs, which could mislead the catheter ablation of those VAs. Understanding such eccentric activation patterns was suggested to be able to improve the outcomes of the catheter ablation of those VAs by the anatomic approach.

Rapid 12-lead automated localization method: Comparison to electrocardiographic imaging (ECGI) in patient-specific geometry

BackgroundRapid accurate localization of the site of ventricular activation origin during catheter ablation for ventricular arrhythmias could facilitate the procedure. Electrocardiographic imaging (ECGI) using large lead sets can localize the origin of ventricular activation. We have developed an automated method to identify sites of early ventricular activation in real time using the 12-lead ECG. We aim to compare the localization accuracy of ECGI and the automated method, identifying pacing sites/VT exit based on a patient-specific model. MethodsA patient undergoing ablation of VT on the left-ventricular endocardium and epicardium had 120-lead body-surface potential mapping (BSPM) recorded during the procedure. (1) ECGI methodology: The L1-norm regularization was employed to reconstruct epicardial potentials based on patient-specific geometry for localizing endocardial ventricular activation origin. We used the BSPM data corresponding to known endocardial pacing sites and a VT exit site identified by 3D contact mapping to analyze them offline. (2) The automatedmethod: location coordinates of pacing sites together with the time integral of the first 120 ms of the QRS complex of 3 ECG predictors (leads III, V2 and V6) were used to calculate patient-specific regression coefficients to predict the location of unknown sites of ventricular activation origin (“target” sites). Localization error was quantified over all pacing sites in millimeters by comparing the calculated location and the known reference location. ResultsLocalization was tested for 14 endocardial pacing sites and 1 epicardial VT exit site. For 14 endocardial pacing sites the mean localization error of the automated method was significantly lower than that of the ECGI (8.9 vs. 24.9 mm, p < 0.01), when 10 training pacing sites are used. Emulation of a clinical procedure demonstrated that the automated method achieved localization error of <5 mm for the VT-exit site; while the ECGI approach approximately correlates with the site of VT exit from the scar within a distance of 18.4 mm. ConclusionsThe automated method using only 3 ECGs shows promise to localize the origin of ventricular activation as tested by pacing, and the VT-exit site and compares favourably to inverse solution calculation, avoiding cumbersome lead sets. As 12-lead ECG data is acquired by current 3D mapping systems, it is conceivable that the algorithm could be directly incorporated into a mapping system. Further validation in a prospective cohort study is needed to confirm and extend observations reported in this study.

Safety and efficacy of catheter ablation of ventricular arrhythmias with para-Hisian origin via a systematic direct approach from the aortic sinus cusp

Catheter ablation of ventricular arrhythmias (VAs) originating from the para-Hisian region could be challenging because of a potential damage to atrioventricular conduction system. The purpose of this study was to evaluate the safety and efficacy of catheter ablation of VAs originating from the para-Hisian region via a systematic direct approach from aortic sinus cusps (ASCs). Twenty-one consecutive patients with VAs with para-Hisian origin were included. Electrophysiological mapping of the entire right ventricle was initially performed, and then retrograde ASC mapping was performed when the earliest ventricular activation was recorded in the His bundle region. Ablation was preferentially performed within ASCs in all patients. Radiofrequency energy delivery resulted in the elimination of VAs in 17 of 21 patients (81%). In the remaining 4 patients, radiofrequency application was initiated at the target site of the right ventricular septum around the His bundle region and clinical VAs were finally successfully eliminated without junctional rhythm in 2 of 4 patients. During a mean follow-up of 34.8 ± 11.3 months, 1 of the 19 acute successful patients had VA recurrence. No procedure-related complications occurred during ablation or follow-up. Catheter ablation of VAs originating from the para-Hisian region via a direct approach from ASCs may be safe and effective in most unselected patients.

Coexistence of Brugada and Wolff Parkinson White Syndrome: A Case Report and Review of the Literature

A 31-year-old male patient presented with complaints of palpitations, dizziness, and recurrent episodes of syncope. A 12-lead electrocardiogram (ECG) revealed manifest ventricular preexcitation, which suggested Wolff Parkinson White syndrome. In addition, an incomplete right bundle branch block and a 3-mm ST segment elevation ending with inverted T-waves in V2 were consistent with coved-type (type 1) Brugada pattern. An electrophysiological study was performed, and during the mapping, the earliest ventricular activation with the shortest A-V interval was found on the mitral annulus posterolateral site. After successful radiofrequency catheter ablation of the accessory pathway, the Brugada pattern on the ECG changed, which prompted an ajmaline provocation test. A type 1 Brugada ECG pattern occurred following the administration of ajmaline. Considering the probable symptom combinations of these 2 coexisting syndromes and the presence of recurrent episodes of syncope, programmed ventricular stimulation was performed and subsequently, ventricular fibrillation was induced. An implantable cardioverter-defibrillator was implanted soon after.

Incessant fascicular VT presenting as cardiogenic shock with multi-organ dysfunction syndrome

We report a rare clinical presentation of incessant idiopathic fascicular ventricular tachycardia (FVT), presenting as multi-organ dysfunction (MOD) syndrome with cardiogenic shock. Our patient was a 19-year-old male who presented with slowly progressive dyspnea from New York Heart Association (NYHA) II to NYHA IV at the time of presentation, palpitations, and dilated cardiomyopathy due to drug-refractory FVT. The patient was in cardiogenic shock with raised central venous pressures and required inotropic support for maintaining systolic blood pressure above 90mmHg. The MOD was seen in the form of deranged liver and kidney parameters. Echocardiography showed a dilated left ventricle (LV, 58mm at end-diastole, 52mm at end-systole) and decreased ejection fraction (20%). Electrocardiography showed a wide-QRS tachycardia (QRS 140ms, cycle length 440ms), with RsR’ in lead V1 and a QRS axis of −60°. After stabilization with ventilation, inotropic support, and cautious use of diuretics, an electrophysiologic study was performed. A Purkinje potential with early local ventricular activation was recorded from the LV inferoseptal region. The tachycardia was ablated at this site with radiofrequency (RF) energy (40W for 35sec). Over a 3-month follow-up, the patient remained asymptomatic and the LV size and function returned to normal.<Learning objective: To highlight a rare and unreported complication of fascicular ventricular tachycardia presenting as multi-organ dysfunction and its reversion with radiofrequency ablation.>

50 is the new 70: Short ventriculoatrial times are common in children with atrioventricular reciprocating tachycardia.

One of the basic electrophysiological principles of atrioventricular reciprocating tachycardia (AVRT) is that ventriculoatrial (VA) times during tachycardia are >70 ms. We hypothesized, however, that children may commonly have VA times <70 ms in AVRT. This study sought to determine the incidence and characteristics associated with short-VA AVRT in children. A retrospective single-center review of children with AVRT from 2000 to 2014 was performed. All patients ≤18 years of age with AVRT at electrophysiology study were included. Patients with persistent junctional reciprocating tachycardia, atrioventricular nodal reentry tachycardia, and tachycardia not unequivocally proven to be AVRT were excluded. VA time was defined as the time between earliest ventricular activation and earliest atrial activation in any lead and was confirmed by 2 electrophysiologists. Patients with VA times <70 ms (SHORT-VA) and those with standard VA times ≥70 ms (STD-VA) were compared. Logistic regression analysis identified characteristics of SHORT-VA patients. A total of 495 patients with AVRT were included (mean age 11.7 ± 4.1 years). There were 265 patients (54%) with concealed accessory pathways (APs) and 230 (46%) with Wolff-Parkinson-White syndrome. AP location was left-sided in 301 patients (61%) and right-sided in 194 (39%). The mean VA time in AVRT was 100 ± 33 ms. A total of 63 patients (13%) had VA times <70 ms (SHORT-VA). The shortest VA time during AVRT was 50 ms. There was no difference in age, AV nodal block cycle, or body surface area between SHORT-VA and STD-VA patients, but SHORT-VA patients had lower weight (43 ± 17 vs 51 ± 23 kg, P = .02), lower AV nodal effective refractory period (AVNERP; 269 ± 50 vs 245 ± 52 ms, P < .01), and more left-sided APs (50 [79%] vs 251 [58%]; P < .01]. On multivariate logistic regression, factors associated with SHORT-VA included left-sided AP (odds ratio [OR] 5.79, confidence interval [95% CI] 2.21-15.1, P < .01), shorter AVNERP (OR 0.99, CI 0.98-0.99, P < .01), and lower weight (OR 0.97, CI 0.95-0.99, P < .01). Children with AVRT can frequently have VA times <70 ms, with 50 ms being the shortest VA time. This finding debunks the classic electrophysiology principle that VA times in AVRT must be >70 ms. SHORT-VA AVRT was more common in children with left-sided APs.

Necessity of epicardial ablation for ventricular tachycardia after sequential endocardial approach

BackgroundCatheter ablation (CA) of ventricular tachycardia (VT) is an important treatment option in patients with structural heart disease (SHD) and implantable cardioverter defibrillator (ICD). A subset of patients requires epicardial CA for VT. ObjectiveThe purpose of the study was to assess the significance of epicardial CA in these patients after a systematic sequential endocardial approach. MethodsBetween January 2009 and October 2012 CA for VT was analyzed. A sequential CA approach guided by earliest ventricular activation, pacemap, entrainment and stimulus to QRS-interval analysis was used. Acute CA success was assessed by programmed ventricular stimulation. ICD interrogation and 24h-Holter ECG were used to evaluate long-term success. ResultsOne hundred sixty VT ablation procedures in 126 consecutive patients (114 men; age 65±12years) were performed. Endocardial CA succeeded in 250 (94%) out of 265 treated VT. For 15 (6%) VT an additional epicardial CA was performed and succeeded in 9 of these 15 VT. Long-term FU (25±18.2month) showed freedom of VT in 104 pts (82%) after 1.2±0.5 procedures, 11 (9%) suffered from repeated ICD shocks and 11 (9%) died due to worsening of heart failure. ConclusionsDespite a heterogenic substrate for VT in SHD, endocardial CA alone results in high acute success rates. In this study additional epicardial CA following a sequential endocardial mapping and CA approach was performed in 6% of VT.Thus, due to possible complications epicardial CA should only be considered if endocardial CA fails.

Catheter Ablation of an Anteroseptal Accessory Pathway Guided by Three-dimensional Electroanatomical Mapping in Symptomatic Wolff-Parkinson-White Syndrome

OBJECTIVE: To report a case of a successful anteroseptal accessory pathway ablation in a 32-year old male with symptomatic Wolf-Parkinson-White (WPW) syndrome with the guidance of three-dimensional (3D) electroanatomical mapping. CLINICAL PRESENTATION: This is the case of a 32-year old male with symptomatic WPW syndrome presenting as frequent episodes of palpitations since 2002 despite being maintained on flecainide 100 mg twice daily. He was initially admitted in another institution for electrophysiological study (EPS), which showed orthodromic tachycardia using an anteroseptal pathway. Due to the proximity of the accessory pathway to the bundle of His, ablation was not attempted. He was referred to our institution and eventually underwent successful radiofrequency (RF) ablation of the anteroseptal accessory pathway with the guidance of 3D electroanatomical mapping. At baseline, the His proximal electrodes appeared to have the earliest ventricular activation in sinus rhythm, and the earliest His bundle activation with ventricular pacing as well. During tachycardia, there was concentric ventriculo-atrial (VA) conduction via the accessory pathway, with the earliest VA conduction at the His electrode essentially fused. The accessory pathway was mapped to the anteroseptal region of the tricuspid annulus that was 2 to 3 mm from the Bundle of His. RF application in this area during sinus rhythm with 3D electroanatomical guidance resulted in loss of the delta wave after 2 seconds of energy application of 30 watts at 35° (right antero-oblique), which persisted after the ablation. SIGNIFICANCE: EPS with RF ablation is the first-line treatment for symptomatic WPW syndrome. However, due to the potential for atrioventricular block especially in the anteroseptal accessory pathway ablation because of its close proximity to the His bundle, precise mapping of the tract is essential and can be accomplished using 3D electroanatomical mapping. KEYWORDS: Wolff-Parkinson-White syndrome, electroanatomical mapping, anteroseptal accessory pathway, septal ablation, radiofrequency ablation complications, atrioventricular block.

Impact of the Patient Torso Model on the Solution of the Inverse Problem of Electrocardiography

Cardiac diagnostics based on a solution of the inverse problem of electrocardiography offers new tools for visual assessment of cardiac ischemia. The accuracy of the inverse solution is influenced by fidelity of the patient torso model. As optimum, an individual torso model with real heart shape and position obtained from CT or MRI is desirable. However, imaging is not always available in clinical practice, hence we investigated, if a generic torso shape individually adjusted according to patient‘s chest dimensions, with a simplified heart model placed to a vertical position obtained from inverse localization of the early ventricular activation can result in an inverse solution close to the result obtained with an accurate torso model. Simulated inverse localization of 18 ischemic lesions for 9 subjects showed that the use of individually adjusted generic torso instead of real torso shape led to an acceptable increase of the lesion localization error from 0.7±0.7 cm to 1.1±0.7 cm when accurate heart model was used. However, if simplified heart model was used and placed in a vertical position according to the V2 lead level, the lesion localization error increased to 3.5±0.9 cm. Moving the simplified heart model to a position estimated by the inverse solution decreased the vertical heart positioning error from 1.6±2.3 cm to 0.2±1.2 cm but without adjusting the heart shape and rotation the lesion localization error did not improve and reached 3.7±1.0 cm.

Abstract 19013: Symptomatic Spontaneous Automaticity in a Decrementally Conducting Left Free Wall Accessory Pathway in a Patient With Congenital Heart Block

Introduction: A 20 year-old female with a history of a coil-occluded patent ductus arteriosus and congenital complete atrioventricular (AV) block was admitted for a wide complex tachycardia (WCT) associated with palpitations and dizziness. Her LV function was normal and no additional structural heart disease was noted on a cardiac MRI. Electrophysiology (EP) study was performed. Methods: N/A Results: EP study showed sinus tachycardia with 1:1 antegrade conduction via a left-sided accessory pathway. The accessory pathway demonstrated decremental conduction, adenosine responsiveness, and no retrograde conduction. The earliest ventricular activation was noted in the distal coronary sinus electrode. At slower atrial rates (70-100 bpm), there was isorhythmic dissociation (see figure) between the accessory pathway (QRS identical to maximal pre-excitation) and the sinus node strongly suggesting spontaneous accessory pathway automaticity. The accessory pathway was successfully ablated by targeting an accessory pathway potential located at the anterior aspect of the mitral valve. Post-ablation, there was complete AV block with a narrow junctional escape rhythm at a rate of 64 beats per minute. The patient underwent placement of a dual chamber pacemaker. Conclusion: This is, to our knowledge, the first reported case of a left-sided accessory pathway with both spontaneous automaticity and Mahaim-like properties.