Endocardial Mapping Research Articles

Development of Time- and Voltage-Domain Mapping (V-T-Mapping) to Localize Ventricular Tachycardia Channels During Sinus Rhythm.

In ventricular scar, impulse spread is slow because it traverses split and zigzag channels of surviving muscle. We aimed to evaluate scar electrograms to determine their local delay (activation time) and inequality in voltage splitting (entropy), and their relationship to channels. We reasoned that unlike innocuous channels, which are often short with multiple side branches, ventricular tachycardia (VT) supporting channels have very slow impulse spread and possess low entropy because of their longer protected length and relative lack of side-branching. Patients with ischemic cardiomyopathy and multiple VT were studied. In initial mapping stage (16 patients and 58 VTs), left ventricular endocardial mapping was performed in sinus rhythm. Detailed pace mapping was used to identify VT channels and confirmed, when feasible, by entrainment. Scar electrograms were analyzed in time and voltage domains to determine mean activation time, dispersion in activation time, and entropy. Predictive performances of these properties to detect VT channels were tested. In the application stage (7 patients and 20 VTs), these properties were prospectively tested to guide catheter ablation. A mean number of 763±203 sampling points were taken. From 1770 pace maps, 47 channels corresponded to VTs. A combination of scar electrograms with the latest mean activation time and minimum entropy, in a high activation dispersion region, accurately recognized regions containing VT channels (κ=0.89, sensitivity=86%, specificity=100%, positive predictive value=93%, and negative predictive value=100%). Finally, focused ablation within 5-mm rim of the prospective channel regions eliminated 18 of 20 inducible VTs. Activation time and entropy mapping in the scar accurately identify VT channels during sinus rhythm. The method integrates principles of reentry formation to recognize VT channels without pace mapping or mapping during VT.

Evaluation of a novel high-resolution mapping system for catheter ablation of ventricular arrhythmias

The mapping of ventricular arrhythmias in humans using a minibasket 64-electrode catheter paired with a novel automatic mapping system (Rhythmia) has not been evaluated. The purpose of this study was to evaluate the safety and efficacy of mapping ventricular arrhythmias and clinical outcomes after ablation using this system. Electroanatomic maps for ventricular arrhythmias were obtained during 20 consecutive procedures in 19 patients (12 with ventricular tachycardia [VT] and 2 with ventricular ectopy [VE]). High-density maps were acquired using automatic beat acceptance and automatic system annotation of electrograms. Forty-seven electroanatomic maps (including 3 right ventricular and 9 epicardial maps) were obtained. Left ventricular endocardial mapping by transseptal (n = 13) and/or transaortic (n = 11) access was safe with no complications related to the minibasket catheter. VT substrate maps (n = 14; median 10,184 points) consistently demonstrated late potentials with high resolution. VT activation maps (n = 25; median 6401 points) obtained by automatic annotation included 7 complete maps (covering ≥90% of the tachycardia cycle length) in 5 patients in whom the entire VT circuit was accurately visualized. VE timing maps (n = 8) successfully localized the origin of VEs in all, with all accepted beats consistent with clinical VEs. Over a median follow-up of 10 months, no arrhythmia recurrence was noted in 75% after VT ablation and 86% after VE ablation. In this first human experience for ventricular arrhythmias using this system, ultra-high-density maps were created rapidly and safely, with a reliable automatic annotation of VT and consistent recording of abnormal electrograms. Medium-term outcomes after ablation were encouraging. Further larger studies are needed to validate these findings.

Endocardial voltage mapping of pulmonary veins with an ultra-high-resolution system to evaluate atrial myocardial extensions.

Atrial fibrillation (AF) is mainly triggered by arrhythmogenic foci originating from atrial myocardial extensions (MEs) into the pulmonary veins (PVs). Aim of the study was to evaluate endocardial voltage maps of PVs as a surrogate parameter for the extent of MEs in subjects with AF through a ultra-high-density mapping system. Sixty-four bipolar electrograms were recorded simultaneously from the Orion mini-basket catheter placed in 72 PVs of 18 consecutive patients with paroxysmal/persistent AF undergoing PV isolation (PVI). The Rhythmia system in conjunction with the Orion mini-basket catheter was utilized to create a bipolar electro-anatomic reconstruction of the left atrium and PVs. Mean patients' age was 61±10years, 56% had paroxysmal and 44% persistent AF. Mean endocardial bipolar voltages in the PVs were as follows: 1.06±0.34mV in right superior PV, 1.14±0.52mV in right inferior PV, 1.15±0.44mV in left superior PV and 0.94±0.44 in left inferior PV. PVs had no detectable endocardial signals in 7 out of 72 PVs (9%); a total of 29/72 PVs (40%) revealed a non-uniform arrangement of MEs. The area of MEs was significantly larger in the superior PVs compared to the inferior PVs (9.3±4.7 vs 6.7±4cm2, p=0.002). No statistical differences in terms of MEs length were found among PVs and according to type of AF. In this pilot study using a ultra-high-resolution electro-anatomical mapping system, endocardial voltage maps of PVs as a surrogate parameter of MEs among patients with AF well correspond to previous data from histopathological studies.

Abstract 11802: Transforming the Convergent Procedure- Thinking Inside the Box

Introduction: We report on intermediate follow up using a technique of confluent posterior left atrial wall epicardial ablation designed to eliminate both existing and future atrial fibrillation (AF) substrate. Hypothesis: The purpose of this study is to report on our experience with a technique of extended ablation using a confluent pattern of posterior left atrial epicardial lesions combined with endocardial ablation, as part of the Convergent hybrid closed chest procedure, performed in a single setting. Methods: Multiple confluent epicardial ablations with radiofrequency energy were delivered spanning the vertical and transverse dimensions of the posterior left atrium, along with facilitated pulmonary vein isolation (PVI). Endocardial mapping and ablation were performed to complete PVI and ablate the cavo-tricuspid isthmus. All patients were followed clinically and with 2 to 4 weekly continuous monitoring at 6, 12, and 24 months. Average follow-up was 488 days. Results: Of 57 patients with long-standing or persistent AF (NPAF), mean duration of AF was 5.6 years. Single procedure freedom from AF at 24 months was 64.5% and for all arrhythmias was 58.9%. Sixty-eight percent were off antiarrhythmic drugs (AADs). Four patients (7%) required a second endocardial ablation procedure. Sub-analysis of the observed arrhythmia burden through follow-up showed it to be small (0 to less than 1%) in the majority of patients. Conclusions: This extended posterior wall ablation technique, as part of the Convergent hybrid method, achieved notable single procedure success in a consecutive series of patients with NPAF.

Abstract 13527: Role of Rotor Activation in Persistent Atrial Fibrillation Perpetuated After Pulmonary Vein isolation: Relation to the Complex Fractionated Electrogram Region

Background: Complex fractionated electrogram (CFE) region has been suggested as the substrate of random wave propagation perpetuated after pulmonary vein (PV) isolation in patients with persistent atrial fibrillation (AF). While the rotor has also been suggested as the driving sources. But the relation between CFE and rotor remains unclear. Objectives: We elucidated the significance of CFE and rotor for the maintenance of AF perpetuated after PV isolation in persistent AF patients. Methods: Endocardial non-contact mapping of the left atrium was performed in 16 patients with persistent AF perpetuated after PV isolation. To define the role of CFE and rotor for the maintenance of AF, the number of pivoting activation involved in the CFE was compared with that involved in the rotor activation. The location of rotor and pivoting activation were also compared between the CFE and non-CFE region. Presence of rotor activation was defined when the circular activation around the functional block line once completed its whole reentrant activation. Results: Rotor activation was observed in 11 patients (69%) with a mean number of 2.1±2.0 times/sec. Rotor activation continued at the same site more than once in 2 patients, but shifted to the different location or observed intermittently in the remaining 9 patients. All rotors were observed at CFE region (CFE area; 7.7±2.5 cm2). Total number of pivoting activation was 12.8±4.6 times/sec. The number of pivot activation involved in the CFE region was significantly higher than that in the non-CFE region (12.4±4.9 vs. 0.5±1.0 times/sec, p<0.0001). Thus, 99% of pivoting activations were observed within the CFE region. Pivoting activation involved in the rotor activation was significantly lower than that not involved in the rotor activation (3.5±3.2 vs. 8.7±5.0 times/sec, p<0.01) in the CFE region, but was not different in non-CFE region (0.0±0.0 vs. 0.5±1.0 times/sec, p=NS). Conclusions: Rotor activation was observed within the CFE region after PV isolation. However, few rotors sustained at the stable location. Further, most of pivoting activation was not involved in the rotor activation, suggesting that AF was driven by the meandering non-rotor propagation associated with frequent pivoting activation over the CFE region.

Abstract 13901: Significance of Rotor Activation Observed Outside of the Pulmonary Vein for the Maintenance of Atrial Fibrillation: Three-dimensional Analysis Using a Non-contact Mapping System

Background: It has been suggested pulmonary vein (PV) acts as the driving sources of atrial fibrillation (AF). However, it is unclear whether the rotor, which is located outside the PV, also maintains the AF. Objectives: To define the prevalence and significance of rotor observed outside the PV in the left atrium (LA), LA activation sequence was analyzed during AF after PV isolation. Methods: Endocardial mapping of LA was performed in 25 AF patients (9 paroxysmal and 16 persistent AF) using a non-contact mapping system (EnSite 3000) during AF perpetuated after PV isolation. Presence of rotor activation was defined when the circular activation around the functional block line once completed its whole reentrant activation. To define the role of rotor for the maintenance of AF, the number of pivoting activation involved in the rotor activation was compared with that not involved in the rotor activation. Further, the activation time involved in the rotor activation was compared with that not involved in the rotor activation. Results: Rotor was identified in 14 (56%) patients (3 paroxysmal and 11 persistent AF patients). Rotor was observed at the septum (8 patients), roof (4 patients), anterior (3 patients) and posterior (1 patient), respectively. The number of rotor activation was 1.5±1.8 times/sec. Total number of pivoting activation was 9.2±6.5 times/sec. The number of pivoting activation involved in the rotor activation was significantly fewer than that not involved in the rotor activation (2.7±3.0 vs. 6.5±5.4 times/sec, p=0.0034). The activation time in which the rotor was observed in the LA occupied 18.5±21.1 % of the total recording intervals. Thus, the percentage of activation time involved in the rotor activation was significantly lower than that not involved in the rotor activation (18.5±21.1% vs. 81.5±21.1%, p<0.0001). Conclusions: Rotor activation was observed outside the PV in only half of AF patients. Further, most of pivoting activations were not involved in the rotor activation and the activation time involved in the rotor activation occupied a limited interval during AF. These suggest that AF after PV isolation was not maintained by the rotor, but was driven by the non-stationary random wave propagation associated with frequent pivoting activations.

Combined Right Ventricular Outflow Tract Epicardial and Endocardial Late Potential Ablation for Treatment of Brugada Storm: A Case Report and Review of the Literature.

A 34-year-old man with Brugada syndrome (BrS) presented with electrical storm, manifested as multiple appropriate shocks from his implantable cardioverter-defibrillator over a period of 7 hours. He had not tolerated prior treatment with quinidine, and had self-discontinued cilostazol citing persistent palpitations. After stabilization with intravenous isoproterenol, an electrophysiology study was performed but no spontaneous or induced ventricular ectopic beats were identified. A three-dimensional (3D) endocardial electro-anatomic map of the right ventricular outflow tract (RVOT), pulmonic valve, and pulmonary artery, as well as a 3D epicardial map of the RVOT, were created. Low voltage, complex, fractionated electrograms and late potentials were targeted for irrigated radiofrequency ablation both endocardially and epicardially. Post-procedure, he was maintained on cilostazol (referring clinician preference), and has had no further ventricular tachyarrhythmia episodes over the past forty-one months. We propose that this novel ablation strategy may be useful for acute management of selected patients with BrS.

Association between High Endocardial Unipolar Voltage and Improved Left Ventricular Function in Patients with Ischemic Cardiomyopathy.

We know that endocardial mapping reports left ventricular electrical activity (voltage) and that these data can predict outcomes in patients undergoing traditional revascularization. Because the mapping data from experimental models have also been linked with myocardial viability, we hypothesized an association between increased unipolar voltage in patients undergoing intramyocardial injections and their subsequent improvement in left ventricular performance. For this exploratory analysis, we evaluated 86 patients with left ventricular dysfunction, heart-failure symptoms, possible angina, and no revascularization options, who were undergoing endocardial mapping. Fifty-seven patients received bone marrow mononuclear cell (BMC) injections and 29 patients received cell-free injections of a placebo. The average mapping site voltage was 9.7 ± 2 mV, and sites with voltage of ≥6.9 mV were engaged by needle and injected (with BMC or placebo). For all patients, at 6 months, left ventricular ejection fraction (LVEF) improved, and after covariate adjustment this improvement was best predicted by injection-site voltage. For every 2-mV increase in baseline voltage, we detected a 1.3 increase in absolute LVEF units for all patients (P=0.038). Multiple linear regression analyses confirmed that voltage and the CD34(+) count present in bone marrow (but not treatment assignment) were associated with improved LVEF (P=0.03 and P=0.014, respectively). In an exploratory analysis, higher endocardial voltage and bone marrow CD34(+) levels were associated with improved left ventricular function among ischemic cardiomyopathy patients. Intramyocardial needle injections, possibly through stimulation of angiogenesis, might serve as a future therapy in patients with reduced left ventricular function and warrants investigation.

Directional Influences of Ventricular Activation on Myocardial Scar Characterization: Voltage Mapping With Multiple Wavefronts During Ventricular Tachycardia Ablation.

The effects of varying the wavefront of activation on ventricular scar characterization has not been systematically assessed. Patients referred for ablation of scar-related ventricular tachycardia underwent voltage maps during a minimum of 2 wavefronts of activation. The bipolar and unipolar low-voltage areas were compared, and direct electrogram analysis was performed in regions where discrepancies were seen. Concordance between wavefronts was measured by calculating percentage of overlap between maps. Sixty endocardial voltage maps (360±147 points) were performed in 29 patients during 2 distinct wavefronts, with 3 wavefronts in 7 patients. With median bipolar and unipolar low-voltage areas of 37 and 116 cm(2), respectively, 22% and 14% variability in median scar area was observed with a different activation wavefront. Concordance between wavefronts was lower in patients with mixed scar compared to those with dense scar (52% [interquartile range, 29%-70%] versus 84% [interquartile range, 71%-87%]), with septal scars exhibiting the lowest concordance [(27% (interquartile range, 21%-56%)]. Among 16 critical sites for ventricular tachycardia, 3 (18%) were in a discordant region of scar, with one of the wavefronts showing voltage >1.5 mV. Significant differences in bipolar and unipolar low-voltage characterization of scar were observed with different ventricular activation wavefronts, particularly in septal locations and in patients without dense scar. In patients with a paucity of dense, low-voltage regions identified during substrate mapping, an alternate activation wavefront may increase the sensitivity to detect arrhythmogenic substrate and critical sites for ventricular tachycardia.

Noninvasive epicardial and endocardial electrocardiographic imaging of scar-related ventricular tachycardia

BackgroundThe majority of life-threatening ventricular tachycardias (VTs) are sustained by heterogeneous scar substrates with narrow strands of surviving tissue. An effective treatment for scar-related VT is to modify the underlying scar substrate by catheter ablation. If activation sequence and entrainment mapping can be performed during sustained VT, the exit and isthmus of the circuit can often be identified. However, with invasive catheter mapping, only monomorphic VT that is hemodynamically stable can be mapped in this manner. For the majority of patients with poorly tolerated VTs or multiple VTs, a close inspection of the re-entry circuit is not possible. A noninvasive approach to fast mapping of unstable VTs can potentially allow an improved identification of critical ablation sites. MethodsFor patients who underwent catheter ablation of scar-related VT, CT scan was obtained prior to the ablation procedure and 120-lead body-surface electrocardiograms (ECGs) were acquired during induced VTs. These data were used for noninvasive ECG imaging to computationally reconstruct electrical potentials on the epicardium and on the endocardium of both ventricles. Activation time and phase maps of the VT circuit were extracted from the reconstructed electrograms. They were analyzed with respect to scar substrate obtained from catheter mapping, as well as VT exits confirmed through ablation sites that successfully terminated the VT. ResultsThe reconstructed re-entry circuits correctly revealed both epicardial and endocardial origins of activation, consistent with locations of exit sites confirmed from the ablation procedure. The temporal dynamics of the re-entry circuits, particularly the slowing of conduction as indicated by the crowding and zig-zag conducting of the activation isochrones, collocated well with scar substrate obtained by catheter voltage maps. Furthermore, the results indicated that some re-entry circuits involve both the epicardial and endocardial layers, and can only be properly interpreted by mapping both layers simultaneously. ConclusionsThis study investigated the potential of ECG-imaging for beat-to-beat mapping of unstable reentrant circuits. It shows that simultaneous epicardial and endocardial mapping may improve the delineation of the 3D spatial construct of a re-entry circuit and its exit. It also shows that the use of phase mapping can reveal regions of slow conduction that collocate well with suspected heterogeneous regions within and around the scar.

Outcomes of Combined Endocardial-Epicardial Ablation Compared With Endocardial Ablation Alone in Patients Who Undergo Epicardial Access

Percutaneous epicardial access (EpiAcc) is used in an attempt to improve outcomes of ablation. We aim to report our experience in EpiAcc for management of symptomatic ventricular premature complexes (VPC) and ventricular tachycardia (VT). All patients from January 2004 to July 2014 who underwent EpiAcc as part of a VPC or VT ablation procedure were included. Outcomes between those with endocardial-only (Gp1) and endocardial/epicardial (Gp2) ablation and those for VPC and VT ablation were compared. EpiAcc for VPC or VT ablation was attempted in 173 patients; 10 patients were excluded because of failure of access (n= 7) or no ablation performed (n= 3). Of the remaining 163, 131 patients (80.4%) had undergone previous endocardial ablation. Mean age was 53.7 ± 15.7years; 115 (71%) were men. VT ablation was the indication in 105 patients (64%). The underlying substrate was predominately nonischemic cardiomyopathy (49.1%). Epicardial ablation was performed in 115 (70.6%). Procedural and clinical success was obtained in 92.0% and 69.9% of patients, respectively, with no difference between Gp1 and Gp2. Those who underwent VPC ablation had superior clinical outcomes at 1-year follow-up. EpiAcc is feasible in almost all patients with no previous cardiac surgery and permits acute procedural success in >90% of patients, most of whom had failed previous ablation. However, epicardial ablation was not delivered in 1/3 of patients. Epicardial mapping may be helpful as in the absence of an appropriate epicardial site for ablation, and focus can be shifted to more detailed endocardial mapping and ablation.

96-69: Rapid estimation of 3D ventricular activation from electroanatomic mapping

Purpose Heart failure patients are often affected by a ventricular conduction disorder. Accurate characterization of the tridimensional (3D) activation sequence of the ventricles is fundamental for an effective personalized therapy. Electroanatomical mapping provides the activation times at the endocardium, with limited coverage due to anatomical constraints. Our aim is to develop a robust tool to generate a complete 3D, biventricular activation map from a limited number of endocardial measurements. Method In 6 candidates to cardiac resynchronization therapy a high density endocardial activation map of the right and left ventricle was obtained. High resolution propagating activation was simulated in patient-tailored anatomical heart models using the anisotropic eikonal equation and realistic fiber orientation. Subsequently, the mean square error between the measured and simulated activation times was minimized by varying early activation site(s) and local anisotropic conduction velocities. Results. A close correlation was achieved between the simulated and measured activation time for a single patient (Panel A) while detailed 3D activation maps were achieved (panel B and C). In all cases, the optimal parameters were identified within few minutes and the full activation sequence was computed in less than 2 seconds. A 0.9 to 0.95 Pearson correlation between measured and simulated activation times was obtained in all cases. The mathematical formulation is flexible in terms of the number of activation sites and a possible delay between them, in order to mimic the presence of a partially working Purkinje network. Conclusion Our methodology is able to generate in a clinically affordable computational time (few minutes) reliable, patient-specific, fully volumetric activation map of both ventricles using a local workstation or a laptop.

16-23: Endocardial voltage mapping of pulmonary veins with a new ultra high-resolution electroanatomical mapping system to evaluate atrial myocardial extensions

16-23: Endocardial voltage mapping of pulmonary veins with a new ultra high-resolution electroanatomical mapping system to evaluate atrial myocardial extensions

16-34: Specific CT features indicative of fibrofatty replacement are associated with local conduction delay in ARVC confirmed by endocardial and epicardial electroanatomical mapping

Introduction: ARVC is a hereditary disease characterized by fibrofatty replacement. Fibrofatty infiltration interspersed with bundles of viable myocardium may provide the substrate for localized conduction delay and ventricular tachycardia (VT). Cardiac CT allows delineation of fat and myocardium with high spatial resolution. We aimed to evaluate whether specific CT features may be indicative to fibrofatty replacement patterns that are associated with slow conduction using integrated electroanatomical mapping (EAM) as gold standard. Method: ARVC patients who underwent combined endocardial and epicardial EAM for VT ablation with real-time integration of CT-derived fat mesh were enrolled. Intracardiac electrocardiograms (ICEG) were categorized as abnormal (consistent with conduction delay based on ICEG characteristics) or normal (all remaining points independent from voltages). Abnormal ICEG were subdivided in fragmented (amplitude/duration [mV/ms] ratio ≤0.05 and duration > 50ms) and late potential (inscribing after QRS, separated by isoelectric segment > 20 ms). Reversed registration was performed to superimpose EAM points on the contour of the post processed short-axis CT slice. On short axis slices, fat infiltration was quantified, defined as the percentage of image pixels with Hounsfield units from -100 to -50 HU, within the subepicardial 4 mm layer of the RV free wall. For each mapping site the corresponding percentage of fat infiltration was calculated and compared to the ICEG characteristics. Patients without structural heart disease matched for age and body mass index served as controls for CT derived fat within the subepicardial layer. Receiver operating characteristics curve analysis was performed to determine the optimal cut-off value for the percentage of intramural fat, to differentiate between in ARVC patients and controls. Results: Eight ARVC patients with combined endocardial and epicardial EAM and CT image integration (all male, age 47 ± 18 years, BMI 24 ± 3 kg/m2, ARVC associated mutation in 6 [75%]) and 8 healthy controls (all male, age 48 ± 17 years, BMI 24 ± 4 kg/m2) were enrolled. Of the 4209 exported mapping points; 3416 (81%) were normal and 785 (19%) were abnormal (232 fragmented EGM and 553 late potentials). The median fat percentage was significantly higher at sites with local conduction delay compared to normal sites (5% [IQR, 0-18%] vs. 0% [IQR, 0-7%], P= 0.001, panel A). The mean fat infiltration was higher in ARVC patients compared to healthy matched controls (5.7 ± 3.9% vs. 1.3 ± 0.6%, p= 0.008, panel B). The optimal cut off of fat percentage to differentiate between ARVC patients and healthy matched controls was 2% fat (sensitivity 88% and specificity 100%). Conclusion: A subepicardial fat percentage of 2% may discriminate between ARVC patients and normal controls. In ARVC patients, areas with conduction delay based on electrogram characteristics show a higher amount of fat infiltration, compared to areas without delay. A critical amount of fat infiltration may be required to cause conduction delay, which may be detectable by pre-procedural CT. Whether cardiac CT can be used for the early diagnosis of ARVC and for imaging guided substrate ablation requires further investigation in a larger group of patients.

Noninvasive Localization of Accessory Pathways in Wolff-Parkinson-White Syndrome by Three-Dimensional Speckle Tracking Echocardiography.

We have developed a noninvasive isochrone activation imaging (AI) system with 3-dimensional (3D) speckle tracking echocardiography (STE), which allows visualization of the wavefront image of mechanical propagation of the accessory pathway (ACP) in Wolff-Parkinson-White syndrome. Patients with manifest Wolff-Parkinson-White syndrome were imaged in 3D-STE AI mode, which quantified the time from QRS onset to regional endocardial deformation. In 2 patients with left- and right-side ACP, we confirmed that intraoperative contact endocardial electric mapping and the 3D-STE AI system showed comparable images pre- and postablation. In normal heart assessment by 3D-echo AI, the earliest activation sites were found at the attachment of the papillary muscles in the left ventricle and midseptum in the right ventricle, and none showed earliest activation at the peri-atrioventricular valve annuli. An analyzer who was unaware of the clinical information assessed 39 ACP locations in 38 Wolff-Parkinson-White syndrome patients using 3D-STE. All showed abnormal perimitral or tricuspid annular activations, and the location of 34 ACP (87%) showed agreement with the successful ablation sites within a 2-o'clock range. Especially for left free wall ACP, 17/18 (94%) showed consistency with the ablation site within a 2 o'clock range. Among 15 ACP at the ventricular septum, 9 (60%) showed early local activation in both right and left sides of the septum. Isochrone AI with 3D-STE may be a promising noninvasive imaging tool to assess cardiac synchronized activation in normal hearts and detect abnormal breakthrough of mechanical activation from both atrioventricular annuli in Wolff-Parkinson-White syndrome.

49-05: Defining arrhythmogenic ventricular scar using time- and voltage-domain mapping (V-T-mapping): a new approach to ventricular tachycardia channel localization during sinus rhythm

Aims: In ventricular scar, the impulse spread is slow as it traverses multiple split and zigzag channels of surviving muscle. We aimed to evaluate electrograms in the scar to determine their local delay in relation to the onset of ventricular activation (activation time) and inequality in voltage splitting (entropy), and their relationship to channels. We reasoned that unlike innocuous bystander channels, which are often short with multiple side branches, ventricular tachycardia (VT) supporting channels have very slow impulse spread and possess low entropy due to their longer protected length and relative lack of side branching. Methods: Patients with ischemic cardiomyopathy and multiple inducible VT were studied. In the initial mapping stage (16 patients, 58 VTs), left ventricular endocardial mapping was performed in sinus rhythm. Detailed pace mapping was used to identify VT channels, and confirmed, when feasible, by entrainment. The scar electrograms were analyzed in time- and voltage-domains to determine mean activation time, dispersion in activation time and entropy. The predictive performances of these properties to detect VT channels were tested. In the application stage (7 patients, 20 VTs), these properties were prospectively tested to guide catheter ablation. Results: A mean of 763 ± 203 sampling points per-patient were taken, 451 ± 145 points in dense scar. From 1770 pace maps, 174 channels were identified, and 47 corresponded to inducible VTs. A combination of scar electrograms with the latest mean activation time and minimum entropy, in a high activation dispersion region, accurately recognized regions containing VT channels (kappa = 0.89, sensitivity = 86%, specificity = 100%, positive predictive value = 93%, and negative predictive value = 100%). Finally, focused ablation within the prospective channel regions eliminated 18/20 inducible VTs. Conclusion: Activation time and entropy mapping in the scar accurately identifies VT channels during sinus rhythm. This can expedite recognition of VT channels without pace mapping or mapping during VT and minimize extensive ablation.

98-06: Ablation of Outflow Tract Ventricular Arrhythmias in Patients with Prior Failed Ablation

Introduction: Ablation (RFA) of ventricular arrhythmias (VAs) arising from the outflow tracts (OT) is estimated to have a success rate of 80–90% in published clinical studies. However, in patients with prior failed ablation, they may be referred for redo RFA at tertiary centers or consideration for epicardial RFA. Understanding the reasons for failure of initial RFA may help improve mapping techniques at initial RFA, success rates of initial RFA, and pre-operative counseling prior to redo RFA regarding procedural expectations (ie, need for epicardial puncture, likelihood of success). Methods: Patients referred for redo RFA to a tertiary care center between 2013–2015 for redo RFA of presumed outflow tract PVCs were included. Included patients had detailed summaries of initial RFA procedure, inferiorly directed PVCs with tall, monophasic R waves in leads II, III, and aVF, and otherwise structurally normal hearts. 4 Results: 55 patients were included (67% male; age 62 + 15 years). All patients had prior failed RFA at referring centers. In detailed reports, 10% had 6/55 (11%) had only reported right ventricular OT (RVOT) mapping, 45/55 (82%) had reported comprehensive mapping of left (LV) and right OTs and coronary sinus (CS), and the remainder had LV and RVOT mapping but no reported CS mapping. 50/55 (91%) of patients had acute success after redo RFA, with 47/55 (85%) with long-time success at 3 month follow-up. No patients had epicardial puncture performed. Of 5 acute failures, 3 were due to proximity to coronary arteries with no RFA delivered, and 2 were due to proximity to the His bundle and concern for risk of heart block. In 3 recurrences, 2 had recurrence of PVCs of a different morphology but also arising from the OT (wider QRS, larger maximum deflection index [MDI], and earlier transition than initial VA), and 1 had recurrence of the same VA. Average procedural time was 45 + 29 minutes. The most common site of successful RFA was at the endocardial aspect of the LV summit (15/50, 30%), LV aspect just beneath the left/right (L/R) junction of the aortic cusps or right cusp (15/50, 30%), endocardial aorto-mitral continuity (10/50, 20%), coronary sinus (5/50, 10%), and supravalvar pulmonary artery (5/50, 10%). No acute complications occurred. All patients with prior RVOT only mapping had a V3 or earlier transition and foci in the LVOT. Conclusion: Redo RFA for OT VAs is common and success rates are high. After initial failed RFA, patients rarely require epicardial puncture and traditional endocardial mapping at less common sites (endocardial LV summit, L/R cusp junction, supravalvar pulmonary artery) may be useful.

Simultaneous endocardial and epicardial high-resolution mapping of the human right atrial wall

Simultaneous endocardial and epicardial high-resolution mapping of the human right atrial wall

Conjunction of Endocardial and Coronary Venous System Mapping to Ablate Ventricular Arrhythmias.

Ablation of idiopathic ventricular arrhythmias (VAs) with epicardial or intramural origins is technically challenging. Herein, we have described the successful ablation of left VAs via the coronary venous system (CVS) in conjunction with endocardial map guided by three-dimensional electroanatomical map in six patients. Out of a total consecutive 84 patients with symptomatic idiopathic VAs, radiofrequency ablation via the CVS was performed on six patients (7%). Furthermore, we reviewed patient records and electrophysiologic studies with respect to clinical characteristics. Activation map was conducted in 5 patients, and the earliest activation sites were identified within the CVS. The preceding times to the onset of QRS complex were longer than those at the earliest endocardial sites (36.2 ± 5.6 ms vs. 14.2 ± 6.4 ms, p = 0.02, n = 5). Spiky fractionated long-duration potentials were recorded at the successful ablation sites in all 5 patients. The other patient received pacemapping only because of few spontaneous VAs during the procedure, and the best pacemap spot was found within the CVS. Irrigated catheters were required in 4 out of 6 patients because VAs were temporarily suppressed with regular ones. Idiopathic VAs can be ablated via the CVS in conjunction with endocardial mapping. Additionally, spiky fractionated long-duration potential can function as a clue to identify the good ablation site.

Image Integration to Guide Catheter Ablation in Scar‐Related Ventricular Tachycardia

Although multi-detector computed tomography (MDCT) and cardiac magnetic resonance (CMR) can assess the structural substrate of ventricular tachycardia (VT) in ischemic cardiomyopathy (ICM), non-ICM (NICM), and arrhythmogenic right ventricular cardiomyopathy (ARVC), the usefulness of systematic image integration during VT ablation remains undetermined. A total of 116 consecutive patients (67 ICM; 30 NICM; 19 ARVC) underwent VT ablation with image integration (MDCT 91%; CMR 30%; both 22%). Substrate was defined as wall thinning on MDCT and late gadolinium-enhancement on CMR in ICM/NICM, and as myocardial hypo-attenuation on MDCT in ARVC. This substrate was compared to mapping and ablation results with the endpoint of complete elimination of local abnormal ventricular activity (LAVA), and the impact of image integration on procedural management was analyzed. Imaging-derived substrate identified 89% of critical VT isthmuses and 85% of LAVA, and was more efficient in identifying LAVA in ICM and ARVC than in NICM (90% and 90% vs. 72%, P < 0.0001), and when defined from CMR than MDCT (ICM: 92% vs. 88%, P = 0.026, NICM: 88% vs. 72%, P < 0.001). Image integration motivated additional mapping and epicardial access in 57% and 33% of patients. Coronary and phrenic nerve integration modified epicardial ablation strategy in 43% of patients. The impact of image integration on procedural management was higher in ARVC/NICM than in ICM (P < 0.01), and higher in case of epicardial approach (P < 0.0001). Image integration is feasible in large series of patients, provides information on VT substrate, and impacts procedural management, particularly in ARVC/NICM, and in case of epicardial approach.