Successful Ablation Site Research Articles

Can the QRS morphology of outflow tract ventricular arrhythmia change when right bundle branch block emerges during sinus rhythm?

QRS morphology can change during ventricular arrhythmias (VAs) with the appearance of bundle branch block (BBB). We retrospectively investigated 195 consecutive patients who underwent an initial ablation of VA. The study inclusion criteria were VAs that were successfully ablated in the outflow tract (OT) and in whom right bundle branch block (RBBB) was induced by catheter manipulation close to the His bundle area during sinus rhythm, before any radiofrequency application. We analyzed the QRS morphology of the VAs with and without RBBB during sinus beats. Twenty-four patients (age 59±17 years, female 14) developed RBBB at some point during their procedure. The successful ablation sites of the VAs were the right ventricular outflow tract (RVOT) in 12 patients, pulmonary artery in one, left coronary cusp in five, right coronary cusp in three, right-left cusp junction in two, and great cardiac vein in two. QRS-morphology change was observed in five (20%) cases. The successful ablation sites in that group were the left coronary cusp in three cases, right coronary cusp in one, and RVOT septum in one. The QRS duration of the VAs increased during RBBB. There are some cases of OT-VAs in which the QRS waveform changes with the appearance of catheter induced RBBB. We need to be aware that when QRS morphology changes during an OT-VA ablation, it does not necessarily mean that the origin or exit of the VA has changed.

Accuracy of Different Surface Electrocardiogram Algorithms for Localization of Accessory Pathway in Comparison to Invasive Electrophysiological Localization: An Observational Study

Introduction: Detection of accessory pathway (AP) on surface ECG in sinus rhythm helps in the diagnosis of Wolff-Parkinson-White Syndrome (WPW Syndrome), Catheter ablation of AP was indicated in symptomatic patients with preexcitation. Pre-ablation AP localization inferred from the 12-lead surface electrocardiogram (ECG) facilitates a tailored ablation strategy; there by specific risk can be properly assessed. As they are based on pre-excitation in the basal state, available algorithms can lead to complex and ambiguous analysis, mostly due to the variable influence of the AP over QRS morphology. Though various algorithms on surface ECG are available to predict the site of AP on surface ECG, but none of them are accurate. So, we have compared the accuracy of different algorithms in predicting the AP localization in comparison to electrophysiological study (EPS) diagnosis. Methodology: This retrospective observational study cohort consisted of 100 consecutive patients above 15 years of age presented to the tertiary care center with the history of palpitations or for assessment of a manifest AP. Accessory pathways were identified according to the site where successful radiofrequency energy was applied. Arruda algorithm, Milstein algorithm, Fitzpatrick algorithm and Pambrun algorithm were applied on a sinus rhythm manifest preexcited ECG to predict the AP localization by two independent investigators who are unaware of site of successful catheter ablation. Then those were compared with the EPS localization to test the accuracy of individual algorithm. Then Cohen’s Kappa was run to determine if there was agreement between any of the four different algorithms with EPS using SPSS version 20.0. Results: In the study population of 100 patients, male to female ratio of study population was 1.6:1, with a mean age of presentation 43.86 ± 11.4 years with the most common age group of 31 to 45 year. when the AP locations were categorized based on EP Study 56 percent of the AP were found on the left side while 43 percent of the AP were found on right side, 77 percent of the AP were septal pathways. Among the leftsided pathways, left anteroseptal constitutes majority followed by left posteroseptal pathway. On right side majority were in right posteroseptal location in our study. Based on 4 surface ECG algorithms AP was localized and each algorithm was compared with invasive EPS localization for accuracy using Cohen’s Kappa agreement analysis. As per agreement analysis the kappa value for Milstein, Pambrun algorithm, Fitzpatrik and Arruda were 0.188, 0.343, 0.441, and 0.645 respectively. It was found that Arruda algorithm had moderate strength of agreement with the findings of EPS (κ = 0.645). This is the proportion of agreement over and above chance agreement and which was statistically significant and the strongest among all the four algorithms. Conclusion: Our study has compared the accuracy of 4 surface ECG algorithms in predicting the accessory pathway localization with the EPS; it has demonstrated that the Arruda algorithm is more precise and accurate among the available algorithms followed by Fitzpatrik, Pambrun algorithm and Milstein algorithm, Knowing the pathway prior to ablation allows for optimal procedure preparation, mapping pathways that are difficult to find and finally may lessen the catheter-related injury and shortens the procedural time.

Electrophysiological characteristics and catheter ablation of ventricular arrhythmias arising from the superior septal left ventricle

Background and aimsElectrophysiological characteristics and radiofrequency catheter ablation (RFCA) of premature ventricular contractions (PVCs) originating from the superior septal left ventricle (SSLV) have not yet been fully characterized.Methods and resultsThis study included 247 patients who underwent RFCA for PVCs arising from the ventricular outflow tract between February 2020 and August 2022. The successful ablation site was on the SSLV in 37 of the 247 patients. In 12 (32.4%) of those 37 patients, a low amplitude and high frequency spiky potential (SP) was recognized. Five patients showed a narrow QRS duration (86.8 ± 4.6 ms), with a discrete SP observed in PVCs and sinus rhythm, which showed an isoelectric line with the ventricular electrogram at the earliest activation site. Seven patients showed a wide QRS duration (131.6 ± 4.5 ms), with SP observed in PVCs without an isoelectric line with the ventricular electrogram. RFCA was successful at the site of the earliest SP in all 12 patients. The time from SP onset at the successful ablation site to the QRS onset (local activation time) was 30 ± 12 ms, which differed significantly from that for the remaining 25 patients withoutSP(22.1 ± 7.1 ms, P < 0.05).ConclusionsSPs were recorded in 12 (32.4%) of the 37 patients with PVCs originating from the SSLV. The morphology of the PVCs may show a narrow or wide QRS duration and the target site for successful ablation should be identified by the earliest SP.

A novel endocardial activation–derived predictor for focal paraseptal atrial tachycardias: Evidence from a multicenter cohort study

BackgroundThe electrocardiogram-based algorithm for predicting paraseptal atrial tachycardia (PSAT) is limited by the significant overlaps in P-wave morphology originating from various paraseptal sites. ObjectivesThe goals of this study were to investigate the endocardial activation characteristics of PSAT and to seek an endocardial activation–derived predictor for the ablation site. MethodsForty-four patients [11 men (25%); mean age 62.6 ± 14.7 years] with PSAT ablation in 4 tertiary medical centers were assigned to 3 groups according to the ablation site: right atrial (RA) para-Hisian region (group 1, n = 10), noncoronary cusp (NCC) (group 2, n = 13), and left atrial (LA) paraseptal area (group 3, n = 21). Multiple-chamber activation mapping was performed guided by a 3-dimensional navigation system. The discrepancies in the earliest activation time between 2 of 3 chambers (ΔRA-LA, ΔRA-NCC, and ΔLA-NCC) were calculated in each group and used for pairwise comparisons. ResultsThere was a significant difference in ΔRA-LA, ΔRA-NCC, and ΔLA-NCC among the 3 groups. ΔRA-LA was the only parameter that could consistently predict the ablation site of PSAT with good accuracy (area under the curve 1.000, sensitivity 100% and specificity 100%, and cutoff value 7 ms for predicting right para-Hisian or NCC ablation; area under the curve 0.974, sensitivity 92.3% and specificity 95.2%, and cutoff value −4 ms for predicting NCC or left paraseptal ablation). Based on 2 cutoff values, a 2-step algorithm was developed to predict the ablation site of PSAT with a positive predictive value of 95.4% and a negative predictive value of 97.0%. ConclusionΔRA-LA is a useful endocardial activation–derived parameter for predicting the successful ablation site of PSAT.

Peak frequency annotation algorithm–guided slow pathway ablation in typical atrioventricular nodal reentrant tachycardia

BackgroundThe slow pathway potential is difficult to annotate because it is buried within the atrial potential. Omnipolar technology near field can automatically annotate the peak frequency potential associated with acquired intracardiac electrograms. ObjectivesThis study aimed to visualize the junction between the transitional cells and the slow pathway using a peak frequency map with omnipolar technology near field and evaluate whether the high-frequency site around the tricuspid annulus (TA) is an effective target for slow pathway ablation. MethodsThis prospective observational study enrolled 37 patients with typical atrioventricular nodal reentrant tachycardia. Patients underwent slow pathway ablation using a peak frequency map (n = 17) and the conventional approach based on anatomical and electrophysiological findings (n = 20). ResultsHigh-frequency sites were distributed at the TA side of the 4–5 o’clock position in all patients mapped using the peak frequency map of OTNF. The distance to the His bundle from the successful ablation site was farther (24.0 ± 4.8 mm vs 12.7 ± 4.0 mm; P < .0001), junctional rhythm was slower (88 ± 17 beats/min vs 115 ± 12 beats/min; P < .0001), the time to junctional rhythm after radiofrequency application was shorter (3.4 ± 1.4 seconds vs 8.2 ± 4.6 seconds; P < .0001), and the elimination rate of jump ups (71% vs 30%; P = .02) was higher in the peak frequency map–guided group. ConclusionThe high-frequency site of the TA at 4–5 o’clock in the peak frequency map could be a novel target of slow pathway ablation with high safety, efficiency, and efficacy.

Prevalence and electrocardiographic and electrophysiological characteristics of idiopathic ventricular arrhythmias originating from the septal left ventricular summit.

The left ventricular summit (LVS) is the highest point on the epicardial surface of the left ventricle. A part of the LVS that is located between the left coronary arteries (lateral-LVS) is one of the major sites of idiopathic ventricular arrhythmia (VA) origins. Some idiopathic epicardial VAs can be ablated at endocardial sites adjacent to the epicardial area septal to the lateral-LVS (septal-LVS). This study examined the prevalence and electrocardiographic and electrophysiological characteristics of septal-LVS VAs. We studied consecutive patients with idiopathic VAs originating from the LVS (67 patients) and aortic root (93 patients). Based on the ablation results, among 67 LVS VAs, 54 were classified as lateral and 13 as septal-LVS VAs. As compared with the lateral-LVS VAs, the septal-LVS VAs were characterized by a greater prevalence of left bundle branch block with left inferior-axis QRS pattern, later precordial transition, lower R-wave amplitude ratio in leads III to II, lower Q-wave amplitude ratio in leads aVL to aVR, and later local ventricular activation time relative to the QRS onset during VAs (V-QRS) in the great cardiac vein. The electrocardiographic and electrophysiological characteristics of the septal-LVS VAs were similar to those of the aortic root VAs. However, the V-QRS at the successful ablation site was significantly later during the septal-LVS VAs than aortic root VAs (p < .0001). The precordial transition was significantly later during the septal-LVS VAs than aortic root VAs (p < .05). Septal-LVS VAs are considered a distinct subgroup of idiopathic VAs originating from the left ventricular outflow tract.

The optimal slow pathway ablation site in atrioventricular nodal reentrant tachycardia cases with an inferiorly located His bundle.

The optimal slow pathway (SP) ablation site in cases with an inferiorly located His bundle (HIS) remains unclear. In 45 patients with atrioventricular nodal reentrant tachycardia, the relationship between the HIS location and successful SP ablation site was assessed in electroanatomical maps. We assessed the location of the SP ablation site relative to the bottom of the coronary sinus ostium in the superior-to-inferior (SPSI), anterior-to-posterior (SPAP), and right-to-left (SPRL) directions. The HIS location was assessed in the same manner. The HIS location in the superior-to-inferior direction (HISSI), SPSI, SPAP, and SPRL were 17.7±6.4, 1.7±6.4, 13.6±12.3, and -1.0±13.0mm, respectively. The HISSI was positively correlated with SPSI (R2=0.62; P<.01) and SPAP (R2=0.22; P<.01), whereas it was not correlated with SPRL (R2=0.01; P=.65). The distance between the HIS and SP ablation site was 17.7±6.4mm and was not affected by the location of HIS. The ratio of the amplitudes of atrial and ventricular potential recorded at the SP ablation site did not differ between the high HIS group (HISSI≥13mm) and low HIS group (HISSI<13mm) (0.10±0.06vs. 0.10±0.06; P=.38). In cases with an inferiorly located HIS, SP ablation should be performed at a lower and more posterior site than in typical cases.

Relationship between the atrial-activation pattern around the triangle of Koch and successful ablation sites in slow-fast atrioventricular nodal reentrant tachycardia.

The precise details of atrial activation around the triangle of Koch (ToK) remain unknown. We evaluated the relationship between the atrial-activation pattern around the ToK and success sites for slow-pathway (SP) modification ablation in slow-fast atrioventricular reentrant tachycardia (AVNRT). Thirty patients with slow-fast AVNRT who underwent successful ablation were enrolled. Atrial activation around the ToK during sinus rhythm was investigated using ultra-high-density mapping pre-ablation. The relationships among features of atrial-activation pattern and success sites were examined. Of 30 patients (22 cryoablation; 8 radiofrequency ablation), 26 patients had a collision site of two wavefronts of delayed atrial activation within ToK, indicating a success site. The activation-search function of Lumipoint software, which highlights only atrial activation with a spatiotemporal consistency, showed non-highlighted area on the tricuspid-annulus side of ToK. In 23 of the patients, a spiky potential was recorded at that collision site outside the Lumipoint-highlighted area. Fifteen cryoablation patients with a success site coincident with a collision site outside the Lumipoint-highlighted area had significantly more frequent disappearances of SP after initial cryoablation (46.7% vs. 0%, p = .029), fewer cryoablations (3.7 ± 1.8 vs. 5.3 ± 1.3, p = .045), and shorter procedure times (170 ± 57 vs. 228 ± 91 min, p = .082) compared to the seven cryoablation patients without such sites. Four patients had transient AV block by ablation inside the Lumipoint-highlighted area with fractionated signals, but no patient developed permanent AV block or recurrence post-procedure (median follow-up: 375 days). SP modification ablation at the collision site of atrial activation of the tricuspid-annulus side along with a spiky potential could provide a better outcome.

Anatomically Based Ablation of Left Ventricular Summit Premature Ventricular Complexes Guided by Intracardiac Echocardiography.

Catheter ablation of premature ventricular contractions (PVCs) arising from the left ventricular summit (LVS) presents technical challenges due to the regional anatomy and frequent intramural site of origin (SOO). Intracardiac echocardiography (ICE) and the CARTOSOUND® (Biosense Webster, Diamond Bar, CA, USA) module allow the operator to directly reconstruct and visualize the dimensions and orientation of the LVS live and present it in relation to neighboring structures. We retrospectively reviewed consecutive cases between January 2021 and December 2022 of patients undergoing PVC ablation for a presumed LVS origin. The LVS was reconstructed by creating a three-dimensional representation of the left ventricular septum, using two-dimensional ICE sections. The earliest site in each chamber was tagged on the reconstructed LVS, and the presumed SOO was localized using a geometrical center point from all sites. Ablation was first delivered to the earliest site, except when the presence of coronary branches precluded radiofrequency delivery within the great cardiac vein. Of 20 patients (8 women, 62.4 ± 7.1 years old) with a presumed LVS origin, 12 had PVC recurrence within the monitoring period after the initial ablation for 192.5 ± 37.2 s at the earliest site. Among them, earliest activation was seen at the sinus of Valsalva (SoV), coronary venous system (CVS), and left ventricular endocardium (LVE) in four, six, and two patients, respectively. Using the reconstructed LVS, the anatomically closest site to the SOO was identified in the SoV, CVS, and LVE in four, two, and six cases, respectively. Throughout the study period (14.5 months; range, 9.3-19.7 months), 17 patients (85%) had complete elimination of PVCs as evaluated by 24-h event monitors at the 12-month visit. In 50% of cases, among patients in whom ablation at the earliest signal was unsuccessful, the site of successful ablation did not correlate with the second earliest signal or had no identifiable signal during initial activation mapping. The reconstructed LVS not only guided activation mapping but also identified sites proximal to the center point that had either a late activation signal, a low-amplitude signal, or no signal at all.

Paradigm shift of catheter ablation of atypical atrioventricular nodal tachycardia: 3D mapping-based ablation of exits of slow pathway

Abstract Background In current practice, the ablation target of atypical atrioventricular nodal tachycardia (AVNRT) is the earliest atrial activation site in the coronary sinus (CS) or conventional slow pathway (SP) region. Objectives The purpose of this study was to map the site of earliest retrograde atrial activation using electroanatomic 3D mapping during atypical AVNRT and to evaluate successful ablation sites. Methods Forty-two patients with a total of 49 AVNRTs (slow/fast 30; fast/slow 15; slow/slow 4) underwent EP study and ablation. Among them there were 14 patients (10 women, 60±19 y/o) in whom 19 atypical AVNRT (fast/slow 15; slow/slow 4) were induced. Results The intracardiac electrocardiograms or 3D mapping of the exit site during tachycardia revealed that 7 patients had exit sites solely inside the CS (left inferior extension=LIE), 3 solely in the right postero-septal tricuspid annulus (TA) (right inferior extension=RIE), and 4 had both LIE and RIE exits. The distance from the CS ostium to LIE exits was 14±6 mm. RIE exits were located on the TA posterior to the CS ostium (between 5 and 6 o’clock in the LAO projection). Ablation targeting these exits or traditional SP succeeded in long term elimination of AVNRT in 13 of the 14 patients (93%). There were no complications. Conclusions Catheter ablation targeting the exit sites of LIE or RIE mapped at the CS or TA holds promise as an effective and safe alternative approach to the current targets of ablation for atypical AVNRT cases.Distribution of exit sites during atypicthe circuit of atypical AVNRT：the exit s

Abstract 13269: Clinical and Electrophysiological Features of New Onset Ventricular Arrythmias Following Catheter Ablation of Atrial Fibrillation

Introduction: Data on new onset ventricular arrhythmias (VAs) following catheter ablation of atrial fibrillation (AF) is sparse. Hypothesis: We aimed to assess the incidence of new onset VA post AF RFA. Methods: We conducted a retrospective study of all patients at our institution that underwent AF ablation who also developed symptomatic high burden premature ventricular complexes (PVCs) requiring catheter ablation within 1 year of the index AF ablation procedure. All patients underwent post AF ablation monitoring with either 48 hr Holter monitors or implantable cardiac monitors. New onset VA was defined as symptomatic new onset PVC with &gt;5% burden. Data on PVC morphology and successful ablation sites was analyzed. Results: Out of 175 patients that underwent AF ablation during the study period, 2.8 % (n=5) patients developed new onset high burden PVCs requiring catheter ablation therapy within 1 year of AF ablation. Mean age was 68.6 + 11 years and all patients were male. Mean baseline LVEF was 56 + 9.6% and mean PVC burden was 10.3 + 8.8 %. A total of 9 PVCs were mapped in 5 patients. The number of VA morphology was 1 in 2 (40%) patients, 2 in 2 (40%) and 3 in 1 (20%) patient. Site of origin for the PVCs was in the left ventricle in all patients, with majority (55%) localizing to the LV outflow tract and summit region (table). Average time from AF RFA to PVC ablation was 4 + 2.9 months. PVC ablation was successful in all patients except one where ablation was deferred due to proximity to the conduction system. Conclusions: New onset VAs following catheter ablation of AF tend to localize to the LV outflow tract and areas of bipolar voltage abnormality. Potential mechanisms of new onset PVCs could include altered sympathetic tone due to ablation of cardiac ganglia, unmasking of PVCs due to regularization of ventricular rate and withdrawal of anti-arrhythmic medications. Further prospective studies are needed to understand true incidence of new onset VAs following AF ablation.

Abstract 17188: Electrocardiographic Algorithms for Localization Ventricular Ectopy From the Ventricular Outflow Tracts Demonstrate Poor Accuracy and Agreement

Background: Premature ventricular contractions (PVCs) and ventricular tachycardia (VT) commonly arise from the outflow tracts of the left and right ventricles and can be treated with catheter ablation when symptomatic or associated with cardiomyopathy. Accurate localization of these ectopic sources aids procedural planning. Several different electrocardiographic (ECG) algorithms have been published, but their relative performance has not been assessed. Objective: Compare the accuracy and agreement of three ECG algorithms for PVC localization. Methods: ECGs from patients who underwent catheter ablation for PVCs or VT originating the outflow tract region were analyzed using three published PVC localization algorithms. The predictions from these algorithms were then compared to the site of successful catheter ablation (right ventricular outflow tract [RVOT], left ventricular outflow tract [LVOT], or epicardium). The accuracy and agreement of the three algorithms were compared. Results: A total of 43 patients were evaluated and ectopy was suppressed via ablation from a single chamber in 37 (86%) of patients. VT/PVCs originated from the RVOT (N=10), LVOT (N=26), and epicardium (N=1). The three studied algorithms demonstrated accuracy rates of 46-70%. The algorithms disagreed on the predicted ectopy location for 19 (51%) patients. When all algorithms agreed (N=18), the prediction was accurate for only 11 patients (61%). Conclusion: Rules-based ECG algorithms demonstrate poor performance and use of different published algorithms frequently result in disparate results. More accurate and consistent methods incorporating individualized electroanatomic variation may improve accuracy and periprocedural management for PVC and VT ablation.

Abstract 13989: Automated VT Localization System Based on Patient-Specific Integration of Two-Dimensional (2D) Intracardiac Echocardiography (ICE) and 3DElectroanatomic (EA) Mapping

Introduction: We have previously developed an intraprocedural automated localization system to identify VT-exit sites projected onto a patient-specific CT geometry using 12-lead ECGs. However, the accuracy of the system depends on a registered reconstruction of the cardiac surface. Objective: To assess the feasibility of using a registered integration of 2D ICE and 3D EA mapping to perform intraprocedural localization, while avoiding errors being introduced by registration of the CT geometry and EA map. Methods: Four patients with 7 VTs (5 LV VTs, 2 RV VTs) were enrolled. A 3D patient-specific shell of both ventricles that combines ICE and EA map was reconstructed during the ablation procedure. It was imported into the automated localization system post-procedure for offline analysis. The system was used to estimate the location of VT-exit sites on the reconstructed 3D geometry. Localization accuracy was quantified for the VT-exit sites by comparing the distance of the calculated site to the site of successful ablation or that of best pacing site match. Results: Five reentrant VT-exit sites were identified using activation and entrainment mapping, supplemented by pace-mapping at the scar margin; two focal VTs were identified by pace mapping. The proposed system achieved mean localization accuracy of 6.4 mm for 7 VTs. Conclusions: ICE and EA mapping can be successfully integrated for intraprocedural automated localization of ventricular activation in both ventricular chambers and may avoid registration errors of CT geometry integration.

The Use of Local Activation Timing Histogram in Ablation of Focal and Re-Entrant Atrial Tachycardias

BackgroundActivation mapping is often used to differentiate focal from re-entrant arrhythmias. This can be challenging but is critical to ablation success. The local activation time (LAT) histogram, which depicts point distribution over isochronal segments, may help characterize arrhythmia mechanisms and identify an optimal ablation strategy. ObjectivesThis study aimed to investigate features of the LAT histogram associated with the focal vs re-entrant mechanism of atrial tachycardias (ATs) and the use of the LAT histogram in the identification of target ablation sites. MethodsWe retrospectively evaluated cases of focal and re-entrant ATs performed at a single academic tertiary care center for which activation mapping was performed using CARTO 3 version 7 software (Biosense Webster). Baseline patient, arrhythmia, and procedural characteristics as well as LAT histogram features were evaluated for each case. LAT histogram–guided ablation targets were also compared against actual ablation sites. ResultsAmong 52 ATs assessed, 17 were focal, and 35 were re-entrant. Tachycardia cycle length was significantly shorter in re-entrant than in focal ATs (288.2 milliseconds [Q1-Q3: 250-306.5 milliseconds] vs 370 milliseconds [Q1-Q3: 285-400 milliseconds], respectively; P = 0.006). LAT histograms contained more “valleys” in re-entrant than in focal ATs (3 [Q1-Q3: 2-4] vs 1 [Q1-Q3: 1-1]; P < 0.001). No focal ATs contained >2 and no re-entrant ATs contained <1 LAT valley(s). All successful ablation sites correlated with LAT histogram–suggested sites. ConclusionsLAT histograms can help distinguish focal from re-entrant Ats and identify effective ablation sites.

Novel method to avoid serious injurious effects on the atrioventricular nodal (AVN) conduction during catheter ablation of the AVN slow pathway utilizing cryofreezing energy

BackgroundSlow pathway elimination of the atrioventricular node (AVN) is essential to treat AVN reentrant tachycardia (AVNRT). However, injury to the AVN conduction (IAVN) is one of the serious complications. Cryofreezing energy is expected to reduce the incidence of IAVN. This study aimed to investigate the usefulness of a novel method to avoid IAVN during cryoablation of AVNRT. MethodsA total of 157 patients (average age, 65.8 years; male, 71) suffering from AVNRT were included. Once the AVNRT terminated during cryo-ablation, then rapid atrial constant pacing (RACP) was performed during freezing at a rate lower 10 bpm than that inducing Wenchebach AV block in 74 (47.1 %) patients (Group A). The RACP rate was decreasingly reduced by 10 bpm in case of the occurrence of IAVN. When the RACP reached 100 bpm, the cryoablation was prematurely terminated. Group B patients (83 = 52.9 %) underwent cryoablation during sinus rhythm. All patients were allocated in a randomized fashion. We compared the severity of the IAVN between Groups A and B. ResultsThere were no significant differences at 12 months regarding the freedom from the AVNRT between Groups A and B. However, the duration of the IAVN was significantly longer in Group B than A (p = 0.02). There were no significant differences regarding the distance between the His recording sites and successful ablation sites between Groups A and B. No permanent IAVN requiring pacemaker implantation was provoked in either group. ConclusionRACP was useful to avoid sustained and serious IAVN during cryoablation of AVNRT.

Unipolar and bipolar electrograms to predict successful ablation site of premature ventricular contractions originating from the free wall of the tricuspid annulus.

This study aimed to identify the characteristics of unipolar and bipolar electrogram (UniEGM and BiEGM) in guiding successful ablation of premature ventricular contractions (PVCs) originating from the free wall of the ventricular aspect of the tricuspid annulus (TA). We hypothesized that the negative concordance pattern (NCP) on the onset of UniEGM and BiEGM, together with the least value of the difference between the earliest BiEGM and UniEGM dV/dTmax, might improve the accuracy of conventional mapping. Thirty consecutive patients who underwent successful catheter ablation from February 2018 to July 2021 were retrospectively analyzed. The BiEGM and UniEGM for successful ablation sites were compared with those for non-successful ablation sites. Among the 30 patients, 30 successful and 26 nonsuccessful ablation sites were compared. The earliest activation time of the BiEGM (BiEGMoneset-QRS) was 25 ± 6 ms for the successful ablation sites and 21 ± 6 ms for the nonsuccessful ablation sites (p = .47). The value of the difference in the earliest BiEGM and UniEGM dV/dTmax differed between successful and nonsuccessful ablation sites (6.4 ± 3.6 ms vs. 10.4 ± 6.8 ms). NCP was observed at 90.0% and 42.3% of the successful and nonsuccessful ablation sites, respectively. Alignment of NCP and BiEGMonset-UniEGM ≤6 ms was applied as the mapping criterion for successful PVC suppression (73.1% sensitivity and 87.7% specificity). The area under the receiver-operating characteristic curve for this cutoff was 0.85. Mapping based on an NCP at the onset of the BiEGM and UniEGM and the least difference value of the earliest BiEGM and UniEGM dV/dTmax had an excellent predictive value for successful ablation. These strategies may reduce the number of radiofrequency catheter ablation (RFCA) applications for free-wall tricuspid annular PVCs.

Paradigm Shift for Catheter Ablation of Atypical Atrioventricular Nodal Re-Entrant Tachycardia: 3-Dimensional Mapping–Based Ablation

BackgroundIn current practice, the ablation target of atypical atrioventricular nodal re-entrant tachycardia (AVNRT) is the earliest atrial activation site in the coronary sinus (CS) or conventional slow pathway region. ObjectivesThe purposes of this study were to map the site of earliest retrograde atrial activation using electroanatomic three-dimensional mapping during atypical AVNRT and to evaluate successful ablation sites. MethodsA total of 42 patients with a total of 49 AVNRTs (slow/fast: 30; fast/slow: 15; slow/slow: 4) underwent electrophysiological study and ablation. Among them there were 14 patients (10 women; 60 ± 19 years of age) in whom 19 atypical AVNRT (fast/slow: 15; slow/slow: 4) were induced. ResultsThe intracardiac electrocardiograms or three-dimensional mapping of the exit site during tachycardia revealed that 7 patients had exit sites solely inside the CS (left inferior extension [LIE]), 3 solely in the right postero-septal tricuspid annulus (TA; right inferior extension [RIE]), and 4 had both LIE and RIE exits. The distance from the CS ostium to LIE exits was 14 ± 6 mm. RIE exits were located on the TA posterior to the CS ostium (between 5 and 6 o’clock in the left anterior oblique projection). Ablation targeting these exits or conventional slow pathway succeeded in long-term elimination of AVNRT in 13 of the 14 patients (93%). There were no complications. ConclusionsCatheter ablation targeting the exit sites of LIE or RIE mapped at the CS or TA holds promise as an effective and safe alternative approach to the current targets of ablation for atypical AVNRT cases.

Implications of the anatomy of papillary muscle connections for mapping and ablation of focal ventricular arrhythmias

Ventricular arrhythmias (VAs) originating from papillary muscles (PAPs) can be challenging when targeted with catheter ablation. Reasons may include premature ventricular complex pleomorphism, structurally abnormal PAPs, or unusual origins of VAs from PAP-myocardial connections (PAP-MYCs). The purpose of this study was to correlate PAP anatomy with mapping and ablation of PAP VAs. In a series of 43 consecutive patients with frequent PAP arrhythmias referred for ablation, the anatomy and structure of PAPs and VA origins were analyzed using multimodality imaging. Successful ablation sites were analyzed for location on the PAP body or a PAP-MYC. In a total of 17 of 43 patients (40%), VAs originated from a PAP-MYC (in 5 of 17 patients, the PAP inserted into the mitral valve anulus); and in 41 patients, VAs originated from a PAP body. VAs from a PAP-MYC more often had delayed R-wave transition than did other PAP VAs (69% vs 28%; P < .001). Patients with failed procedures had more PAP-MYCs (24.8 ± 8 PAP-MYCs per patient vs 16 ± 7 PAP-MYCs per patient; P < .001). Multimodality imaging identifies anatomic details of PAPs that facilitate mapping and ablation of VAs. In more than a third of patients with PAP VAs, VAs originate from connections between PAPs and the surrounding myocardium or between other PAPs. VA electrocardiographic morphologies are different when VAs originate from PAP-connection sites as compared with VAs originating from the PAP body.

Distinctive characteristics of His bundle potentials in patients with atrioventricular nodal reentrant tachycardia.

His bundle (HB) potentials vary in amplitude and duration in patients with and without slow pathways. The aim of this study was to determine the characteristics of HB potentials and to elucidate whether they can provide clues for identification of slow pathway (SP). The present research prospectively studied the electrophysiological findings of 162 patients with symptomatic atrioventricular nodal reentrant tachycardia (AVNRT) due to slow-fast or fast-slow type and atrioventricular reentrant tachycardia (AVRT). Maximal HB potential (HBmax, HB with the highest amplitude) among HB cloud was recorded in both groups. For AVNRT patients, the following were measured: (1) AH interval at the "jump" during programmed atrial stimulation (A2H2, taken as a reflection of SP conduction time); (2) Distance from HBmax to the successful SP ablation site (HBmax-ABL) and from HBmax to the ostium of coronary sinus (HBmax-CSO). HBmax was 0.29 ± 0.10 mV in AVNRT patients, whereas it was 0.17 ± 0.05 mV in AVRT group (p < 0.0001). Likewise, the HBmax duration was 22 ± 5 ms in AVNRT group and 16 ± 3 ms in AVRT group (p < 0.0001). The area under the receiver operating characteristic curve of HBmax amplitude in AVNRT patients was 0.86 and the optimal HBmax cut-off to predict AVNRT was ≥ 0.22 mV with a sensitivity of 0.78 and specificity of 0.84. HBmax-CSO was positively correlated with HBmax-ABL, and HBmax-ABL was positively correlated with A2H2. HBmax amplitudes were higher and durations longer in patients with AVNRT, as compared to those with AVRT. Moreover, the distance between HBmax and successful ablation site was positively correlated with the SP conduction time and with the distance from HBmax to the CSO.

Epicardial ablation of left atrial flutter

Abstract Funding Acknowledgements Type of funding sources: None. Background Left atrial flutter (LAFL) may have epicardial components not accessible to endocardial ablation by radiofrequency (RF) application. Subxiphoid access to the pericardial space has been reported in isolated cases. Purpose to prospectively evaluate the efficacy and safety of subxiphoid access to the pericardial space to map and ablate LAFL refractory to endocardial RF application. Methods Patients with LAFL confirmed by activation and entrainment mapping and refractory to endocardial RF application were consecutively enrolled. An epicardial component of the tachycardia circuit was suspected when parts of the AFL activation, channels of slow conduction or conduction gaps on previous ablation lines intersecting the AFL circuit were not found. Pericardial access was obtained by subxiphoid puncture performed conventionally or facilitated by saline infusion or CO2 insufflation into the pericardial space. Following pericardial access, epicardial mapping and ablation was performed with a conventional RF irrigated tip ablation catheter. All procedures were performed under oral anticoagulation and during following heparin infusion for 350 sec activation clotting time target. Results 15 patients with 18 LAFL were included (61.0 ± 8.8 years, 80% male). 14 patients have had a previous atrial fibrillation (AF) ablation. Epicardial ablation was attempted after a previous LAFL endocardial ablation procedure in 6 patients and during the same endocardial ablation procedure in the last 9 patients. Pericardial access was not achieved in 1 patient due to pericardial adhesions (after prior cardiac surgery). Ablation was successfully performed in 11 patients (73.33%) and failed in 4 patients with perimitral AFL (1 patient also had a peri-left appendage AFL). The successful ablation site was found in the transverse sinus of Theile over the Bachmann bundle in 14 patients with perimitral, septal and anterior-wall LAFL and in the oblique sinus in a posterior-wall LAFL. No patient presented relevant complications except for 2 patients who presented hemopericardium and 1 with delayed cardiac tamponade following accidental RV puncture and who required pericardiocentesis. No patient presented AFL recurrences at 19.8 months (range 6-34 months) follow-up except for 2 patients in whom ablation failed or pericardial access was not achieved. Conclusions Epicardial ablation of LAFL refractory to endocardial ablation is successful in most patients following successful pericardial access. This approach appears associated with low risk of significant complications.