Anatomical Ablation Research Articles

Anatomical Ablation of the Atrioventricular Node.

Atrioventricular (AV) conduction ablation has been achieved by targeting the area of penetration of the conduction axis as defined by recording a His bundle potential. Ablation of the His bundle may reduce the possibility of a robust junctional escape rhythm. It was hypothesised that specific AV nodal ablation is feasible and safe. The anatomical position of the AV node in relation to the site of penetration of the conduction axis was identified as described in dissections and histological sections of human hearts. Radiofrequency (RF) ablation was accomplished based on the anatomical criteria. Specific anatomical ablation of the AV node was attempted in 72 patients. Successful AV nodal ablation was accomplished in 63 patients (87.5%), following 60 minutes (IQR 50-70 minutes) of procedure time, 3.4 minutes (IQR 2.4-5.5 minutes) of fluoroscopy time, and delivery of 4 (IQR 3-6) RF lesions. An escape rhythm was present in 45 patients (71%), and the QRS complex was similar to that before ablation in all 45 patients. Atropine was administered in six patients after the 10-min waiting period and did not result in restoration of conduction. In nine patients, AV conduction could not be interrupted, and AV block was achieved with ablation of the His after delivery of 12 (IQR 8-15) RF lesions. No cases of sudden death were encountered, and all patients had persistent AV block during a median 10.5 months (IQR 5-14 months) of follow-up. Anatomical ablation of the AV node is feasible and safe, and results in an escape rhythm similar to that before ablation.

Intracardiac echocardiography guided anatomical ablation of the arcuate ridge for drug refractory inappropriate sinus tachycardia.

Inappropriate sinus tachycardia (IST) is a common condition with frequently not tolerated beta-blockers or ivabradine and a high rate of complication in ablation strategy; we describe an alternative anatomical approach of sinus node (SN) modulation. This retrospective study describes a case series of 6 patients from two centers diagnosed with symptomatic IST undergoing SN ablation. The mean age was 40.6 ± 13.9 years; five of the six patients were female, 100% of patients reported heart palpitations, and 66% reported dizziness, the average heart rate(HR) on a 24-h Holter was 93.2 ± 7.9 bpm. HR during the first stage of a stress test using a standard Bruce protocol was 150 ± 70 bpm, The average HR on 24-h Holter postablation was 75 ± 5.6 bpm, the sinus rate HR during stage 1 of a Bruce protocol exercise stress test was 120 ± 10 bpm. This is the first case series reporting the acute and long-term results of a novel anatomical approach for SN modulation to treat IST targeting the arcuate ridge(AR) under intracardiac echography(ICE) guidance. The novel anatomic ICE-guided catheter ablation approach aimed to identify the earliest activation at the AR with an extension of RF lesions towardits septal region seems effective and safe to modulate the SN in symptomatic patients with IST refractory to medical treatment.

Acute impact of vein of marshall ethanol infusion combined with anatomical ablation validated by pacing in redo ablation of persistent atrial fibrillation

Abstract Background Catheter ablation with radiofrequency in persistent atrial fibrillation (PeAF) has limited success and a significant proportion of patients requires redo ablation. Several trials showed that addition of vein of Marshall ethanol infusion (Vom-EI) to catheter ablation, compared with catheter ablation alone, increases the possibilities of remaining free of AF. No data are available about the effect on VoM-EI in Pe-AF patients that undergo a redo ablation. Purpose We evaluated acute impact on lesion formation post-VoM-EI and the mitral line block validation after a methodical approach including VoM-EI and check of pulmonary vein isolation (PVI), roof-line, mitral line (ML) and cavo-tricuspid isthmus line in a population of PeAF patients undergone redo ablation. We aimed also the results of a short follow-up. Methods Consecutive patients undergoing redo ablation for PeAF were enrolled. All patients underwent check of PVI, left atrium (LA) roofline and cavotricuspid isthmus line and, if necessary, ablation was completed. In all patients, after a detailed electroanatomical map of the LA (filter at 0.05-0.5 mV if the patient was in sinus rhythm or 0.05-0.3 mV in the case of AF), we proceeded with the VoM-ETHO. LA map was thus repeated to assess the extension of the newly-formed low voltage area (LVA). According to the newly-formed LVAs, the validation of mitral line was obtained by the evidence of bidirectional block. In presence of conduction through the mitral line also after endocardial revision, we proceeded to mapping and ablating in the CS epicardial gaps in the "anchored wall" or in the "free-wall"of the great cardiac vein (GCV). Results Twenty consecutive patients (64±8 years and 65% male) undergone redo ablation for AF with VoM-EI were included in this study. All patients underwent PVI in the previous procedure but only in 11 roof line has been performed. In twenty patients (52%) reconnection of PV was observed (12/20 in right superior pulmonary vein). In 4/11 roof line was not complete. The medium value of basal LA-LVAs was 3.38土5.27 cmq and the newly-formed LVAs after the VoM-EI procedure was 9.21土5.63 cmq. All patients achieved bidirectional block validated across ML: in 8/20 after epicardial gaps ablations into the anchored wall of GCV and in 6/20 after epicardial gaps ablation in the free wall of GCV. The ML procedural time was 18.82土12.79 minutes. The number of radiofrequency irrigation was 20.11土10.56. No major complications occurred. Five patients had VOM dissection without consequences. During a short follow-up period (6土5 months), only one patient had AF recurrences after the blanking period of one month. Conclusions VoM ethanol ablation added to PVI and linear lesions in the context of a methodical and anatomical approach during redo ablation of PeAF patients seems to have promising results and to be safe. Longer follow-up is needed to understand the role of this technique in redo ablation.

Atrial voltage analysis following vein of marshall alcohol infusion predicts mitral line block

Abstract Background The vein of Marshall (VOM) is a promising therapeutic target for the atrial fibrillation (AF) treatment, fitting perfectly with the "Coumel triangle" as it contains triggers of focal activities and stable reentries, autonomic parasympathetic and sympathetic connection and it represents substrate for perimitral flutters. Lateral mitral line (ML) represents a fundamental part of the anatomical ablation setup for the treatment of AF but its bidirectional block is very difficult to achieve by endocardial ablations. Ethanol infusion into the VoM (VOM-EI) has demonstrated high effectiveness in facilitating ML block. Newly-formed bipolar lesion after VOM-EI is considered an index of effectiveness of the alcoholization procedure. Voltage analysis assessment after VOM-EI in predicting ML block is poorly investigated. Purpose To compare unipolar and bipolar low-voltage areas (LVAs) along VOM trajectory after VOM-EI, and their role in predicting ML block. Methods We enrolled 59 patients undergoing catheter ablation for persistent AF or mitral isthmus dependent atrial flutter. We performed first a high-density voltage map of the left atrium. After VOM-EI, a LA remap was performed. The area width difference was obtained and defined as ∆LVA (see Figure 1). Normal Bipolar voltage cutoffs were 0.50 mV in case of sinus rhythm or 0.29 mV in case of AF. Unipolar cutoffs were respectively 2.7 mV in sinus rhythm and 1.1 mV in AF. The anatomical lesions set, after VOM-EI, included wide antral PVI, linear lesion for dome and ML isthmus following the newly-formed lesion after the VOM-EI. Systematic lines block validation was performed. ML block was defined after coronary sinus electrograms sequence inversion (septal-to-lateral) during left atrial appendage pacing. In case of residual conduction gaps, RF applications into the coronary sinus-great cardiac vein were done to target residual epicardial gaps. Ablation time to obtain ML block (AblTime) was obtained. Results In our group, 56/59 patients (94.5%) achieved mitral isthmus block. Bipolar and unipolar low voltage areas after VOM-EI were 9.9 ± 6.9 cm2 and 12.2 ± 5.9 cm2 respectively. Bipolar ∆LVAs were significantly lower compared with unipolar ∆LVA (8.2 ± 6.5 cm2 vs 9.4 ± 6.0 cm2; p= 0.03). A strong linear correlation between AblTime and bipolar ∆LVA (R: 0.76) and a significant correlation between AblTime and unipolar ∆LVA (R: 0.6) were found (Figure 2). Patients that required coronary sinus applications to reach ML block (13/59, 22%), presented lower ∆LVAs at logistic regression both at bipolar (p<0.01) and unipolar (p=0.03) analysis. Conclusions Unipolar and bipolar voltage analysis along the mitral isthmus trajectory predicts ML block achievement, with VOM-EI inducing wider unipolar LVAs than bipolar LVAs. Furthermore, wider unipolar and bipolar LVAs post VOM-EI are linked to a shorter AblTime and an increased probability of avoiding the need to target epicardial gaps via the CS musculature.LVA along VOM territory after VOM EI∆LVAs linear correlation with AblTime

Impact of Vein of Marshall Ethanol Infusion Combined with Anatomical Ablation for the Treatment of Persistent Atrial Fibrillation: A Long-Term Follow-Up Based on Implantable Loop Recorders.

The best ablation treatment for persistent atrial fibrillation (PeAF) patients is still debated. The vein of Marshall (VOM) seems to be a promising target for ablation and could be combined with a linear set of ablation lesions. The aim of our study is to evaluate the incidence of AF recurrences in a PeAF population treated with a comprehensive ablation approach consisting of VOM ethanol infusion (EI), pulmonary vein isolation (PVI), a left atrial (LA) roofline, a mitral line (guided by the newly formed lesion after alcohol infusion into the VOM and validated by pacing), and a cavotricuspid isthmus line. Consecutive patients undergoing the first ablation procedure of catheter ablation (CA) for PeAF were enrolled. All patients underwent VOM-EI, PVI, and ablation lines along the roof of the LA, mitral, and cavotricuspid isthmus. LA voltage mapping before and after VOM-EI was also performed. An implantable loop recorder (ILR) was implanted at the end of the ablation in each patient. Thirty-one consecutive patients (66 ± 8 years and 71% male) affected by PeAF were included in this study. The VOM-EI procedural phase lasted 21.4 ± 10.1 min. PV isolation and lines were validated in all subjects. The ML block was achieved within 10.8 ± 8.7 min. At a mean follow-up of 12 ± 7 months, 27 out of 31 (87%) patients remained free from AT/AF recurrences. Among the patients with recurrences, two (50%) had incomplete ablation lesions and three (75%) had "suboptimal" VOM-EI. In 23/31 patients (74%), antiarrhythmic drugs (AADs) were discontinued after 1 month of follow-up. No significant complications were reported during the follow-up. this single-center experience demonstrates that VOM-EI systematically combined with an anatomical ablation set in patients with PeAF resulted in feasible, safe, and effective freedom from AF/AT recurrences in 87% of the population after a 1-year follow-up period according to an ILR.

Efficacy of Vein of Marshall Ethanol Infusion Added to Left Atrial Anatomical Ablation for Treatment of Persistent Atrial Fibrillation in Patients with Hypertrophic Cardiomyopathy.

Radiofrequency catheter ablation (RFCA) has been shown to have low efficacy for the treatment of persistent atrial fibrillation (AF) in patients with hypertrophic cardiomyopathy (HCM). We conducted this study to evaluate the benefit of adjunctive vein of Marshall (VOM) ethanol infusion during RFCA for persistent AF (PsAF) in patients with non-obstructive HCM. This multicenter retrospective observational study included 102 consecutive non-obstructive HCM patients with PsAF who underwent RFCA plus VOM ethanol infusion (VOM-EI) (RFCA + VOM, n = 56) or RFCA alone (RFCA, n = 46) for the first time. The efficacy endpoint was survival without AF or atrial tachycardia (AT) after the blanking period. We completed the VOM-EI in 92.9% (52/56) patients. The left pulmonary vein antrum ablation time (RFCA + VOM: 19.9 6.1 min vs. RFCA: 27.2 9.3 min), mitral isthmus (MI) ablation time (RFCA + VOM: 16.9 3.7 min vs. RFCA: 28.4 7.8 min), and rate of coronary sinus (CS) vein ablation (RFCA + VOM: 57.69% vs. RFCA: 80.43%) were lower but the acute success rate of MI block (RFCA + VOM: 98.1% vs. RFCA: 84.8%) were higher in the RFCA + VOM group than those in the RFCA group (all p 0.05). After twelve months follow-up, 84.6% of patients (44/52) survived without AF/AT in the RFCA + VOM group, compared to 65.2% of patients (30/46) in the RFCA group (p = 0.03; odds ratio = 2.93, 95% CI: 1.18-7.79). VOM-EI combined with RFCA decreased the recurrence rate of AF/AT at 12 months in HCM patients with PsAF. VOM-EI simplified the ablation of the left pulmonary vein antrum and MI and increased the success rate of MI bidirectional block.

Anatomical ablation for small hepatocellular carcinomas using multiple applicators: a preliminary study

BackgroundAnatomical ablation, defined as thermal ablation of tumor-bearing small portal territories, may provide excellent local tumor control in peripherally-located small hepatocellular carcinomas (HCC), which has been a major concern with percutaneous ablation alone.PurposeTo evaluate the technical feasibility and therapeutic outcomes of anatomical ablation using multiple radiofrequency (RF) applicators for the ablation of tumor-bearing small portal territories of peripherally-located small (≤ 4 cm) HCCs.Materials and methodsPatients with peripherally-located single HCCs (≤ 4 cm) to be treated with anatomical ablation using multiple RF applicators between January 2020 and March 2022 were enrolled in this prospective study. Anatomical ablation was performed for the index tumor under real-time US-CT/MR fusion imaging guidance, with one or two clustered electrode needles placed across the tumor-bearing portal vein branches. Technical success and complications of anatomical ablations were assessed. Cumulative incidence of local tumor progression (LTP) and recurrence-free survival were estimated using the Kaplan–Meier method.ResultsFifty-five HCCs (mean size, 1.77 ± 0.59 cm) in 55 participants (mean age, 66.4 ± 7.7 years; 39 men, 16 women) were treated with anatomical ablation; 98.2% (54/55) technical success was achieved. No major complications were noted. Among the 55 participants, LTP occurred in only one patient who had experienced technical failure of anatomical ablation. Estimated 1- and 2-year cumulative incidences of LTP were 0% and 3.7%, respectively. Five patients developed intrahepatic remote recurrence during the median follow-up period of 19.2 months (range, 3.7–28.8 months); therefore, estimated 1- and 2-year recurrence-free survival was 91.7% and 85.0%, respectively.ConclusionAnatomical ablation using multiple RF applicators provided the excellent results of local tumor control in patients with peripherally-located small (≤ 4 cm) HCCs.Trial registrationclinicaltrial.gov identifier: NCT05397860.

False Tendons in the Left Ventricle: Implications for Successful Ablation of Left Posterior Fascicular Tachycardias

BackgroundThe anatomical substrate for left posterior fascicular ventricular tachycardia (LPF-VT) is still unclear. ObjectivesThe purpose of this study is to describe the endocavitary substrate of the re-entrant loop of LPF-VT. MethodsA total of 26 consecutive patients with LPF-VT underwent an electrophysiology study and radiofrequency ablation. ResultsIntracardiac echocardiography imaging observed a 100% prevalence of false tendons (FTs) at the left posterior septal region in all patients, and 3 different types of FTs could be classified according to their location. In 22 patients, a P1 potential could be recorded via the multielectrode catheter from a FT. In 4 patients without a recorded P1 during LPF-VT, the earliest P2 potentials were recorded from a FT in 3 patients, and from a muscular connection between 2 posteromedial papillary muscles in 1 patient. Catheter ablation focused on the FTs with P1 or earliest P2 (in patients without P1) was successful in all 26 patients. After 19 ± 8.5 months of follow-up, no patients had recurrence of LPF-VT. ConclusionsFTs provide an electroanatomical substrate for LPF-VT and a “culprit FT” may be identified as the critical structure bridging the macro–re-entrant loop. Targeting the “culprit FT” is a novel anatomical ablation strategy that results in long-term arrhythmia-free survival.

193 13 SECONDS OF ASYSTOLE IN YOUNG: IS A PACEMAKER NECESSARY?

Abstract Introduction Cardioinhibitory neurocardiogenic syncope (CNS) is caused by inappropriately trigger-activated cardiac reflex which finally precipitates asystole, sinus bradycardia, or atrioventricular block. In the absence of structural heart disease, the prognosis is excellent, but frequent syncopal episodes can have a significant impact on quality of life. No medical therapy has proved to be really effective and studies concerning pacemaker implantation are often controversial. However, in young individuals, especially those under 40 years of age, implanting a pacemaker may carry more risks than benefits. Thus, alternative techniques such as ablation of the cardiac atrial parasympathetic ganglia (GP) have emerged. Case report A 34-year-old man with frequent episodes of reflex syncope performed a tilt test in March 2022 that diagnosed cardio-inhibitory syncope with 13-second asystole interrupted with external cardiac massage and intravenous atropine. In May 2022 he had an MRI scan showing normal biventricular systolic function and absence of late-gadolinium enhancement and underwent loop recorder implantation. He came to our centre in June 2022 and underwent electrophysiological study and electroanatomical mapping of the right atrium (Carto 3) during general anaesthesia. The anatomical areas of the supero-posterior and infero-posterior GPs of the right atrium were identified by electroanatomical mapping of complex fractionated atrial electrograms (CFAE). Radiofrequency pulses (Thermocool 30 watts) were delivered at these points, resulting in the disappearance of the CFAEs and an increase in basal heart rate. The greatest number of ganglia are allocated on the posterior surface of the right atrium and in particular the supero-posterior GP is the nexus point for vagal input to the GPs before innervating the atria. Therefore, it was decided to localise and ablate exclusively the GPs of the right atrium. The procedure was completed without complications. The patient has not complained of any syncopal episodes since, and the loop has not recorded any significant pauses. Conclusions The anatomic ablation of GP only in the right atrium could represent a feasible method to reduce CNS, to increase the warning symptoms period, and to delay as much as possible pacemaker implant, especially in young patients who have experienced a related physical trauma. This approach significantly decreased the procedural time and risks.

Simplified stepwise anatomical ablation strategy for mitral isthmus: efficacy, efficiency, safety, and outcome.

Bidirectional and durable block of mitral isthmus (MI) is essential for catheter ablation of persistent atrial fibrillation (PeAF) and perimitral flutter (PMF), but it remains a challenge. The aim of this study was to create a simple anatomical ablation strategy with minimal fluoroscopy that would yield a high success rate for MI block. Patients with PeAF or PMF were included. Mitral isthmus was ablated in a stepwise strategy. In Step 1, endocardial MI linear ablation was performed; in Step 2, ablation was targeted to the posterolateral portion of the left atrium along the MI line; in Step 3, epicardial ablation within the coronary sinus (CS) was performed across the MI line to the ostium of the vein of Marshall (VOM) or performed within the VOM if available; in Step 4, the catheter was rotated and ablated in the CS to isolate the CS; and in Step 5, the early activation site with complex component potential above the MI line during distal CS pacing was considered as the ablation target. All patients were followed up. A total of 178 (17 patients with mechanical prosthetic mitral valve) were included. One hundred and sixty-six patients achieved a confirmed MI bidirectional conduction block (93%). One patient had cardiac tamponade. Four patients showed re-conduction across the MI line during a repeated ablation. In the latest follow-up [12 (7, 16) months], 161 of 178 (90%) patients maintained their sinus rhythm. A simple stepwise anatomical ablation strategy for MI shows a high success rate with low fluoroscopy exposure.

Effect of Direct Slow Pathway Capture Mapping–Guided Ablation on Typical Atrioventricular Nodal Re-Entrant Tachycardia

BackgroundDirect slow pathway capture (DSPC) mapping is a novel electrophysiological technique for detecting antegrade slow pathway input sites. However, the effect of DSPC mapping–guided ablation on atrioventricular nodal re-entrant tachycardia (AVNRT) is unknown. ObjectivesThis study aimed to evaluate the efficacy and safety of DSPC mapping–guided ablation in typical AVNRT patients. MethodsA multicenter retrospective study was conducted in 301 consecutive typical AVNRT patients. The outcomes in patients who underwent DSPC mapping–guided ablation (DSPC group) and those who underwent conventional anatomical ablation (conventional group) were compared. The conventional group was established before introducing DSPC mapping–guided ablation. Positive DSPC sites were defined as sites with a return cycle atrioventricular prolongation of ≥20 ms with high-output (10-20 V) pacing during tachycardia or the last paced beat of the atrial extrastimulation. ResultsAmong 116 patients in the DSPC group, 102 (88%) had positive DSPC sites, and 86 (74%) had a successful ablation at that site. Of the remaining 30 patients, 27 had a successful anatomical ablation. The DSPC group had a significantly lower frequency of radiofrequency applications and shorter total application time than the conventional group (median: 5.5 [IQR: 3-11] times vs 9 [IQR: 5-15] times, and 168 [IQR: 108-266] seconds vs 244 [IQR: 158-391] seconds, respectively; P < 0.01). Moreover, the DSPC group had a numerically lower incidence of permanent pacemaker implantations and AVNRT recurrences than the conventional group (0% vs 1.6%; P = 0.17, and 1.7% vs 3.2%; P = 0.43, respectively). ConclusionsDSPC mapping–guided ablation was associated with a lower operative time, which can reduce the risk of AV conduction injury in typical AVNRT.

Clinical Efficacy of Catheter Ablation in the Treatment of Vasovagal Syncope.

Catheter ablation of ganglionated plexi (GPs) performed as cardioneuroablation in the left atrium (LA) has been reported previously as a treatment for vasovagal syncope (VVS). However, the efficacy and safety of catheter ablation in the treatment of VVS remains unclear. The objective of this study is to explore the efficacy and safety of catheter ablation in the treatment of VVS and to compare the different ganglion-mapping methods for prognostic effects. A total of 108 patients with refractory VVS who underwent catheter ablation were retrospectively enrolled. Patients preferred to use high-frequency stimulation (HFS) (n = 66), and anatomic landmark (n = 42) targeting is used when HFS failed to induce a positive reaction. The efficacy of the treatment is evaluated by comparing the location and probability of the intraoperative vagal reflex, the remission rate of postoperative syncope symptoms, and the rate of negative head-up tilt (HUT) results. Adverse events are analyzed, and safety is evaluated. After follow-up for 8 (5, 15) months, both HFS mapping and anatomical ablation can effectively improve the syncope symptoms in VVS patients, and 83.7% of patients no longer experienced syncope (<0.001). Both approaches to catheter ablation in the treatment of VVS effectively inhibit the recurrence of VVS; they are safe and effective. Therefore, catheter ablation can be used as a treatment option for patients with symptomatic VVS.

Comparison of anatomical thermal ablation and routine thermal ablation for hepatocellular carcinoma≤50mm: Apropensity score matching.

The present study was to evaluated the clinical value of anatomical thermal ablation to treat hepatocellular carcinoma compared with routine thermal ablation. Hepatocellular carcinoma patients with tumor diameter ≤50mm treated by thermal ablation at our center were retrospectively enrolled from October 2015 to December 2018. Enrolled patients were grouped into the anatomical ablation group and routine ablation group, respectively. To minimize the effects of potential confounders from selection bias, a propensity score matching was carried out. Technical efficacy, recurrence and survivals rates were compared. Altogether 101 patients (119 lesions) were grouped into the anatomical ablation group and 101 patients (131 lesions) into the routine ablation group. The ablation zone volume of the anatomical ablation group was 36.8 (2.5-176.9) ml, significantly larger than that of the routine ablation group (28.5 [28.5 (2.8-184.3) ml] (p=0.005)). Adjusted with propensity score matching, The 1-, 2-, and 3-year local recurrence rates were 0.0%, 0.0%, and 0.0% for the anatomical ablation group and 6.9%, 10.1%, and 10.1% for the routine ablation group, respectively (p=0.013). The cumulative 1-, 2-, and 3-year progression-free survival rates were 93.4%, 82.7%, and 79.0% for the anatomical ablation group, 74.2%, 56.9%, and 51.6% for the routine ablation group (p=0.001). Anatomical ablation could be a favorable ablation strategy to improve therapeutic effect of thermal ablation for HCC with visible feeding vessels and reserved liver function.

Ventricular arrhythmias ablated successfully in the subvalvular interleaflet triangle between the right and left coronary cusps: Electrophysiological characteristics and catheter ablation.

Ventricular arrhythmias (VAs) ablated successfully at the right-left subvalvular interleaflet triangle (R-L ILT) between right and left coronary cusps have not been fully characterized. The purpose of this study was to investigate the electrophysiological characteristics of these VAs and their relationships with the left ventricular (LV) summit. Twenty-eight VAs ablated successfully at the R-L ILT were studied. Ninety-six percent of VAs had an early precordial electrocardiographic transition. R-wave amplitude in lead V1 was relatively high (RS morphology, R-wave amplitude 0.35 ± 0.09 mV; R/S ratio 0.35 ± 0.27), whereas the morphology of lead I was R-shaped in 71% and M-shaped in 50% of VAs. Earliest potential was recorded at the R-L ILT in 13 of 28 patients and the left pulmonary sinus cusp (LC) in 6 of 28 patients. Mapping the summit communicating vein (summit-CV) failed because of anatomic or instrumental limitations in these 19 patients. In the other 9 patients, earliest potential was successfully recorded at the summit-CV, while perfect pacemapping was achieved. Poor pace mapping was achieved at the R-L ILT or LC in most patients (27/28). Target site was located at the top of the R-L ILT in all cases. A presystolic potential was present at the target site in 18 of 28 patients. A U-curve via the retrograde method was conventionally used to reach the top of the R-L ILT. VAs ablated successfully at the R-L ILT have unique electrophysiological characteristics, and R-L ILT may be an endocardial anatomic ablation target for VAs originating from the base of the LV summit.

B-PO05-131 TYPICAL BRIDGE FOR ATYPICAL AVNRT

Lower ablation success rates have been associated with atypical AVNRT. Evidence for ablation strategies for atypical AVNRT remain limited due to low prevalence. Anatomical ablation and identification of slow pathway through retrograde conduction have been reported. Voltage gradient mapping guided ablation has been evaluated in typical, “slow-fast” AVNRT. We describe two cases of atypical AVNRT that were successfully treated with targeting low voltage bridge for catheter ablation. N/A A 19yo man with symptomatic SVT presented for EPS and ablation. During EPS, tachycardia was initiated with atrial extrastimuli, and atypical AVNRT was diagnosed using standard pacing maneuvers (Figure, Panel A). A voltage map was created during sinus rhythm and low voltage bridge was identified (Figure, Panel B). Additionally, earliest atrial activation was mapped during tachycardia and localized to low voltage bridge (Figure, Panel C). RFA lesions were delivered over the low voltage bridge with associated junctional beats. He was non-inducible and is arrhythmia-free in follow up. Another case of atypical AVNRT in a 42yo male was approached similarly. Low voltage bridge was identified with voltage mapping during sinus rhythm and subsequently earliest atrial activation in tachycardia was identified. This case also demonstrated overlap in the localization of earliest atrial activation during tachycardia and low voltage bridge. To our knowledge, these are the first reported cases of atypical AVNRT successfully ablated by identifying a low voltage bridge, which correlated to site of earliest atrial activation, as a target for ablation.

Effectiveness of ethanol infusion into the vein of Marshall combined with a fixed anatomical ablation strategy (the "upgraded 2C3L" approach) for catheter ablation of persistent atrial fibrillation.

Linear ablation in addition to pulmonary vein antrum isolation (PVAI) has failed to improve the success rate for persistent atrial fibrillation (PeAF), due to incomplete block of ablation lines, especially in the mitral isthmus (MI). The study enrolled 191 patients (66 in group 1 and 125 in group 2). In group 1, ethanol infusion into the vein of Marshallwas firstperformed, followed by radiofrequency (RF) applications targeting bilateral PVAI and bidirectional block in the roofline, cavotricuspid isthmus, and MI. In group 2, PVAI and the three linear ablations were completed using only RF energy. MI block was achieved in 63 (95.5%) and 101 (80.8%) patients in groups 1 and 2, respectively (p = .006). Patients in group 1 had shorter ablation time for left pulmonary vein antrum (8.15vs. 12.59 min, p < .001) and MI (7.0vs. 11.8 min, p < .001) and required less cardioversion (50 [78.5%] vs. 113 [90.4%], p = .007). During the 12-month follow-up, 58 (87.9%) patients were free from atrial fibrillation/atrial tachycardia in group 1 compared with 81 (64.8%) in group 2 (p < .001). In multivariate cox regression, the "upgraded 2C3L" procedure is associated with a lower recurrence rate (hazard ratio = 0.27, 95% confidence interval = 0.12-0.59). Compared with the conventional "2C3L" approach, the "upgraded 2C3L" approach has higher effectiveness for ablation of PeAF.

Extent of parahippocampal ablation is associated with seizure freedom after laser amygdalohippocampotomy.

The authors aimed to examine the relationship between mesial temporal subregion ablation volume and seizure outcome in a diverse cohort of patients who underwent stereotactic laser amygdalohippocampotomy (SLAH) for mesial temporal lobe epilepsy (MTLE). Seizure outcomes and pre- and postoperative images were retrospectively reviewed in patients with MTLE who underwent SLAH at a single institution. Mesial temporal subregions and the contrast-enhancing ablation volume were manually segmented. Pre- and postoperative MR images were coregistered to assess anatomical ablation. Postoperative MRI and ablation volumes were also spatially normalized, enabling the assessment of seizure outcome with heat maps. Twenty-eight patients with MTLE underwent SLAH, 15 of whom had mesial temporal sclerosis (MTS). The rate of Engel class I outcome at 1 year after SLAH was 39% overall: 47% in patients with MTS and 31% in patients without MTS. The percentage of parahippocampal gyrus (PHG) ablated was higher in patients with an Engel class I outcome (40% vs 25%, p = 0.04). Subregion analysis revealed that extent of ablation in the parahippocampal cortex (35% vs 19%, p = 0.03) and angular bundle (64% vs 43%, p = 0.02) was positively associated with Engel class I outcome. The degree of amygdalohippocampal complex (AHC) ablated was not associated with seizure outcome (p = 0.30). Although the AHC was the described target of SLAH, seizure outcome in this cohort was associated with degree of ablation for the PHG, not the AHC. Complete coverage of both the AHC and PHG is technically challenging, and more work is needed to optimize seizure outcome after SLAH.

Electroanatomic Characterization and Ablation of Scar-Related Isthmus Sites Supporting Perimitral Flutter.

The authors reviewed 3-dimensional electroanatomic maps of perimitral flutter to identify scar-related isthmuses and determine their effectiveness as ablation sites. Perimitral flutter is usually treated by linear ablation between the left lower pulmonary vein and mitral annulus. Conduction block can be difficult to achieve, and recurrences are common. Patients undergoing atrial tachycardia ablation using CARTO3 (Biosense Webster Inc., Irvine, California) were screened from 4 centers. Patients with confirmed perimitral flutter were reviewed for the presence of scar-related isthmuses by using CARTO3 with the ConfiDense and Ripple Mapping modules. Confirmed perimitral flutter was identified in 28 patients (age 65.2 ± 8.1 years), of whom 26 patients had prior atrial fibrillation ablation. Scar-related isthmus ablation was performed in 12 of 28 patients. Perimitral flutter was terminated in all following correct identification of a scar-related isthmus using ripple mapping. The mean scar voltage threshold was 0.11 ± 0.05mV. The mean width of scar-related isthmuses was 8.9 ± 3.5mm with a conduction speed of 31.8 ± 5.5cm/s compared to that of normal left atrium of 71.2 ± 21.5cm/s (p<0.0001). Empirical, anatomic ablation was performed in 16 of 28, with termination in 10 of 16 (63%; p=0.027). Significantly less ablation was required for critical isthmus ablation compared to empirical linear lesions (11.4 ± 5.3 min vs. 26.2 ± 17.1min; p=0.0004). All 16 cases of anatomic ablation were reviewed with ripple mapping, and 63% had scar-related isthmus. Perimitral flutter is usually easy to diagnose but can be difficult to ablate. Ripple mapping is highlyeffective at locating the critical isthmus maintaining the tachycardia and avoiding anatomic ablation lines. This approach has a higher termination rate with less radiofrequency ablation required.

Marshall bundle elimination, Pulmonary vein isolation, and Line completion for ANatomical ablation of persistent atrial fibrillation (Marshall-PLAN): Prospective, single-center study

Beyond pulmonary vein isolation (PVI), the optimal ablation strategy for persistent atrial fibrillation (AF) remains poorly defined. The purpose of this study was to examine a novel comprehensive ablation strategy (Marshall bundle elimination, Pulmonary vein isolation, and Line completion for ANatomical ablation of persistent atrial fibrillation [Marshall-PLAN]) strictly based on anatomical considerations. Left atrial (LA) sites were sequentially targeted as follows: (1) coronary sinus and vein of Marshall (CS-VOM) musculature; (2) PVI; and (3) anatomical isthmuses (mitral, roof, and cavotricuspid isthmus [CTI]). The primary endpoint was 12-month freedom from AF/atrial tachycardia (AT). Seventy-five consecutive patients were included (age 61 ± 9 years; 10 women; AF duration 9 ± 11 months; mean LA volume 197 ± 43 mL). VOM ethanol infusion was completed in 69 patients (92%). The full Marshall-PLAN lesion set (VOM, PVI, mitral, roof, and CTI with block) was successfully completed in 68 patients (91%). At 12 months, 54 of 75 patients (72%) were free from AF/AT after a single procedure (no antiarrhythmic drugs) in the overall cohort. In the subset of patients with a complete Marshall-PLAN lesion set (n = 68), the single procedure success rate was 79%. After 1 or 2 procedures, 67 of 75 patients (89%) remained free from AF/AT (no antiarrhythmic drugs). After 1 or 2 procedures, VOM ethanol infusion was complete in 72 of 75 patients (96%). A novel ablation strategy that systematically targets anatomical atrial structures (VOM ethanol infusion, PVI, and prespecified linear lesions) is feasible, safe, and associated with a high rate of freedom from arrhythmia recurrence at 12 months in patients with persistent AF.

Effectiveness of a 3D mapping benchmark for ablation in patients with atrioventricular nodal reentrant tachycardia.

Avoiding excessively fast junctional rhythm (JR) during slow pathway (SP) modification for atrioventricular nodal reentrant tachycardia (AVNRT) helps prevent serious atrioventricular block. This study investigated the usefulness of a predictive ablation point that lies near the boundary line between appropriate and excessively fast JRs with three-dimensional (3D) electroanatomical mapping in AVNRT patients. Participants were 141 consecutive patients with common AVNRT who received anatomical ablation to an antegrade SP at our institution between August 2013 and December 2019. Patients were divided into two groups: Group A, treated using a location marker that predicts successful ablation sites in a 3D mapping system, and Group B, treated prior to the development of this marker and therefore without it. The average age was 61.9±16.9years, and 41.1% of patients were male. Excessively fast JRs appeared less frequently in Group A than in Group B, though this difference did not reach significance. The distance from the His bundle to the successful ablation point was significantly longer in Group A than in Group B (13.4±4.5 vs 10.8±4.4mm, P<.01). The number of ablations near the successful ablation point was significantly lower in Group A (6.5±5.2 vs 11.4±9.9, P<.01), and a greater number of accelerated JRs at the successful ablation point were observed in Group A (46.9±29.2 vs 32.8±19.2, P<.01). Using our benchmark for a predictive successful ablation point in 3D mapping simplifies and improves common AVNRT ablation procedures.