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Abstract Introduction The safety of hyperbaric oxygen treatment (HBO2) in patients with cardiovascular implanted electronic devices (CIED) remains unclear. Methods We conducted a retrospective analysis of seven CIED patients (median age 79 [73–83] years, five males [71.4%]), including five with pacemakers and two with implantable cardioverter defibrillators (ICD), who underwent HBO2 between June 2013 and April 2023. During the initial session, electrocardiogram monitoring was conducted, and CIED checks were performed before and after the treatment. In addition, the medical records were scrutinized to identify any abnormal CIED operations. Results All seven CIED patients underwent HBO2 within the safety pressure range specified by the CIED manufacturers or general pressure test by the International Organization for Standardization (2.5 [2.5–2.5] atmosphere absolute × 18 [5–20] sessions). When comparing the CIED parameters before and after HBO2, no significant changes were observed in the waveform amplitudes, pacing thresholds, lead impedance of the atrial and ventricular leads, or battery levels. All seven patients, including two with the rate response function activated, exhibited no significant changes in the pacing rate or pacing failure. Two ICD patients did not deactivate the therapy, including the defibrillation; however, they did not experience any arrhythmia or inappropriate ICD therapy during the HBO2. Conclusion CIED patients who underwent HBO2 within the safety pressure range exhibited no significant changes in the parameters immediately after the HBO2 and had no observable abnormal CIED operations during the treatment. The safety of defibrillation by an ICD during HBO2 should be clarified.

Abstract Background We explore an optimized approach for increasing lesion size using a novel ablation catheter with a surface thermocouple and efficient irrigation in a temperature‐control setting. Methods We conducted radiofrequency applications at various power levels (35 W, 40 W, and 45 W), contact forces (CFs, 10 g/20 g), and durations (60 s/120 s/180 s) in perpendicular/parallel catheter orientations, with normal saline irrigation (NS‐irrigation) and Half NS‐irrigation (HNS‐irrigation) in an ex‐vivo model (Step 1). In addition, we performed applications (35 W/40 W/45 W for 60 s/120 s/180 s in NS‐irrigation and 35 W/40 W for 60 s/120 s/180 s in HNS‐irrigation) in four swine (Step 2), evaluating lesion characteristics and the occurrence of steam pops. Results In Step 1, out of 288 lesions, we observed 47 (16.3%) steam pops, with 13 in NS‐irrigation and 34 in HNS‐irrigation (p = .001). Although steam pops were mostly observed with the most aggressive setting (45 W/180 s, 54%) with NS‐irrigation, they happened in less aggressive settings with HNS irrigation. Lesion size significantly increased with longer‐duration ablation but not with HNS‐irrigation. The optimal %impedance‐drop cutoff to predict steam pops was 20% with a negative‐predictive‐value (NPV) = 95.1% including NS‐ and HNS‐irrigation groups, and 22% with an NPV = 96.1% in NS‐irrigation group. In Step 2, similar to the ex‐vivo model, lesion size significantly increased with longer‐duration ablation but not with HNS‐irrigation. Steam pops were absent with NS‐irrigation (0/35) even with the largest %impedance‐drop reaching 31% at 45 W/180 s. All steam pops were observed with HNS‐irrigation (6/21, 29%). The optimal %impedance‐drop cutoff predicting steam pops was 24% with an NPV = 96.3% including both NS‐ and HNS‐irrigation groups. Conclusions Rather than using HNS‐irrigation, very long‐duration of radiofrequency applications up to 45 W/180 s may be recommended to safely and effectively increase lesion dimensions using this catheter with NS‐irrigation.

Abstract Background Lesion size is reported to become larger as contact force (CF) increases. However, this has not been systematically evaluated in temperature‐guided very high‐power short‐duration (vHPSD) ablation, which was therefore the purpose of this study. Methods Radiofrequency applications (90 W/4 s, temperature‐control mode) were performed in excised porcine myocardium with four different CFs of 5, 15, 25, and 35 g using QDOT‐MICRO™ catheter. Ten lesions for each combination of settings were created, and lesion metrics and steam‐pops were compared. Results A total of 320 lesions were analyzed. Lesion depth, surface area, and volume were smallest for CF of 5 g than for 15, 25, and 35 g (depth: 2.7 mm vs. 2.9 mm, 3.0 mm, 3.15 mm, p

The ligament of Marshall is an epicardial structure characterized by its composition of fat, fibrous tissue, blood vessels, muscle bundles, nerve fibers, and ganglia. Its intricate network forms muscular connections with the coronary sinus and left atrium, alongside adjacent autonomic nerves and ganglion cells. This complexity plays a pivotal role in initiating focal electrical activities and sustaining micro- and macro-reentrant circuits, thereby contributing to the onset of atrial fibrillation and atrial tachycardia. However, endocardial ablation in this area may encounter challenges due to anatomical variations and insulation by fibrofatty tissue. Combining ethanol infusion into the vein of Marshall with radiofrequency ablation presents a promising strategy for effectively and safely eliminating this arrhythmogenic structure and terminating associated tachycardias.

The Ligament of Marshall (LOM) is a remnant of the embryonic sinus venosus and the left cardinal vein, containing a combination of fat, fibrous tissue, blood vessels, muscle bundles, nerve fibers, and ganglia. Various muscular connections exist between the LOM and the left atrium (LA) and the coronary sinus (CS). The LOM is richly innervated by autonomic nerves, with ganglion cells distributed around it. The unique characteristics of the LOM are responsible for generating focal electrical activities and enable it to serve as a substrate for micro- and macro-reentrant circuits. This, in turn, leads to the initiation and perpetuation of atrial fibrillation (AF) and atrial tachycardia (AT). Endocardial ablation in this region does not consistently succeed due to anatomical constraints within the left lateral LA, including the presence of a thicker and longer mitral isthmus (MI), anatomical variations between the MI and epicardial structures such as the CS and vein of Marshall (VOM) and circumflex artery, and the presence of fibrofatty tissue insulating the LOM. Furthermore, epicardial ablation is challenging for inexperienced institutions because of its invasive nature. Ethanol infusion into the VOM (EI-VOM) represents an effective and safe approach that can be employed in conjunction with radiofrequency ablation to eliminate this arrhythmogenic structure.

In the setting of structural heart disease, ventricular tachycardia (VT) is typically associated with a re-entrant mechanism. In patients with hemodynamically tolerated VTs, activation and entrainment mapping remain the gold standard for the identification of the critical parts of the circuit. However, this is rarely accomplished, as most VTs are not hemodynamically tolerated to permit mapping during tachycardia. Other limitations include noninducibility of arrhythmia or nonsustained VT. This has led to the development of substrate mapping techniques during sinus rhythm, eliminating the need for prolonged periods of mapping during tachycardia. Recurrence rates following VT ablation are high; therefore, new mapping techniques for substrate characterization are required. Advances in catheter technology and especially multielectrode mapping of abnormal electrograms has increased the ability to identify the mechanism of scar-related VT. Several substrate-guided approaches have been developed to overcome this, including scar homogenization and late potential mapping. Dynamic substrate changes are mainly identified within regions of myocardial scar and can be identified as local abnormal ventricular activities. Furthermore, mapping strategies incorporating ventricular extrastimulation, including from different directions and coupling intervals, have been shown to increase the accuracy of substrate mapping. The implementation of extrastimulus substrate mapping and automated annotation require less extensive ablation and would make VT ablation procedures less cumbersome and accessible to more patients.

Abstract Accelerated idioventricular rhythm (AIVR) originating from the right bundle branch (RBB) (RBB‐AIVR) is a rare ventricular arrhythmia. We delineated RBB and myocardial activation separately during RBB‐AIVR, which revealed the spatial relationship of the AIVR origin, preferential pathway, and breakout site. Radiofrequency ablation to the preferential pathway successfully eliminated this arrhythmia.

A 67-year-old man underwent a third ablation procedure for a recurrent atrial tachycardia (AT) after an extensive pulmonary vein (PV) isolation, linear ablation along the left atrial (LA) roof and posterolateral mitral isthmus (MI), and defragmentation of persistent atrial fibrillation and an induced perimitral AT. High-resolution mapping during the clinical AT using the Rhythmia system (Boston Scientific) suggested that the AT was a ridge-related reentrant AT and exhibited a reconnection of the left PVs (LPVs). The residual electrograms in the posterior LPVs were surrounded by endocardial scar, which was like an island consisting of residual LPV electrograms. Retrograde venography of the vein of Marshall (VOM) demonstrated that the VOM reached the posterior left superior PV through the ridge between the LA appendage and left inferior PV and then the LPV carina. An ethanol infusion into the VOM resulted in a simultaneous AT termination and complete electrical isolation of the LPVs, that is, the disappearance of the residual LPV electrograms. The insular residual LPV electrograms in the present case did not appear to be endocardially connected to the LA, because the LPV electrograms were surrounded by endocardial scar and there was a large time gap between the earliest activation in the posterior LPVs and activation in the surrounding area. The VOM course on the venography and elimination of the residual LPV electrograms with an ethanol infusion into the VOM suggested that the insular residual LPV electrograms were electrically connected to the posterolateral LA via the VOM and its branches.

Background: Catheter ablation (CA) of paroxysmal atrial fibrillation (PAF) is an effective treatment. However, the frequency of asymptomatic AF recurrence after CA in patients with PAF and sick sinus syndrome (SSS) is not clear. The aim of this study was to elucidate the real AF recurrence after CA in patients with PAF and a pacemaker for SSS. Methods and results: Fifty-one consecutive patients (mean age 66.6 ± 7.0 years, male 34) with PAF and SSS and pacemakers underwent CA. All patients were followed at 1, 3, 6, 9, and 12 months after the CA using a 12-lead ECG, Holter-ECG, and 1-month event recorder as a conventional follow-up. In addition, the pacemakers were interrogated every 12 months. During a 5-year follow-up after the final CA procedure, AF recurrences were observed in 7 patients (13.7%) with a conventional follow-up, including 1 (2.0%) asymptomatic patient. Pacemaker-interrogation revealed another 10 patients (19.6%) with asymptomatic AF recurrences. Ultimately, the conventional follow-up plus pacemaker-interrogation provided a higher incidence of AF recurrences (P = 0.009). Multiple CA procedures contributed to a significant increase in the AF-free survival rate at 5 years: 58.6% after a single CA and 86.0% after multiple CA procedures with a conventional follow-up, but which decreased to 40.6% and 60.9% with a conventional follow-up plus a pacemaker interrogation, respectively. Conclusions: One-third of PAF patients with SSS and pacemakers recurred after multiple CA sessions. However, 65% of them were asymptomatic and difficult to be identified with conventional follow-up. Pacemaker interrogation significantly increased the detection rate of AF-recurrence.

Background: The present study aimed to elucidate the safety and effectiveness of a noble and unique airway management technique in which a pediatric intubation tube is used in adult patients with atrial fibrillation (AF) undergoing catheter ablation (CA) under continuous deep sedation. Methods: In total, 246 consecutive patients with AF (mean age, 65±10 years; 60 women) underwent CA under dexmedetomidine-based continuous deep sedation. A 4-mm pediatric intubation tube guided by a 10-French intratracheal suction tube was inserted smoothly, and the tip of the tube was located at the base of the epiglottis. The maximum shifting distance of the heart (MSDH) was measured with the 3D mapping system (Ensite NavX system) before and after inserting the pediatric intubation tube. Results: At baseline, the MSDH of patients under continuous deep sedation was 23±14 mm. The pediatric intubation tube reduced the MSDH to 13±6 mm (mean reduction from baseline, 38.4±21.7%; P

Background Fat deposition (FD) is part of the healing process after myocardial infarction. The characteristics of FD and its impact on the outcome in patients undergoing ventricular tachycardia (VT) ablation have not been thoroughly studied. Methods and Results We studied consecutive patients undergoing post–myocardial infarction VT ablation with pre‐procedural cardiac computed tomography. FD was defined as intra‐myocardial attenuation ≤ −30 HU on computed tomography. Clinical, anatomical, and post‐procedural outcome was assessed in the overall population. Electrophysiological characteristics were assessed is a subgroup of patients with high‐density electro‐anatomical maps. Sixty‐nine patients were included (66±12 years). FD was detected in 44 (64%) patients. The presence of FD related to scar age (odds ratio [OR]: 1.14 per year; P=0.001) and scar extent (OR: 1.27 per segment; P=0.02). On electro‐anatomical maps, FD was characterized by lower bipolar amplitude (P

Herein, we report a 47-year-old woman with ischemic cardiomyopathy who underwent ablation therapy due to an electrical storm without any triggers. The voltage mapping in sinus rhythm with the Rhythmia system and Orion catheter displayed several LAVAs in and around the anteroapical scar area. Although the patient did not tolerate the induced clinical ventricular tachycardia, which was reproductively induced, 35-second-mapping in the scar zone with the Orion catheter demonstrated the VT circuit with the critical isthmus. This report shows the possibility of the new ultra-high density mapping system in a specific ischemic VT patient.

An early repolarization pattern can be observed in 1% up to 13% of the overall population. Whereas, this pattern was associated with a benign outcome for many years, several more recent studies demonstrated an association between early repolarization and sudden cardiac death, so-called early repolarization syndrome. In early repolarization syndrome patients, current imbalances between epi- and endo-cardial layers result in dispersion of de- and repolarization. As a consequence, J waves or ST segment elevations can be observed on these patients' surface ECGs as manifestations of those current imbalances. Whereas, an early repolarization pattern is relatively frequently found on surface ECGs in the overall population, the majority of individuals presenting with an early repolarization pattern will remain asymptomatic and the isolated presence of an early repolarization pattern does not require further intervention. The mismatch between frequently found early repolarization patterns in the overall population, low incidences of sudden cardiac deaths related to early repolarization syndrome, but fatal, grave consequences in affected patients remains a clinical challenge. More precise tools for risk stratification and identification of this minority of patients, who will experience events, remain a clinical need. This review summarizes the epidemiologic, pathophysiologic and diagnostic background and presents therapeutic options of early repolarization syndrome.

AF is a heterogeneous rhythm disorder that is related to a wide spectrum of etiologies and has broad clinical presentations. Mechanisms underlying AF are complex and remain incompletely understood despite extensive research. They associate interactions between triggers, substrate and modulators including ionic and anatomic remodeling, genetic predisposition and neuro-humoral contributors. The pulmonary veins play a key role in the pathogenesis of AF and their isolation is associated to high rates of AF freedom in patients with paroxysmal AF. However, ablation of persistent AF remains less effective, mainly limited by the difficulty to identify the sources sustaining AF. Many theories were advanced to explain the perpetuation of this form of AF, ranging from a single localized focal and reentrant source to diffuse bi-atrial multiple wavelets. Translating these mechanisms to the clinical practice remains challenging and limited by the spatio-temporal resolution of the mapping techniques. AF is driven by focal or reentrant activities that are initially clustered in a relatively limited atrial surface then disseminate everywhere in both atria. Evidence for structural remodeling, mainly represented by atrial fibrosis suggests that reentrant activities using anatomical substrate are the key mechanism sustaining AF. These reentries can be endocardial, epicardial, and intramural which makes them less accessible for mapping and for ablation. Subsequently, early interventions before irreversible remodeling are of major importance. Circumferential pulmonary vein isolation remains the cornerstone of the treatment of AF, regardless of the AF form and of the AF duration. No ablation strategy consistently demonstrated superiority to pulmonary vein isolation in preventing long term recurrences of atrial arrhythmias. Further research that allows accurate identification of the mechanisms underlying AF and efficient ablation should improve the results of PsAF ablation.

Idiopathic ventricular fibrillation (IVF) is the main cause of unexplained sudden cardiac death, particularly in young patients under the age of 35. IVF is a diagnosis of exclusion in patients who have survived a VF episode without any identifiable structural or metabolic causes despite extensive diagnostic testing. Genetic testing allows identification of a likely causative mutation in up to 27% of unexplained sudden deaths in children and young adults. In the majority of cases, VF is triggered by PVCs that originate from the Purkinje network. Ablation of VF triggers in this setting is associated with high rates of acute success and long-term freedom from VF recurrence. Recent studies demonstrate that a significant subset of IVF defined by negative comprehensive investigations, demonstrate in fact subclinical structural alterations. These localized myocardial alterations are identified by high density electrogram mapping, are of small size and are mainly located in the epicardium. As reentrant VF drivers are often colocated with regions of abnormal electrograms, this localized substrate can be shown to be mechanistically linked with VF. Such areas may represent an important target for ablation.

BackgroundAlthough several studies have reported an association between atrial fibrillation (AF) and alcohol, the impact of alcohol consumption on the outcome after catheter ablation (CA) for AF has not been discussed. We aimed to elucidate the effect of alcohol consumption on the outcome of CA for paroxysmal AF. Methods and ResultsWe examined 1361 consecutive patients with paroxysmal AF (mean age, 61±11 years, 334 women) who underwent CA, including 623 (45.8%) patients who consumed alcohol. The clinical characteristics and outcomes of CA were compared between patients who did and did not consume alcohol. No significant differences were seen in the left atrial size, duration of AF history, and incidence of nonpulmonary vein foci between 2 groups (P=NS). Although the AF recurrence‐free rate after the initial CA was higher in patients who did not consume alcohol (261/623 [41.9%] versus 252/738 [34.1%]; mean follow‐up, 44.4±30.7 months; P=0.003), the outcome after the final CA was similar between 2 groups (patients who consumed alcohol: 111/628 [17.7%] versus patients who did not consume alcohol: 138/738 [18.7%]; mean follow‐up, 53.1±25.8 months; P=0.67). The frequency (hazard ratio 1.07 per 1 day/week increase, CI 1.00–1.15, P=0.04) of alcohol consumption was significantly associated with AF recurrence after CA. ConclusionsThe frequency of alcohol consumption may be associated with AF recurrence after the initial CA for paroxysmal AF, but it may not affect the outcome after the final CA.

Background: There is limited data regarding the outcomes after stepwise ablation for persistent atrial fibrillation (AF) in patients with heart failure (HF). Methods and results: Patients without structural heart disease undergoing stepwise ablation for persistent AF (continuous AF≤1 year) were studied (n=108; age, 61±10 years) and 32 patients had a history of HF. The HF patients were further grouped on the basis of left ventricular ejection fraction (LVEF)≤45% (n=15) and >45% (n=17). During a median follow-up period of 2.2 years, repeated ablations were necessary in 65 patients. The proportion of patients that were arrhythmia free 1 year after the last ablation was 67% in patients with LVEF≤45%, 86% in LVEF>45%, and 91% in no HF (p=0.0009). In patients with LVEF≤45%, the AF burden was reduced to less than one paroxysmal episode per month, and patients with and without recurrences both showed significant increases in LVEF over the follow-up period (38±7% to 60±10% and 37±6% to 53±10%, respectively). Conclusions: HF patients with LVEF≤45% had lower chances to remain free from arrhythmias after stepwise ablation for persistent AF than those with LVEF>45%. Nevertheless, LVEF also improved in patients with recurrences, reflecting the observed reduction in AF burden and emphasizing the benefits of ablation.

A 39-year-old man with a seemingly non-remodeled, small heart suffered persistent atrial fibrillation (AF). Extensive isolation of the pulmonary vein, superior vena cava, and posterior left atrium, in conjunction with right atrium focal ablation, was performed to ablate multiple AF foci during two catheter ablation sessions. Sinus arrest occurred suddenly during follow-up, despite the absence of recurrent AF, ultimately necessitating pacemaker implantation. This case underscores the necessity of careful follow-up after catheter ablation, highlighting the risk of sudden, severe sinus node dysfunction, even in young AF patients with small hearts.

Aims: This study investigated whether disappearance patterns of pulmonary vein (PV) potentials (PVPs) during PV isolation (PVI) affect the outcome of catheter ablation (CA) in patients with paroxysmal atrial fibrillation (PAF). Methods and results: Extensive PVI was performed in 1149 PAF patients (age, 61 ± 10 years). Clinical and demographic characteristics, ablation data, and follow-up outcomes were prospectively collected. During an initial CA, simultaneous disappearance of superior and inferior PVPs in both right and left PVs was observed in 464 (40.4%) patients (Group S). Atrial fibrillationrecurrence free rates at 1, 3, and 5 years after the initial CA in Group S were 78.9, 71.9, and 68.1%, respectively, which were higher than those in Group Non-S (P = 0.004). However, those were similar after the final CA between both groups. The incidence of PV-left atrium (LA) electrical reconnection was significantly lower in Group S than in Group Non-S in the second (Group S, 65.6% vs. Group Non-S, 82.1%; P = 0.004) and third (Group S, 8.3% vs. Group Non-S, 47.6%; P = 0.03) CAs. Furthermore, the reconnections more frequently occurred on the side of PVs where simultaneous PVP elimination had not been achieved at the initial CA. Simultaneous disappearance of superior and inferior PVPs in both right and left PVs independently reduced the risk of AF recurrence after the initial CA by 26%. Conclusion: The simultaneous disappearance of superior and inferior PVPs in both right and left PVs is associated with less frequent PV-left atrium reconnection and may yield a better clinical outcome after the initial CA. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation is now an alternative approach to antiarrhythmic drug therapy for patients with symptomatic atrial fibrillation (AF). We focused on younger patients in whom the prevalence of AF is low, and we sought clinical factors associated with unsuccessful ablation outcomes. Methods and results: Among 1983 consecutive symptomatic patients who underwent AF ablation proce-dures, 95 patients (4.8%), age <40 years, were prospectively included. Of them, 64 had paroxysmal AF, and the remaining 31 had persistent AF. All patients underwent pulmonary vein isolation and cavotricus-pid isthmus ablation. When AF recurred, redo ablations were performed if the patients desired. The mean number of ablation procedures was 1.3 ± 0.6 times per patient. During the follow-up of 40 [27.8-49.6] months, sinus rhythm was maintained in 86 patients (90.5%) without any antiarrhythmic drugs, but not in the remaining 9 patients (9.5%). Low body mass index (BMI) and persistent AF were associated with unsuccessful ablation procedures. In multivariate logistic regression analysis, a low BMI had the most significant value, with an odds ratio of 7.33 (p = 0.022). The receiver operating characteristic curve demonstrated a BMI cut point of 22.1 kg/m², with an area under the curve of 0.773. Conclusion: In symptomatic younger AF patients, a low BMI was an independent clinical factor for unsuc-cessful AF ablation outcomes. [ABSTRACT FROM AUTHOR]

Dabigatran is a direct thrombin inhibitor that has been approved for preventing stroke in patients with atrial fibrillation. In this study, we aimed to assess the associations between the dabigatran concentration (calculated through plasma-diluted thrombin time, as assessed using the Hemoclot assay) and the activated partial thromboplastin time (aPTT) and activated clotting time (ACT). We recruited 137 patients with atrial fibrillation who were receiving a normal dose of dabigatran (300 mg/d) or a reduced dose of dabigatran (220 mg/d, usually administered to patients who were elderly, had moderate renal dysfunction, or who were also receiving verapamil). We then assessed the aPTT, ACT, and Hemoclot results of the patients and calculated the plasma dabigatran concentration. The mean plasma concentration of dabigatran was 127 ± 88 ng/ml, although no significant differences in dabigatran concentration, ACT, or aPTT were observed when we compared the 2 doses of dabigatran (300 or 220 mg/d). The dabigatran concentration was within the therapeutic levels in most patients, although a high value (>300 ng/ml) was observed in several patients, which indicated a high risk of bleeding. The dabigatran concentration was strongly and positively correlated with ACT and aPTT (r = 0.87, p <0.001; and r = 0.76, p <0.001; respectively). Multivariate analysis revealed that verapamil use was independently associated with elevated dabigatran concentrations (p <0.001). Therefore, ACT and aPTT may be useful for bedside assessment of the anticoagulant activity of dabigatran, and verapamil use may be a risk factor for elevated dabigatran concentrations. [ABSTRACT FROM AUTHOR]