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Neither the actual in vivo tissue temperatures reached with 90W/4sec-very high-power short-duration (vHPSD) ablation for atrial fibrillation nor the safety and efficacy profile have been fully elucidated.We conducted a porcine study in which, after right thoracotomy, we implanted 6-8 thermocouples epicardially in the superior vena cava, right pulmonary vein, and esophagus close to the inferior vena cava. We compared tissue temperatures close to a QDOT MICRO catheter, between during 90W/4sec-vHPSD ablation during ablation index (AI: target 400)-guided 50W-HPSD ablation, both targeting a contact force of 8-15 g.Maximum tissue temperature reached during 90W/4sec-vHPSD ablation did not differ significantly from that during 50W-HPSD ablation (49.2±8.4ºC versus 50.0±12.1ºC; P=0.69) and correlated inversely with distance between the catheter tip and the thermocouple, regardless of the power settings (r=-0.52 and r=-0.37). Lethal temperature (≥50°C) was best predicted at a catheter tip-to-thermocouple distance cut-point of 3.13 and 4.27 mm, respectively. All lesions produced by 90W/4sec-vHPSD or 50W-HPSD ablation were transmural. Although there was no difference in the esophageal injury rate (50% versus 66%, P=0.80), the thermal lesion was significantly shallower with 90W/4sec-vHPSD ablation than with 50W-HPSD ablation (381.3±127.3 versus 820.0±426.1μm from the esophageal adventitia; P=0.039).Actual tissue temperatures reached with 90W/4sec-vHPSD ablation appear similar to those with AI-guided 50W-HPSD ablation, with the distance between the catheter tip and target tissue being shorter for the former. Although both ablation settings may create transmural lesions in thin atrial tissues, any resulting esophageal thermal lesions appear shallower with 90W/4sec-vHPSD ablation. This article is protected by copyright. All rights reserved.

Neither the actual in vivo tissue temperatures reached with lesion size index (LSI)-guided high-power short-duration (HPSD) ablation for atrial fibrillation nor the safety profile has been elucidated.We conducted a porcine study (n = 7) in which, after right thoracotomy, we implanted 6-8 thermocouples epicardially in the superior vena cava, right pulmonary vein, and esophagus close to the inferior vena cava. We compared tissue temperatures reached during 50 W-HPSD ablation with those reached during standard (30 W) ablation, both targeting an LSI of 5.0 (5-15 g contact force).TActual tissue temperatures reached with LSI-guided HPSD ablation appear to be modestly higher, with a shorter distance between the catheter tip and thermocouple achieving lethal temperature, than those reached with standard ablation. HPSD ablation lasting6 s may help minimize lethal thermal injury to the esophagus lying at a close distance.

A new hot balloon system that registers balloon surface temperature (BST) during energy delivery is now available for clinical use in Japan. This study sought to investigate the utility of BST measurement for achievement of pulmonary vein isolation (PVI) by a single-shot energy delivery strategy during hot balloon ablation (HBA).We applied and tested the system in 30 consecutive patients undergoing HBA for paroxysmal or early-persistent atrial fibrillation (AF). We also performed real-time PV potential monitoring using a circular catheter.Acute PVI was achieved with single hot balloon shots in 88% (106/120) of the PVs. Real-time BSTs and PV potentials were recorded in all cases. Mean BST at documentation of PVI was 49.4°C, and acute reconnections were observed in most cases (86%, 12/14) in which the single-shot technique was ineffective. Time-to-isolation (TTI) (23.1 ± 8.7 s vs. 36.3 ± 9.3 s, p .01) and median BST (59.9 ± 2.6°C vs. 55.7 ± 1.9°C, p .01) differed significantly between cases in which PVI was achieved (vs. those in which PVI was not achieved). Multivariable analysis revealed strong association between both TTI and median BST and acute PVI. The best median BST cutoff value for achieving PVI with a single shot was58.7°C (sensitivity 67.0%, specificity 100%).Our data suggest that real-time BST monitoring during energy applications is useful for predicting achievement of acute PVI by a single shot during HBA.

BACKGROUND Although low-voltage zones (LVZs) in the left atrium (LA) are considered arrhythmogenic substrates in some patients with atrial fibrillation (AF), the pathophysiologic factors responsible for LVZ formations remain unclear. OBJECTIVE To elucidate the anatomical relationship between the LA and ascending aorta responsible for anterior LA wall remodeling. METHODS We assessed the relationship between existence of LVZs on the anterior LA wall and the three-dimensional computed tomography image measurements in 102 patients who underwent AF ablation. RESULTS Twenty-nine patients (28%) had LVZs grearer than 1.0 cm2 on the LA wall in the LA-ascending aorta contact area (LVZ group); no LVZs were seen in the other 73 patients (no-LVZ group). The LVZ group (vs. no-LVZ group) had a smaller aorta-LA angle (21.0 ± 7.7° vs. 24.9 ± 7.1°, p = .015), greater aorta-left-ventricle (LV) angle (131.3 ± 8.8° vs. 126.0 ± 7.9°; p = .005), greater diameter of the noncoronary cusp (NCC; 20.4 ± 2.2 vs. 19.3 ± 2.5 mm; p = .036), thinner LA wall-thickness adjacent to the NCC (2.3 ± 0.7 vs. 2.8 ± 0.8 mm; p = .006), and greater cardiothoracic ratio (percentage of the area in the thoracic area, 40.1 ± 7.1% vs. 35.4 ± 5.7%, p

Introduction Preferential pathway conduction is mostly detected as fractionated presystolic-potentials preceding the QRS during premature ventricular contractions (PVCs) and late-potentials during sinus rhythm (SR), but the electrophysiologic mechanisms and significance of these potentials have not been fully clarified. We describe a PVC case series in which the preferential pathway conduction was three-dimensionally visualized. Methods Five PVCs (two from the left coronary cusp, two from the commissure of the left and right coronary cusps, and one from the pulmonary artery) in four patients for which a fractionated presystolic-potential during the PVCs and late-potential during SR were recorded at the successful ablation site were reviewed, and three-dimensional coherent activation maps with the conduction velocity vector during the PVCs and SR were reconstructed. Results At the successful ablation site, an "M"-shaped discrete presystolic-potential and "W"-shaped discrete late-potential were recorded in all patients. The configuration of the inverted electrogram of the presystolic-potential was similar to that of the electrogram exhibiting the late-potential. We created coherent activation maps annotating the onset of the presystolic-potentials during the PVCs and offset of the late-potentials during SR, which suggested bidirectional conduction of the preferential pathway connecting the PVC origin to the myocardium. Conclusion Detailed activation mapping of these PVCs is consistent with the presence of fibers along the aortic or pulmonic valve ring that have preferential directions for conduction. PVCs produce a presystolic-potential. In SR, the fiber is activated late and from the opposite direction, producing an inverted potential inscribed on the end of the QRS.

INTRODUCTION Hot-balloon ablation depends solely on thermal conduction, and myocardial tissue is ablated by only conductive heating from the balloon surface. Despite growing clinical evidence of the efficacy and safety of hot-balloon ablation for atrial fibrillation (AF), the actual tissue temperature and the mechanism of heating during such ablation has not been clarified. To determine, by means of a porcine study, the temperatures of tissues targeted during hot-balloon ablation of AF performed with hot-balloon set temperatures of 73°C or 70°C, in accordance with the temperatures now used clinically. METHODS After a right thoracotomy, thermocouples with markers were implanted epicardially on the superior vena cava (SVC) and pulmonary veins (PVs) in six pigs. The tissue temperatures during hot-balloon ablation (balloon set temperatures of 73°C and 70°C, 180 s/PV) were recorded, and the maximum tissue temperatures and fluoroscopically measured distance from the balloon surface to the target tissues were assessed. RESULTS Sixteen SVC- and 18 PV-targeted energy deliveries were performed. Full-thickness circumferential PV lesions were created with all hot-balloon applications. A significant inverse relation was found between the recorded tissue temperatures and distance (r = -.67; p

INTRODUCTION Cryoablation has emerged as an alternative to radiofrequency ablation for treating atrioventricular nodal reentrant tachycardia (AVNRT). The aim of this prospective study was to evaluate the efficacy and safety of cryoapplication at sites within the mid/high septal region of Koch's triangle and the relation between sites of transient AV block (AVB) and sites of successful cryoablation. METHODS AND RESULTS Included were 45 consecutive patients undergoing slow-fast AVNRT cryoablation. Initial delivery of cryoenergy was to the mid-septal to high septal region of Koch's triangle. Transient AVB occurred during cryoenergy delivery in 62% (28/45) of patients. Median distance between sites at which cryofreezing successfully eliminated slow pathway conduction and sites of AVB was 4.0 (3.25-5.0) mm. Sites of successful cryoablation tended to be to the left and inferior to the AVB sites. The atrial/ventricular electrogram ratio was significantly lower at sites of successful cryoablation than at AVB sites (0.25 [0.17-0.56] vs. 0.80 [0.36-1.25], p

Introduction Although electrophysiologic and anatomic factors associated with the need for touch-up radiofrequency (RF) applications after cryoballoon ablation (CBA) for atrial fibrillation (AF) have been well described, those associated with the need for such touch-up after hot balloon ablation (HBA) have not. We aimed to identify factors predictive of the need for touch-up applications following HBA. Methods Anatomic and electrophysiologic factors predictive of the need for touch-up RF ablation were compared between 46 propensity score-matched pairs of patients who underwent HBA or CBA for AF. Results Touch-up RF ablation was more frequently required after HBA than after CBA (57% vs 30%, respectively; P = .01), and mostly at the anterior aspect of the left superior pulmonary vein (LSPV) carina after HBA (35%) but at the inferior aspect of the right inferior PV (RIPV) after CBA (71%). Post HBA touch-up was associated with male gender, a CHA 2 DS 2 -VASc score ≤ 2, PV-left atrial bipolar voltage ≥ 1.35 mV, and PV trunk length ≥ 24.0 mm; post CBA touch-up associated with a history of heart failure. Conclusion Following balloon ablation for AF, there may be a need for touch-up applications, especially at the LSPV ridge after HBA but at the RIPV after CBA. It may behoove operators to expect a need for touch-up following HBA when patients are male, have a CHA2 DS 2 -VASc score ≤ 2 points, when PV-LA bipolar voltage is ≥ 1.35 mV, or when the PV trunk is ≥ 24.0 mm or following CBA when there is a history of heart failure.

One Electrogram-Tracing Tells All: what is the mechanism of this supraventricular tachycardia?Moyuru Hirata, MD*, Yuji Wakamatsu, MD*, Koichi Nagashima, MD, PhD*, Sayaka Kurokawa, MD, PhD*, Naoto Otsuka, MD*, Seina Yagyu, MD*, Shu Hirata, MD*, Toshiko Nakai, MD, PhD*, Yasuo Okumura, MD, PhD*.*Division of Cardiology, Department of Medicine, Nihon University School of Medicine, Tokyo, JapanCorrespondenceKoichi Nagashima, MD, PhD; Division of Cardiology, Department of Medicine, Nihon University School of Medicine, 30-1 Ohyaguchi-kamicho, Itabashi-ku, Tokyo 173-8610, JapanTel: +81-3-3972-8111Fax: +81-3-3972-1098E-mail: cocakochan@gmail.comTotal word count: 1036 words, 2 FiguresFunding: (None)Disclosures: (None)The work described was supported by departmental resources only.Keywords: narrow QRS tachycardia, atrioventricular nodal reentrant tachycardia, accessary pathway.

BACKGROUND How obesity and epicardial fat influence atrial fibrillation (AF) is unknown. METHODS To investigate the effect of obesity/epicardial fat on the AF substrate, we divided 20 beagle dogs of normal weight into four groups (n = 5 each): one of the four groups (Obese-rapid atrial pacing [RAP] group) served as a novel canine model of obesity and AF. The other three groups comprised dogs fed a standard diet without RAP (Control group), dogs fed a high-fat diet without RAP (Obese group), or dogs fed a standard diet with RAP (RAP group). All underwent electrophysiology study, and hearts were excised for histopathologic and fibrosis-related gene expression analyses. RESULTS Left atrial (LA) pressure was significantly higher in the Obese group than in the Control, RAP, and Obese-RAP groups (23.4 ± 6.9 vs. 11.4 ± 2.1, 11.9 ± 6.4, and 13.5 ± 2.9 mmHg; p = .005). The effective refractory period of the inferior PV was significantly shorter in the RAP and Obese-RAP groups than in the Control group (p = .043). Short-duration AF was induced at greatest frequency in the Obese-RAP and Obese groups (p

Entrainment is a useful method for locating reentrant atrial tachycardia (AT) circuits, but alterations or termination of the AT can derail this process. We assessed whether resetting an upstream site of a neighboring electrode by a scanned extrastimulus at a downstream site (when the upstream tissue was refractory) could diagnose that site within the AT circuit. The procedure was applied to 48 ATs with a cycle length (CL) of 238 ± 42 ms (26 common flutters, 8 perimitral flutters, 7 left atrial [LA] roof-dependent AT, 3 LA scar-related macroreentrant ATs, 2 pulmonary vein-gap reentry tachycardias, 1 right atrial scar-related macroreentrant AT, and 1 with an unidentified circuit). Entrainment and scanned extrastimulation were attempted at the cavotricuspid isthmus, LA roof, and mitral isthmus and/or critical AT isthmus. Within the circuit, the post-pacing interval minus the ATCL after entrainment was < 30 ms for all ATs and resetting of the AT cycle by ≥ 5 ms occurred in 94% of the ATs. No ATs were reset by extrastimulation outside the circuit. The positive predictive value of both maneuvers for locating the circuit was 100%, and the negative predictive value of the extrastimulation was similar to that of entrainment (96% vs. 100%, P = 0.25). The incidence of an AT alteration was lower with extrastimulation than with entrainment (1% vs. 9%, P = 0.01). For ATs with a CL < 210 ms, extrastimulation yielded a good diagnostic performance without any AT alterations. AT resetting by a scanned extrastimulus is diagnostic and avoids AT alterations.

INTRODUCTION The clinical efficacy and safety of hot balloon ablation (HBA) for the treatment of persistent AF (PerAF) remain unclear. We aimed to evaluate the clinical efficacy and safety of HBA versus cryoballoon ablation (CBA) as a treatment for PerAF. METHODS Of 195 consecutive patients who underwent initial catheter ablation for PerAF (AF lasting for longer than 7 days but shorter than 12 months), 158 propensity score-matched (79 HBA and 79 CBA) patients were included in our retrospective study. All patients who underwent HBA received applications of energy to the upper posterior LA wall with a larger balloon in addition to single shots to each pulmonary vein (PV) ostium, whereas those who underwent CBA received simple single-shot applications. The electrically isolated surface area (ISA), including the PV antrum and part of the posterior LA wall, was assessed by high-resolution mapping. RESULTS The success of the PV isolation with balloon shots alone did not differ between HBA and CBA (81% vs. 85%; p = .52). The ISA was generally wide in both groups and significantly larger in the HBA group than in the CBA group (61 ± 16% vs. 51 ± 12%; p

Background: Ganglionated plexi (GPs) play an important role in both the initiation and maintenance of atrial fibrillation (AF). GPs can be located by using continuous high-frequency stimulation (HFS) to elicit a vagal response, but whether the vagal response phenomenon is common to patients without AF is unknown. Methods: HFS of the left atrial GPs was performed in 42 patients (aged 58.0±10.2 years) undergoing ablation for AF and 21 patients (aged 53.2±12.8 years) undergoing ablation for a left-sided accessory pathway. The HFS (20 Hz, 25 mA, 10-ms pulse duration) was applied for 5 seconds at 3 sites within the presumed anatomic area of each of the 5 major left atrial GPs (for a total of 15 sites per patient). We defined vagal response to HFS as prolongation of the R-R interval by >50% in comparison to the mean pre-HFS R-R interval averaged over 10 beats and active-GP areas as areas in which a vagal response was elicited. Results: Overall, more active-GP areas were found in the AF group patients than in the non-AF group patients, and at all 5 major GPs, the maximum R-R interval during HFS was significantly prolonged in the AF patients. After multivariate adjustment, association was established between the total number of vagal response sites and the presence of AF. Conclusions: The significant increase in vagal responses elicited in patients with AF compared with responses in non-AF patients suggests that vagal responses to HFS reflect abnormally increased GP activity specific to AF substrates.

Although pulmonary vein isolation (PVI) guided by the ablation index (AI) has been well-developed, acute PV reconnections (PVRs) still occur. This study aimed to compare the prognostic performance of the modified AI and its optimal cut-off value for the prediction of acute PVRs to ensure durable PVI. Three-dimensional left atrium (LA) voltage maps created before an extensive encircling PVI in 64 patients with atrial fibrillation (AF) (45 men, 62 ± 10 years) were examined for an association between electrogram voltage amplitude recorded from the PV–LA junction and acute post-PVI PVRs (spontaneous PVRs and/or ATP-provoked dormant PV conduction). Acute PVRs were observed in 22 patients (34%) and 33 (3%) of the 1012 PV segments. Acute PVRs were significantly associated with segments with higher bipolar voltage zones (3.23 ± 1.17 vs. 1.97 ± 1.20 mV, P

Background: Hot balloon ablation (HBA) and cryoballoon ablation (CBA) were developed to simplify ablation for atrial fibrillation. Because the lesion characteristics and efficacy of these balloon modalities have not been clarified, we compared lesion characteristics and outcomes of HBA and CBA. Methods: Of 165 consecutive patients who underwent initial catheter ablation for atrial fibrillation, 74 propensity scorematched (37 HBA and 37 CBA) patients were included in our study. RESULTS: Patients’ clinical characteristics, including age, sex, body mass index, atrial fibrillation subtype, CHA 2 DS 2 -VASc score, and left atrial dimension, were similar between the 2 groups. Touch-up radiofrequency ablation was required for residual/dormant pulmonary vein conduction in 52% of the patients with HBA versus 24% of the patients with CBA ( P =0.02) and often in the anterior aspect of the left superior pulmonary vein after HBA (41%) versus the inferior aspect of the inferior pulmonary veins after CBA (22%). HBA lesions were smaller than CBA lesions (23.8±7.9 versus 33.5±14.5 cm 2 ; P =0.0007). Similar results were observed when lesions in each pulmonary vein were compared between groups. Twentyfour hours after the procedure, serum levels of the cardiac biomarkers, including troponin-T, creatine kinase, and creatine kinase-MB, were higher in the HBA group than in the CBA group. Atrial fibrillation recurrence did not differ between the groups within 6 (3% versus 11%; P =0.36) or 12 months (16% versus 16%; P =1.00). Conclusions: Although HBA lesions appear to be smaller than CBA lesions, middle-term outcomes are not statistically different between these balloon modalities.