Optimal cardiac rhythm during substrate mapping in scar-related ventricular tachycardia: Significance of wavefront direction on identifying critical sites.

BACKGROUND: A rotational activation pattern (RAP) around the localized line of a conduction block often correlates with sites specific to the critical zones of ventricular tachycardia (VT). The wavefront direction during substrate mapping affects manifestation of the RAP and line of block. OBJECTIVE: The purpose of this study was to investigate the most optimal cardiac rhythm for identifying RAP and line of block in substrate mapping. METHODS: We retrospectively evaluated 71 maps (median 3205 points/map) in 46 patients (65 ± 15 years; 33% with ischemic cardiomyopathy) who underwent high-density substrate mapping and ablation of scar-related VT. Appearance of a RAP during sinus, right ventricular (RV)-paced, left ventricular (LV)-paced, and biventricular-paced rhythms was investigated. RESULTS: RAP was identified in 24 of 71 maps (34%) in the region where wavefronts from a single direction reached but not in the region where wavefronts from multiple directions centripetally collided. The probability of identifying the RAP depended on scar location; that is, anteroseptal and inferoseptal, inferior and apical, and basal lateral RAPs were likely to be identified during sinus/atrial, RV-paced, and LV-paced rhythms, respectively. In 13 patients, the RAP was not evident in the baseline map but became apparent during remapping in the other rhythm, in which the wavefront reached the site earlier within the entire activation time. CONCLUSION: The optimal rhythm for substrate mapping depends on the spatial distribution of the area of interest. A paced rhythm with pacing sites near the scar may facilitate the identification of critical VT zones.

Incidence of cryoballoon expansion dislodgement during pulmonary vein isolation-An underappreciated frequent cause of incomplete isolation.

BACKGROUND: Cryoballoon ablation for atrial fibrillation (AF) requires adequate contact between the pulmonary vein (PV) antrum and cryoballoon. The surge of intraballoon pressure during the initial phase of ablation may change the balloon's shape and compliance, resulting in balloon dislodgement and loss of PV occlusion. Without continuous monitoring, this phenomenon is often undetected but can be associated with incomplete PV isolation (PVI). METHODS: Primary cryoablation of AF was performed in 15 patients. PV occlusion status pre- and post-freezing were analyzed with intracardiac echocardiography (ICE) and dielectric imaging-based occlusion tool (DIOT) to calculate the incidence of expansion dislodgement of cryoballoon. RESULTS: A total of 105 cryoablation applications were performed on 57 veins, including three common ostiums of left pulmonary veins. In the evaluation of PV occlusion, both modalities reported consistent results in 86.7% of the assessments. Despite complete PV occlusion before ablation, peri-balloon leak after initiation of freezing was detected by ICE in 5/22 (22.7%) applications and by DIOT in 8/25 (32%) applications. CONCLUSION: Incidence of expansion dislodgement of the cryoballoon was detected in one-fourth to one-third of cryoablation applications depending on the imaging modality used, which was clinically frequent and significant.

Balloon surface temperature-controlled ablation using a second-generation radiofrequency HotBalloon: an in vivo feasibility study.

AIMS: The first-generation radiofrequency HotBalloon (RHB) is a size-adjustable single-shot device used in atrial fibrillation. The energy output is determined by its central temperature and not by its balloon surface temperature (BST), thus limiting its efficacy and safety. Therefore, a second-generation RHB was developed to monitor BST and enable BST-controlled ablation. This animal study aims to evaluate the accuracy of a newly developed BST-monitoring system and validate the optimal BST for ablation. METHODS AND RESULTS: In Protocol 1, thermocapsules were attached to the superior vena cava (SVC) epicardium. The accuracy of BST monitoring was examined during SVC isolation. In Protocol 2, the efficacy and safety of different BST-controlled ablations were examined. In the acute model, electrophysiological and pathological findings were assessed after energy applications with BST at 51, 54, 57, and 60°C. In the chronic model, the lesion durability and pathological findings were assessed 8 weeks after BST-controlled ablation (57 and 60°C). A significant positive correlation was found between the epicardial temperature and the BST-monitoring value (r = 0.98). In the acute model, all target veins were electrically isolated with BST-controlled ablation at ≥57°C (18/18, 100%). In the chronic model, durable lesions were observed in all veins at 60°C, while 44% of the veins showed reconnection at 57°C. In both pathological analyses, significantly greater lesions were observed at 60°C than at 57°C. There were no significant differences in adverse events between the two groups. CONCLUSION: Balloon surface temperature-controlled ablation at 60°C using the second-generation RHB may be optimal for creating durable lesions without compromising safety.

Catheter ablation of ventricular tachycardia in dilated-phase hypertrophic cardiomyopathy: Substrate characterization and ablation outcome.

INTRODUCTION: Catheter ablation is a therapeutic option to suppress ventricular tachycardia (VT) in the setting of dilated-phase hypertrophic cardiomyopathy (DHCM). However, the characteristics of the arrhythmogenic substrate and the ablation outcome are not fully illustrated. METHOD: A total of 23 ablation procedures for drug-refractory sustained monomorphic VTs in 13 DHCM patients (60 ± 11 years, one female, the left ventricular [LV] ejection fraction 39% ± 9%, the LV mass index 156 ± 39 g/m2 ) were performed. The distribution of VT substrate as endocardial or epicardial/intramural was based on detailed mapping and ablation response during VT. RESULT: Two patients underwent ablation of sustained monomorphic VT that was not scar-mediated tachycardia. Of the remaining 11 patients, eight (73%) patients had VT substrate in the basal regions, most frequently at the epicardial and/or intramural basal antero-septum. None of the patients had VT substrate located at the LV inferolateral region. Ablation at the right ventricular septum and the aortic cusps was done in four and five patients, respectively. Other approaches including bipolar and chemical ablations, were done in three and two patients, respectively. Six (55%) out of 11 patients (two patients lost follow-up) had VT recurrence. All the six patients had basal substrate. However, anti-tachycardia pacing was sufficient for VT termination except in one patient. CONCLUSION: Catheter ablation of VT in patients with DHCM is challenging because of the predominant basal anteroseptal epicardial/intramural location of arrhythmogenic substrate. An ablation approach from multiple sites and/or adjunctive interventional techniques are often required.

Stellate Ganglion Phototherapy Using Low-Level Laser: A Novel Rescue Therapy for Patients With Refractory Ventricular Arrhythmias.

OBJECTIVES: This study investigates the effect of stellate ganglion (SG) phototherapy in healthy participants and assesses its efficacy in suppressing electrical storm (ES) refractory to antiarrhythmic drugs and catheter ablation. BACKGROUND: Modulation of the autonomic nervous system has been shown to be an effective adjunctive therapy for ES. METHODS: Ten-minute SG phototherapy was performed twice weekly for 4 weeks in 20 healthy volunteers. To evaluate the acute and chronic effects of SG phototherapy, heart rate variability and serum concentrations of adrenaline, noradrenaline, and dopamine were obtained before phototherapy, immediately after the first phototherapy session, after 8 sessions of phototherapy, and 3 months after the first phototherapy session. In addition, the efficacy of SG phototherapy was evaluated in 11 patients with ES refractory to medication, sedation, and catheter ablation. RESULTS: In healthy participants, serum adrenaline concentration significantly decreased after phototherapy, whereas low-frequency power/high-frequency power significantly decreased during phototherapy. Moreover, the effect on heart rate variability did not last beyond 3 months. In the clinical pilot study, 7 patients had a suppression of ES after SG phototherapy; however, without maintenance therapy, 2 patients had a recurrence of ventricular arrhythmias. Furthermore, it did not control ES in 4 patients. CONCLUSIONS: SG phototherapy reduced sympathetic activity and may be a safe and effective adjunctive therapy to control ES in some patients, but its long-term efficacy remains unknown. Chronic phototherapy might help reduce ES recurrence.

Lesion durability after antral pulmonary vein isolation using a radiofrequency hot balloon catheter.

PURPOSE: Antral pulmonary vein isolation (PVI) using a radiofrequency hot balloon catheter (RHB) is a feasible therapeutic option for treating atrial fibrillation (AF). Lesion durability after antral RHB-PVI remains unknown. This study aimed to evaluate lesion durability and the associations between procedural characteristics after antral RHB-PVI. METHODS: A total of 200 patients received antral RHB-PVI using the single-shot technique between April 2016 and March 2018. Antral RHB-PVI was performed following a pre-specified protocol and RHB energy application was performed for a maximum of two times for each PV. Consecutive patients who underwent repeated procedures for recurrence of any type of atrial tachyarrhythmia were enrolled. RESULTS: Twenty-six (13%) patients underwent repeated ablation and 20 patient documented AF recurrence (AF group) and 6 patients documented non-AF recurrence (non-AF group). Repeated ablation was performed at a median (25th, 75th percentiles) of 378 days (217, 487) after the initial procedure and durable PVI was observed in 86 (83.5%) PVs. Durability reached 89.7% when PVI was achieved only using an RHB. In the AF group (79 PVs), durable PVI was observed in 62 (78.5%) PVs, whereas all 24 PVs were still isolated in the non-AF group. The majority of reconnection sites were around the superior PVs. CONCLUSIONS: Antral RHB-PVI shows high lesion durability, especially with both inferior PVs.

Predictors of Recurrence after Catheter Ablation of Paroxysmal Atrial Fibrillation in Different Follow-Up Periods.

Background and objectives: Pulmonary vein (PV) reconnection is a major reason for recurrence after catheter ablation of paroxysmal atrial fibrillation (PAF). However, the timing of the recurrence varies between patients, and recurrence >1 year after ablation is not uncommon. We sought to elucidate the characteristics of atrial fibrillation (AF) that recurred in different follow-up periods. Materials and Methods: Study subjects comprised 151 consecutive patients undergoing initial catheter ablation of PAF. Left atrial volume index (LAVi) and atrial/brain natriuretic peptide (ANP/BNP) levels were systematically measured annually over 3 years until AF recurred. Results: Study subjects were classified into four groups: non-recurrence group (n = 84), and short-term- (within 1 year) (n = 30), mid-term- (1-3 years) (n = 26), and long-term-recurrence group (>3 years) (n = 11). The short-term-recurrence group was characterized by a higher prevalence of diabetes mellitus (hazard ratio 2.639 (95% confidence interval, 1.174-5.932), p = 0.019 by the Cox method), frequent AF episodes (≥1/week) before ablation (4.038 (1.545-10.557), p = 0.004), and higher BNP level at baseline (per 10 pg/mL) (1.054 (1.029-1.081), p < 0.0001). The mid-term-recurrence group was associated with higher BNP level (1.163 (1.070-1.265), p = 0.0004), larger LAVi (mL/m2) (1.033 (1.007-1.060), p = 0.013), and longer AF cycle length at baseline (per 10 ms) (1.194 (1.058-1.348), p = 0.004). In the long-term-recurrence group, the ANP and BNP levels were low throughout follow-up, as with those in the non-recurrence group, and AF cycle length was shorter (0.694 (0.522-0.924), p = 0.012) than those in the other recurrence groups. Conclusions: Distinct characteristics of AF were found according to the time to first recurrence after PAF ablation. The presence of secondary factors beyond PV reconnections could be considered as mechanisms for the recurrence of PAF in each follow-up period.

Predictors of increase in pacing threshold after transcatheter pacing system implantation due to micro-dislodgement.

BACKGROUND: Achieving a favorable pacing threshold with a Micra transcatheter pacing system (Micra-TPS) is needed to reduce battery depletion. In some cases, the threshold increases shortly after the device is implanted, and a higher pacing threshold may be required. This study aims to identify the causes and predictors of the increase in pacing threshold observed shortly after Micra-TPS implantation. METHODS: The study included 64 consecutive patients who underwent Micra-TPS implantation between 2017 and 2020. The patients were divided into two groups depending on their pacing threshold: the increased pacing threshold (IPT) group (threshold increased by ≥0.5 V/0.24 ms within 1 month of implantation) and the stable pacing threshold (SPT) group. RESULTS: Excluding four patients who could not be followed up, of the 60 remaining patients, nine (15%) were in the IPT group and 51 (85%) were in the SPT group. The IPT group had significantly lower implant impedance values and higher implant thresholds than the SPT group (582 ± 59 vs 755 ± 167 Ω [P < .001] and 1.29 ± 0.87 vs 0.71 ± 0.40 V/0.24 ms [P = .014]). Implant impedance and threshold may serve as predictors of a threshold increase after implantation (area under the curve: 0.737-0.943 and 0.586-0.926, respectively). CONCLUSIONS: An IPT was noted shortly after Micra-TPS implantation owing to micro-dislodgement because of insufficient anchoring of the device to the myocardium. Impedance >660 Ω and threshold <1.0 V/0.24 ms may predict an increase in pacing threshold.

Early clinical experience of radiofrequency catheter ablation using an audiovisual telesupport system.

BACKGROUND: An audiovisual telesupport system that enables real-time audiovisual communications between 2 long-distance hospitals is one method of telemedicine. The usefulness and safety of radiofrequency catheter ablation (RFCA) using an audiovisual telesupport system has not been well established. OBJECTIVE: The purpose of this study was to evaluate the effectiveness and safety of RFCA using an audiovisual telesupport system. METHODS: An audiovisual telesupport system using a strictly secured virtual network was established between Kamisu Saiseikai Hospital (operator with 10 years' experience and 800 procedures) and the University of Tsukuba (advisor with >20 years' experience and 8000 procedures). We evaluated 19 initial consecutive patients who underwent RFCA using this system for tachyarrhythmia: 10 with atrial fibrillation (AF), 5 with paroxysmal supraventricular tachycardia (PSVT), 3 with premature ventricular contraction (PVC), and 1 with atrial flutter. Electrophysiological and procedural characteristics were retrospectively assessed. RESULTS: Acute success was achieved in all 19 patients without any major complications, with the advisor's audiovisual assistance. Mean procedure time and fluoroscopic time were 161 ± 44 minutes and 24 ± 14 minutes for AF, 110 ± 17 minutes and 28 ± 8 minutes for PVC, and 132 ± 19 minutes and 32 ± 2 minutes for PSVT, respectively. There was no recurrence of clinical arrhythmia in 17 of the 19 patients (89%) during 13 ± 9 month follow-up. CONCLUSION: An audiovisual telesupport system for RFCA is a useful and safe method that enabled the electrophysiologist with limited human resources to make an optimal decision regarding procedural strategy and endpoint with the remote advisor's audiovisual assistance.

Stepwise approach to induce infrequent premature ventricular complex using bolus isoproterenol and epinephrine infusion.

BACKGROUND: Paucity of a premature ventricular complex (PVC) during ablation procedures may occur and be associated with a lower success rate. Isoproterenol (ISP) injections are commonly used to induce PVC; however, the induced tachycardia sometimes prevents the appearance of PVC. Epinephrine (EPI) administration may be an alternative strategy to induce PVC due to its smaller effect on heart rate (HR). This study sought to examine the electrophysiological impact of EPI injection, with a stepwise induction protocol, for infrequent intraprocedural PVC. METHODS: We studied 78 consecutive patients who underwent catheter ablation of idiopathic frequent PVC. If no PVC was observed at the beginning of the procedure, ISP (10 µg) was injected. If clinical PVC was not induced by ISP administration, EPI (10 µg) was injected. RESULTS: Of 18 patients without PVC at baseline, ISP injection induced PVC in five patients. Of the remaining 13 patients, EPI injection successfully induced PVC in seven patients (53%). The maximum HR and increments of HR after EPI injection were significantly lower than those after ISP injection (99 ± 15 vs 137 ± 15 bpm, P = .001; 22 ± 10 vs 53 ± 12 bpm, P < .001, respectively). There were no complications related to the induction protocol. CONCLUSION: EPI injection following ISP injection is an effective and safe stepwise approach for the induction of infrequent PVC in the electrophysiology laboratory. It is hypothesized that α- and ß-adrenergic receptor stimulation by EPI injections, with reduced HR acceleration compared to that with ISP injections, may result in the successful induction of PVC.

Upgrade of cardiac resynchronization therapy by utilizing additional His-bundle pacing in patients with inotrope-dependent end-stage heart failure: a case series.

BACKGROUND: His-bundle pacing (HBP) alone may become an alternative to conventional cardiac resynchronization therapy (CRT) utilizing right ventricular apical (RVA) and left ventricular (LV) pacing (BiVRVA+LV) in selected patients, but the effects of CRT utilizing HBP and LV pacing (BiVHB+LV) on cardiac resynchronization and heart failure (HF) are unclear. CASE SUMMARY: We presented two patients with inotrope-dependent end-stage HF in whom the upgrade from conventional BiVRVA+LV to BiVHB+LV pacing by the addition of a lead for HBP improved their HF status. Patient 1 was a 32-year-old man with lamin A/C cardiomyopathy, atrial fibrillation, and complete atrioventricular (AV) block. Patient 2 was a 70-year-old man with ischaemic cardiomyopathy complicated by AV block and worsening of HF resulting from ablation for ventricular tachycardia storm. The HF status of both patients improved dramatically following the upgrade from BiVRVA+LV to BiVHB+LV pacing. DISCUSSION: End-stage HF patients suffer from diffuse intraventricular conduction defect not only in the LV but also in the right ventricle (RV). The resulting dyssynchrony may not be sufficiently corrected by conventional BiVRVA+LV pacing or HBP alone. Right ventricular apical pacing itself may also impair RV synchrony. An upgrade to BiVHB+LV pacing could be beneficial in patients who become non-responsive to conventional BiV pacing as the His-Purkinje conduction defect progresses.

Structural relation between the superior vena cava and pulmonary veins in patients with atrial fibrillation.

The superior vena cava (SVC) is a main source of non-pulmonary vein (PV) ectopies that initiate atrial fibrillation (AF). Although the critical role of structural remodeling of the left atrium (LA) in the occurrence of AF was extensively investigated by atrial voltage mapping, that of PVs and the SVC has been less explored. Study subjects comprised 47 patients undergoing catheter ablation of lone AF. During sinus rhythm, PV, SVC, and atrial voltage maps were acquired, and sleeve length of each PV and SVC was determined by an electroanatomical mapping system. The sleeves of the superior PVs were significantly longer than those of the inferior PVs (left superior PV (LSPV): 21 ± 5, left inferior PV: 14 ± 4, right superior PV (RSPV): 19 ± 5, right inferior PV: 15 ± 5, and SVC: 23 ± 10 mm, p < 0.0001). The LSPV sleeve was longer in men than in women (22 ± 6 vs. 19 ± 4 mm, p < 0.05). The sleeve length in the LSPV correlated positively with the body surface area (BSA) (p = 0.003, R = 0.42). Of note, there was a significant correlation in sleeve length between the RSPV and SVC (p < 0.0001, R = 0.64). In conclusion, not right- but left-sided PV sleeves were associated with the BSA of the patients, whereas a structural relation between the right-sided PVs and the SVC was implied based on sleeve mapping. This novel finding may provide mechanistic implications for the development of AF in future studies.

Iatrogenic aortic regurgitation after radiofrequency ablation of idiopathic ventricular arrhythmias originating from the aortic valvular region.

BACKGROUND: Radiofrequency ablation at the aortic root has the potential risk of aortic regurgitation (AR). OBJECTIVE: This study investigated the incidence and clinical features of iatrogenic AR after catheter ablation of idiopathic ventricular arrhythmias originating from the aortic root. METHODS: We studied 45 consecutive patients with idiopathic ventricular arrhythmias originating from the aortic cusps (ACs; AC group; n = 32 [71%]) and papillary muscles (control group; n = 13 [29%]) who underwent ablation via a retrograde aortic approach and serial echocardiography before and within 24 hours after the ablation procedure. No patients had preexisting AR. RESULTS: After ablation, mild AR occurred in 5 AC group patients and 1 control group patient. Regurgitant flow was observed at the center of the aortic leaflets in 3 patients, the left coronary cusp-noncoronary cusp commissure in 2 patients, and both in 1 patient. No patients undergoing ablation only above the aortic valve developed AR. In AC group patients, the occurrence of AR was associated with a longer ablation time (24 ± 14 minutes vs 10 ± 5 minutes; P < .01) and higher average output (36.6 ± 4.2 W vs 32.0 ± 3.2 W; P = .01). The same severity of AR still existed after 16.2 ± 3.6 months of follow-up. No patients required any additional medical management or surgical intervention. CONCLUSION: Iatrogenic mild AR after ablation in the aortic root occurred with a noticeable prevalence, which was associated with extensive ablation both above and below the ACs as well as catheter-related mechanical factors. Although it did not appear to aggravate the hemodynamic status during the mid-term follow-up, careful monitoring of AR progression should be considered.

Initial Result of Antrum Pulmonary Vein Isolation Using the Radiofrequency Hot-Balloon Catheter With Single-Shot Technique.

OBJECTIVES: This study sought to determine the feasibility of a novel simplified ablation protocol targeting only the pulmonary vein antrum using the radiofrequency hot-balloon catheter in patients with paroxysmal atrial fibrillation. BACKGROUND: Radiofrequency hot-balloon (RHB) catheter has been recently introduced into clinical practice for pulmonary vein isolation (PVI). The authors hypothesized that a novel simplified ablation protocol targeting only the PV antrum with energy application for a longer time (single-shot technique) could be an alternative approach to achieve PVI, while avoiding unnecessary energy application at the PV ostium. METHODS: A total of 61 consecutive paroxysmal atrial fibrillation patients (age 64.1 ± 10.9 years, 48 male) who underwent antrum RHB-PVI were enrolled. Energy applications were performed following the pre-specified protocol only targeting the PV antrum. If the PVI was not achieved after 2 energy applications using the RHB, a touch-up ablation was performed. RESULTS: Of 241 PV, including 3 left common PV, 194 (80%) were isolated exclusively using the RHB. The target PVI average per group of 15 consecutive procedures improved from 75% (initial 15) to 89% (last 16) of patients. The injected volume was greatest in the right superior PV (13.1 ± 2.0 ml) and the smallest in the left inferior PV (10.8 ± 1.1 ml), and 23 PV (9.5%) required over 15 ml (estimated balloon diameter of 30 mm). Periprocedural complications were noted in 3 patients (4.9%), but phrenic nerve injury was not observed. Sinus rhythm maintenance at 12-month follow-up was achieved in 57 patients (93%). CONCLUSIONS: A novel simplified antrum RHB-PVI appears to be a feasible technique for the treatment of paroxysmal atrial fibrillation.

Epicardial connection between the right-sided pulmonary venous carina and the right atrium in patients with atrial fibrillation: A possible mechanism for preclusion of pulmonary vein isolation without carina ablation.

BACKGROUND: Ablation of the pulmonary venous carina is occasionally required for pulmonary vein isolation (PVI) despite its nonessential role in ipsilateral PVI from the anatomical (endocardial) viewpoint. Although the Bachmann bundle (BB) is a common and main interatrial band, local variations in small tongues of muscular fibers were frequently found in autopsy studies. OBJECTIVE: We sought to clarify the effect of the electrical conduction pattern from the right atrium (RA) to the left atrium (LA) during sinus rhythm on the necessity of performing right-sided pulmonary venous carina ablation to achieve PVI. METHODS: Study subjects comprised 37 consecutive patients undergoing initial catheter ablation of lone atrial fibrillation. During sinus rhythm, RA and LA activation maps were acquired using an electroanatomical mapping system. LA breakthroughs were classified into 3 sites: BB, fossa ovalis (FO), and right-sided pulmonary venous carina. Patients were divided into the carina-ABL (ablation) or non-carina-ABL group on the basis of the necessity of pulmonary venous carina ablation to achieve PVI. RESULTS: Patients were classified in the non-carina-ABL group (n = 26 [70%]) and carina-ABL group (n = 8 [22%]) after excluding 3 patients (8%) because of their complex ablation lesion sets. Breakthrough occurred in the BB (n = 21 patients [62%]), FO (n = 7 [21%]), carina (n = 1 [3%]), carina and BB (n = 3 [9%]), and carina and FO (n = 2 [6%]). Carina breakthrough occurred in 6 patients (75%) in the carina-ABL group but in no patients in the non-carina-ABL group (P < .0001). CONCLUSION: PVI was not achievable without carina ablation in one-fifth of patients, probably because of epicardial connections present between the right-sided pulmonary venous carina and the RA.

Idiopathic Ventricular Arrhythmias Originating From the Vicinity of the Communicating Vein of Cardiac Venous Systems at the Left Ventricular Summit.

BACKGROUND: The communicating vein (CV) between the great cardiac vein and small cardiac venous systems passes between the aortic and pulmonary annulus and is located in close association with the left ventricular summit (summit CV). METHODS AND RESULTS: Thirty-one patients with idiopathic ventricular arrhythmias (VAs) underwent mapping of the left ventricular summit by using a 2F microcatheter introduced into the summit CV with coronary sinus venographic guidance. Of these, 14 patients were found to have summit-CV VAs. The remaining 17 patients (control group) had VAs originating from the right ventricular outflow tract and the aortic cusps. In patients with summit-CV VAs, the earliest activation during VAs in the summit CV preceded QRS onset by 34.1±5.3 ms. The summit-CV VAs exhibited inferior axis, negative polarity in lead I, deeper QS wave in lead aVL than aVR, and nonspecific bundle branch block morphology with an R/S ratio in lead V1 of 0.67±0.33, which could be distinguishable from VAs originating from the right ventricular outflow tract and the right coronary cusp. Because of the inaccessibility of the summit CV to ablation catheter, ablation of summit-CV VAs was attempted at adjacent structures where an excellent pacemap was rarely obtained. Overall ablation success was achieved in 10 (71%) patients with summit VAs and 15 (88%) patients in control group (P=0.24). CONCLUSIONS: The myocardium near the summit CV can be the source of idiopathic VAs. Direct monitoring of the summit CV is helpful for identifying the site of origin and provides a landmark of the ablation target, which may facilitate ablation through adjacent structures.

Fascicular Ventricular Tachycardia Originating From Papillary Muscles: Purkinje Network Involvement in the Reentrant Circuit.

BACKGROUND: Verapamil-sensitive fascicular ventricular tachycardia (FVT) has been demonstrated to be a reentrant mechanism using the Purkinje network as a part of its reentrant circuit. Although the papillary muscles (PMs) are implicated in arrhythmogenic structure, reentrant FVT originating from the PMs has not been well defined. METHODS AND RESULTS: We studied 13 patients in whom FVT was successfully eliminated by ablation at the posterior PMs (n=8; PPM-FVT) and anterior PMs (n=5; APM-FVT). Although intravenous administration of verapamil (5 mg) terminated ventricular tachycardia (VT) in 6 patients, VT was only slowed in the remaining 7 patients. PPM-FVT exhibited right bundle branch block and superior right axis (extreme right axis) or horizontal axis deviation. APM-FVT exhibited right bundle branch block configuration and right axis deviation with deep S wave in leads I, V5, and V6. VT was reproducibly induced by programmed atrial or ventricular stimulation. His-ventricular interval during VT was shorter than that during sinus rhythm. Ablation at the left posterior or anterior fascicular regions often changed the QRS morphology but did not completely eliminate it. Mid-diastolic Purkinje potentials were recorded during VT around the PMs, where ablation successfully eliminated the tachycardia. All patients have been free from recurrent VT after ablation. CONCLUSIONS: Reentrant circuit of verapamil-sensitive FVT can involve the Purkinje network lying around the PMs. PM-FVT is a distinct entity that is characterized by distinctive electrocardiographic characteristics and less sensitivity to verapamil administration compared with common type FVT. Ablation targeting the mid-diastolic Purkinje potentials around the PMs during tachycardia can be effective in suppressing this arrhythmia.

J Waves Are Associated With the Increased Occurrence of Life-Threatening Ventricular Tachyarrhythmia in Patients With Nonischemic Cardiomyopathy.

INTRODUCTION: Recent studies showed that J waves were associated with higher incidence of ventricular tachyarrhythmia (VT/VF) in patients with idiopathic ventricular fibrillation (VF) and myocardial infarction. We sought to assess the association between J waves and VT/VF in patients with nonischemic cardiomyopathy (NICM). METHODS AND RESULTS: We retrospectively enrolled 109 patients (79 men; mean age, 60 ± 15 years) with NICM who underwent implantable cardioverter defibrillator (ICD) implantation. The primary endpoint of this study was the occurrence of appropriate device therapy due to sustained VT/VF. The J wave was electrocardiographically defined as an elevation of the terminal portion of the QRS complex of >0.1 mV in at least 2 contiguous inferior or lateral leads. Among the 109 patients, 37 (34%) experienced an episode of appropriate device therapy during a median follow-up period of 25.9 (IQR 11.5-54.3) months. Kaplan-Meier curves showed that the presence of J waves on the 12-lead ECG obtained before device implantation was associated with an increased occurrence of appropriate device therapy (P < 0.001). Multivariate Cox proportional regression analysis revealed that the presence of J waves (HR 2.95; 95% CI 1.31-6.64; P = 0.009) was an independent predictor for the occurrence of appropriate device therapy. In the subgroup analysis of the patients with dilated or hypertrophic cardiomyopathy, J wave tended to increase the occurrence of appropriate device therapy (P = 0.056 and P = 0.092, respectively). CONCLUSIONS: The presence of J waves was an independent predictor for the occurrence of appropriate device therapy in patients with NICM who underwent ICD implantation.

Successful coronary stenting in anomalous right coronary artery by using an inner catheter with mother and child technique under multislice CT guidance.

The ectopic location and unusual coronary course of the anomalous right coronary artery (RCA) from the left sinus of Valsalva makes percutaneous coronary intervention difficult. In this report, we describe a case of successful stent implantation in an anomalous RCA performed using a 4.5F inner catheter with a 6F guiding catheter used in the mother and child system under the guidance of multislice computed tomography. This approach was found to be safe and feasible in cases involving anomalous coronary origin because of the excellent engagement and support provided by the guiding catheter.