Published papers

Introduction Lead failures (LFs) are one of the most common complications in patients implanted with cardiovascular implantable electronic devices. LFs often cause serious secondary complications such as inappropriate ICD shocks or asystole. This study aimed to identify the clinical factors associated with the occurrence of LFs. Methods A total of 735 consecutive device implantations (mean age 67 ± 15 years, males 64%) performed at a single university hospital setting from 1997 to 2014 were included. The implanted devices consisted of 421 pacemakers, 250 implantable cardioverter defibrillators (ICD), 9 cardiac resynchronization therapy pacemakers (CRT-P), and 55 CRT defibrillators (CRT-D). The primary endpoint was the development of an LF. Results During a mean duration of 5.8 ± 4.3 years, 38 LFs developed in 31 patients (mean age 56 ± 14 years). LFs included 32 ICD (7 Sprint Fidelis, 2 Riata), and 6 pacing leads. Nine patients received inappropriate ICD shocks and 1 had syncope due to an LF. All patients underwent lead reinsertions with device replacements. Eight patients required opposite site implantations due to venous occlusions. The predictive factors of LFs were the age, male sex, taller body length, ICD vs. pacemaker, lesser lead number, extra-thoracic puncture of the axillary vein vs. a cut-down of the cephalic vein, use of recalled leads and patients with idiopathic ventricular fibrillation (IVF) and Brugada syndrome (BrS). Conclusion LFs occurred mainly with ICD leads. A lesser age, the puncture method, lead model, and diagnosis of IVF/BrS were associated with the development of LFs.

Background: Protocols on the use of novel oral anticoagulants for stroke prevention in patients with atrial fibrillation (AF) undergoing electrical cardioversion (ECV) are lacking. Aim: The study was aimed at evaluating the efficacy of dabigatran (Dabi) treatment in preventing peri-ECV stroke. Methods: A retrospective survey of the incidence and fate of left atrial (LA) thrombus during Dabi therapy in patients with AF was conducted between December 2012 and January 2013 by the Japanese Heart Rhythm Society. Results: A total of 198 patients from 299 institutions underwent transesophageal echocardiography (TEE) to rule out LA thrombus before ECV. Of these, LA thrombus was found in eight patients (4%), who tended to be older (67.3 vs. 61.3 years, p=0.175), had higher CHADS2 scores (1.88 vs. 0.95, p=0.058), and a higher prevalence of prior stroke or transient ischemic attack (22.2% vs. 2.6%, p=0.034) than those without LA thrombus. Of the eight patients with LA thrombus, one had LA thrombus during a Dabi 150 mg b.i.d treatment, whereas the remaining seven were receiving 110 mg b.i.d for 3 weeks or longer. In 6 of the 8 patients with LA thrombus, a second TEE was performed, revealing complete resolution of LA thrombus in five; among these five patients, one received Dabi dosage of 150 mg b.i.d unchanged, two received an increased dosage from 110 mg to 150 mg b.i.d, and two were switched to warfarin. Two patients had a stroke 3 and 15 days after ECV, and one had a major large intestine bleeding episode during Dabi therapy. Conclusions: LA thrombus developed in 4% of patients with AF receiving Dabi. Older patients with a higher CHADS2 score receiving a lower Dabi dosage were more likely to develop LA thrombus, which was resolved with a prolonged or increased dosage. A higher Dabi dosage may be more beneficial before ECV but prospective randomized studies would be needed to confirm these results.

Aims Photodynamic therapy (PDT) is based on non-thermal injury mediated by singlet oxygen species and is used clinically in cancer therapy. In our continuing efforts to apply this technology to cardiac catheter ablation, we clarified the optimal condition for creating PDT-mediated lesions using a laser catheter. Methods and results In a total of 35 canines, we applied a laser directly to the epicardium of the beating heart during open-chest surgery at 15 min after administration of a photosensitizer, talaporfin sodium. We evaluated the lesion size (depth and width) using hematoxylin-eosin staining under varying conditions as follows: laser output (5, 10, 20 W/cm2), irradiation time (0-60 s), photosensitizer concentration (0, 2.5, 5 mg/kg), blood oxygen concentration (103.5 ± 2.1 vs. 548.0 ± 18.4 torr), and contact force applied during irradiations (low: <20 g, high: >20 g). A laser irradiation at 20 W/cm2 for 60 s under 5 mg/kg (29 μg/mL) of photosensitizer induced a lesion 8.7 ± 0.8 mm deep and 5.2 ± 0.2 mm wide. The lesion size was thus positively correlated to the laser power, irradiation time, and photosensitizer concentration, and was independent of the applied contact force and oxygen concentration. In addition, the concentration of the photosensitizer strongly correlated with the changes in the pulse oximetry data and fluorescence of the backscattering laser, suggesting that a clinically appropriate condition could be estimated in real time. Conclusion Photodynamic therapy-mediated cardiac lesions might be controllable by regulating the photosensitizer concentration, laser output, and irradiation time.

Aims The left atrial appendage (LAA) represents the major source of cardiac thrombus formation in patients with atrial fibrillation (AF). Phased-array intracardiac echocardiography (ICE) has become available and frequently used during catheter ablation of AF. We attempted to study the feasibility of using ICE for the visualization and evaluation of the LAA from the pulmonary artery (PA) in patients with AF. Methods and Results Eighty patients with AF undergoing catheter ablation (70 males, 57.5 ± 9.1 years) were included. Transoesophageal echocardiography was performed on the prior day before the catheter ablation, and ICE was performed just before the transseptal puncture during the catheter ablation. The ICE catheter was advanced up into the PA from the femoral vein, where the LAA was clearly and entirely visualized by manipulating the ICE catheter. We compared the degree of spontaneous echo contrast, and the correlation was obtained between the ICE and TEE (κ = 0.534, P < 0.001). Furthermore, the LAA flow velocity (LAA emptying and filling velocities) measured by ICE had a good correlation to that measured by TEE (R = 0.872, P < 0.01 and R = 0.753, P < 0.01, respectively). No patients developed any complications. Conclusion The utilization of ICE in the PA is feasible for the observation and evaluation of the LAA.

Background J waves can be observed in individuals of the general population, but electrocardiographic characteristics are poorly understood. Objective The purpose of this study was to examine the J-wave dynamicity in a general patient population. Methods The responses of J waves (>0.1 mV above the isoelectric line in 2 contiguous leads) to varying RR intervals were analyzed. Patients with aborted sudden cardiac death, documented ventricular fibrillation, or a family history of sudden cardiac death were excluded. The J-wave amplitude was measured at baseline, in beats with short RR intervals in conducted atrial premature beats (APBs) or atrial stimulation during the electrophysiology study, and in the beats next to APBs with prolonged RR intervals. Results Mainly notched J waves were identified in 94 of 701 (24.5%) general patients (13.4%), and APBs were present in 23 of 94 (24.5%) patients. The mean baseline amplitude of J waves was 0.20 ± 0.06 mV at the baseline RR interval of 853 ± 152 ms, 0.25 ± 0.11 mV at the RR interval in the conducted APB of 545 ± 133 ms (P =.0018), and 0.19 ± 0.08 mV at the RR interval of 1146 ± 314 ms (P =.3102). The clinical characteristics were not different between patients with and without tachycardia-dependent augmentation of J waves. Augmentation of J waves was confirmed by the electrophysiology study: 0.28 ± 0.12 mV vs 0.42 ± 0.11 mV at baseline and in the beats of atrial stimulation, respectively (P =.0001). However, no bradycardia-dependent augmentation (>0.05 mV) was observed. Such tachycardia-dependent augmentation can represent depolarization abnormality rather than repolarization abnormality. Conclusion J waves in a general patient population were augmented at shorter RR intervals, but not at prolonged RR intervals. Mechanistically, conduction delay is most likely responsible for this.

Rhythm control therapy by sodium channel blockers is widely performed for the treatment of paroxysmal atrial fibrillation. Here, we present a case of acquired Brugada syndrome by pill-in-the-pocket treatment using pilsicainide. It is important that this therapy should be applied only after confirming the drug safety to the patients. © 2010 Aizawa et al, publisher and licensee Dove Medical Press Ltd.

We have proposed a new type of atrial fibrillation treatment with the early state photodynamic therapy (PDT), in which the interval time between the photosensitizer injection and irradiation is shorter than that in conventional way. We had demonstrated the acute electrical blockade by the PDT with talaporfin sodium and a red (670 nm) diodelaser in ex vivo and in vivo experiment using rat normal myocardial tissue. The previous study of intracellular Ca2+ concentration measurement in rat cardiac myocytes during the PDT indicated that Ca2+ influx induced by the plasma membrane damage might be the main cause of the acute reaction of myocardial tissue. We found that the cell damage of cardiac myocytes triggered by the PDT was mainly influenced by the site where the photosensitizer exists. In this study, we examined the relationship between the sites of talaporfin sodium existing and cell death phenotypes in response to the PDT, in order to clarify the mechanism of the acute electrical blockade induced by the PDT in myocardial tissue. The talaporfin sodium fluorescence was observed after the various incubation times to visualize the time-lapse intracellular photosensitizer localization. The distribution of the photosensitizer was dependent on the incubation time. The change in intracellular Ca2+ concentration during the PDT was examined with a fluorescent Ca2+ indicator by a high-speed Nipkow confocal laser microscope (CSU-X1, Yokogawa Electric Company). We obtained the Ca2+ dynamics during the PDT which can explain the PDT-induced cell death pathways. We concluded that the Ca2+ influx induced by plasma membrane damage is the possible mechanism of the electrical blockade by the early state PDT. © 2009 SPIE.

Background: The coronary sinus (CS) including the great cardiac vein is an important anatomic structure that is considered a landmark for the mitral annulus (MA) and also a target for catheter ablation. Objective: This study evaluated the anatomical relationship between the CS and its surrounding structures visualized by multi-detector computed tomography (MDCT). Methods: We performed MDCT on 42 patients, and the ranges of the coronary arteries (CAs) and esophagus that ran closest (<5 mm) to the CS were examined. In addition, the distances between the CS and the MA and left ventricle and left atrium were compared with the amplitudes of the local atrial and ventricular electrograms in the CS at the most lateral point (3 o'clock) and the inferior point (6 o'clock) in the CS. Results: The distal portion of the right CA ran near the antero-inferior side of the CS ostium in 92% of the patients. The esophagus and the left circumflex CA proximity to the CS ran from 15 to 41 mm and from 53 to 104 mm from the ostium in all patients. At the 3 o'clock and 6 o'clock position of the MA, the distance between the center of the CS and MA was 12 and 13 mm, respectively, and showed negative correlation with the ratio of atrial and ventricular electrograms. Conclusion: The right CA, the left circumflex CA, and the esophagus were frequently located near the CS. The CS was shifted away from the MA, and the CS-MA distance could be predicted with intracardiac electrograms. © 2009 Heart Rhythm Society.

AimsCreation of complete linear lesions in the lateral mitral isthmus (LMI) by catheter ablation for treating atrial fibrillation remains technically challenging. We aimed to clarify whether a high take-off left inferior pulmonary vein (LIPV) can hamper the creation of a complete block at the LMI.Methods and resultsWe included 81 consecutive patients who underwent linear ablation at the LMI and cardiac computed tomography (CT) before ablation. We defined a high take-off LIPV when the level of the lower edge of the LIPV ostium was higher than that of the top of mitral annulus on CT. The clinical backgrounds, parameters, and long-term follow-up were then compared between the success (successful creation of a complete LMI block) and failure groups. A complete LMI block was obtained in 60/81 (76) patients. In the failure group, a high take-off LIPV was noted more commonly and the LMI tended to be longer than the success group. Multivariate analysis revealed that a high take-off LIPV was an independent predictor of failure to achieve a complete LMI block. The sinus rhythm maintenance rate was not different between the success and failure groups.ConclusionA high take-off LIPV hampered the creation of complete linear lesions in the LMI.

Background - The pathophysiological background of catecholaminergic polymorphic ventricular tachycardia is well understood, but the clinical features of this stress-induced arrhythmic disorder, especially the incidence and risk factors of arrhythmic events, have not been fully ascertained. Methods and Results - The outcome in 101 catecholaminergic polymorphic ventricular tachycardia patients, including 50 probands, was analyzed. During a mean follow-up of 7.9 years, cardiac events defined as syncope, aborted cardiac arrest, including appropriate discharges from implantable defibrillators, or sudden cardiac death occurred in 27 patients, including 2 mutation carriers with normal exercise tests. The estimated 8-year event rate was 32% in the total population and 27% and 58% in the patients with and without β-blockers, respectively. Absence of β-blockers (hazard ratio [HR], 5.48; 95% CI, 1.80 to 16.68) and younger age at diagnosis (HR, 0.54 per decade; 95% CI, 0.33 to 0.89) were independent predictors. Fatal or near-fatal events defined as aborted cardiac arrest or sudden cardiac death occurred in 13 patients, resulting in an estimated 8-year event rate of 13%. Absence of β-blockers (HR, 5.54; 95% CI, 1.17 to 26.15) and history of aborted cardiac arrest (HR, 13.01; 95% CI, 2.48 to 68.21) were independent predictors. No difference was observed in cardiac and fatal or near-fatal event rates between probands and family members. Conclusions - Cardiac and fatal or near-fatal events were not rare in both catecholaminergic polymorphic ventricular tachycardia probands and affected family members during the long-term follow-up, even while taking β-blockers, which was associated with a lower event rate. Further studies evaluating concomitant therapies are necessary to improve outcome in these patients. © 2009 American Heart Association, Inc.

Background: Visualization of the inner anatomical relationship of the pulmonary veins (PVs) and left atrium (LA) is important for achieving a better success rate and avoiding complications in circumferential LA ablation for atrial fbrillation (AF). Methods and Results: Twelve patients with AF underwent computed tomography and novel post-processing images that emphasized the boundaries of the PVs and LA were produced. Conclusions: The "Transparent View" images enabled visualization of the inner anatomical relationship of the PVs and LA in the same geometry as in pulmonary venography in all cases.

Ventricular safety pacing (VSP) is an algorithm used to prevent crosstalk inhibition and ventricular capture during the vulnerable period. We report a 78-year-old man with implantable dual-chamber defibrillator, in whom clusters of ventricular tachycardias (VTs) were provoked by the VSP. During rapid DDDR pacing, the delivery of the VSP after every other atrial-paced beat resulted in short-long-short ventricular sequences and induced VTs. An atrial-based lower rate timing, long atrioventricular pacing interval, and automatic gain control also accounted for this arrhythmogenic ventricular sequence. The VSP and the subsequent VT were eliminated by decreasing the pacing rate. © The Author 2008.

Objectives: This study aimed to elucidate the contribution of the repolarization restitution property to the sustained ventricular fibrillation (VF) in Brugada syndrome. Background: Although phase 2 re-entry develops as the trigger of VF, the other precipitating factors have remained unclear. Methods: Twenty-one patients with a type 1 Brugada electrocardiogram underwent programmed electrical stimulation. Before the VF induction, single extrastimuli were delivered at 3 basic drive cycle lengths (BCLs) (400 ms, 600 ms, and 750 ms) from the right ventricular apex (RVA) and outflow tract (RVOT), and the activation recovery interval (ARI) was measured at 5-mm vicinity of the pacing site. The maximum ARI restitution slope was determined using the overlapping least-squares linear segments. Results: We found that VF was inducible in 10 patients. A repeated-measure analysis of variance revealed that the slope in the RVA was steeper in patients with inducible VF than in those without but that in the RVOT was similar. The slope was steeper at longer BCLs and also steeper in the RVA than RVOT at BCLs of 600 and 750 ms. In patients with inducible VF, the percentage of patients exhibiting a slope >1 was 0%, 20%, and 75% in the RVA and 0%, 0%, and 14% in the RVOT at BCLs of 400 ms, 600 ms, and 750 ms, respectively. No patients without inducible VF had a slope >1. Conclusions: These results suggest the repolarization restitution property is a contributing factor to the propensity for VF in Brugada syndrome and, regarding this property, the RVA plays more important role than the RVOT. © 2008 American College of Cardiology Foundation.

Background: A 25-year-old woman experienced three episodes of syncope over the course of 2 years. The attacks all occurred just after she had sat down, and two were accompanied by convulsions. She had no obvious prodromes and no personal or family history of cardiovascular disease. Investigations: Electrocardiography, chest radiography, echocardiography, cerebral and cardiac MRI, electroencephalography, 24 h Holter monitoring, electrophysiological study with drug provocation testing and heart-rate variability analysis. Diagnosis: Vagally mediated ventricular fibrillation initiated by premature ventricular complexes arising from the right ventricular outflow tract. Management: Catheter ablation was performed at the right ventricular outflow tract and an implantable cardioverter-defibrillator was fitted.