論文

Aims: To show 2 examples in which the analysis of the effect of bundle branch block on orthodromic reciprocating tachycardia cycle length was misleading. Methods and results: We performed an electrophysiological study in two patients with orthodromic reciprocating tachycardia showing a transition from wide to narrow QRS during tachycardia. Our two cases of left bundle branch block during reciprocating tachycardia using infero-septal pathways show that ventricular to atrial conduction time prolongation may be larger than 30 ms and may be concealed by a shortening of atrial to ventricular conduction time. In the 2 cases, the atrial insertion of the accessory pathway could be successfully ablated from the right atria at the ostium of the coronary sinus. Conclusions: The observation of the association between left bundle branch block and cycle length prolongation during reciprocating tachycardia may be associated with a successful ablation at the ostium of the coronary sinus. © The European Society of Cardiology 2007. All rights reserved.

Background: T-wave morphology parameters based on principal component analysis (PCA) are candidate to better understand the relation between QT prolongation and torsades de pointes. We aimed to assess the repeatability and to determine the influence of T-end position on PCA parameters. Methods: Digital ECGs recorded from 30 subjects were used to assess short term (5 minutes), circadian and long-term (28 days) repeatability of PCA parameters. The T-end cursor position was moved backward and forward (± 8 ms) from its optimal position. We calculated QRS-T angle, PCA ratio, and T-wave residuum (TWR). Results: At long-term evaluation, coefficients of variation were 11.3 ± 9.9%, 11.7 ± 7.1%, and 23.0 ± 22.0% for the QRS-T angle, PCA ratio, TWR, respectively. After moving the T-end cursor, repeatability was 0.42 ± 0.2%, 1.00 ± 1.04%, 4.0 ± 4.2% for the same PCA parameters. Conclusions: T-wave morphology parameters based on PCA are reproducible with the exception of TWR and QRS-T angle. In addition, PCA is robust, showing only little dependence on T-end cursor position. These data should be taken into account for safety pharmacology trials. © 2007, Copyright the Authors.

We report a case showing 4 types of aberrant conduction and 2 types of gap phenomena produced by single atrial extrastimulus during sinus rhythm. One of the gap phenomena was associated with dual His bundle pathways, demonstrating a fast-to-slow jump-up phenomenon. Of note, a sharp potential considered as retrograde His bundle activations was recorded, which indicated that the activation wave front descended the slow His bundle pathway and turned up the fast His bundle pathway. © 2007 Elsevier Inc. All rights reserved.

During orthodromic AVRT with a left posterior AP, an antidromic AVRT was induced by the right ventricular extrastimulus, which utilized atriofascicular fiber for the anterograde conduction. The cycle length of the antidromic AVRT with LBBB pattern was shorter than that of the orthodromic AVRT. © 2006 by Futura Publishing Company, Inc.

Background: Whether amiodarone can improve the patient's clinical outcome by reducing implantable cardioverter-defibrillator (ICD) therapy deliveries for ventricular tachycardia or fibrillation (VT/VF) has not been clearly evaluated. Methods and Results: A total of 507 patients with VT/VF due to organic heart disease who had ICDs implanted were enrolled in this study. The patients were divided into 3 groups: Amiodarone (n=247), Class I antiarrhythmic drug (n=103) and Control (n=157) groups, and the total cause mortality and arrhythmic event free survival rates were evaluated between the groups. The mean follow-up period was 38±27 months. The left ventricular ejection fraction was significantly decreased in the Amiodarone group (Amiodarone: 37±15%; Class I: 39±16%; Control: 44±17%). The mortality and arrhythmic events were significantly higher in the Class I group than the Amiodarone group (p<0.05), but there was no significant difference between the Amiodarone and Control groups (arrhythmic event free rate at 5 years: Amiodarone: 53%; Class I: 35%; Control: 48%; 5 year survival: 86%, 74% and 77%, respectively). Side effects from amiodarone were found in 12% of the patients, but no fatal events were observed. Conclusions: The present study could not demonstrate the benefit of amiodarone in ICD patients, probably due to a significant clinical bias exerted in selecting this drug.

Background: Para-Hisian pacing is an effective method of differentiating between pathways for retrograde conduction over the accessory pathway (AP) and over the atrioventricular node (AVN). When performing para-Hisian pacing, the pacing spike sometimes captures only the His bundle, which we named "pure" Hisian pacing (Hc). Objective: We evaluated the significance of pure Hisian pacing for predicting the pathways of ventriculoatrial conduction. Methods: In 62 patients with supraventricular tachycardia, both para-Hisian and pure Hisian pacing were carried out during the sinus rhythm, resulting in three different types of electrocardiographic complexes with wide (local ventricular myocardial capture), slightly narrow (both local myocardial and His bundle capture), and very narrow QRS widths (Hc). A change of atrial activation sequence as demonstrated by these pacing modes indicated the presence of multiple retrograde pathways. The diagnosis of retrograde pathways by para-Hisian pacing with or without Hc was evaluated. Results: In 22 patients with AVN reentrant tachycardia, para-Hisian pacing alone was able to correctly predict ventriculo-atrial conduction exclusively through the AVN without requiring findings from Hc. In 40 AP patients, para-Hisian pacing showed a pattern of retrograde conduction through the AVN in six, through both the AVN and AP in 10, and through an AP in 24 patients. Four of these 24 patients were diagnosed as having multiple pathways (AP+AVN or dual APs) by the addition of Hc. Conclusion: Pure Hisian pacing can help disclose another pathway for retrograde conduction in AP patients, which is unpredicted by ordinary para-Hisian pacing. © 2006 Heart Rhythm Society.

Arrhythmogenic right ventricular dysplasia (ARVD) is a cardiomyopathy of the right ventricle due to adipose infiltration of the myocardium with surviving myocardial fibres surrounded by fibrosis. It gives rise to right ventricular dilatation, which starts locally before becoming diffuse, and, sometimes in the late stages, to symptoms of cardiac failure. It may also be associated with left ventricular involvement. The main complication is sudden death due to a ventricular arrhythmia. ARVD is responsible for 3 to 10% of all unexplained sudden deaths before 65 years of age. ARVD has a genetic origin, with some recessive but a majority of autosomal dominant forms. Nine different loci have been reported in the autosomal dominant forms and four genes have been identified. A number of these mutations is responsible for abnormalities of cellular junction, more specifically of the desmosomes. These studies have shown several different forms of ARVD and, consequently, the term arrhythmogenic right ventricular cardiomyopathy would be a more appropriate terminology for the pathology. This paper reviews the diagnostic, genetic and therapeutic aspects of the disease. In particular, the evaluation of the arrhythmic risk is underlined as it is an important and difficult problem which has not yet been satisfactorily resolved. It requires integration of clinical and electrocardiographic criteria with morphological and functional imaging methods. Molecular biology could play a role in the prognostic assessment in the future.

Background: ST segment elevation in the right precordial leads constitutes the electrocardiogram (ECG) hallmark of Brugada syndrome (BS). This pattern is variable and can be concealed, but the magnitude and the cause of ST segment fluctuations have been poorly investigated. Objective: Our goal was to quantify ST changes and to assess rate and autonomic influences on ST level. Methods: A 12-lead ECG was continuously recorded during 24 hours in 20 patients with BS (ages 49 ± 12) and 10 healthy subjects (ages 32 ± 7). Using two-dimensional binning we obtained average QRS-T complexes every 30 minutes (time bins) and at different RR intervals (rate bins) for each subject. ST level was measured at five different points located 90, 100, 110, 120, and 140 ms after Q onset (Qo). In BS patients, the highest ST elevation was measured 110 ms after Qo (Qo+110). Results: ST level changes between time points were significantly greater in patients with BS compared with control subjects: on lead V2, the range of ST level at Qo+110 was 264 ± 85 μV in BS and 91 ± 22 μV in control subjects (P <.01). In BS, ST level decreased with heart rate acceleration: the difference in ST level at Qo+110 for RR = 900 and 600 ms was 55 ± 53 μV (P <.01). HFnu was positively, although weakly, correlated with ST level (R2 = 0.02, P <.01). Conclusions: ECG changes observed in patients with BS are related in part to heart rate influences on ST segment level. These spontaneous fluctuations over a 24-hour time period suggest that Holter recordings may improve the ECG diagnosis sensitivity in BS. © 2006 Heart Rhythm Society.

We present a patient with ventricular fibrillation (VF) associated with J-wave manifestation following pericarditis after catheter ablation of paroxysmal atrial fibrillation (AF). The premature ventricular contraction induced VF with J-waves in the inferior leads 2 days after the procedure. The patient's juvenile onset of AF and a family history of sudden cardiac death strongly suggested an underlying hereditable channelopathy. The late gadolinium enhancement in the posterior wall, viewed by cardiac magnetic resonance imaging, matched the leads of the J-waves. VF might develop in juvenile onset of AF especially in individuals with a family history of sudden cardiac death. © 2013 Canadian Cardiovascular Society.

Background: Radiofrequency ablation has limitations, largely related to creation of lesions by heating. Here, we report the first nonthermal ablation by applying photodynamic therapy (PDT) to cardiac tissues using a custom-made deflectable laser catheter. The present study investigated the feasibility of PDT for cavotricuspid isthmus ablation in a canine model. Methods and Results: We evaluated the pharmacokinetic profiles of 17 canines after administration of a photosensitizer (talaporfin sodium) by various protocols. We succeeded in maintaining the photosensitizer concentration at a level in excess of the clinically effective dose for humans. Using a 4-polar 7-French deflectable laser catheter, we performed PDT-mediated cavotricuspid isthmus ablation in 8 canines. PDT caused oxidative injury only to the irradiated area and successfully produced a persistent electric conduction block. No acute, gross changes such as edematous degeneration, thrombus formation, steam pops, or traumatic injury were observed after irradiation. Hematoxylin and eosin staining of tissues samples also showed well-preserved endothelial layers. Testing of the blood samples taken before and after the procedure revealed no remarkable changes. Lesion size at 2 weeks after the procedure and the temperature data collected during irradiation were compared between the PDT and irrigated radiofrequency ablation procedures. A ventricular crosssection revealed a solid PDT lesion, which was as deep as a radiofrequency lesion. In addition, endocardial, surficial, and intramural temperature monitoring during the PDT irradiation clearly demonstrated the nonthermal nature of the ablation technique. Conclusions: Nonthermal PDT-mediated catheter ablation is a potentially novel treatment for cardiac arrhythmias. © 2013 American Heart Association, Inc.

Rapid electrical firing originating from notably deep inside the PV travelled from the focus to the LA with heterogeneous conduction properties and captured the LA resulting in an absolute irregular atrial arrhythmia in this patient. © 2013 Wiley Periodicals, Inc.

Objectives This study sought to characterize patients with idiopathic ventricular fibrillation (IVF) who develop electrical storms. Background Some IVF patients develop ventricular fibrillation (VF) storms, but the characteristics of these patients are poorly known. Methods Ninety-one IVF patients (86% male) were selected after the exclusion of structural heart diseases, primary electrical diseases, and coronary spasm. Electrocardiogram features were compared between the patients with and without electrical storms. A VF storm was defined as VF occurring ≥3 times in 24 h and J waves >0.1 mV above the isoelectric line in contiguous leads. Results Fourteen (15.4%) patients had VF storms occurring out-of-hospital at night or in the early morning. J waves were more closely associated with VF storms compared to patients without VF storms: 92.9% versus 36.4% (p < 0.0001). VF storms were controlled by intravenous isoproterenol, which attenuated the J-wave amplitude. After the subsidence of VF storms, the J waves decreased to the nondiagnostic level during the entire follow-up period. Implantable cardioverter-defibrillator therapy was administered to all patients during follow-up. Quinidine therapy was limited, but the patients on disopyramide (n = 3), bepridil (n = 1), or isoprenaline (n = 1) were free from VF recurrence, while VF recurred in 5 of the 9 patients who were not given antiarrhythmic drugs. Conclusions The VF storms in the IVF patients were highly associated with J waves that showed augmentation prior to the VF onset. Isoproterenol was effective in controlling VF and attenuated the J waves, which diminished to below the diagnostic level during follow-up. VF recurred in patients followed up without antiarrhythmic agents. © 2013 by the American College of Cardiology Foundation Published by Elsevier Inc.

BACKGROUND-: The characteristic ECG of Brugada syndrome (BS) can be masked by complete right bundle-branch block (CRBBB) and exposed by resolution of the block or pharmacological or pacing maneuvers. METHODS AND RESULTS-: The study consisted of 11 patients who had BS and CRBBB. BS was diagnosed before the development of CRBBB, on the resolution of CRBBB, or from new characteristic ST-segment changes that could be attributable to BS. Structural heart diseases were excluded, and coronary spasm was excluded on the basis of a provocation test at catheterization. In 7 patients, BS was diagnosed before the development of CRBBB. BS was diagnosed when CRBBB resolved spontaneously (n=1) or by right ventricular pacing (n=3). The precipitating cause for the spontaneous resolution of CRBBB, however, was not apparent. On repeated ECGs, new additional upward-convex ST-segment elevation was found in V2 or V3 in 3 patients. In 2 patients, new ST-segment elevation was induced by class IC drugs. The QRS duration was more prolonged in patients with BS and CRBBB compared with age-and sex-matched controls: 170±13 versus 145±15 milliseconds in V1 and 144±19 versus 128±7 milliseconds in V5 (both P<0.0001). The amplitude of R in V1 was larger in the BS patients than in the control subjects (P=0.0323), but that of R′ was similar (P=0.0560). CONCLUSIONS-: BS can coexist behind CRBBB, and CRBBB can completely mask BS. BS might be demonstrated by relief of CRBBB or by spontaneous or drug-induced ST-segment elevation. The prevalence, mechanism, and clinical significance of a combination of CRBBB and BS are yet to be determined. © 2013 American Heart Association, Inc.

Background A substantial number of patients with idiopathic ventricular fibrillation (IVF) present with no specific electrocardiographic (ECG) findings. Objective To evaluate complete right bundle branch block (RBBB) in patients with IVF. Methods Patients with IVF showing complete RBBB were included in the present study. Structural and primary electrical diseases were excluded, and provocation tests were performed to exclude the presence of spastic angina or Brugada syndrome (BrS). The prevalence of complete RBBB and the clinical and ECG parameters were compared either in patients with IVF who did not show RBBB or in the general population and age and sex comparable controls with RBBB. Results Of 96 patients with IVF, 9 patients were excluded for the presence of BrS. Of 87 patients studied, 10 (11.5%) patients showed complete RBBB. None had structural heart diseases, BrS, or coronary spasms. The mean age was 44 ± 15 years, and 8 of 10 patients were men. Among the ECG parameters, only the QRS duration was different from that of the other patients with IVF who did not show complete RBBB. Ventricular fibrillation recurred in 3:2 in the form of storms, which were well suppressed by isoproterenol. Complete RBBB was found less often in control subjects (1.37%; P <.0001), and the QRS duration was more prolonged in patients with IVF: 139 ± 10 ms vs 150 ± 14 ms (P =.0061). Conclusions Complete RBBB exists more often in patients with IVF than in controls. A prolonged QRS complex suggests a conduction abnormality. Our findings warrant further investigation of the role of RBBB in the development of arrhythmias in patients with IVF. © 2013 Heart Rhythm Society.

Ridge-Related Reentry Introduction The ridge between the left pulmonary veins (PV) and the left atrial appendage composes part of the lateral mitral isthmus (LMI). Following circumferential PV isolation and LMI linear ablation for the treatment of atrial fibrillation (AF), a critical pathway might develop over the ridge leading to a ridge-related reentry (RRR). Methods and Results Out of 61 patients who underwent circumferential PV isolation appended by LMI ablation, 5 patients developed RRR. The diagnosis of RRR was based on (1) macro-reentrant atrial tachycardia involving the septum, anterior and inferior wall of the left atrium; (2) slow conduction along the ridge; (3) wide-split double potentials in the ventricular aspect of the LMI were identified with the coronary sinus (CS) electrodes. RRR was investigated with electroanatomical mapping and entrainment mapping and catheter ablation was carried out in all patients. The mean cycle length (CL) of RRR was 312 ± 82 milliseconds and the PPIs at the left atrial septum, inferior and anterior wall during RRR were 10 ± 6, 12 ± 8, 9 ± 5 milliseconds longer than the RRR CL. The interval of the double potentials recorded in the CS electrodes crossing the LMI was 164 ± 38 milliseconds during RRR and the PPI on the LMI near the mitral annulus was 57 ± 10 milliseconds longer than the RRR CL. Catheter ablation was performed anatomically by targeting the ridge and successfully terminated RRR. Conclusion After circumferential PV isolation and ablation for LMI in patients with AF, RRR can develop by utilizing the surviving myocardial tissue of the ridge as a critical pathway. © 2013 Wiley Periodicals, Inc.

AimsPhrenic nerves (PNs) can be damaged during interventional cardiovascular therapy because of the nerves' proximity to the heart. This study aimed to analyse the anatomy of the PN by performing three-dimensional (3-D) imaging and pace mapping.Methods and resultsForty consecutive patients with atrial fibrillation referred for catheter ablation were enrolled in this study and underwent preoperative cardiovascular computed tomography (CT). In 10 patients with sinus rhythm during tomography, 3-D images of the right and left pericardiophrenic bundles (PBs), consisting of the ipsilateral PN and accompanying vessels, were reconstructed from the CT data. During the electrophysiological study, PN pace mapping was performed from both atria. The course of the PBs generated by CT imaging and the PN pace map generated by the 3-D mapping system were compared. By electrical pacing, the PNs were captured in 40 individuals (100%) from the superior vena cava and the right atrium, and in 17 patients (43%) from the left atrial appendage. Clear 3-D images of PBs were reconstructed in all cases in which CT-reconstruction was performed. The distance between the locations of the right PB generated by CT imaging and those of the right PN-capture sites in the right-sided heart on the mapping system was 8.7 ± 5.8 mm.ConclusionsThe 3-D routes of the bilateral PNs passing near the heart were verified by pace mapping. The preoperatively reconstructed 3-D course of the PB succeeded in locating the PN, which may facilitate the comprehension of PN anatomy to avoid its injury during interventional cardiovascular therapy. © 2013 The Author.