Publications by authors named "Kimie Okubo"

Introduction: Data are lacking on the extent to which patients with non-valvular atrial fibrillation (AF) who are aged ≥80 years benefit from ablation treatment. The question pertains especially to patients' postablation quality of life (QoL) and long-term clinical outcomes.

Methods And Analysis: We are initiating a prospective, registry-based, multicentre observational study that will include patients aged ≥80 years with non-valvular AF who choose to undergo treatment by catheter ablation and, for comparison, such patients who do not choose to undergo ablation (either according to their physician's advice or their own preference).

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Background: Atrial fibrillation (AF) and chronic kidney disease (CKD) often coexist, but the real-world data after approval of direct oral anticoagulants (DOACs) are still lacking in Japan. We investigated the association of the baseline renal function and adverse clinical events and risk of adverse clinical events with DOACs compared to warfarin for each renal functional level in Japanese AF patients.

Methods: The present substudy was based on the SAKURA AF Registry, a Japanese multicenter observational registry (median follow-up period: 39 months).

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To explore factors related to changing renal function and the prognostic effect of worsening renal function in patients with atrial fibrillation (AF). The present substudy was based on the SAKURA AF Registry, a Japanese multicenter prospective observational registry that includes 3267 AF patients from 63 institutions in the Tokyo area. Worsening renal function was defined as an estimated glomerular filtration rate (eGFR) decrease equaling more than 20% of the patient's baseline eGFR.

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Background: Oxidative stress is involved in the initiation and progression of atherosclerosis, and hyperglycemia is known to increase oxidative stress, which injures the endothelium and accelerates atherosclerosis. To clarify the relation between oxidative stress, diabetes mellitus (DM), and acute myocardial infarction (AMI), we evaluated and compared time-specific oxidative stress after AMI in patients with and without DM by simple measurement of derivatives of reactive oxygen metabolites (d-ROMs) levels as indices of reactive oxygen species production.

Methods: Sixty-eight AMI patients were enrolled (34 non-DM patients and 34 DM patients).

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Objective: Although the plaque characteristics have been recognized in patients with acute myocardial infarction (AMI), the plaque spatial distribution is not well clarified. Using color-mapping intravascular ultrasound (iMAP-IVUS), we examined culprit lesions to clarify plaque morphology, composition and spatial distribution of the sites of potential vulnerability.

Methods: Sixty-eight culprit lesions in 64 consecutive AMI patients who underwent angiography and IVUS examinations before intervention were analyzed.

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Although diagnostically indispensable, magnetic resonance imaging (MRI) has been, until recently, contraindicated in patients with an implantable cardiac device. MR conditional cardiac devices are now widely used, but the mode programming needed for safe MRI has yet to be established. We reviewed the details of 41 MRI examinations of patients with a MR conditional device.

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Although the most feared cardiac manifestation in cardiac sarcoidosis is the onset of ventricular arrhythmia, some patients may present with supraventricular arrhythmias. We present a rare case of cardiac sarcoidosis associated with double tachycardia manifesting as atrial flutter and ventricular tachycardia.

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Objectives: This study evaluated the pause-dependency of the J-wave to characterize this phenomenon in idiopathic ventricular fibrillation (VF).

Background: The J-wave can be found in apparently healthy subjects and in patients at risk for sudden cardiac death, and risk stratification is therefore needed.

Methods: Forty patients with J-wave-associated idiopathic VF were studied for J waves with special reference concerning pause-dependent augmentation.

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A 61-year-old man with prior anteroseptal myocardial infarction (ejection fraction: 40%) presented with recurrent episodes of palpitations. Twelve-lead ECG during palpitations showed an incessant ventricular tachycardia (VT1) with right bundle branch block (RBBB) morphology and inferior axis. Electrophysiologic study revealed that the clinical VT originated from the anterolateral left ventricle.

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Transvenous endocardial pacemaker implantation is contraindicated in patients after prosthetic tricuspid valve replacement. A 65-year-old woman underwent both replacement of the mitral and tricuspid valves and pacemaker implantation with epicardial lead for bradycardia with chronic atrial fibrillation. At 2 years after this operation, the pacemaker's battery became low, and she was admitted for a battery exchange.

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Background: Brain natriuretic peptide (BNP) level has been shown to increase in patients with chronic atrial fibrillation (CAF) without overt heart failure (HF). Although atrial electrical remodeling associated with CAF has been described, little is known about the effects of the BNP level on the electrophysiological properties in CAF patients.

Methods And Results: In 42 CAF patients without overt HF, the atrial monophasic action potential duration (MAPD) at pacing cycle lengths (CLs) of 300-800 msec and P-wave signal-averaged electrograms were recorded after cardioversion.

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Whether the activation sequence of the right or left atrium plays a role in the morphology of the flutter wave in common atrial flutter is not completely understood. We present two patients with common counterclockwise atrial flutter in whom changes in the left atrial activation sequence produced significant changes in flutter wave polarity (+ to - and - to -/+ biphasic) without a change in the activation sequence within the right atrium. These cases highlight the possible role of alterations of the interatrial connections in the genesis of atypical manifestations of common atrial flutter.

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Introduction: The cavotricuspid isthmus (CTI) is crucial in the ablation of typical atrial flutter (AFL), and consequently the CTI anatomy and/or its relation to resistant ablation cases have been widely described in human angiographic studies. Intracardiac echocardiography (ICE) has been shown to be a useful tool for determining detailed anatomical information. Thus, this technology may also allow the visualization of the anatomical characteristics of the CTI, providing an opportunity to further understand the anatomy.

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Background: There is evidence that some patients with Brugada syndrome (BS) exhibit atrial tachyarrhythmias including paroxysmal atrial fibrillation. We investigated whether BS associated not only with vulnerability to ventricular fibrillation, but also with vulnerability to atrial fibrillation.

Methods And Results: In 15 patients with BS and Brugada-type electrocardiogram (ECG) (14 men, 1 woman; age 52.

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Background: Previous studies have shown that both atrioventricular nodal reentrant tachycardia (AVNRT) and atrial flutter (AFL) have an area of slow conduction located in the low posterior right atrium near the ostium of the coronary sinus. The aim of this study was to evaluate the inducibility of AFL in patients with AVNRT.

Methods And Results: One hundred and seventy patients were prospectively evaluated for inducibility of tricuspid valve - inferior vena cava isthmus-dependent AFL.

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Background: Chronic atrial fibrillation (AF) is characterized by a marked decrease in the atrial effective refractory period (ERP) and in the ERP adaptation to rate as well as a decrease in the atrial conduction velocity. Little information is available about the ionic mechanisms underlying AF in humans.

Materials And Methods: We studied the effect of IKr blocker nifekalant on the rate-dependent changes in atrial action potential duration in 11 patients after successful internal cardioversion of chronic AF of >2 months duration and in 7 patients without AF.

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Brugada syndrome is characterized by right bundle branch block morphology and ST-segment elevation in the right precordial leads and a propensity to develop ventricular arrhythmias. Mutations in a cardiac sodium channel gene have been linked to this syndrome, and the ionic mechanisms responsible for the electrocardiographic phenotype are temperature-dependent. This case report describes a patient in whom a typical Brugada ECG pattern developed during fever and could be reproduced at normal body temperature by administration of pilsicainide.

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Atrioventricular nodal reentrant tachycardia (AVNRT) is a relatively common paroxysmal supraventricular tachycardia. This study investigated whether adenosine-5'-triphosphate (ATP) injection during sinus rhythm might be useful in the noninvasive diagnosis of dual AV nodal pathways. The study group consisted of 9 patients with slow/fast AVNRT and 11 control patients without antegrade dual AV nodal physiology (DAVNP).

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A 32-year-old man with a 20-year history of palpitation showed a short PQ interval and delta wave on 12-lead ECG. An electrophysiological study showed that the atrio-His (AH) and His-ventricular intervals were not influenced by rapid right atrial pacing or by bolus injection of adenosine triphosphate (ATP). The AH interval was shortened by coronary sinus ostium (CSos) pacing.

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Right atrial monophasic action potentials were recorded before and after 60 minutes of rapid atrial pacing (pacing cycle length (CL); 127 +/- 10 ms) in 12 closed-chest dogs. The right atrial (RA) monophasic action potential (MAP) duration at 90% repolarization (RAMAPD) was measured at CLs of 400 ms and 250 ms. CL-dependent changes in RAMAPD (CL 400 ms - 250 ms) before and after rapid atrial pacing were 24 +/- 1 ms and 16 +/- 5 ms, respectively (p < 0.

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Background: The relation between ECG and activation patterns within atria in typical atrial flutter (AFL) patients (pts) has not been defined due to the lack of simultaneous multisite right and left atrial mapping.

Methods: In 13 pts with AFL, a Halo catheter was positioned along tricuspid annulus and multipolar catheters were placed in right atrial appendage, His bundle region, coronary sinus (CS), proximal portion of right pulmonary artery (Bachmann's bundle region, BB) and esophagus (Eso) to record right and left atrial activation simultaneously.

Results: In counterclockwise (CCW) AFL (11 pts), 9 showed negative flutter wave (F) and 2 positive F in the inferior leads.

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Right bundle branch block and ST segment elevation (RBBB-STE) in the right precordial leads have been reported as a distinct clinical and electrocardiographic syndrome in patients prone to ventricular fibrillation (VF) in the absence of structural heart disease (Brugada syndrome). The purpose of the study was to investigate the role of signal averaged electrocardiogram (SAECG) in identifying patients at high risk among asymptomatic RBBB-STE patients. Thirteen patients with the RBBB-STE ECG were identified.

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Unlabelled: Since myocardial lesion size during radio-frequency (RF) ablation is limited at high power by impedance rise when electrode tip temperature exceed 100 degrees C, controlling tip temperature by continuous intraelectrode saline infusion could permit generation of larger lesion. (1) Two dogs randomly received either standard or cooled tip RF ablation at 4 to 6 separate LV sites. Power output of 30 W was delivered via modified 7 Fr deflectable catheter with 4 mm tip for up to 120 sec or until impedance rise occurred.

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