Sonoko Ashino

Prediction of the efficacy of pulmonary vein isolation for the treatment of atrial fibrillation by the signal-averaged P-wave duration

Background: The noninvasive methods for predicting a successful pulmonary vein isolation (PVI) have not been well described. The aim of this study was to assess the usefulness of the P‐wave signal‐averaged electrocardiogram (P‐SAECG) in predicting the chance of a successful PVI in patients with atrial fibrillation (AF).

Differential Pacing for Distinguishing Slow Conduction from Complete Conduction Block of the Tricuspid-Inferior Vena Cava Isthmus after Radiofrequency Ablation for Atrial Flutter—Role of Transverse Conduction through the Crista Terminalis

Background: Partial conduction block has been suggested a predictor of recurrence of atrial flutter (AFL).Aim: The aim of this study was to assess transverse conduction by the crista terminalis (CT) as a problem in evaluating isthmus block and the usefulness of differential pacing for distinguishing slow conduction (SC) and complete conduction block (CB) across the ablation line.Methods: We assessed 14 patients who underwent radiofrequency catheter ablation of the eustachian valve/ridge–tricuspid valve isthmus for typical AFL. Activation patterns along the tricuspid annulus (TA) suggested incomplete CB across the isthmus. In these patients, atrial pacing was performed from the low posteroseptal (PS) and anteroseptal (AS) right atrium (RA) while the ablation catheter was placed at the ablation line where double potentials (DPs) could be recorded. The pattern of activation of the RA free wall was assessed by a 20-pole catheter positioned along the CT during pacing from the coronary sinus (CS) ostium (CSos) and low lateral RA (LLRA).Results: Faster transverse conduction across the CT resulted in simultaneous or earlier activation of the distal halo electrodes than of the more proximal electrodes, suggesting incomplete conduction block across the isthmus. CB (13) and SC (1) were detected as changes in the activation times of the first and second components of DPs (DP1, DP2) during PS RA pacing and AS RA. Similar changes in the activation times DP1 and DP2 during AS RA pacing as compared to PS RA reflected SC through the isthmus, whereas increased DP1 activation time and decreased of DP2 activation time reflected complete conduction block across the isthmus.Conclusions: Transverse conduction across the CT influences the sequence of activation along the TA after isthmus ablation. Differential pacing can distinguish SC from complete conduction block across the ablation line in the isthmus.

Anatomic and Electrophysiologic Differences between Chronic and Paroxysmal Atrial Flutter: Intracardiac Echocardiographic Analysis

Background : It remains unknown why atrial flutter (AFL) occurs as either a chronic or paroxysmal arrhythmia.

Functional atrioventricular conduction block in an elderly patient with acquired long QT syndrome: elucidation of the mechanism of block.

The long QT syndrome (LQTS) is occasionally complicated by impaired atrioventricular (AV) conduction. This form of LQTS can manifest before birth or during neonatal life, and no previous report has demonstrated LQTS complicated by impaired AV conduction in elderly patient. This case report describes an elderly patient with an acquired form of LQTS who developed ventricular fibrillation that was successfully defibrillated during admission to the hospital. Electrophysiologic study demonstrated that HV interval was 38 milliseconds and QT interval was 635 milliseconds during sinus rhythm cycle length of 1167 milliseconds. 1:1 AV conduction was maintained to a pacing cycle length of 545 milliseconds with an AH interval of 144 milliseconds, HV interval of 44 milliseconds, and right ventricular monophasic action potential duration of 360 milliseconds. However, 2:1 HV block developed at a pacing cycle length of 500 milliseconds. Intravenous administration of mexiletine decreased the cycle length of developing HV block to 360 milliseconds.

Change in Atrial Flutter Wave Morphology—Insight into the Sources of Electrocardiographic Variants in Common Atrial Flutter

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.

Assessment of Efficacy and Necessity of Routine Defibrillation Threshold Testing in Patients Undergoing Implantable Cardioverter-Defibrillator (ICD) Implantation

Defibrillation threshold (DFT) testing is performed routinely in patients undergoing implantable cardioverter-defibrillator (ICD) implantation to verify the ability of the ICD to terminate ventricular fibrillation (VF). However, neither the efficacy nor the safety of DFT testing has been proven; thus, the necessity of such testing is controversial. We conducted a retrospective study of the efficacy of DFT testing, particularly with respect to long-term outcomes of ICD implantation.The study included 150 patients (125 men, 25 women, aged 59.0 ± 17.6 years) who underwent ICD or cardiac resynchronization therapy defibrillator implantation, with (n = 73) or without (n = 77) intraoperative DFT testing, between June 1996 and September 2007. VF was induced by delivery of a T-wave shock, and a 20-25-J shock was then delivered. If the 20-25-J shock failed to terminate VF, 30 J was delivered. We assessed whether undersensed VF events occurred during DFT testing and/or during patient follow-up and checked for any association between undersensing and delayed shock delivery. During DFT testing, fine VF was sensed, and shocks were delivered in a timely manner. Nevertheless, 2 patients in the DFT testing group died from VF within 3 years after device implantation.DFT testing, in comparison to non-DFT testing, appeared to have no influence on the long-term outcomes of our patients, suggesting that DFT testing at the time of ICD implantation is limited.

Upper turnaround point of the reentry circuit of common atrial flutter--three-dimensional mapping and entrainment study.

BackgroundAlthough the anterior and posterior boundaries of cavotricuspid isthmus-dependent atrial flutter (AFL) are reported to be located at the tricuspid annulus and sinus venosa region or crista terminalis, the exact upper turnaround point of the AFL circuit remains unclear. The aim of this study was to determine the upper turnaround site of the AFL circuit by means of three-dimensional (3D) mapping and entrainment pacing.MethodsSubjects were 21 patients with counter-clockwise AFL in whom high-density mapping of the high right atrium (RA) and superior vena cava (SVC) orifice was performed with an electroanatomical or non-contact mapping system. Entrainment pacing was performed around the SVC-RA junction.ResultsIn 20 of the 21 patients, the wavefront from the septal RA split into two wavefronts: one that traveled anterior to the SVC and another that traveled to the posterior RA where it was blocked. In the remaining patient, the wavefront from the septal RA split into two wavefronts: one that propagated through the anterior portion of the SVC orifice and another that propagated transversely across the posterior portion of the SVC orifice. The two wavefronts joined in the lateral RA. Entrainment pacing from the SVC-RA junction demonstrated that the anterior boundary was within the circuit in all patients, but the posterior boundary also constituted a circuit in four patients.ConclusionsWe surmise that the upper turnaround site of the AFL circuit is located in the anterior portion of the SVC-RA junction in the majority of patients with AFL.

Implantation of a pacemaker in a patient with severe Parkinson's disease and a pre-existing bilateral deep brain stimulator.

A 72-year-old man who suffered dizziness and syncope was referred to the Division of Cardiology Division, Nihon University Hospital in 2006. A 12-lead electrocardiogram recorded at the outpatient clinic showed complete atrioventricular block with a ventricular escape rhythm of 26 bpm. In 1997, he had been as referred to the Department of Neurosurgery for implantation of bilateral deep brain stimulators (DBSs) to treat advanced Parkinsons disease refractory to medical treatment. Six days after admission to our department, a permanent cardiac pacemaker was implanted to …

MRI Mode Programming for Safe Magnetic Resonance Imaging in Patients With a Magnetic Resonance Conditional Cardiac Device

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. There were no associated adverse events. However, in 3 cases, paced beats competed with the patients own beats during the MRI examination. We describe 2 of the 3 specific cases because they illustrate these potentially risky situations: a case in which the intrinsic heart rate increased and another in which atrial fibrillation occurred. Safe MRI in patients with an MR conditional device necessitates detailed MRI mode programming. The MRI pacing mode should be carefully and individually selected.

Left bundle branch block-type ventricular tachycardia originating from the left ventricular septum in a patient with cardiac sarcoidosis

This case report describes a left bundle branch block (LBBB)-type ventricular tachycardia (VT) with a unique reentrant circuit in a patient with cardiac sarcoidosis. The VT morphology and pace mapping supported an exit site of the VT from the basal posterior right ventricle (RV) septum. Nonetheless, concealed entrainment was established by pacing from a septal left ventricular (LV) site recording a diastolic potential, opposite site to the RV site. A point ablation at that LV site could successfully terminate the VT, suggesting that a critical isthmus was located on the LV side of the interventricular septum despite the demonstration of an LBBB-type VT.