Junjiroh Koyama

Importance of pericardial fat in the formation of complex fractionated atrial electrogram region in atrial fibrillation

BACKGROUND/OBJECTIVES Pericardial fat (PF) and complex fractionated atrial electrogram (CFAE) are both associated with atrial fibrillation (AF). Therefore, we examined the relation between PF and CFAE area in AF. METHODS The study population included 120 control patients without AF and 120 patients with AF (80 paroxysmal AF and 40 persistent AF) who underwent catheter ablation. Total cardiac PF volume, representing all adipose tissue within the pericardial sac, was measured by contrast-enhanced computed tomography. The location and distribution of CFAE region were identified by left atrial endocardial mapping using a three-dimensional mapping system. We analyzed the significance of total cardiac PF volume and total area of CFAE region on AF, persistence of AF from paroxysmal to persistent form, and the relation between total cardiac PF volume and total CFAE area. We also evaluated the regional distribution of PF volume and CFAE area in five areas of the left atrium (LA). RESULTS Total cardiac PF volume correlated with AF (odds ratio [OR]: 1.024, p<0.001). Total cardiac PF volume and total CFAE area were both independently associated with persistence of AF (OR: 1.018, p=0.018, OR: 1.144, p=0.002, respectively). Multivariate linear regression analysis identified total cardiac PF volume as a significant and independent determinant of total CFAE area (r=0.488, p<0.001). Furthermore, regional PF volume correlated with local CFAE area in an each LA area. CONCLUSIONS PF volume correlated significantly with CFAE area in patients with AF. This finding suggests that PF is directly related to the progression of CFAE area and promotes the pathogenic process of AF.

Demonstration of anatomical reentrant tachycardia circuit in verapamil-sensitive atrial tachycardia originating from the vicinity of the atrioventricular node

BACKGROUND The anatomical location of the reentry circuit in verapamil-sensitive atrial tachycardia originating from the vicinity of atrioventricular node (V-AT) is not well clarified. OBJECTIVE To define the reentry circuit of V-AT. METHODS In 17 patients with V-AT, rapid atrial pacing at a rate 5 beats/min faster than the tachycardia rate was delivered from multiple sites of the right atrium (RA) during tachycardia to define the direction of the proximity of the slow conduction area of the reentry circuit. After identification of manifest entrainment and orthodromic capture of the earliest atrial activation site (EAAS), radiofrequency energy was delivered starting at a site 2 cm away from the EAAS in the direction of the pacing site. Radiofrequency energy application site was then gradually advanced toward EAAS until the termination of tachycardia to define the entrance of the slow conduction area. RESULTS The EAAS was orthodromically captured by pacing delivered from one of the high anterolateral RA (n = 6), high posteroseptal RA (n = 9), and RA appendage (n = 2). Radiofrequency energy delivery to the site, 10.1 ± 2.8 mm away from the EAAS, terminated V-AT immediately after the onset of delivery (2.9 ± 1.0 seconds). The successful ablation site located outside the Kochs triangle, being more distant from the His bundle site than the EAAS (12.4 ± 2.9 vs 6.4 ± 1.9 mm; P <.0001). CONCLUSION The reentry circuit of V-AT located outside the Kochs triangle. V-AT was eliminated by the radiofrequency energy delivered to the entrance of the reentry circuit, which was more distant from the His bundle site than the EAAS, under the navigation of entrainment.

Analysis of the mechanisms initiating random wave propagation at the onset of atrial fibrillation using noncontact mapping: Role of complex fractionated electrogram region

BACKGROUND The complex fractionated atrial electrogram (CFAE) region has been suggested to contribute to the maintenance of atrial fibrillation (AF), but its role for the initiation of AF has not been clarified. OBJECTIVE We analyzed the mechanisms of the initiation of random reentrant wave propagation at AF onset, especially in relation to CFAE region. METHODS Endocardial mapping of the left atrium using a 3-dimensional noncontact mapping system was performed in 19 patients. RESULTS Thirty-two spontaneous AF onset episodes, which were initiated by the focal repetitive discharges (9 ± 9 beats), deriving from the pulmonary veins (PV) (n = 17) and from non-PV CFAE regions (n = 15) were observed. The coupling intervals of the focal discharges that initiated AF (AF-D) were significantly shorter than those that did not initiate AF (non-AF-D) (179 ± 33 ms vs. 217 ± 45 ms, P = .0005). After the AF-D, localized conduction blocks occurred in the CFAE region. Subsequently, the waves propagated to the remainder of the atrium, accompanying the anchored activation around the localized conduction block lines in the CFAE regions. Left atrial activation times of AF-D were significantly longer than those of non-AF-D (151 ± 35 ms vs. 83 ± 17 ms, P < .0001). These longer activation times after AF-D enabled the waves to reenter the previously blocked CFAE region from the opposite direction, and thus the meandering reentrant wave propagation was initiated. CONCLUSION Unidirectional conduction block in the CFAE region and subsequent prolonged left atrial activation time following short coupled premature discharge were the underlying mechanisms of AF initiation, suggesting the importance of the CFAE region as the substrate for AF onset.

An autopsy case of the rupture of a giant aneurysm in a saphenous vein graft: 18 years after CABG

The saphenous vein is a widely used blood vessel for arterial bypass procedures. Failures of saphenous vein aortocoronary bypass grafts are predominantly the result of subsequent vein graft atherosclerotic disease. Rarely saphenous vein grafts undergo aneurysmal degeneration. This report describes a case of a ruptured aneurysm in a saphenous vein graft that occurred in an 82-year-old female who underwent a coronary artery bypass operation 18 years previously. We could not resuscitate her, but describe the autopsy findings in detail.

Multiple forms of atypical atrioventricular nodal reentrant tachycardia with different right- and left-sided retrograde slow pathways

A 56-year-old man was admitted for the treatment of supraventricular tachycardia. After successful ablation of the left concealed accessory pathway, four fast-slow forms of atrioventricular nodal reentrant tachycardia associated with different right- and left-sided retrograde slow pathways were induced. The locations of retrograde slow pathway were observed at the left inferior paraseptum, left mid-septum, right inferior paraseptum, and coronary sinus ostium, respectively. These retrograde slow pathways formed the integral limb of each tachycardia because conduction block of each slow pathway by catheter ablation was associated with the termination of tachycardia or abrupt change in the atrial activation sequence.

Usefulness of non-contact mapping for catheter ablation of ventricular tachycardias originating at the right ventricular outflow tract

Different QRS morphologies are often observed in idiopathic ventricular tachycardias or premature ventricular contractions originating from the right ventricular outflow tract (RVOT). However, the precise mechanism underlying multiple QRS morphologies has not been clarified adequately. The purpose of this study was to examine the mechanism underlying different QRS morphologies in RVOT arrhythmia. We also investigated the usefulness of non‐contact mapping guided radiofrequency catheter ablation for RVOT arrhythmia.

Thoracoscopic phrenic nerve patch insulation to avoid phrenic nerve stimulation with cardiac resynchronization therapy

A 76‐year‐old female was implanted with a cardiac resynchronization therapy (CRT) device, with the left ventricular lead implanted through a transvenous approach. One day after implantation, diaphragmatic stimulation was observed when the patient was in the seated position, which could not be resolved by device reprogramming. We performed thoracoscopic phrenic nerve insulation using a Gore‐Tex patch. The left phrenic nerve was carefully detached from the pericardial adipose tissue, and a Gore‐Tex patch was inserted between the phrenic nerve and pericardium using a thoracoscopic technique. This approach represents a potential option for the management of uncontrollable phrenic nerve stimulation during CRT.

Electrophysiologic mechanism of typical atrial flutter termination by nifekalant: effect of a pure IKr -selective blocking agent.

Little is known about the effect of nifekalant, a pure IKr‐selective blocker, on typical atrial flutter (AFL) and its termination mechanism.

Atrial tachycardia caused by a superior vena cava fibrillation with conduction block

Here, we report a case of a 62‐year‐old man with a history of incessant atrial tachycardia (AT) for several years. An electrophysiological study revealed rapid and irregular activity in the superior vena cava (SVC), but the surface 12‐lead electrocardiogram (ECG) exhibited a relatively regular AT (atrial cycle length=240 ms). CARTO mapping of the right atrium (RA) demonstrated that the earliest atrial activation occurred at the posterior septum of the upper RA (the SVC–RA junction). Intravenous administration of 20 mg adenosine triphosphate (ATP) led to an acceleration of the SVC–RA conduction up to 1:1 conduction, and the atrial cycle length decreased, consequently converting the AT to transient atrial fibrillation (AF). Application of single radiofrequency energy at the earliest atrial activation site during tachycardia terminated the AT and achieved isolation of the SVC from the RA, despite the continued presence of fibrillation in the SVC. We speculated that SVC fibrillation with spontaneous conduction block at the SVC–RA junction was the cause of this AT.

Electromagnetic Interference with Cardiac Implantable Devices by Household and Industrial Appliances

Modern cardiac implantable devices (CIDs. such as pacemakers (PMs), implantable cardioverter defibrillators (ICDs), and defibrillators for cardiac resynchronization therapy (CRT‐Ds. are engineered to be resistant to electromagnetic interference (EMI). However, such interference is still a concern when patients are exposed to household and occupational appliances in daily life. The aim of this study was to evaluate the risk of EMI caused by several types of household and industrial appliances. EMI with 20 CIDs (12 PMs, 7 ICDs, 1 CRT‐D. was tested for 16 household and 19 industrial appliances using three methods of measurement: Irnichs human body model, an alternating electric field device, and an alternate‐current and static‐current magnetic field device. The thresholds for the risk of EMI were defined as an alternating electric field of 5000 V/m, an alternate‐current magnetic field of 20 mT, and a static‐current magnetic field of 10 G. In 35 tests, 15 of the 16 household appliances showed no EMI with any CIDs, but an induction oven showed a potential risk of EMI with 2 PMs. None of the 19 industrial appliances showed EMI with any CIDs, provided that an appropriate distance from the appliances was maintained. These findings should allow physicians to evaluate whether patients with a CID can safely return to their homes and workplaces.