Yasuaki Tanaka

Mechanisms of the maintenance of atrial fibrillation: Role of the complex fractionated atrial electrogram assessed by noncontact mapping

BACKGROUNDnThe role of complex fractionated atrial electrograms (CFAEs) in the maintenance of atrial fibrillation (AF) has not been well clarified.nnnOBJECTIVEnThe purpose of this study was to examine the mechanisms of AF maintenance, especially in relation to CFAE.nnnMETHODSnEndocardial mapping of the left atrium was performed during AF using a three-dimensional noncontact mapping system in 16 patients with paroxysmal AF.nnnRESULTSnDuring AF, focal discharges were found at the pulmonary vein and sites within the CFAE region (3.0 +/- 1.9 vs. 2.8 +/- 1.5 times/s; P = NS) but not in the non-CFAE region. One to four meandering waves propagated over various pathways during AF. The frequency of the wave break and pivoting activation in the CFAE region were significantly higher than in the non-CFAE region (5.6 +/- 3.6 vs. 0 +/- 0 times/s, P <.0001 and 5.0 +/- 2.1 vs. 0.3 +/- 0.8 times/s; P <.0001). Wave fusion in the CFAE region was more frequently observed than in the non-CFAE region (6.5 +/- 5.8 vs. 3.6 +/- 3.1 times/s; P <.05). Conduction velocity in the CFAE region was slower than in the non-CFAE region (0.7 +/- 0.4 vs. 1.9 +/- 0.5 m/s; P <.0001). The generation of a new wave was associated with the wave break, fusion, and focal discharge. Furthermore, perpetuation of these waves accompanied by slow conduction and pivoting activation was mostly observed in the CFAE region.nnnCONCLUSIONnThe CFAE region plays an important role in the perpetuation of AF. In addition to focal discharge, wave break and fusion associated with slow conduction and pivoting activation in the CFAE region sustained wave propagation, resulting in the maintenance of AF.

Changes in plasma von Willebrand factor and ADAMTS13 levels associated with left atrial remodeling in atrial fibrillation.

INTRODUCTIONnPrevious studies have shown raised plasma von Willebrand factor (VWF) levels in patients with atrial fibrillation (AF). However, little is known about changes of VWF associated with VWF-cleaving protease (ADAMTS13) in AF. The aim of this study was to examine the relationship between changes in plasma VWF and ADAMTS13 levels, and left atrial remodeling in AF patients.nnnMATERIALS AND METHODSnWe measured plasma VWF and ADAMTS13 antigen levels in 70 paroxysmal AF (PAF) patients, 56 chronic AF (CAF) patients, and 55 control subjects.nnnRESULTSnPlasma VWF levels (mU/ml) were significantly higher in CAF and PAF patients compared with the controls (2103 +/- 743, 1930 +/- 676, 1532 +/- 555, respectively, P < 0.0001 in CAF vs. controls, P = 0.001 in PAF vs. control), while ADAMTS13 levels (mU/ml) were significantly lower in CAF and PAF patients compared with the controls (795 +/- 169, 860 +/- 221, 932 +/- 173, respectively, P = 0.0002 in CAF vs. controls, P = 0.04 in PAF vs. control). The VWF/ADAMTS13 ratio was significantly higher in patients with CAF than PAF or controls (2.81 +/- 1.30, 2.34 +/- 0.92, 1.73 +/- 0.83, respectively; P = 0.01 in CAF vs. PAF, P < 0.0001 in CAF vs. controls). There was a significant correlation between the VWF/ADAMTS13 ratio and left atrial diameter (positive correlation; r = 0.275, P = 0.0002) and left atrial appendage flow velocity (negative correlation; r = -0.345, P = 0.0018).nnnCONCLUSIONSnThese findings suggest that the imbalance between plasma VWF and ADAMTS13 levels caused by left atrial remodeling might be closely associated with intra-atrial thrombus formation in AF patients.

B-type natriuretic peptide after hormone therapy in postmenopausal women with chest pain and normal coronary angiogram.

Objectives: Coronary heart disease is relatively uncommon in premenopausal women but shows a sharp increase after menopause. The decline of endogenous ovarian hormones is commonly assumed to be a major component of this phenomenon. The effects of estrogens on the vasculature have been investigated extensively in previous studies. However, the effects of estrogens on myocardial function have not been evaluated in humans. We sought to examine the effects of hormone therapy (HT) on myocardial function and cardiac natriuretic peptides in postmenopausal women with chest pain and a normal coronary angiogram. Design: Transdermal HT (estradiol: 0.72 mg/2 d) was administered to 15 postmenopausal women with chest pain and a normal coronary angiogram (mean age, 53 y) for 12 weeks, and oral HT (conjugated equine estrogens: 0.625 mg/d) was administered to another 15 postmenopausal women (mean age, 54 y) for 12 weeks. Echocardiography or cardiac catheterization showed no cardiac dysfunction in any woman at baseline. Cardiac function was evaluated by echocardiography, and plasma B-type natriuretic peptide was measured every 4 weeks. Results: B-type natriuretic peptide levels increased after transdermal HT (baseline: 13.1 ± 3.1, 4 wk: 22.1 ± 2.9, 8 wk: 33.2 ± 3.1, 12 wk: 38.4 ± 3.3 pg/mL; P < 0.01 vs baseline). The levels were also augmented after oral HT (baseline: 14.1 ± 3.8, 4 wk: 23.2 ± 3.3, 8 wk: 35.6 ± 3.9, 12 wk: 39.6 ± 3.5 pg/mL; P < 0.01 vs baseline). Serial echocardiography showed no changes in ventricular function in either treatment group. At baseline the serum estradiol levels in the transdermal group were comparable with those in the oral group. Conclusions: The estradiol levels after HT increased in both groups, but there was no significant difference between the two groups. B-type natriuretic peptide levels increased without cardiac dysfunction, and the chest symptoms were relieved in some participants after HT. Thus, estrogen supplementation augments natriuretic peptide levels without harmful effects on ventricular function.

Analysis of Atrioventricular Nodal Reentrant Tachycardia with Variable Ventriculoatrial Block: Characteristics of the Upper Common Pathway

Background: The precise nature of the upper turnaround part of atrioventricular nodal reentrant tachycardia (AVNRT) is not entirely understood.

Vector Mapping in Localizing the Transverse Conduction Site of the Crista Terminalis in Patients with Typical Atrial Flutter

Background: The difference in the conduction properties of the crista terminalis (CT) along its course, has not been fully clarified. Using the vector mapping method, we localized the transverse conduction (TC) site of the CT and elucidated its conduction capabilities in patients with typical atrial flutter (AF).

Tachycardia circuit in typical atrial flutter: The role of a posterolateral line of block in the perpetuation of the tachycardia

Background: The essential boundaries in typical atrial flutter (AF) are unknown.

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.

Spontaneous Polymorphic Ventricular Tachycardia after Administration of Pilsicainide in a Patient Resuscitated from Ventricular Fibrillation

We performed a pilsicainide challenge test in a 38‐year‐old man who was resuscitated from ventricular fibrillation without apparent baseline electrocardiogram (ECG) abnormality. His father had a history of ventricular fibrillation and his brother had multiple episodes of syncope. Pilsicainide (1 mg/kg) induced short coupled ventricular premature beats followed by repetitive polymorphic ventricular tachycardia without apparent J wave and ST elevation, and excessive changes in QRS duration and QT interval. An implantable cardioverter defibrillator was implanted.

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.

Catheter ablation of multiple focal atrial tachycardias originating from the tricuspid annulus using non-contact mapping system

We describe an 81-year-old man with multiple focal atrial tachycardias (ATs) originating from the tricuspid annulus. Non-contact mapping showed 3 incessant ATs, originating from the vicinity of His bundle region, inferior portion of coronary sinus ostium, and coronary sinus ostium, and 2 premature atrial contractions (PACs) originating from the tricuspid annulus in the 5 oclock position and 6 oclock position in the left anterior oblique view. Radiofrequency energy application to these 5 sites successfully eliminated the ATs and PACs. The patient has remained free from ATs or any symptoms without medication during the 16-month follow-up period. Non-contact mapping was useful in identifying the multiple AT origins, especially even if the tachycardia origin shifted occasionally or the tachycardia was non-sustained.