Norihisa Toh

Application of Real-Time Three-Dimensional Transesophageal Echocardiography Using a Matrix Array Probe for Transcatheter Closure of Atrial Septal Defect

BACKGROUND The aim of this study was to demonstrate the utility of real-time three-dimensional (3D) transesophageal echocardiography (RT3D-TEE) using a matrix array 3D transesophageal echocardiographic probe for morphologic evaluation and guidance of transcatheter closure of atrial septal defects (ASDs). METHODS Forty-eight consecutive patients scheduled for the intervention were included. Two-dimensional (2D) transesophageal echocardiography (2D-TEE) and RT3D-TEE were performed before and during the procedures. Measurements of maximal ASD diameter and surrounding rims obtained on RT3D-TEE were compared with those obtained on 2D-TEE. RESULTS In 46 patients (96%), optimal 3D images for the morphologic evaluation of ASDs were obtained. RT3D-TEE facilitated the evaluation of ASD morphology and surrounding rims and was able to provide intraprocedural information clearly. A Bland-Altman plot showed a mean maximal diameter difference of -0.12 mm between the means (95% limits of agreement, -2.2 to 2.5 mm). CONCLUSION RT3D-TEE is a clinically useful, complementary option to 2D-TEE for evaluation of ASD morphology and for interventional guidance.

Alogliptin ameliorates postprandial lipemia and postprandial endothelial dysfunction in non- diabetic subjects: a preliminary report

BackgroundPostprandial hyperlipidemia impairs endothelial function and participates in the development of atherosclerosis. We investigated the postprandial effects of a dipeptidyl peptidase IV inhibitor, alogliptin, on endothelial dysfunction and the lipid profile.MethodsA randomized cross-over trial design in 10 healthy volunteers (8 males and 2 females, 35 ± 10 years) was performed. The postprandial effects before and after a 1-week treatment of 25 mg/day alogliptin on endothelial function were assessed with brachial artery flow-mediated dilation (FMD) and changing levels of lipids, apolipoprotein B48 (apoB-48), glucose, glucagon, insulin, and glucagon-like peptide-1 (GLP-1) during fasting and at 2, 4, 6, and 8 h after a standard meal loading test.ResultsAlogliptin treatment significantly suppressed the postprandial elevation in serum triglyceride (incremental area under the curve [AUC]; 279 ± 31 vs. 182 ± 32 mg h/dl, p = 0.01), apoB-48 (incremental AUC; 15.4 ± 1.7 vs. 11.7 ± 1.1 μg h/ml, p = 0.04), and remnant lipoprotein cholesterol (RLP-C) (incremental AUC: 29.3 ± 3.2 vs. 17.6 ± 3.3 mg h/dl, p = 0.01). GLP-1 secretion was significantly increased after alogliptin treatment. Postprandial endothelial dysfunction (maximum decrease in%FMD, from −4.2 ± 0.5% to −2.6 ± 0.4%, p = 0.03) was significantly associated with the maximum change in apoB-48 (r = −0.46, p = 0.03) and RLP-C (r = −0.45, p = 0.04).ConclusionAlogliptin significantly improved postprandial endothelial dysfunction and postprandial lipemia, suggesting that alogliptin may be a promising anti-atherogenic agent.

Left Atrial Volume Combined With Atrial Pump Function Identifies Hypertensive Patients With a History of Paroxysmal Atrial Fibrillation

Identifying patients at high risk for the occurrence of atrial fibrillation is one means by which subsequent thromboembolic complications may be prevented. Left atrial enlargement is associated with progression of atrial remodeling, which is a substrate for atrial fibrillation, but impaired atrial pump function is also another aspect of the remodeling. Our objective was to differentiate patients with a history of paroxysmal atrial fibrillation using echocardiography. We studied 280 hypertensive patients (age: 66±7 years; left ventricular ejection fraction: 65±8%), including 140 consecutive patients with paroxysmal atrial fibrillation and 140 age- and sex-matched control subjects. Left atrial volume was measured using the modified Simpson method at both left ventricular end systole and preatrial contraction and was indexed to body surface area. Peak late-diastolic mitral annular velocity was measured during atrial contraction using pulsed tissue Doppler imaging as an atrial pump function. Left atrial volume index measured at left ventricular end systole had a 74% diagnostic accuracy and a 71% positive predictive value for identifying patients with paroxysmal atrial fibrillation; these values for the ratio of left atrial volume index at left ventricular end systole to the peak late-diastolic mitral annular velocity were 82% and 81%, respectively, and those for the ratio of left atrial volume index at preatrial contraction to the peak late-diastolic mitral annular velocity were 86% and 90%, respectively. In conclusion, left atrial size combined with atrial pump function enabled a more accurate diagnosis of a history of paroxysmal atrial fibrillation than conventional parameters.

Identification of high-risk syncope related to ventricular fibrillation in patients with Brugada syndrome

BACKGROUND Syncope in patients with Brugada syndrome is usually associated with ventricular tachyarrhythmia, but some episodes of syncope can be related to autonomic disorders. OBJECTIVE The purpose of this study was to investigate the characteristics of syncope to differentiate high-risk syncope episodes from low-risk events in patients with Brugada syndrome. METHODS We studied 84 patients with type 1 electrocardiogram and syncope. Patients were divided into 2 groups: patients with prodrome (prodromal group; n = 41) and patients without prodrome (nonprodromal group; n = 43). RESULTS Ventricular fibrillation (VF) was documented at index event in 19 patients: 4 patients (21%) with documented VF experienced a prodrome prior to the onset of VF, whereas 15 patients (79%) did not have symptoms prior to documented VF (P <.01). Twenty-seven patients in the prodromal group and 7 patients in the nonprodromal group were considered to have syncope related to autonomic dysfunction. Syncope in other patients was defined as unexplained syncope. During the follow-up period (48 ± 48 months), recurrent syncope due to VF occurred in 13 patients among patients with only unexplained syncope and was more frequent in the nonprodromal group (n = 10) than in the prodromal group (n = 3; P = .044). In multivariate analysis, blurred vision (hazard ratio [HR] 0.20) and abnormal respiration (HR 2.18) and fragmented QRS (HR 2.39) were independently associated with the occurrence of VF. CONCLUSION Syncope with prodrome, especially blurred vision, suggests a benign etiology of syncope in patients with Brugada syndrome.

Fragmented QRS is associated with torsades de pointes in patients with acquired long QT syndrome

BACKGROUND Acquired long QT syndrome (LQTS) is a disease due to a secondary repolarization abnormality induced by various predisposing factors. In contrast to congenital LQTS, risk factors that produce acquired LQTS include organic heart diseases that often exhibit depolarization abnormality. Although various repolarization parameters have been evaluated in acquired LQTS, the existence of depolarization abnormality in association with torsades de pointes (TdP) has not been reported. OBJECTIVE The purpose of this study was to evaluate both repolarization (QT components) and depolarization parameters (fragmented QRS [fQRS]) in acquired LQTS patients with markedly prolonged QT interval. METHODS Seventy patients with acquired severe QT prolongation (QTc ≥ 550 ms) were studied. Thirty-two patients had syncope or TdP (syncope group). Thirty-eight patients did not have any symptoms (asymptomatic group). The existence of fQRS and QT components (QT, QTc, Tpe [interval between peak and end of T wave] intervals, and U-wave voltage) was analyzed. RESULTS The syncope group had more frequent fQRS (81%) than did the asymptomatic group (21%, P < .01) and the incidence of fQRS was not different before and after removal of predisposing factors. The incidence of organic heart disease was not different between the two groups. No differences in QTc interval were noted between the syncope and asymptomatic groups, although the syncope group had longer QT and Tpe intervals and higher U wave than the asymptomatic group (P < .01). CONCLUSION Acquired predisposing factors promoted repolarization abnormality (especially prolongation of QT and Tpe intervals), and the existence of fQRS had an important role in the development of TdP in patients with acquired LQTS.

Efficacy of Low-Dose Bepridil for Prevention of Ventricular Fibrillation in Patients With Brugada Syndrome With and Without SCN5A Mutation

It has been reported that bepridil prevents ventricular fibrillation (VF) in patients with Brugada syndrome, but the comparative efficacy with and without mutation in the SCN5A gene has not been elucidated. The purpose of this study was to assess the efficacy of low-dose bepridil (100 mg/day) for VF prevention in patients with Brugada syndrome with and without SCN5A mutation. Among 130 patients with Brugada-type electrocardiogram (ECG), low-dose bepridil was administered to seven patients because of repetitive VF episodes, including three with and four without SCN5A mutation. Preventive effect for VF recurrence and changes of the ECG and the signal-averaged ECG were evaluated. Frequencies of VF episodes were reduced after treatment with low-dose bepridil in all three patients with the SCN5A mutation (before: 0.33 versus after: 0.02 episodes/month, P < 0.01), but not in all four patients without the SCN5A mutation (before: 0.43 versus after: 2.94 episodes/month, P = nonsignificant). Levels of ST-segment elevation at J points and duration of low-amplitude signals less than 40 μV in the terminal filtered QRS complex (LAS40) in signal-averaged ECG were improved exclusively in patients with the SCN5A mutation. Treatment with bepridil prevented recurrence of VF along with improvement of ST elevation and LAS40 in patients with Brugada syndrome with the SCN5A mutation.

Transcatheter closure of atrial septal defect in elderly patients with permanent atrial fibrillation.

The aim of this study is to evaluate the feasibility and efficacy of device closure of atrial septal defect (ASD) in elderly patients with permanent atrial fibrillation.

Spontaneous electrocardiogram alterations predict ventricular fibrillation in Brugada syndrome

BACKGROUND Patients with Brugada syndrome (BS) often have spontaneous changes in their electrocardiogram (ECG). OBJECTIVE To evaluate the significance of ECG alterations, we investigated the relationships between the ECG and the occurrence of ventricular fibrillation (VF) in both patients and an experimental model of BS. METHODS In study 1, we evaluated ECG alterations in BS patients with (VF+, n = 33) and without (VF-, n = 41) spontaneous VF. We defined type 0 ECG as coved-type ST elevation without a negative T wave, which represents the existence of loss-of-dome (LOD) type action potentials (APs). In study 2, we optically mapped epicardial APs and recorded transmural ECGs in 34 canine right ventricular tissues with a drug-induced BS model by a combination of pinacidil and pilsicainide. RESULTS In study 1, changes in ST level ≥0.2 mV were more frequent in the VF+ group than in the VF- group (P <.01). Spontaneous ECG alterations and appearances of types 1 and 0 ECGs were more frequent in the VF+ group than in the VF- group (P <.01). In study 2, BS model with spike-and-dome (SAD) epicardial APs exhibited type 1 ECG. Deepening of the phase 1 notch of the APs induced heterogeneous conversion of the APs (SAD→LOD) and resulted in ECG conversion from type 1 to type 0. Significant AP heterogeneity often appeared during AP alterations and initiated phase 2 reentry. Tissues having ventricular tachycardia (VT; n = 20) had more frequent alterations in APs and ECG than in tissues without VT (n = 14; P <.01). CONCLUSION ECG alterations, especially conversion between types 0 and 1, are associated with significant AP heterogeneity that can initiate VF in BS.

Plasma adiponectin levels predict cardiovascular events in the observational Arita Cohort Study in Japan: the importance of the plasma adiponectin levels.

As the plasma level of adiponectin is related to metabolic syndrome and cardiovascular events, a low plasma adiponectin level may either cause or trigger cardiovascular disorders. The purpose of this study was to determine whether a low adiponectin level contributes to cardiovascular events, and to investigate the factors influencing adiponectin in the Japanese Arita-cho cohort study.We followed about 2000 subjects in Arita-cho, Saga, Japan as a cohort study, and we enrolled 637 subjects (205 men; 65.1±8.3 years old) who participated in annual health checks from 2005 to 2008 and underwent measurement of the plasma adiponectin level and an oral glucose tolerance test. We monitored the incidence of cardiovascular or cerebrovascular events in these subjects until the end of 2010, discontinuing follow-up at 3 years after the start of enrollment. Subjects with low plasma adiponectin levels (<10.5 ng ml−1) had a higher incidence of newly diagnosed cardiovascular diseases such as acute heart failure or acute myocardial infarction than those with high plasma adiponectin levels (⩾10.5 ng ml−1) over an average of 2.95 years of follow-up. Multivariate analysis showed that the adiponectin level was predicted by the following parameters in all subjects: age (β=0.16), male gender (β=−0.267), homeostasis model assessment of insulin resistance (β=−0.140) and the plasma levels of high-density lipoprotein cholesterol (β=0.104), uric acid (β=−0.13), triglycerides (β=−0.169) and brain natriuretic peptide (β=0.151). The difference in plasma glucose before and 120 min after the intake of a 75-g glucose load did not influence the plasma adiponectin level. The plasma adiponectin level is useful for predicting cardiovascular events, and is a measure of the risk of lifestyle-related diseases.

Atrial Electrophysiological and Structural Remodeling in High-Risk Patients with Brugada Syndrome: Assessment with Electrophysiology and Echocardiography

BACKGROUND Atrial fibrillation (AF) often occurs in Brugada syndrome (BrS), and BrS patients with spontaneous AF often experience ventricular fibrillation (VF) attacks. Atrial vulnerability providing a substrate for AF is known to be enhanced in BrS, but there are no data on atrial structural attributes. OBJECTIVE The objective of this study was to assess atrial electrophysiological and structural characteristics in BrS and their relationships with gene mutations. METHODS We studied 57 patients with BrS. Intra-atrial conduction time (CT) was defined as the interval from the stimulus at the high right atrium to atrial deflection at the distal portion of the coronary sinus. Left atrial volume index (LAVI) was measured by the modified Simpson method at left ventricular end-systole using echocardiography. SCN5A mutations were analyzed in all patients. RESULTS In patients with documented VF, spontaneous AF frequently occurred and prolonged CT and increased LAVI were observed compared with those in patients without VF (all P < .05; LAVI: 22 +/- 5 vs. 32 +/- 7 ml/m(2)). Even among patients without AF, CT and LAVI were still increased in patients with VF (all P < .05; LAVI: 22 +/- 5 vs. 29 +/- 5 ml/m(2)). The presence of SCN5A mutation was associated with prolonged CT (P < .05) and increased LAVI (P < .01), but not with arrhythmic episodes. CONCLUSION Both atrial vulnerability and structural remodeling are enhanced in high-risk patients with BrS, even in those without AF. These morphological characteristics suggest that BrS is a form of genetic myocardial disease.