Toshihiko Ohara

Prediction of atrial fibrillation after ischemic stroke using P-wave signal averaged electrocardiography

BACKGROUNDnAtrial fibrillation (AF) is highly prevalent in patients with ischemic stroke, but the diagnosis is often difficult.nnnMETHODSnThis study consisted of 68 stroke patients in sinus rhythm without history of AF. All patients underwent P-wave signal-averaged electrocardiography (P-SAECG), echocardiography, 24-h Holter monitoring, and measurement of plasma B-type natriuretic peptide (BNP) concentrations at admission.nnnRESULTSnAn abnormal P-SAECG was found in 34 of 68 stroke patients. In the follow-up period of 11 ± 4 months, AF developed in 17 patients (AF group). The remaining 51 patients were classified as the non-AF group. The prevalence of atrial late potentials (ALP) on P-SAECG, and the number of premature atrial contractions (PACs) were significantly higher in the AF group than those in the non-AF group (88.2% vs 37.3%; p<0.001, 149 ± 120 vs 79 ± 69; p=0.030, respectively). However, there were no significant differences in age, left atrial dimension, or BNP concentrations between both groups. Cox proportional hazards analysis revealed that the presence of ALP (risk ratio 11.15; p=0.002) and frequent PACs (more than 100/24h) (risk ratio 4.53; p=0.007) had significant correlation to the occurrence of AF.nnnCONCLUSIONSnALP may be a novel predictor of AF in stroke patients. P-SAECG should be considered in stroke of undetermined etiology.

Wavelet transform system makes one-beat analysis possible in late potential evaluation.

High-frequency components of the QRS complex, including late potentials, can be analyzed by signal averaging (SA). However, this method may fail to detect transient changes as a result of cancellation. The wavelet transform, which has a superior time-frequency resolution, was used to analyze beat-to-beat changes of the QRS components in 50 normal subjects and 50 patients who showed positive late potentials. The transformed data, displayed in three dimensions and in color, were highly reproducible in each patient. Measurement of high-power duration at a frequency of 50 Hz (WD50) showed a significant correlation between WD50 and filtered QRS duration in both groups. When the mean +/- SD of WD50 in normal subjects was defined as normal, 96% of patients with late potentials were out of the normal range. The wavelet signals in patients with late potentials were more inhomogeneous than those of normal subjects. It is concluded that this newly developed color display, three-dimensional wavelet transform system showed extremely good time-frequency resolution in analyzing every beat without signal averaging.

Prognostic significance of ventricular late potentials in patients with pulmonary sarcoidosis

BACKGROUNDnEarly detection of cardiac involvement in sarcoidosis is difficult but essential to achieve optimal treatment. Signal-averaged electrocardiography (SAECG) can detect subtle cardiac electrical abnormalities termed late potentials (LPs) and would be useful for the early diagnosis of cardiac involvement.nnnOBJECTIVEnThis study aims to investigate the prognostic significance of LP in patients with pulmonary sarcoidosis.nnnMETHODSnWe prospectively studied 74 patients with pulmonary sarcoidosis without overt electrocardiographic abnormalities. All participants underwent SAECG, cardiac echocardiography, and 24-hour ambulatory Holter monitoring. Serum angiotensin-converting enzyme and B-type natriuretic peptide levels were also evaluated. We followed these patients for the evaluation of incidence of cardiac events including cardiac death, arrhythmias, and heart failure requiring hospital admission.nnnRESULTSnOf the studied population, 29 patients (39.2%) had detectable LP. During a mean follow-up period of 9.8 years, 8 patients with LPs had cardiovascular events, including development of complete atrioventricular block (n = 4), ventricular tachycardia (n = 2), and heart failure (n = 2). Meanwhile, only 1 of 45 patients without LP developed cardiac event (heart failure). Multivariate analyses revealed that LPs were associated with an increased risk of developing cardiac events (hazard ratio 9.66; 95% confidence interval 1.20-78.01; P = .033) whereas age, sex, serum angiotensin-converting enzyme and B-type natriuretic peptide levels, number of premature ventricular contractions on 24-hour Holter monitoring, and echocardiographic parameters were not associated with subsequent cardiac events.nnnCONCLUSIONnSAECG might possibly be useful for the early detection of cardiac sarcoidosis and, if independently validated, could eventually be considered as a screening test for further risk stratification.

Acute Effects on Signal-Averaged Electrogram Parameters and Suppressing Premature Ventricular Contractions in Single or Combined Use of Class I Antiarrhythmic Drugs

Disopyramide (DP), mexiletine (MX), and flecainide (FL) are class I antiarrhythmic drugs. However, these drugs exert different effects on the electrocardiogram (ECG) based on their unique actions on cardiac myocytes. The electrocardiographic changes during combination therapy with these drugs are not well understood. The purpose of the present study was to evaluate acute morphologic changes in the ECG based on signal‐averaged high resolution ECG (SAECG) after administration of the drugs in relation to their antiarrhythmic eficacy and safety. Twenty‐one patients with frequent and stable premature ventricular contractions (PVC) were studied. Changes in the filtered QRS duration (f‐QRS) and the root mean square voltage of the last 40 msec of the QRS complex (RMS40) were evaluated. Suppression of PVCs was achieved soon after intravenous administration of the drugs (63% for DP, 43% for MX, 86% for FL and 100% for DP+MX). Although DP and FL significantly prolonged f‐QRS, MX had little effect on f‐QRS. DP+MX also prolonged f‐QRS, but the degree of prolongation was moderate. RMS40 was significantly decreased by DP and FL, but not by MX. DP+MX also decreased RMS40, but the decrease was less than for DP alone. Late potentials were observed after administration in 56% of patients with DP, 0% with MX, 67% with FL and 0% with DP+MX. No adverse events were reported during the study.

Gymnastic Formation-related Injury to Children in Physical Education

OBJECTIVEnCurrent data indicate that the rate of trauma in children during gymnastic formation is increasing, especially while creating a structure with a certain height, such as the human pyramid. The goal of the present study was to clarify the clinical characteristics of these injuries.nnnMETHODSnIn this single-institution review, all children treated for a gymnastic formation-related injury at Nippon Medical School Hospital from 2013 through 2015 were identified through the institutions registry. The injury mechanism was classified, and injury severity, interventions, and outcome were examined.nnnRESULTSnEight children were treated for a gymnastic formation-related injury. They were 7 boys and 1 girl aged 10 to 15 years (mean age, 13.1±1.8 years). Neurotrauma ranging from concussion to spinal cord injury without radiographic abnormality occurred in 6 patients (75%). No intracranial hemorrhagic lesions were detected. The Glasgow Coma Scale score on arrival was 15 in all 8 patients, and neurological deficits were present in 1 patient. No patient required surgical intervention. All patients made a full recovery after discharge from the hospital. No patients died. The average follow-up period was 2.1±0.9 weeks.nnnCONCLUSIONSnNeurotrauma is a frequent result of gymnastic formation accidents in children. Healthcare workers and teachers should recognize this type of injury, and public education that targets parents should be introduced.