Kazuko Ohmura

Successful radiofrequency catheter ablation of an anteroseptal (superoparaseptal) atrioventricular accessory pathway from the left ventricular outflow tract.

This case report describes a patient with Wolff‐Parkinson‐White syndrome in whom the ECG exhibited a typical pattern of an anteroseptal (superoparaseptal) accessory pathway. Successful radiofrequency catheter ablation was achieved from the septal side of the left ventricular outflow tract. It might be worthwhile to map the left side of the anterior septum if an accessory pathway potential is not appreciable along the tricuspid annulus to avoid the potential complication of AV block in patients with a typical anteroseptal accessory pathway ECG pattern. (PACE 2004; 27:668–670)

Electrocardiographic and Electrophysiological Characteristics of Atrial Fibrillation Organized Into Atrial Flutter by Oral Administration of Class I Antiarrhythmic Agents

OHMURA, K., et al. Electrocardiographic and Electrophysiological Characteristics of Atrial Fibrillation Organized Into Atrial Flutter by Oral Administration of Class I Antiarrhythmic Agents. The aim of this study was to evaluate the electrocardiographic (ECG) and electrophysiological characteristics of atrial fibrillation (AF) that organized into atrial flutter during oral administration of class I antiarrhythmic agents. The former clinical study included 72 consecutive patients (58 paroxysmal AF, 14 persistent AF) in whom class I antiarrhythmic agents were orally administered in the outpatient clinic for termination or prophylaxis of AF. The clinical background and ECG variables were compared between the patients with and without atrial flutter during class I antiarrhythmic agents therapy. An electrophysiological study was performed in ten patients with paroxysmal AF (five with [group A] and five without atrial flutter [group B] during oral class I antiarrhythmic agents therapy. Local electrograms from five different atrial sites (high and low right free wall, high and low septum, and distal coronary sinus) were analyzed during induced AF. The activation pattern of the right free wall during AF was also analyzed using a Halo catheter. Atrial flutter was documented during class I antiarrhythmic agents therapy in 14 (24%) patients with paroxysmal AF, whereas in none with persistent AF. The mean cycle length (f‐f interval) and amplitude of the fibrillation waves in leads II and V1 from the surface ECG were significantly greater in the patients with than in those without atrial flutter. In the electrophysiological study, the mean cycle lengths for the low and high right free wall were significantly longer in group A than in group B, whereas those for the low septums and distal coronary sinus did not differ between the two groups. During the induced AF, the ratio of time exhibiting a consistent activation pattern (cranio‐caudal, caudo‐cranial, or undetermined) along the right free wall was significantly greater in group A than in group B. Atrial flutter newly developed during class I antiarrhythmic agents therapy in patients with coarse AF on the surface ECG and a relatively organized activation in the right atrial free wall. The observation of these findings may facilitate the identification of candidates for hybrid pharmacologic and ablative therapies. (PACE 2003; 26:692–702)

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.

Clinical significance and contributing factors of long-term variability in induced ventricular tachyarrhythmias.

Introduction: Ventricular arrhythmias induced during electrophysiologic study (EPS) may vary over time, making arrhythmia induction studies unreliable. The aim of this prospective study was to clarify the clinical significance of long‐term variability in induced arrhythmias and to elucidate factors determining this variability.

Electrical Excitation of the Pulmonary Venous Musculature May Contribute to the Formation of the Last Component of the High Frequency Signal of the P Wave

Pulmonary veins (PVs) have been shown to play an important role in the induction and perpetuation of focal AF. Fifty‐one patients with AF, and 24 patients without AF as control subjects, were enrolled in this study. Signal‐averaged P‐wave recording was performed, and the filtered P wave duration (FPD), the root‐mean‐square voltage for the last 20, 30 and 40 ms (RMS20, 30, and 40, respectively) were compared. In 7 patients with AF, these parameters were compared before and after the catheter ablation. The FPD was significantly longer and the RMS20 was smaller in the patients with AF than those without AF. Because RMS30 was widely distributed between 2 and 10 µV, the AF group was sub‐divided into two groups; Group 1 was comprised of the patients with an RMS30 ≧5.0 µV, and group 2, <5.0 µV. In group 1, short‐coupled PACs were more frequently documented on Holter monitoring, and exercise testing more readily induced AF. After successful electrical disconnection between the LA and PVs, each micropotential parameter was significantly attenuated. These results indicate that the high frequency signal amplitude of the last component of the P wave is relatively high in patients with AF triggered by focal repetitive excitations most likely originating from the PVs. That is, attenuation by the LA‐PV electrical isolation, and thus the high frequency P signals of the last component, may contain the electrical excitation of the PV musculature.