Over the past decade, most of the electrophysiologic mechanisms in patients with focal atrial tachycardias (ATs) have been well studied. Recently, advanced mapping systems have revealed the precise propagation, and the relationship between non-radial propagation pattern and substrate property of focal AT. Non-radial activation pattern of focal AT may mimic macrorentrant AT and may lead to inappropriate ablation strategy. In this review, we will focus on the current state of mapping and ablation techniques, safety, and efficacy associated with the catheter ablation for focal AT.

View full abstract

Background: There have been numerous reports about coronary sinus (CS) anomalies related to posteroseptal accessory pathways (APs). The purpose of this study was to explore the diameter and morphology of CS in patients with posteroseptal APs.
Methods: We performed direct CS angiography in 105 patients with 22 posteroseptal APs and 83 APs in other regions, and 25 control subjects. We compared the diameter of the CS ostium in all subjects, and assessed the correlation of the local activation time in the patients with posteroseptal APs.
Results: The proximal size (diameter) of the CS in the patients with posteroseptal APs (13.6±1.1 mm) was larger than that in the patients with other types of APs (10.2±1.8 mm [p<0.001]) and that in the control subjects (9.6±1.5 mm [p<0.001]). Dilatation of the CS in the patients with posteroseptal APs extended up to 20 mm inside the CS. In 15 (68%) of the patients with posteroseptal APs, the proximal site of the CS demonstrated a windsock appearance.
Conclusions: We concluded that the larger size and the wind cone appearance of proximal CS were unique structural characteristics in most patients with posteroseptal APs.

View full abstract

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 efficacy 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.
In summary, the class I antiarrhythmic drugs exerted different acute effects on SAECG parameters. The combination of DP and MX increased the efficacy on suppressing PVC without excess additive changes on SAECG parameters. We conclude that combination therapy with DP and MX is efficacious and safe in patients with PVC and the analysis of SAECG during antiarrhythmic therapy is clinically important.

View full abstract

Objective: In Japan, the number of elderly people with cerebral vascular disease (CVD) and dementia is increasing, resulting in increased expenditures to treat such patients. Reports indicate that music therapy can reduce anxiety in patients with myocardial infarction. However, it is unclear whether music therapy can have beneficial effects on very elderly patients with CVD and dementia, as these conditions may influence cardiac autonomic nerve functions. Therefore, we investigated the effects of music therapy on the autonomic nerve system in elderly patients with CVD and dementia, using an ambulatory Holter ECG system.
Methods and Results: The subjects were 12 elderly patients aged ≥75 years, hospitalized for CVD and dementia. We measured their heart rate variability (HRV) indices of power domain and frequency domain analysis. The mean RR significantly increased during music therapy, from 842±174 to 1022±284 (p<0.05), and decreased to 820±284 ms after music therapy. HF significantly increased during music therapy, from 59±41 to 127±97 ms² (p<0.01), and decreased to 77±60 ms² after music therapy. LF/HF decreased from 2.2±1.3 to 1.7±1.3 during music therapy (p<0.10), and increased to 2.0±1.1 after music therapy. Time domain (HRV) indices increased during music therapy and decreased after music therapy: RMSSD increased from 19.4±11 to 39.8±17 ms, and then decreased to 19.4±8.3 ms; pNN50 increased from 3.6±3.2 to 16.1±13.3% (p<0.01), and then decreased to 4.3±4.2%.
Conclusions: Music therapy enhanced parasympathetic activity and decreased sympathetic activity in elderly patients with CVD and dementia. These findings suggest that music therapy is useful for alleviating anxiety, increasing comfort and facilitating relaxation for elderly patients with CVD and dementia.

View full abstract

Introduction: The Rho/Rho-kinase pathway has been related to various physiological responses of the cardiovascular system. Previous reports have suggested a significant effect of Rho signals on the electrophysiological characteristics of the heart. We hypothesized that the Rho/Rho-kinase system would contribute to the rapid pacing-related change of atrial effective refractory period (AERP).
Methods and Results: In 17 dogs, AERP was measured at the right atrial appendage (RAA) and posterior left atrium (LA) before, during, and after 6-hours rapid atrial pacing at 500 bpm. Saline control (n=5), verapamil (n=5), or fasudil (n=7) were infused throughout the protocol. The shortening of AERP after rapid pacing was abrogated by the administration of verapamil, as reported in previous studies. Furthermore, fasudil (Rho/Rho-kinase inhibitor) influenced the change of AERP in a manner similar to the infusion of verapamil throughout the experiments.
Conclusions: Since the AERP was attenuated by fasudil, rapid pacing-related atrial electrophysiological changes might involve the Rho/Rho-kinase pathway.

View full abstract

A 50-year-old man who had suffered from old myocardial infarction presented with an episode of syncope. DC shock was required for the interruption of frequent pleomorphic ventricular tachycardia (VT). Although the treatment for heart failure decreased the frequency of VT attacks, hemodynamically unstable VT occurred several times. A 12-lead Holter electrocardiogram was used to determine the triggering premature ventricular contraction (PVC) and catheter ablation was performed by targeting this PVC. The site of origin of the triggering PVC was considered to be located between damaged cardiac muscle and intact Purkinje’s fiber. No episode of PVC and VT was observed after a few days of ablation. An implantable cardioverter defibrillator was implanted but VT did not recur for more than 20 months.

View full abstract

We successfully performed radiofrequency catheter ablation (RFCA) in 2 cases involving patients with idiopathic ventricular tachycardias (VTs) and premature ventricular contractions (PVCs) originating from the pulmonary artery (PA). The QRS morphology of the VTs and PVCs in the two cases exhibited a left bundle-branch block (LBBB) morphology with an inferior axis. Activation and pace mappings were performed in the right ventricular outflow tract (RVOT) and above the pulmonary valve to determine the origin of the VTs and PVCs. In both cases, the earliest ventricular activation was recorded in the PA above the pulmonary valve. Applications of radiofrequency current at those sites in the PA resulted in the elimination and noninducibility of the VT and PVC. During the follow-up, the VT or PVC did not recur without any antiarrhythmic drug administration.

View full abstract

The authors present a case report of a patient with an implanted VDD pacemaker whose postoperative ECG revealed sinus bradycardia, showing the heart rate remarkably lower than the programmed lower rate limit. Upon assessing some pacemaker manufacturers’ mechanisms to set the lower rate limit in VDD mode, it was found that they can be classified into four types. The mechanisms are based on keeping atrioventricular (AV) synchronous pacing in VDD mode or maintaining the lower rate limit in VVI mode. AV synchronous pacing results in producing an actual heart rate which is lower than the programmed lower rate limit. The classification also depends on whether the pacemakers are operating on either atrial-based or ventricular-based lower rate timing. Therefore, the actual heart rate can be lower than the programmed lower rate limit, depending on the VDD pacemaker model.

View full abstract