Prolongation of QT/QTc interval during medical treatment can occur not only with cardiovascular drugs but also with non-cardiovascular drugs. It may result in ventricular tachyarrhythmia, a high-risk condition which may trigger sudden cardiac death. Thus, to avoid drug-induced long QT syndrome and serious complications careful attention should be paid in the clinical setting.
Moreover, in the last several years objective evaluation by strictly applying electrocardiogram (ECG) data has been strongly recommended for the development of all new drugs in discussions held at the International Conference on Harmonization (ICH). This recommendation has already been adopted in the USA and the EU and is expected to be announced shortly in our country.
Not only the drugs but a variety of patient background factors may influence ECG parameters, especially the QT/QTc interval. It is necessary to introduce an appropriate study protocol that can evaluate the risk for QT/QTc prolongation related to the drug. Additionally, an adequate system to record, measure, and evaluate ECG with high objectivity must be applied to all clinical trials.

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The effects of restoration and maintenance of sinus rhythm by a combination of catheter ablation and antiarrhythmic drugs (AADs) on atrial function in patients with chronic atrial fibrillation (AF) remain unknown. In 15 patients with chronic AF (>1 year), we attempted to restore and maintain sinus rhythm by ablation targeting complex fractionated atrial electrocardiograms (CFAEs) combined with pulmonary vein isolation with or without AADs. Sinus rhythm was restored in all patients. At 17.7±7.2 months after AF ablation, maintenance of sinus rhythm was achieved in 20% of patients without AADs and in 73.3% of patients with AADs. The left atrial diameter decreased significantly by 9.5±8.1% (P<0.05) during the 12-month followup. AADs did not have any adverse effects. The aggressive strategy for maintenance of sinus rhythm involving AF ablation and AADs potentially led to recovery of structural changes in the LA in patients with chronic AF.

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In recent years right ventricular septal pacing (RVSP) has been performed instead of right ventricular apical pacing (RVAP) because of the detrimental effects on the ventricular function associated with the latter type of pacing. However, little information has been available on the comparison of the cardiac function between RVAP and RVSP in individual patients. Therefore, we compared the changes in the cardiac index (CI) between RVAP and RVSP (right ventricular outflow tract or mid-ventricular tract) in each patient in whom a permanent pacemaker was implanted. We measured both the QRS duration and acute phase of the cardiac function by means of a Swan-Ganz catheter and compared the results between RVAP and RVSP. RVSP was associated with a shorter QRS duration (139.5±4.6 vs. 180.6±4.6 msec, p<0.0001) in comparison to RVAP. Although there was no significant difference in the CI between the 2 pacing positions (2.71±0.12 vs. 2.74±0.13 L/min/m², p=0.6969), the CI among the patients with complete atrioventricular block (cAVB) had a strong tendency of being better with RVSP patients (2.65±0.19 vs. 2.84±0.19 L/min/m², p=0.1444). It is suggested that the beneficial effect of RVSP differs according to the causal disorder for pacemaker implantation.

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Background: As the indications for catheter ablation of complex arrhythmias has expanded, the radiation exposure to the operator has increased. Recently, a radiation protection cabin (RPC) has been developed. However, the effect of reducing the radiation exposure of the operator has not been fully evaluated. The aim of this study was to evaluate the efficacy the RPC during catheter ablation (CA).
Method & Results: Twenty-six patients who underwent CA were included in this study. The patients were divided into two groups, those in which the RPC was used (RPC group; n=11) and those in which it was not used (no RPC group; n=15). The radiation dosage was measured with thermoluminescent dosimeters placed on the head and chest. The decrement rates at the unprotected area of not only the operator but also the assistant in the RPC group were significantly higher than those in the no RPC group. There was no significant difference in the decrement rate in the protected areas between the two groups.
Conclusion: This study shows that the RPC protects from radiation exposure not only the operator but also the assistant and frees us from using a heavy apron.

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Aim and method: There have been few reports about the risk of ischemic stroke in elderly patients with non-valvular paroxysmal atrial fibrillation (NVPAF). The aim of this study was to evaluate the validity of the guidelines issued by the Japanese Circulation Society to prevent ischemic stroke for NVPAF in patients without a high risk of ischemic stroke. The risk evaluation was made based on the CHADS2 Score. However, we excluded age in this study, but included coronary disease. This study investigated a total of 150 patients with paroxysmal atrial fibrillation (AF) who did not have a high risk of stroke (117 men and 33 women, mean age 68±12 years). The patients were divided into three groups according to age: the patients who were less than 60 years old (Group I, N=58, Antithrombic therapy (+) = 18), those who were between 60 and 75 years old (Group II, N=68, Antithrombic therapy (+) = 36) and those who were more than 75 years old (Group III, N=24, Antithrombic therapy (+) = 7). The annual rates of thromboembolism among three groups were retrospectively analyzed. The mean follow-up periods were 56±37 months.
Results: (1) The annual rate of thromboembolism in Group III (4.0%) was significantly higher than in Group I (1.4%) and Group II (1.8%) (P<0.05). (2) The annual rates of thromboembolism in patients without antithrombotic therapy were 2.1% in Group I, 1.3% in Group II and 3.9% in Group III. The annual rate was significantly lower in Group II than in Group III (P<0.05). (3) The annual rates of thromboembolism with aspirin treatment (80–100 mg/day) were 0% in Group I, 3.0% in Group II and 8.4% in Group III. There was a significant difference in the annual rate among the three groups (P<0.05). (4) The annual rate of thromboembolism in patients with warfarin treatment was 0% in Group I, 1.5% in Group II and 0% in Group III (P=NS among 3 groups).
Conclusion: Antithrombic therapy is required in elderly patients with NVPAF to prevent ischemic stroke. Antithrombic therapy with Warfarin, but not aspirin, reduces ischemic stroke in patients with NVPAF regardless of their age.

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Introduction: Bepridil is a multi-ion channel blocker similar to amiodarone. Recent clinical studies have indicated that bepridil shows a favorable efficacy for the treatment of atrial fibrillation (AF). The purpose of this study is to evaluate the effectiveness of bepridil for electrical remodeling induced by rapid atrial stimulation particularly in the acute-phase.
Methods and Results: We studied 18 pigs subjected to right atrial appendage rapid pacing at 500 beats/min for 3 hours that were randomly assigned to the absence or presence of bepridil administration for 14 days. They were divided into 2 groups, an atrial pacing only group (PG; n=10) and an atrial pacing plus bepridil group (PBG; n=8). We measured the effective refractory period (ERP) at the right atrial free wall (RAFW), the right atrial appendage (RAA) and the left atrial free wall (LAFW), as well as the monophasic action potential duration at 90% (MAPD₉₀) in RAA during the rapid pacing phase and recovery phase.
In the PG, the ERP decreased gradually at all atrial sites during the 3 hour phase of rapid pacing. In contrast, the shortening of the ERP was suppressed significantly at the RAFW and LAFW in the PBG. The MAPD₉₀ was also shortened by rapid atrial pacing in the PG. This shortening was suppressed significantly in the PBG.
We evaluated the effect of bepridil on the inducibility of AF during all time spans. The mean number of AF occurrences in the PBG was significantly fewer than in the PG. (2.1±2.4 vs. 8.5±7.0, p<0.05)
Conclusions: Bepridil prevented the shortening of the ERP and MAPD₉₀ induced by rapid atrial pacing in the acute phase. The results of this study might explain the efficacy of bepridil for preventing the recurrence of paroxysmal AF.

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We present a 72-year-old man with interruption of inferior vena cava (IVC) with azygos continuation, who underwent radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT).
We recorded a His bundle electrogram with an electrode catheter positioned in the aortic root. We also introduced an electrode catheter through the right femoral vein, advanced it via an enlarged azygos vein and the superior vena cava and positioned it at the right ventricular apex (RVA). AVNRT was induced by programmed pacing from a coronary sinus catheter introduced through the left subclavian vein. It was successfully ablated with an ablation catheter introduced through the right internal jugular vein.
In a patient with interruption of IVC, it is impossible to access the right side of the heart directly via femoral vein and IVC. In this case, however, alternative routes to the His bundle, RVA and ablation site enabled us to perform an electrophysiologic study and a successful catheter ablation.

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We describe a patient with nonischemic cardiomyopathy who underwent radiofrequency (RF) catheter ablation for a drug-refractory ventricular tachycardia (VT). RF ablation from a left ventricular (LV) endocardial site failed to eliminate the VT. Using a conventional ablation catheter with the temperature-controlled mode, RF ablation from the LV epicardium resulted in failed ablation because of low power due to a temperature limitation function. However, by using a pericardial pigtail catheter for manual infusion and removal of saline within the pericardial space, adequate energy could be delivered, and the ablation overlying the low-voltage area successfully eliminated the VT.

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An implantation of a cardioverter-defibrillator was attempted in a 32-year-old man with atrial tachycardia, ventricular tachycardia and sinus node dysfunction. He had undergone a Senning operation and half closure of ventricular septal defect in order to correct a transposition of the great arteries. Cardiac catheterization revealed severe pulmonary hypertension and Eisenmenger syndrome. Prior knowledge of the complex cardiac anatomy obtained by magnetic resonance imaging helped in determining the suitable site for implanting the leads and planning the procedural strategy. With repletion of a large amount of saline and oral anticoagulation with warfarin, no complications related to thromboembolism occurred during a 10-month follow-up period.

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