Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a highly lethal form of inherited arrhythmogenic disease characterized by adrenergically mediated polymorphic VT. The identification of the genetic substrate of the disease has allowed to achieve important milestones in the understanding of the arrhythmogenic mechanisms of the disease. Abnormal calcium leak from the mutant cardiac ryanodine receptor has been associated with the induction of delayed afterdepolarization suggesting that arrhythmogenesis in CPVT is likely to be induced by triggered activity. Here we review the current knowledge and some controversial issues about the molecular mechanism of arrhythmias initiation in CPVT and we discuss their implications for the development of novel therapeutic strategies in CPVT.

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Despite the advent of drug-eluting stents in Japan, bare metal stents or conventional balloon angioplasty are still indicated in some patients needing elective percutaneous coronary intervention (PCI) and in patients with acute coronary syndrome if these patients develop side effects while taking ticlopidine. In such patients, restenosis is a problem that is difficult to diagnose. To investigate the comparative diagnostic accuracy of the exercise-stress electrocardiogram (ECG) for detecting restenosis after PCI, we measured conventional ST-segment changes and QT dispersion during exercise-stress testing in 173 patients with elective PCI (63±10 years old). Exercise-stress testing was performed 3 to 6 months after successful PCI, and restenosis was confirmed by follow-up coronary angiogram. There were 98 patients with a prior myocardial infarction (prior MI group) and 76 patients with no prior myocardial infarction (no MI group). Restenosis was found in 45 patients (46%) in the prior MI group and 26 patients (34%) in the no MI group. Conventional ST-segment depression (>1.0 mm, J 60 ms) indicating exercise-induced myocardial ischemia had a sensitivity of around 50% and a specificity of around 70% for diagnosing restenosis in both groups. In the prior MI group, QT dispersion was increased by exercise-stress testing in both patients with and without restenosis, whereas in the no MI group, QT dispersion increased only in patients with restenosis. With a cut-off value of >60 ms, QT dispersion had a sensitivity of 54% and a specificity of 68% for detecting restenosis in the no MI group; these values were comparable to those seen with conventional ST-segment changes. In conclusion, due to its low cost, exercise-stress ECG remains useful for diagnosing restenosis following PCI if the clinician understands its limited sensitivity and specificity. The presence of a prior MI must be considered when QT dispersion during exercise-stress testing is used for detecting restenosis.

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Atrial premature depolarizations (APDs) triggering atrial fibrillation (AF) originate from mainly the pulmonary veins (PVs), but, in some cases, atrial ectopic beats (AEBs) triggering AF originate from the right atrium (RA) or the superior vena cava. Accurate identification of the origin of APDs in the PVs by means of RA and coronary sinus mapping is difficult. Purpose: The aim of this study was to identify the origin of AEBs triggering AF before transseptal catheterization. Electrode catheters were placed in the posteroseptal RA (PSRA), right pulmonary artery (RPA), left pulmonary artery (LPA), and esophagus in 10 patients with paroxysmal AF. We analyzed endocardial electrograms from the PSRA, RPA and LPA, and epicardial electrograms from the esophagus. The origin of the AEBs in the PVs was determined before PV ablation by mapping 4 PVs simultaneously. Four AEBs originated from the left superior PV (LSPV), 2 from the left inferior PV (LIPV), 4 from the right superior PV (RSPV), 2 from the RA or superior vena cava. In AEBs originating from the RA, the PSRA activation was the earliest and it proceeded in a cranial to caudal direction. In AEBs originating from the RUPV, RPA was the earliest. The esophageal activation sequence was in a cranial to caudal direction. In AEBs from the LSPV, LPA was the earliest and the esophageal activation sequence proceeded in a cranial to caudal direction. In AEDs from LIPV, LPA was the earliest, and the esophageal activation sequence was nearly simultaneous. Atrial activation sequences from the PSRA, RPA, LPA, and esophageal catheters can accurately identify the location of the initiating foci of AF before a transseptal procedure.

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Electrical isolation of the pulmonary veins (PV) has become a curative treatment for patients with atrial fibrillation (AF). Recently, there have been many reports that circumferential PV isolation (CPI) on the atrial side has a better outcome than segmental ostial PV isolation (SOPI). However, reports on the combination of CPI using electoroanatomic mapping and SOPI using a circular mapping catheter have been few. The aim of the present study was to investigate the efficacy and safety of a combined therapy using CPI and supplemental SOPI for the treatment of AF. We performed CPI in 120 patients with drug-refractory AF. In 27 of those patients CPI resulted in a disconnection between the left atrium (LA) and PVs. In the remaining patients, supplemental SOPI completed the LA-PV disconnection. After an average follow-up period of 10.4 months, 81.7%, 90.5% and 71.4% of the patients with paroxysmal, persistent and chronic AF, respectively, have been free of AF. In 14.1% of the patients with paroxysmal AF, a greatly reduced frequency and/or duration of the episodes of AF were observed after the ablation. No fatal complications were encountered. The present results suggest that the combination of CPI and supplemental SOPI is efficient and safe for the treatment of AF.

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Introduction: Imbalanced autonomic activity in the area of the pulmonary veins (PVs) can result in spontaneous atrial fibrillation (AF). Histologic characteristics of the PV sleeve musculature and associated autonomic nerve are not fully understood. We investigated the arrangement of autonomic nerve fibers around PV-left atrium (LA) junctional musculature.
Methods: Thirteen autopsied adult hearts (9 men and 4 women; mean age at death, 66.2 years) were studied. The atria were removed from each heart, along with all PV stalks, and cut longitudinally to each PV myocardial sleeve. After treatment with azan-Mallory stain and immunohistochemical staining for S-100 and tyrosine hydroxylase (TH), autonomic nerve distribution was assessed by counting the numbers of TH-positive (adrenergic) and -negative (non-adrenergic) fibers within S-100-positive fibers (>50 μm in diameter) in the anterior, posterior, and septal junctions.
Results: TH-positive adrenergic fibers, consisting of sympathetic nerves, were most predominant in the anterior and septal junctions. In the anterior junction, these fibers were packed tightly among myocardial sleeve fascicles. In the posterior junction, the numbers of adrenergic and non-adrenergic fibers were fewer. In the septal junction, the number of TH-negative non-adrenergic fibers (predominantly parasympathetic nerves) was greater, concomitant diffuse ganglionic nodule distribution in the interatrial fat pad.
Conclusions: In each PV-LA junction, autonomic nerves were localized on the anterior and septal walls. Heterogeneous distribution of TH-positive and TH-negative fibers and ganglion nodules around each PV opening appears to represent the major histologic characteristic in these areas.

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An 80-year-old man was implanted with a DDD pacemaker to treat his sick sinus syndrome in 1990. Eleven years later, he had a pocket infection and cutaneous inflammation. Blood cultures were negative, and ⁶⁷Ga scintigraphy revealed uptake in the left subclavian region. However, intense abnormal fluorodeoxyglucose (FDG) uptake along the pacemaker leads was detected with positron emission tomography (PET). Thoracotomy was performed, vegetations were removed from the right atrial wall and the tricuspid leaflet, encapsulating fibrous tissue was incised, and the lead was removed from the right ventricle.

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The patient was a 67-year-old female diagnosed with dilated cardiomyopathy. She had chronic atrial fibrillation (AF) with bradycardia and low left ventricular function (left ventricular ejection fraction (LVEF) 40%). She was admitted for congestive heart failure. She remained New York Heart Association (NYHA) functional class III due to AF bradycardia. Pacemaker implantation was necessary for treatment of heart failure and administration of dose intensive β-blockers. As she had normal His-Purkinje activation, we examined the optimal pacing sites. Hemodynamics of His-bundle pacing and biventricular pacing were compared. Pulmonary capillary wedge pressure (PCWP) was significantly lower on His-bundle pacing than right ventricular (RV) apical pacing and biventricular pacing (13 mmHg, 19 mmHg, and 19 mmHg, respectively) with an almost equal cardiac index. Based on the examination we implanted a permanent pacemaker for Direct His-bundle pacing (DHBP). After the DHBP implantation, the LVEF immediately improved from 40% to 55%, and BNP level decreased from 422 pg/ml to 42 pg/ml. The number of premature ventricular complex (PVC) was decreased, and non sustained ventricular tachycardia (NSVT) disappeared. Pacing threshold for His-bundle pacing has remained at the same level. His-bundle pacing has been maintained during 27 months and her long-term DHBP can improve cardiac function and the NYHA functional class.

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