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 mm 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 THnegative 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. (J Arrhythmia 2006; 22: 234-241)

Introduction: Some studies have reported that transmural dispersion of repolarization (TDR) is involved in the onset of ventricular arrhythmia. We investigated the effects of nicorandil (NIC) and nifekalant (NIF) injected into the pericardial space, on TDR and T waves in the pig. Methods and Results: We injected NIC 4 or 8 mg and NIF 50 or 100 mg at intervals into the pericardial space for eleven pigs. The effects of these drugs were investigated on the effective refractory period (ERP) between the endocardial and epicardial myocardial cells, as well as on QT time, QT peak-end (QTcpe) as an index of TDR, and T waveforms, respectively. QTcpe increased from 91 AE 21 to 116 AE 19 msec, 2.8 min after injection of NIC (p < 0.01), although corrected QT (QTc) interval did not changed. But 5.5 min after injection, QTc decreased while QTcpe recovered. T wave amplitude significantly increased, and epicardium ERP decreased. When NIF was injected, TDR decreased from 55 AE 10 msec to 44 AE 8 msec (p < 0.01) although QTc did not change. In a later phase, QTc increased (p < 0.01) and QTcpe recovered. T wave amplitude rapidly decreased and became negative. Conclusion: Injected into the pericardial space, NIC and NIF brought about certain changes in ERP, QT and T waveform. Furthermore, NIC increased TDR while NIF decreased TDR. (J Arrhythmia 2007; 23: 46-57)

The goal of this study was to measure the effective refractory period (ERP), the conduction velocity (CV) and the wavelength (WL) after cardioversion in patients with persistent atrial fibrillation (AF) and to determine the effects of the adenosine triphosphate sensitive potassium channel (K ATP ) opening agent, nicorandil, on those parameters in patients with persistent AF.METHODS: Patients with AF underwent elective cardioversion followed by measurement of ERP and CV before and after administration of nicorandil. Parameters were measured again one week later, and the ERP and the CV was used to calculate WL.RESULTS: ERP was significantly shorter immediately after termination of AF than at the 1-week time point (193.4 vs. 228.7 msec p < 0:01). While there was no significant difference in ERP immediately after termination of AF when comparing measurements taken before and after the administration of nicorandil, ERP at the 1-week time point was shorter after nicorandil administration than before nicorandil administration (193.4 vs. 191.4 msec, n.s.; 228.7 vs. 217.2 msec, p < 0:01). Further, WL was higher at the 1-week time point after nicorandil administration than before nicorandil administration.CONCLUSIONS: These data indicate that the electrical remodeling that occurs after cardioversion is at least partially mediated by changes in K ATP channel behavior. Further, the electrophysiologic properties, that is, nicorandil prolonging the WL, may be of benefit in reducing the recurrence rate of AF. (J Arrhythmia 2005; 21: 371-377)