Advances in Electrocardiology 2004, pp. 64-68 (2005) No AccessHETEROGENIC PROCESS OF THE APPEARANCE OF THE ATRIAL ELECTRICAL REMODELING IN CANINE RAPID STIMULATION MODELJISHO KOJIMA, SHINICHI NIWANO, DAISUKE SATO, MASAHIKO MORIGUCHI, YUKO WAKISAKA, KAZUKO IKEDA, KIMIATSU INUO, HIDEYUKI HARA, TOHRU YOSHIDA, and TOHRU IZUMIJISHO KOJIMADepartment of Internal Medicine, Kitasato University, Kanagawa, Japan, SHINICHI NIWANODepartment of Internal Medicine, Kitasato University, Kanagawa, Japan, DAISUKE SATODepartment of Internal Medicine, Kitasato University, Kanagawa, Japan, MASAHIKO MORIGUCHIDepartment of Internal Medicine, Kitasato University, Kanagawa, Japan, YUKO WAKISAKADepartment of Internal Medicine, Kitasato University, Kanagawa, Japan, KAZUKO IKEDADepartment of Internal Medicine, Kitasato University, Kanagawa, Japan, KIMIATSU INUODepartment of Internal Medicine, Kitasato University, Kanagawa, Japan, HIDEYUKI HARADepartment of Internal Medicine, Kitasato University, Kanagawa, Japan, TOHRU YOSHIDADepartment of Internal Medicine, Kitasato University, Kanagawa, Japan, and TOHRU IZUMIDepartment of Internal Medicine, Kitasato University, Kanagawa, Japanhttps://doi.org/10.1142/9789812702234_0014Cited by:0 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail Abstract: Background: Although it is well known that rapid atrial activation causes electrical remodeling, processes of electrical remodeling at different atrial sites are still unclear. In present study, atrial electrophysiologic parameters were monitored at several atrial sites during rapid atrial stimulation for 2weeks to clarify heterogeneity of process of atrial electrical remodeling. Methods: RAA or LAA was paced with 400bpm for 2weeks. At 4atrial sites of RAA, Bachmann's bundle (BB), IVC and LAA, AERP, AERP dispersion(AERPd) and inducibility of atrial fibrillation were evaluated at several points in pacing and recovery phase. Results: AERP shortening (Δ AERP)was heterogeneous in 4atrial sites in process of atrial electrical remodeling. In RAA stimulation group, Δ AERP was larger in RAA and LA sites than other sites. In contrast, LAA stimulation group showed larger Δ AERP at BB site than others. Maximal AERPd was larger in LAA than RAA stimulation group. AF inducibility was highest at LA site in both groups, but inducibility was higher in LAA than RAA stimulation group. Conclusions: In this model, process of the atrial electrical remodeling was heterogeneous in different parts of atria. Δ AERP was largest at LA site regardless of rapid pacing site, but AERPd was larger and AF inducibility was higher in LAA stimulation group than RAA stimulation group. LA seemed to play an important role in causing AF in canine rapid stimulation model of atrial electrical remodeling. Keywords: Atrial FibrillationElectrical RemodelingElectrophysiology FiguresReferencesRelatedDetails Advances in Electrocardiology 2004Metrics History KeywordsAtrial FibrillationElectrical RemodelingElectrophysiologyPDF download

The purpose of this study was to evaluate the electrical remodeling of the ventricular myocardium in the experimental autoimmune myocarditis (EAM) model in Lewis rats. EAM was induced by immunization with cardiac myosin. During the active myocarditis phase, the effective refractory period (ERP), the duration of the monophasic action potential (MAPD) was extracted from the left ventricular free wall, and the mRNA levels of Kv1.4, 4.2, 4.3 and L type Ca2+ channel were determined by RNase protection assays. The inducibility of ventricular arrhythmia was higher in EAM rats than in the control rat, and the direct relationship between the coupling intervals of the premature stimulus and the ventricular arrhythmia in EAM rats. The ERP was prolonged in EAM rats compared with the control group. The MAPDs determined as 20% and 90% repolarization time, were both longer in EAM rats than in the controls. The level of expression of Kv4.2 mRNA was reduced in EAM rats in comparison with the controls, whereas those of Kv1.4, 4.3 and the L type Ca2+ channel were unchanged. Ventricular vulnerability was higher in EAM rats than in the control rats, and some of the ventricular arrhythmias observed in the EAM group seemed to be based on triggered activity. The level of expression of Kv4.2 mRNA was significantly reduced, and this change was compatible with prolongation of the action potential duration. (Circ J 2002; 66: 97 - 103)

Post-repolarization refractoriness (PRR) is an important factor in determining conduction block and is the difference between the effective refractory period (ERP) and the duration of the monophasic action potential (MAPD). In the present study, conduction block in an artificial isthmus in the canine atrium was evaluated and the coupling interval of a premature beat, which caused the block, was defined as the block coupling interval (BCI). The usefulness of this value was also evaluated. Radiofrequency linear ablation was performed on the right atrial surface parallel to the atrioventricular groove in 5 mongrel dogs, and an artificial isthmus (8-10mm wide and 25-30mm long) was created. Fourteen simultaneous unipolar recordings were performed in the isthmus with a resolution of 1.2mm. Single extra-stimuli with basic drive train were delivered to induce conduction block in the isthmus and when it occurred, the coupling interval at the recording site just proximal to the site of the block was defined as the BCI. At the site of the block, the ERP and MAPD at each drive cycle length were measured. The PRR was calculated using 2 different formulae: (1) [ERP-MAPD], and (2) [BCI-MAPD]. It was found that each value was shortened in accordance with the shortening of the basic drive cycle length. In all basic drive trains, BCI>ERP>MAPD, and [ERP-MAPD] was always shorter than [BCI-MAPD]. In the shorter cycle length of basic drives, the difference between [ERP-MAPD] and [BCI-MAPD] was more prominent. In the artificial isthmus model in the canine atrium, BCI was always longer than the ERP measured at the same site as the block. Because the ERP may not directly reflect the block phenomenon, the electrophysiologic evaluation should use the BCI instead, as in the PRR evaluation.