Single site radiofrequency catheter ablation of atrial fibrillation: studies guided by simultaneous multisite mapping in the canine sterile pericarditis model

AbstractOBJECTIVESTo test the hypothesis that when activation of Bachmann’s bundle (BB) is critical to the unstable reentrant circuits that maintain atrial fibrillation (AF) in the sterile pericarditis canine model, a lesion in BB would prevent induction of stable AF.BACKGROUNDOne mechanism of induced AF in this model is multiple unstable reentrant circuits, which frequently include BB as part of the reentrant pathway.METHODSSimultaneous multisite mapping studies during AF and after ablation of BB were performed by recording (384 to 396 electrodes) from both atria and the atrial septum during six induced AF episodes in six dogs with sterile pericarditis. Activation maps of AF (mean duration, 24 ± 28 min) during 12 consecutive 100-ms windows were analyzed.RESULTSDuring AF, multiple unstable reentrant circuits (mean, 1.2 ± 0.2 per window; range, 1 to 4) were observed, 68% involving BB. Nonactivation zones (mean duration, 57 ± 16 ms in the right atrium and 53 ± 23 ms in the left atrium) observed during AF were reactivated by a wave front most often coming from the atrial septum via BB (right atrium, 62%; left atrium, 67%). After successful radiofrequency catheter ablation of the midportion of BB, AF >5 s was not induced in all dogs. Mapping studies of transient AF (≤5 s) induced after ablation showed neither reentrant circuits nor wave fronts activating the right atrium via BB.CONCLUSIONSIn this AF model, catheter ablation of BB terminates and prevents the induction of AF by preventing 1) formation of unstable reentrant circuits that involve BB, and 2) activation of the atrial-free walls after a nonactivation period

Cancer gene expression database (CGED): a database for gene expression profiling with accompanying clinical information of human cancer tissues

Gene expression profiling of cancer tissues is expected to contribute to our understanding of cancer biology as well as developments of new methods of diagnosis and therapy. Our collaborative efforts in Japan have been mainly focused on solid tumors such as breast, colorectal and hepatocellular cancers. The expression data are obtained by a high-throughput RT–PCR technique, and patients are recruited mainly from a single hospital. In the cancer gene expression database (CGED), the expression and clinical data are presented in a way useful for scientists interested in specific genes or biological functions. The data can be retrieved either by gene identifiers or by functional categories defined by Gene Ontology terms or the Swiss-Prot annotation. Expression patterns of multiple genes, selected by names or similarity search of the patterns, can be compared. Visual presentation of the data with sorting function enables users to easily recognize of relationships between gene expression and clinical parameters. Data for other cancers such as lung and thyroid cancers will be added in the near future. The URL of CGED is http://cged.hgc.jp