Abstract 2438: Local Bipolar Atrial Electrogram Monitoring during the Extensive Encircling Pulmonary Vein Isolation: Implications of the ``QS Pattern” in the Local Bipolar Atrial Electrogram after the Ablation

BACKGROUND During the extensive encircling pulmonary vein (PV) isolation (EEPVI) for atrial fibrillation (AF), it is crucial to recognize whether or not a sufficient lesion was created by an ablation in each ablation site. The local electrogram (EG)-based criteria to predict a sufficient local lesion formation, however, remain to be established. This study was performed to define local EG-based criteria for the local lesion formation during the EEPVI for AF. METHODS Among 31 patients (pts) with AF who had successful EEPVI during coronary sinus pacing, bipolar local EGs at 2271 ablation sites (73+/-19 sites/pt, posterior wall (PW) of the left atrium (LA)/anterior LA-PV junction=976/1295 sites) before and after energy delivery were reviewed. In EEPVI, ipsilateral PVs, antral regions and parts of the PW of the LA were isolated as a whole by linear ablation at the PW of the LA and semi-linear ablation at the anterior LA-PV junction. Each energy application was performed with a temperature controlled mode (maximal temperature: 55 degrees Celsius, maximal output: 35 watt) and duration of 25 to 35 seconds. RESULTS After the ablation, all PVs, antral regions and parts of the PW of the LA were successfully isolated in all 31 pts (duration of each energy application: 31+/-3 sec/site, total energy application time: 37+/-10 min/pt). After the effective ablation at each site, the local EGs exhibited predominant reduction in the amplitude of positive deflection (Ap) as compared to that of negative deflection (An) (% reduction in Ap vs An: 91+/-10 vs 30+/-59%; p<0.01, Ap/An ratio before vs after ablation: 2.3+/-3.4 vs 0.3+/-0.1; p<0.01) as well as total amplitude reduction (67+/-22%) and EG widening (57+/-43%), and the morphology of the local EG changed to the ``QS” or ``rS” patterns. At 25 sites without those morphological changes, residual LA-PV conduction gaps were observed and additional ablations were required to achieve a complete EEPVI in 20 pts. CONCLUSION We propose that a morphological change of local EGs to ``QS” or ``rS” patterns with predominant attenuation of positive deflection of local EGs can reflect sufficient local lesion formation and can be one of the practical endpoints for energy delivery at each ablation site during the EEPVI.

Independent Expression of the First Two Triple Gene Block Proteins of Beet Necrotic Yellow Vein Virus Complements Virus Defective in the Corresponding Gene but Expression of the Third Protein Inhibits Viral Cell-to-Cell Movement

Cell-to-cell movement of beet necrotic yellow vein furovirus is controlled by three slightly overlapping genes on RNA 2 called the triple gene block (TGB) encoding, in order, P42, P13, and P15. Synthesis of P42 is directed by subgenomic RNA 2suba while synthesis of both P13 and P15 is probably directed by a dicistronic subgenomic RNA, 2subb. For complementation experiments, each TGB protein gene was inserted into a “replicon” derived from viral RNA 3. In mixed infections, the replicons expressing P42 and P13 complemented RNA 2 mutants defective in the corresponding gene. A P15-containing replicon did not complement a P15-defective RNA 2 but complementation was observed with a dicistronic replicon containing the P15 gene placed behind the P13 gene. In mixed infections with wild-type viral RNAs, the P15-containing replicon did not inhibit viral RNA replication in protoplasts but blocked local lesion formation on leaves. Infection of leaves was also inhibited by an RNA3-derived replicon containing the third TGB gene from another furovirus, peanut clump virus. The results are consistent with a model in which viral cell-to-cell movement requires production of appropriate relative amounts of P13 and P15, and their expression from a dicistronic subgenomic RNA provides a mechanism for coordinating their synthesis.

Interaction of calcium with indole-3-acetic acid and kinetin during the formation of local lesions in bean (Phaseolus vulgaris) by alfalfa mosaic virus

A study was conducted on the interaction of Ca2+ with 3-indoleacetic acid (IAA) and kinetin on local lesion formation by alfalfa mosaic virus on bean leaves. Local lesion number was reduced when IAA solutions alone were applied as postinoculation sprays, as compared with water sprays. The reduction was slight at 10−4 and 10−5 M but was large at 10−3 M. Although addition of 0.03 M CaCl2 to 10−4 and 10−5 M IAA sprays reversed the effect of IAA on local lesion formation, addition of the same concentration of calcium to 10−3 M IAA had little effect on local lesion production. Kinetin, except at the 10−4 M concentration, caused no increase in the number of local lesions, as compared with treatment with distilled water. However, with 0.03 M CaCl2 added, the local lesion production at all kinetin concentrations increased significantly over distilled water or 0.03 M CaCl2. The sizes of local lesions on leaves sprayed with 10−3, 10−4, and 10−5 M IAA were reduced by approximately 52, 26, and 10%, respectively, and on leaves sprayed with kinetin by approximately 44, 26, and 24%, respectively. Addition of 0.03 M CaCl2 to IAA and kinetin lessened their effect on the size of local lesions but did not eliminate the effect totally.