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976-9 Effects of Facilitation on Human AV Nodal Fast and Slow Pathways

The effect of facilitation on AV nodal function was studied in twelve patients before and after radiofrequency ablation (RFA) of the slow pathway. AV nodal recovery time (H1A2 or H2A3)was plotted against AV nodal conduction time (A2H2 or A3H3) for test intervals from control and facilitation protoco...

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Bibliographic Details
Published in:Journal of the American College of Cardiology 1995-02, Vol.25 (2), p.254A-255A
Main Authors: Kidwell, Gregory A., Fahy, Gerard J.
Format: Article
Language:English
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Summary:The effect of facilitation on AV nodal function was studied in twelve patients before and after radiofrequency ablation (RFA) of the slow pathway. AV nodal recovery time (H1A2 or H2A3)was plotted against AV nodal conduction time (A2H2 or A3H3) for test intervals from control and facilitation protocols respectively (see figure). The mean A1A2 for the facilitation protocol was 363±15ms. The minimal recovery time (RT), functional refractory period (FRP) and conduction time (CT) of both the fast and slow pathways were determined. The effect of facilitation on CT was assessed at the minimal RT obtained during control testing. Fast PathwaySlow PathwayPre-RFARTFRPCTRTFRPCTControl271±22430±30161±12198±14462±22273±15Facilitation228±25391±17132±9131±15421±20231±11p value0.003000070.0006<0.0001<000010.0006 Fast and slow pathway properties were enhanced by facilitation in all patients. Facilitation significantly decreased the minimal RT. FRP and CT of both pathways (see table). The window of test impulses over which slow pathway conduction was observed was significantly increased by the facilitation protocol (81±17 vs 110±23 ms. p=0.04) and in four patients facilitation unmasked dual AV nodal physiology and resulted in AVNRT induction. The effect of facilitation on fast pathway CT persisted after RFA but changes in minimum RT and FRP were not observed. 1) Facilitation enhances AV nodal fast and slow pathway function and promotes the induction of AVNRT. 2) The effects of facilitation on fast pathway function are attenuated following slow pathway ablation. [Display omitted]
ISSN:0735-1097
1558-3597
DOI:10.1016/0735-1097(95)92516-8