Europace Advance Access published online on November 15, 2007
Europace, doi:10.1093/europace/eum238
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Investigation of pacing site-related changes in global restitution dynamics by non-contact mapping
1 Cardio Vascular, Medtronic Inc., 7601 Northland Drive, Brooklyn Park, MN 55428, USA; 2 Wessex Cardiac Centre, Southampton General Hospital, Mailpoint 46, Tremona Road, Southampton SO16 6YD, UK; 3 CRDM, Medtronic, Inc., 8200 Coral Sea Street NE, Mounds View, MN 55112, USA; 4 Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA; 5 Department of Physiology, University of Minnesota, Minneapolis, MN 55455, USA; 6 Department of Surgery, University of Minnesota, Minneapolis, MN 55455, USA
Aims: The determination of dynamic changes in ventricular repolarization may provide insight into arrhythmogenic mechanisms as a consequence of pacing site. This study investigated acute pacing site effects on global characteristics of electrical restitution using high resolution, non-contact mapping (NCM).
Methods and results: Activation-recovery intervals (ARIs) were determined from reconstructed left ventricular electrograms by the NCM system and were analysed during pacing from the right atrial appendage (RAA, intrinsic), right ventricular apex (RVA), and right ventricular septum (RVS) with extrasystoles delivered at intermediate and short coupling intervals in anesthetized swine (n = 5). Electrical restitution curves were determined by the S1–S2 pacing protocol. Activation-recovery interval restitution slopes were determined by the overlapping linear segments regression method. Global distribution of repolarization was defined as the coefficient of variation of the ARIs during restitution. The maximum ARI slopes yielded by RVA pacing were significantly greater than RAA pacing (0.44 vs. 0.32; P < 0.05) and RVS pacing (0.44 vs. 0.37; P = 0.05). There was no significant difference between RAA and RVS pacing (0.32 vs. 0.37). The global distribution of ARIs during restitution from RVA pacing was significantly greater than RAA pacing (12.0 vs. 8.1%; P < 0.05).
Conclusion: Right ventricular apex pacing is associated with impaired global repolarization patterns compared to RAA and RVS. These observations support the hypothesis that RVA pacing may be associated with increased risk of ventricular arrhythmias compared to RVS pacing.
Key Words: Pacing, Mapping, Dynamics, Arrhythmia, Electrical restitution
* Corresponding authors. Tel: +44 23 8079 6240; fax: +44 23 8079 8942. E-mail address: jmm{at}cardiology.co.uk
Manuscript submitted 27 July 2007. Accepted after revision 1 October 2007.