Objective: Right ventricular (RV) pacing has been associated with abnormal cardiac electrical and mechanical dyssynchrony, resulting in impaired global and regional ventricular pump function. This study aimed to characterize the relative effects of pacing site on left ventricular (LV) activation patterns and associated hemodynamic performances. Methods: Acute pacing was performed in anesthetized swine (n = 10) instrumented for RV and LV pressure, non-contact mapping (NCM) of endocardial unipolar electrograms, surface ECG, aortic flow, and sonomicrometry. Bipolar endocardial pacing leads were positioned in the right atrial appendage (RAA), RV apex (RVA), and RV outflow tract (RVOT), while bipolar epicardial leads were positioned on the LV-free wall (LVFW) and LV apex (LVA). Results: LVFW and RVA pacing induced the largest increase in intraventricular electrical dyssynchrony (IVED; 32.2 ± 10 ms, 21.7 ± 4.1 ms, respectively; both p < 0.01), whereas pacing from all sites increased QRS and total endocardial LV activation durations (p < 0.01). The largest impairment of LV and RV contractility (dP/dt max) and relaxation (dP/dt min) was observed during RVA pacing (p = ns). Synchronous electrical activation patterns were observed on NCM during RVOT and LVA pacing. LVFW pacing was the only site that significantly increased tau values as compared to RAA pacing (∼25%), whereas LVA pacing elicited only slight increases (∼1%). Conclusions: In swine with preserved ventricular conduction, in vivo pacing of the RVOT and LVA was associated with preserved, physiologically similar electrical activation sequences and LV function relative to RAA pacing. In contrast, RVA pacing caused widespread electrical dyssynchrony of the LV and prolonged activation durations, thereby impairing associated cardiac performance. Such insights into alternate site cardiac pacing, which employed the combination of high-resolution electrical mapping with real-time hemodynamic assessments, may further increase acute and long-term benefits in patients requiring permanent pacemaker support.
|Original language||English (US)|
|Number of pages||10|
|Journal||Journal of Interventional Cardiac Electrophysiology|
|State||Published - Dec 2009|
Bibliographical noteFunding Information:
This research was in part financially supported by Medtronic, Inc., and by the Institute for Engineering in Medicine of the University of Minnesota. Dr. Skadsberg is an employees of Medtronic. N.D.Skadsberg.D.R.Kaiser.T.M.Fischer Medtronic, Inc., Minneapolis, MN 55432, USA P. A. Iaizzo (*) Departments of Surgery, Biomedical Engineering, and Integrative Biology and Physiology, University of Minnesota, MMC 195, B172 Mayo, 420 Delaware St. SE, Minneapolis, MN 55455, USA e-mail: firstname.lastname@example.org
Copyright 2010 Elsevier B.V., All rights reserved.
- Activation sequence
- Cardiac mapping
- Cardiac pacing
- Left ventricle
- Non-contact mapping