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Differential effects of left ventricular pacing sites in an acute canine model of contraction dyssynchrony

Johnson, L and Hyung, KK and Tanabe, M and Gorcsan, J and Schwartzman, D and Shroff, SG and Pinsky, MR (2007) Differential effects of left ventricular pacing sites in an acute canine model of contraction dyssynchrony. American Journal of Physiology - Heart and Circulatory Physiology, 293 (5). ISSN 0363-6135

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The goal of the present study was to assess the effects of left ventricular (LV) pacing sites (apex vs. free wall) on radial synchrony and global LV performance in a canine model of contraction dyssynchrony. Ultrasound tissue Doppler imaging and hemodynamic (LV pressure-volume) data were collected in seven anesthetized, opened-chest dogs. Right atrial (RA) pacing served as the control, and contraction dyssynchrony was created by simultaneous RA and right ventricular (RV) pacing to induce a left bundle-branch block-like contraction pattern. Cardiac resynchronization therapy (CRT) was implemented by adding simultaneous LV pacing to the RV pacing mode at either the LV apex (CRTa) or free wall (CRTf). A new index of synchrony was developed via pair-wise cross-correlation analysis of tissue Doppler radial strain from six midmyocardial cross-sectional regions, with a value of 15 indicating perfect synchrony. Compared with RA pacing, RV pacing significantly decreased radial synchrony (11.1 ± 0.8 vs. 4.8 ± 1.2, P < 0.01) and global LV performance (cardiac output: 2.0 ± 0.3 vs. 1.4 ± 0.1 l/min and stroke work: 137 ± 22 vs. 60 ± 14 mJ, P < 0.05). Although both CRTa and CRTf significantly improved radial synchrony, only CRTa markedly improved global function (cardiac output: 2.1 ± 0.2 l/min and stroke work: 113 ± 13 mJ, P < 0.01 vs. RV pacing). Furthermore, CRTa decreased LV end-systolic volume compared with RV pacing without any change in LV end-systolic pressure, indicating an augmented global LV contractile state. Thus, LV apical pacing appears to be a superior pacing site in the context of CRT. The dissociation between changes in synchrony and global LV performance with CRTf suggests that regional analysis from a single plane may not be sufficient to adequately characterize contraction synchrony. Copyright © 2007 the American Physiological Society.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Johnson, L
Hyung, KK
Tanabe, M
Gorcsan, Jgorcsan@pitt.eduGORCSAN
Schwartzman, D
Shroff, SGsshroff@pitt.eduSSHROFF
Pinsky, MRpinsky@pitt.eduPINSKY0000-0001-6166-700X
Date: 1 November 2007
Date Type: Publication
Journal or Publication Title: American Journal of Physiology - Heart and Circulatory Physiology
Volume: 293
Number: 5
DOI or Unique Handle: 10.1152/ajpheart.00728.2007
Schools and Programs: School of Medicine > Critical Care Medicine
Refereed: Yes
ISSN: 0363-6135
PubMed ID: 17873017
Date Deposited: 05 Mar 2012 17:27
Last Modified: 30 Jan 2020 16:55


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