{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,2]],"date-time":"2026-02-02T21:47:20Z","timestamp":1770068840643,"version":"3.49.0"},"reference-count":44,"publisher":"American Physiological Society","issue":"5","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["American Journal of Physiology-Heart and Circulatory Physiology"],"published-print":{"date-parts":[[2007,11]]},"abstract":"<jats:p> 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 \u00b1 0.8 vs. 4.8 \u00b1 1.2, P &lt; 0.01) and global LV performance (cardiac output: 2.0 \u00b1 0.3 vs. 1.4 \u00b1 0.1 l\/min and stroke work: 137 \u00b1 22 vs. 60 \u00b1 14 mJ, P &lt; 0.05). Although both CRTa and CRTf significantly improved radial synchrony, only CRTa markedly improved global function (cardiac output: 2.1 \u00b1 0.2 l\/min and stroke work: 113 \u00b1 13 mJ, P &lt; 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. <\/jats:p>","DOI":"10.1152\/ajpheart.00728.2007","type":"journal-article","created":{"date-parts":[[2007,9,15]],"date-time":"2007-09-15T00:58:52Z","timestamp":1189817932000},"page":"H3046-H3055","source":"Crossref","is-referenced-by-count":15,"title":["Differential effects of left ventricular pacing sites in an acute canine model of contraction dyssynchrony"],"prefix":"10.1152","volume":"293","author":[{"given":"Lauren","family":"Johnson","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyung Kook","family":"Kim","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Masaki","family":"Tanabe","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"John","family":"Gorcsan","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David","family":"Schwartzman","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sanjeev G.","family":"Shroff","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Michael R.","family":"Pinsky","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"24","reference":[{"key":"R1","doi-asserted-by":"publisher","DOI":"10.1056\/NEJMoa013168"},{"key":"R2","doi-asserted-by":"publisher","DOI":"10.1016\/j.jacc.2003.04.003"},{"key":"R3","doi-asserted-by":"publisher","DOI":"10.1016\/S0735-1097(02)01895-8"},{"key":"R4","doi-asserted-by":"publisher","DOI":"10.1016\/j.jacc.2005.09.019"},{"key":"R5","unstructured":"Bonow RO. 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