HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 286/6/H2401    most recent 01013.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Ashikaga, H. Articles by Covell, J. W. Search for Related Content PubMed PubMed Citation Articles by Ashikaga, H. Articles by Covell, J. W.

Transmural mechanics at left ventricular epicardial pacing site

Departments of ¹Medicine and ²Bioengineering, University of California, San Diego, La Jolla 92093; and ³Laboratory of Cardiovascular Physiology and Biophysics, Palo Alto Medical Foundation, Research Institute, Palo Alto 94301; and ⁴Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California 94305

Submitted 27 October 2003 ; accepted in final form 22 January 2004

Left ventricular (LV) epicardial pacing acutely reduces wall thickening at the pacing site. Because LV epicardial pacing also reduces transverse shear deformation, which is related to myocardial sheet shear, we hypothesized that impaired end-systolic wall thickening at the pacing site is due to reduction in myocardial sheet shear deformation, resulting in a reduced contribution of sheet shear to wall thickening. We also hypothesized that epicardial pacing would reverse the transmural mechanical activation sequence and thereby mitigate normal transmural deformation. To test these hypotheses, we investigated the effects of LV epicardial pacing on transmural fiber-sheet mechanics by determining three-dimensional finite deformation during normal atrioventricular conduction and LV epicardial pacing in the anterior wall of normal dog hearts in vivo. Our measurements indicate that impaired end-systolic wall thickening at the pacing site was not due to selective reduction of sheet shear, but rather resulted from overall depression of fiber-sheet deformation, and relative contributions of sheet strains to wall thickening were maintained. These findings suggest lack of effective end-systolic myocardial deformation at the pacing site, most likely because the pacing site initiates contraction significantly earlier than the rest of the ventricle. Epicardial pacing also induced reversal of the transmural mechanical activation sequence, which depressed sheet extension and wall thickening early in the cardiac cycle, whereas transverse shear and sheet shear deformation were not affected. These findings suggest that normal sheet extension and wall thickening immediately after activation may require normal transmural activation sequence, whereas sheet shear deformation may be determined by local anatomy.

epicardial pacing; transmural deformation; fiber; sheet

This article has been cited by other articles:

				J. E. Stelzer, H. S. Norman, P. P. Chen, J. R. Patel, and R. L. Moss Transmural variation in myosin heavy chain isoform expression modulates the timing of myocardial force generation in porcine left ventricle J. Physiol., November 1, 2008; 586(21): 5203 - 5214. [Abstract] [Full Text] [PDF]

				H. Ashikaga, B. A. Coppola, K. G. Yamazaki, F. J. Villarreal, J. H. Omens, and J. W. Covell Changes in regional myocardial volume during the cardiac cycle: implications for transmural blood flow and cardiac structure Am J Physiol Heart Circ Physiol, August 1, 2008; 295(2): H610 - H618. [Abstract] [Full Text] [PDF]

				H. Ashikaga, B. A. Coppola, B. Hopenfeld, E. S. Leifer, E. R. McVeigh, and J. H. Omens Transmural Dispersion of Myofiber Mechanics: Implications for Electrical Heterogeneity In Vivo J. Am. Coll. Cardiol., February 27, 2007; 49(8): 909 - 916. [Abstract] [Full Text] [PDF]

				J. E. Stelzer and R. L. Moss Contributions of Stretch Activation to Length-dependent Contraction in Murine Myocardium J. Gen. Physiol., October 1, 2006; 128(4): 461 - 471. [Abstract] [Full Text] [PDF]

				N. D. Epstein and J. S. Davis When Is a Fly in the Ointment a Solution and not a Problem? Circ. Res., May 12, 2006; 98(9): 1110 - 1112. [Full Text] [PDF]

				P. P. Sengupta, B. K. Khandheria, J. Korinek, J. Wang, A. Jahangir, J. B. Seward, and M. Belohlavek Apex-to-Base Dispersion in Regional Timing of Left Ventricular Shortening and Lengthening J. Am. Coll. Cardiol., January 3, 2006; 47(1): 163 - 172. [Abstract] [Full Text] [PDF]

				P. P. Sengupta, B. K. Khandheria, J. Korinek, J. Wang, and M. Belohlavek Biphasic tissue Doppler waveforms during isovolumic phases are associated with asynchronous deformation of subendocardial and subepicardial layers J Appl Physiol, September 1, 2005; 99(3): 1104 - 1111. [Abstract] [Full Text] [PDF]

				H. Ashikaga, J. W. Covell, and J. H. Omens Diastolic dysfunction in volume-overload hypertrophy is associated with abnormal shearing of myolaminar sheets Am J Physiol Heart Circ Physiol, June 1, 2005; 288(6): H2603 - H2610. [Abstract] [Full Text] [PDF]

				H. Ashikaga, J. H. Omens, and J. W. Covell Time-dependent remodeling of transmural architecture underlying abnormal ventricular geometry in chronic volume overload heart failure Am J Physiol Heart Circ Physiol, November 1, 2004; 287(5): H1994 - H2002. [Abstract] [Full Text] [PDF]