This Article Figures Only Full Text Full Text (PDF) All Versions of this Article: j.jacc.2006.07.074v1 49/8/909    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ashikaga, H. Articles by Omens, J. H. Search for Related Content PubMed Articles by Ashikaga, H. Articles by Omens, J. H. Related Collections Related Article

PRECLINICAL STUDIES

Transmural Dispersion of Myofiber Mechanics

Implications for Electrical Heterogeneity In Vivo

Hiroshi Ashikaga, MD^_*,,_*, Benjamin A. Coppola, BS^_*, Bruce Hopenfeld, PhD, Eric S. Leifer, PhD, Elliot R. McVeigh, PhD and Jeffrey H. Omens, PhD^_*

^{_{* *}}Department of Medicine and Bioengineering, University of California, San Diego, La Jolla, California
Laboratory of Cardiac Energetics
Office of Biostatistics Research, National Heart, Lung, and Blood Institute, Bethesda, Maryland

Manuscript received April 26, 2006; revised manuscript received July 5, 2006, accepted July 10, 2006.

^_* Reprint requests and correspondence: Dr. Hiroshi Ashikaga, Laboratory of Cardiac Energetics, NIH/NHLBI, 9000 Rockville Pike, Building 10/B1D416, Bethesda, Maryland 20892. (Email: ha8000{at}gmail.com).

OBJECTIVES: We investigated whether transmural mechanics could yield insight into the transmural electrical sequence.

BACKGROUND: Although the concept of transmural dispersion of repolarization has helped explain a variety of arrhythmias, its presence in vivo is still disputable.

METHODS: We studied the time course of transmural myofiber mechanics in the anterior left ventricle of normal canines in vivo (n = 14) using transmural bead markers under biplane cineradiography. In 4 of these animals, plunge electrodes were placed in the myocardial tissue within the bead set to measure transmural electrical sequence.

RESULTS: The onset of myofiber shortening was earliest at endocardial layers and progressively delayed toward epicardial layers (p < 0.001), resulting in transmural dispersion of myofiber shortening of 39 ms. The onset of myofiber relaxation was earliest at epicardial layers and most delayed at subendocardial layers (p = 0.004), resulting in transmural dispersion of myofiber relaxation of 83 ms. There was no significant transmural gradient in electrical repolarization (p = NS).

CONCLUSIONS: Despite lack of evidence of significant transmural gradient in electrical repolarization in vivo, there is transmural dispersion of myofiber relaxation as well as shortening.

Abbreviations and Acronyms   AoP = central aortic pressure   ECG = electrocardiogram   LA = left atrial   LAD = left anterior descending coronary artery   LAP = left atrial pressure   LCx = left circumflex coronary artery   LV = left ventricular   LVP = left ventriclar pressure   RMANOVA = repeated-measures analysis of variance   TDRelax = transmural dispersion of myofiber relaxation   TDRepol = transmural dispersion of repolarization   TDShort = transmural dispersion of myofiber shortening   3-D = 3-dimensional

Related Article

Of That Waltz in My Heart

Jagat Narula, Mani A. Vannan, and Anthony N. DeMaria
J. Am. Coll. Cardiol. 2007 49: 917-920. [Full Text] [PDF]

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]

				Y. Ait Mou, C. Reboul, L. Andre, A. Lacampagne, and O. Cazorla Late exercise training improves non-uniformity of transmural myocardial function in rats with ischaemic heart failure Cardiovasc Res, September 12, 2008; (2008) cvn229v3. [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]

				P. P. Sengupta, A. J. Tajik, K. Chandrasekaran, and B. K. Khandheria Twist Mechanics of the Left Ventricle: Principles and Application J. Am. Coll. Cardiol. Img., May 1, 2008; 1(3): 366 - 376. [Abstract] [Full Text] [PDF]

				H. Ashikaga, E. R. McVeigh, and J. H. Omens Reply J. Am. Coll. Cardiol., August 14, 2007; 50(7): 650 - 650. [Full Text] [PDF]

				H. S. Karagueuzian On the Mechanisms of Transmural Dispersion of Myocardial Mechanics J. Am. Coll. Cardiol., August 14, 2007; 50(7): 649 - 650. [Full Text] [PDF]