Author + information
- Received April 26, 2006
- Revision received July 5, 2006
- Accepted July 10, 2006
- Published online February 27, 2007.
- Hiroshi Ashikaga, MD⁎,†,⁎ (, )
- Benjamin A. Coppola, BS⁎,
- Bruce Hopenfeld, PhD†,
- Eric S. Leifer, PhD‡,
- Elliot R. McVeigh, PhD† and
- Jeffrey H. Omens, PhD⁎
- ↵⁎Reprint requests and correspondence:
Dr. Hiroshi Ashikaga, Laboratory of Cardiac Energetics, NIH/NHLBI, 9000 Rockville Pike, Building 10/B1D416, Bethesda, Maryland 20892.
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.
This study was supported by the following grants: AHA 0225001Y (to Dr. Ashikaga, Western States Affiliate), NHLBI R01-HL32583 (to Dr. Omens), and Z01-HL4004609 (to Dr. McVeigh). Frits W. Prinzen, MD, served as Guest Editor for this article.
- Received April 26, 2006.
- Revision received July 5, 2006.
- Accepted July 10, 2006.
- American College of Cardiology Foundation