Transmural left ventricular mechanics underlying torsional recoil during relaxation

Hiroshi Ashikaga, John C. Criscione, Jeffrey H. Omens, James W. Covell, Neil B. Ingels

Research output: Contribution to journalArticlepeer-review

Abstract

Early relaxation in the cardiac cycle is characterized by rapid torsional recoil of the left ventricular (LV) wall. To elucidate the contribution of the transmural arrangement of the myofiber to relaxation, we determined the time course of three-dimensional fiber-sheet strains in the anterior wall of five adult mongrel dogs in vivo during early relaxation with biplane cineangiography (125 Hz) of implanted transmural markers. Fiber-sheet strains were found from transmural fiber and sheet orientations directly measured in the heart tissue. The strain time course was determined during early relaxation in the epicardial, midwall, and endocardial layers referenced to the end-diastolic configuration. During early relaxation, significant circumferential stretch, wall thinning, and in-plane and transverse shear were observed (P < 0.05). We also observed significant stretch along myofibers in the epicardial layers and sheet shortening and shear in the endocardial layers (P < 0.01). Importantly, predominant epicardial stretch along the fiber direction and endocardial sheet shortening occurred during isovolumic relaxation (P < 0.05). We conclude that the LV mechanics during early relaxation involves substantial deformation of fiber and sheet structures with significant transmural heterogeneity. Predominant epicardial stretch along myofibers during isovolumic relaxation appears to drive global torsional recoil to aid early diastolic filling.

Original languageEnglish (US)
Pages (from-to)H640-H647
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume286
Issue number2 55-2
DOIs
StatePublished - Feb 2004
Externally publishedYes

Keywords

  • Fiber
  • Restoring force
  • Sheet
  • Transmural deformation

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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