Unique strain history during ejection in canine left ventricle

A. S. Douglas, E. K. Rodriguez, W. O'Dell, W. C. Hunter

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Understanding the relationship between structure and function in the heart requires a knowledge of the connection between the local behavior of the myocardium (e.g., shortening) and the pumping action of the left ventricle. We asked the question, how do changes in preload and afterload affect the relationship between local myocardial deformation and ventricular volume? To study this, a set of small radiopaque beads was implanted in ~1 cm3 of the isolated canine heart left ventricular free wall. Using biplane cineradiography, we tracked the motion of these markers through various cardiac cycles (controlling pre- and afterload) using the relative motion of six markers to quantify the local three dimensional Lagrangian strain. Two different reference states (used to define the strains) were considered. First, we used the configuration of the heart at end diastole for that particular cardiac cycle to define the individual strains (which gave the local ''shortening fraction'') and the ejection fraction. Second, we used a single reference state for all cardiac cycles i.e., the end-diastolic state at maximum volume, to define absolute strains (which gave local fractional length) and the volume fraction. The individual strain versus ejection fraction trajectories were dependent on preload and afterload. For any one heart, however, each component of absolute strain was more tightly correlated to volume fraction. Around each linear regression, the individual measurements of absolute strain scattered with standard errors that averaged <7% of their range. Thus the canine hearts examined had a preferred kinematic (shape) history during ejection, different from the kinematics of filling and independent or pre- or afterload and of stroke volume.

Original languageEnglish (US)
Pages (from-to)H1596-H1611
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume260
Issue number5 29-5
DOIs
StatePublished - 1991
Externally publishedYes

All Science Journal Classification (ASJC) codes

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

Keywords

  • Cardiac kinematics
  • Cardiac mechanics
  • Cardiac motion
  • Myocardial strains
  • Ventricular volume

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