Small apex-to-base heterogeneity in radius-to-thickness ratio by three- dimensional magnetic resonance imaging

R. Beyar, J. L. Weiss, E. P. Shapiro, W. L. Graves, W. J. Rogers, M. L. Weisfeldt

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Reported large base-to-apex differences in endocardial area ejection fraction may suggest large variability in myocardial function and load. To test ventricular load heterogeneities, we measured the ratio of radius of curvature to wall thickness (R/T), as a stress index reflecting myocardial load. End-diastolic (ED) and end-systolic (ES) magnetic resonance cross- sectional images were obtained in 15 open-chest dogs at 5 levels from base to apex, from which 4 three-dimensional thick disks were generated from adjacent image planes. The average R/T for each disk was calculated by planar and three-dimensional methods, using both midwall and endocardial radii of curvature. R/T was normalized to the apical value to quantify the relative changes in myocardial load. Normalized R/T using the midwall three- dimensional approach was 1.08, 1.11, 1.06, and 1.0 for ED (P = NS) and 1.25, 1.013, 1.08, and 1.0 for ES (P < 0.02), base to apex; respectively, while the other methods yielded higher values. Therefore, R/T calculated by the three- dimensional midwall approach shows only small apex-to base variations at ED (<11%) and ES (<25%), which is substantially less than the variability in area ejection fraction (102%). This suggests only small base-to-apex load heterogeneities, in spite of large changes in the area ejection fraction, an index reflecting specific ventricular geometry rather than local myocardial function.

Original languageEnglish (US)
Pages (from-to)H133-H140
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Issue number1 33-1
StatePublished - 1993
Externally publishedYes


  • left ventricle
  • myocardial load
  • wall thickness

ASJC Scopus subject areas

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


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