Transmural distribution of three-dimensional strain in the isolated arrested canine left ventricle.
Three-dimensional myocardial strains in seven isolated, potassium-arrested dog hearts were measured by biplane radiography of 3 transmural columns of 4-6 radiopaque beads implanted in the midanterior left ventricular free wall. Transmural distributions of strain during inflation of a left ventricular balloon to 20-30 mmHg were computed with respect to the zero pressure state. Magnitudes of the 3 principal strains increased in proportion to ventricular volume (0.0088, 0.0037, and -0.0059 ml-1). At a left ventricular pressure of 8 +/- 4 mmHg, mean circumferential (E11) and longitudinal strains (E22) were similar, increasing from epicardium (0.058 +/- 0.055 and 0.036 +/- 0.024) to subendocardium (0.139 +/- 0.102 and 0.120 +/- 0.084) as did the transmural (wall thinning) strain E33 (-0.053 +/- 0.071 to -0.128 +/- 0.083). Negative in-plane shear E12 was small (-0.008 to -0.052), consistent with a left-handed torsion of the left ventricular wall. Mean transverse shear strains E13 and E23 were small (-0.029 to 0.007) but showed considerable variability between hearts. Fiber strain had no significant transmural variation (P = 0.57). The principal axis of greatest strain was close to the fiber orientation on the epicardium (-15 degrees) but closer to the cross-fiber direction near the endocardium (-40 degrees). Therefore, the end-diastolic fiber lengths are maximized on the epicardium and minimized on the endocardium.
Omens
J H
JH
Department of Medicine, University of California, San Diego, La Jolla 92039.
May
K D
KD
McCulloch
A D
AD
D000818:Animals; D004285:Dogs; D006321:Heart / Q000033:anatomy & histology / Q000502:physiology / Q000503:physiopathology*; D006323:Heart Arrest / Q000139:chemically induced / Q000503:physiopathology*; D006352:Heart Ventricles; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D009929:Organ Size; D011189:Potassium Chloride; D013314:Stress, Mechanical
D011189:Potassium Chloride