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Regional Heterogeneity of Myofiber Orientation in the Ovine Left Ventricle
Author(s) -
Nguyen Tom C.,
Ennis Daniel B,
Riboh Jonathan C,
Harrington Katherine B,
Wigström Lars,
Daughters George T,
Miller Craig D,
Ingels Neil B
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1195
Subject(s) - apex (geometry) , ventricle , anatomy , long axis , geometry , perpendicular , commissure , concentric , biology , mathematics , medicine , cardiology
OBJECTIVE Myofibers are organized in a unique spiral pattern. It is commonly assumed that these myofibers are circumferentially oriented in the midwall. This assertion, however, has not been rigorously tested throughout the entire left ventricle. This study therefore tested the hypothesis that the orientation of myofibers is circumferential in the midwall of the entire left ventricle. METHODS 5 sheep were euthanized with hearts fixed in‐situ, excised, and stored in formalin. A longitudinal axis was defined by a skewer passing from the LV apex to the mitral aspect of the left aortic valve commissure. 8 equally spaced longitudinal meridians parallel to the axis of the skewer were marked. The heart was sectioned transversely from base to apex into 1cm thick slices perpendicular to the long axis. 4 equally spaced slices were studied. Using the longitudinal meridians as guides, 8 blocks (1cm width) were obtained from each slice, for a total of 32 ventricular blocks. Each block was sequentially sectioned parallel to the epicardium at 1mm intervals. Fiber angles (α) were measured in these sections relative to a circumferential axis. RESULTS Representative slice from base of the heart with −20° (dashed line), 0° (solid line), and +20° (dotted line) fiber angles plotted relative to percent wall depth (Figure 1). Normalized fiber angle distribution for the lateral and antero‐septal wall (Figure 2). 12CONCLUSION The orientation of myofibers is not circumferential in the midwall throughout the entire ovine left ventricle and exhibits significant regional heterogeneity. Such regional heterogeneity could have important implications for understanding stress gradients, transmural strain, ventricular torsion, and wall motion throughout the left ventricle.