Unequal normalized diastolic stress-strain relations were observed, indicating that myocardial anisotropy contributes significantly to changes in ventricular shape during diastolic filling.
This study demonstrates that myocardial anisotropy contributes significantly to changes in left ventricular shape during diastolic filling.
The role of myocardial anisotropy in determining change in left ventricular shape during diastolic filling has not yet been demonstrated. Therefore, 11 conscious dogs were instrumented with global ultrasonic dimension transducers to measure left ventricular major and minor axis diameters and equatorial wall thickness. Myocardial geometry was represented as a three-dimensional ellipsoidal shell. Left ventricular transmural pressure was measured with micromanometers, and ventricular volume was varied by inflation of vena caval occluders. Left ventricular wall strains and stresses calculated from the ellipsoidal shell model agreed closely with those measured directly by myocardial force and dimension transducers. Unequal normalized diastolic stress-strain relations were observed in the latitudinal, longitudinal, and wall thickness directions, reflecting anisotropic mechanical properties of the myocardium. Although a greater wall stress in the latitudinal versus longitudinal axis was predicted adequately from left ventricular geometry alone, the observed latitudinal strain exceeded longitudinal strain by an amount greater than was predicted by geometric considerations alone, suggesting that myocardial anisotropy contributes significantly to changes in ventricular shape during diastolic filling.
Olsen et al. (Sun,) reported a other. Variation of ventricular volume by inflation of vena caval occluders was evaluated on Diastolic stress-strain relations in latitudinal, longitudinal, and wall thickness directions. Unequal normalized diastolic stress-strain relations were observed, indicating that myocardial anisotropy contributes significantly to changes in ventricular shape during diastolic filling.