Torsion of the left ventricle during the ejection phase in the intact dog

Abstract

Torsion of the left ventricle (LV) is associated with rotation of the apex with respect to the base around the long axis of the LV. A mathematical model of LV mechanics, which relates torsion to transmural distribution of fibre shortening, was evaluated with two-dimensional echocardiography in nine anaesthetised closed-chest dogs. Torsion was calculated as the difference between the angles of rotation (radians) of echo-derived transverse cross-section projections of the LV obtained at the mitral valve and low papillary level, divided by the axial distance between these projections measured in a long-axis cross-section, and multiplied by the outer radius in a mid-papillary transverse projection of the LV. A shortening to torsion ratio (STR) was defined as the ratio of inner wall shortening to torsion occurring during ejection. In a series of 11 measurements, each based on frame-to-frame analysis of 15 cardiac cycles, STR was found to be 2.31 +/- 0.23 rad-1 (mean +/- SD), whereas the mathematical model predicted a STR value of 2.4 rad-1 over a wide range of preload, afterload and contractility levels. We conclude that two-dimensional echocardiography validates the presence of torsion in the normal canine left ventricle, as predicted by the model of left ventricular mechanics.

Heart wall myofibers are arranged in minimal surfaces to optimize organ function

“…This property suggests that shortening fibers along their length in the direction given by θ could contribute to an efficient shrinkage of volume by yielding a displacement in the direction normal to the heart wall. It has in fact been established that a helical orientation of myofibers is essential to achieve a transmurally homogeneous workload for all myocytes within the healthy myocardium (32)(33)(34). More globally, the helicoidal myofiber architecture induces torsion of the left ventricle during contraction.…”

Relation between torsion and cross-sectional area change in the human left ventricle

“…In several reports torsion and contraction were investigated separately (Buchalter et d., 1994;Gibbons Kroeker et al, 1993;Hansen et al, 1991;Ingels et al, 1989;Ohayon and Chadwick, 1988;Rademakers et al, 1992;Young et ul., 1994). Arts et al (1984) measured the relation between torsion and contraction echographically in dogs. Furthermore, they compared their results with the predictions of a mathematical model of LV mechanics.…”

Feasibility of reproducible vendor independent estimation of cardiac function based on first generation speckle tracking echocardiography

“…We will show below that strain values in general, and their distribution in the LV in particular, may be tailored using this scheme by varying the value of a single parameter. The strain distribution along the left ventricle (LV) can be either made to resemble the distribution obtained by cMRI [29] , as well as that of the pioneering works of the T. Arts group [30,31] , both claiming that the longitudinal strain is evenly distributed along the entire LV, or those obtained by the commercial vendors STE algorithms.…”