Asymptotic slope of log pressure vs log volume as an approximate index of the diastolic elastic properties of the myocardium in man.

Abstract

The goal of this study was to develop, on a rational basis, an index of the intrinsic diastolic elastic properties of the left ventricle. A relatively simple analytic model employing a thin-walled spherical geometry coupled with an approximate formulation of a two-dimensional constitutive relation, was used to examine the primary determinants of the pressure-volume relationship of the intact heart. The results permit comparison with other indices of compliance or wall stiffness. The slope of the dP/dV vs P curve was found to be sensitive to the non-linear elastic constant K, but is also sensitive to variations in cardiac muscle volume. VdP/dV was found to be sensitive to pressure. m = d(log P)/d(log V) = (V/P)(dP/dV) is proposed as an index sensitive to K and relatively insensitive to both pressure and initial cardiac geometry. The index is compared with published studies. Using the data of Fester and Samet, mean values of the asymptotic log-log P-V slope, m, evaluated at end-diastole for normal, idiopathic hypertrophy, mild, moderate and severe coronary artery disease were 3.95 +/- 0.60 (SEM), 5.05 +/- 1.60, 5.24 +/- 0.96, 8.35 +/- 2.06, and 15.13 +/- 3.0, respectively. At values of LVEDP less than 7 mm Hg the concept of simple distension is questioned. The advantages and limitations of this approximate index are discussed. This index seems to afford a practical measure of the elastic properties of the wall over a rather wide range of pressure, volume, wall mass and wall thickness.

An advanced glycation endproduct cross-link breaker can reverse age-related increases in myocardial stiffness

“…Chamber stiffness was derived from the relation dP͞dV ϭ kP. The latter was normalized for the EDV, because the slope of dP͞dV versus P has been found to be sensitive to variations in cardiac muscle volume (10). With a progressive increase in volumes calculated, myocardial stiffness would be expected to increase as a preloaddependent phenomenon (9,11).…”

Single-beat estimation of end-diastolic pressure-volume relationship: a novel method with potential for noninvasive application

“…By definition, the EDPVR indicates the amount of diastolic filling that will occur for a specified filling pressure and is therefore a key physiological determinant of preload (10,13). In addition, assessment of this relationship is fundamental to the study of the pathophysiology of ventricular remodeling in heart failure and in response to surgical, pharmacological, or device-based treatment strategies (8,11,14,21).…”

The relationship between left ventricular functional response to isometric exercise and asynergic contraction and diastolic stiffness

“…To permit comparison of left ventricular chamber volume stiffness under the varying hernodynamic and left ventricular geometric conditions induced by the isometric exercise, we employed the rate constant "knorm" of the volume-normalized exponentially fit left ventricular pressure-volume elasticity relation [2,17,18]. In view of the prominent increase in late diastolic pressures observed during handgrip exercise, pressure-volume relations were also analyzed specifically at end diastole in terms of a) operational end diastolic stiffness (dP/dV at end-diastole) which indicates the "effective" diastolic stiffness at the specific pressure-volume relation at which the left ventricle was operating at the time of each ventriculogram [19], and b) the asymptotic slope of the log pressure-log volume relationship at end diastole, which at pressures above 10 mm Hg is relatively insensitive to ventricular geometry and pressure but sensitive predominantly to "muscle" stiffness [20,21].…”