THEORETICAL ANALYSIS OF THE RELATIONSHIP BETWEEN REGIONAL AND GLOBAL MEASURES OF MYOCARDIAL CONTRACTILITY

概要

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Contractile function of the left ventricle is often measured regionally, particularly in intact animals. In this paper I dispute the validity of the common assumption that regional shortening accurately reflects whole-heart mechanics, even when contractility is homogeneous, by using an ellipsoidal model of the left ventricle to examine the relationship between measures of regional function and whole-heart function. Segment shortening and wall thickening are the most common measures of regional function, while the end-systolic pressure-volume relationship, or E_<max>, is a well-validated index of contractility in the whole heart. Assuming that the arterial end-systolic pressure vs stroke volume relationship is constant, segment shortening shows a monotonically increasing, convex relation to E_<max>. If, in addition, myocardium is considered an incompressible material, then wall thickening also shows a monotonically increasing, convex relation to E_<max>. Thus, segment shortening and wall thickening are quite insensitive when measuring high contractility and overly sensitive when measuring low-contractility. Finally, I consider the non-linear relationship between regional measures of function and global contractility, and thereby re-solve apparently contradictory findings regarding the inotropic responsiveness of stunned myocardium.
社団法人日本循環器学会の論文
1993-08-20