Cardiac assessment mechanics: 1 Left ventricular mechanomyocardiography, a new approach to the detection of diseased myocardial elements and states

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The inadequacies of currently employed methods for assessment of cardiac mechanics are discussed, and the need for development of more intrinsic assessment parameters is emphasised. To this end, a new technique is presented to enable determination of regional mechanical constitutive properties of the myocardium during diastole; this technique has been originally named left-ventricular mechanomyocardiography (or l.v.-m.m.c.g.). The data required for implementation of the techniques consist of left-ventricular sequential dynamic geometry and associated recorded chamber pressure. The method entails matching of the inner-boundary deformations of the instantaneous finite-element model of the left ventricle (which is loaded by the recorded instantaneous incremental pressure) with the actual instantaneous endocardial deformations (as derived from either cineangiocardiography or 2-dimensional echocardiography), to determine the regional distribution of the Young's modulus Ene and the incremental stresses Δσne (and hence the total stress σne=∑nΔσne) of the myocardial elements. The mechanical constitutive properties of the myocardial elements can be then characterised by the constitutive relation Ene=a+bσ. The constitutive parameters a and b have typical ranges for normal and pathological (ischaemic and infarcted) myocardial elements and hence can be employed to distinguish diseased elements. The values of a and b are calculated for normal and pathological subjects and their normal and pathological ranges are presented. © 1980 IFMBE.

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Medical & Biological Engineering & Computing