A method is described for measuring the volume elasticity of the heart under closed chest conditions by simply inserting a catheter in the left ventricle. The heart as a system capable of oscillations detunes an external oscillating system. The shift in resonance frequency is a measure of the volume elasticity. The time course of diastolic volume elasticity values during one filling phase shows that active mechanisms are involved in the filling. The method can be applied to human beings: it allows the measurement of the volume elasticity of the whole ventricle and of small areas of the myocardium.
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