Cardiac assessment mechanics: 2. Left-ventricular mechanopressography, a new approach to noninvasive intrinsic assessment of left-ventricular pumping efficiency

MEASURES AND INDICES FOR INTRINSIC CHARACTERIZATION OF CARDIAC DYSFUNCTION DURING FILLING AND SYSTOLIC EJECTION

The paper discusses the development and application of bioengineering indices for reliable diagnosis of cardiac functional modalities in filling and contraction phases.

During diastolic filling, the left-ventricular (LV) volume developed is a response to left-atrium (LV) suction at early rapid filling and LA contraction at late filling. However, in LV ejection, the LV flow-rate and aortic pressure constitute response to LV myocardial stress and intra-LV pressure generation. The differential equations used in the governing of these relationships have been developed. By matching the solutions of these differential equations with the clinical data of LV volume and pressure, we can determine the heart model "differential equations" parameters, as well as the derived indices. These parameters and indices include: compliance and resistance-to-filling for characterizing diastolic-filling function, together with the index of LV contractility (in terms of maximum LV contractile power and stress-velocity relationship for contractile element). By evaluating them, it is possible to diagnose more reliably and differentially heart diseases due to an increase in filling-resistance and contractility abnormalities.