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The cardiac pumping mechanics can be characterized by both the maximal systolic elastance (E max ) and theoretical maximum flow (Q max ), which are generated using an elastance-resistance model. The signals required to fit the elastance-resistance model are the simultaneously recorded left ventricular (LV) pressure and aortic flow (Q m ), followed by the isovolumic LV pressure. In this study, we evaluated a single-beat estimation technique for determining the E max and Q max by using the elastance-resistance model based solely on the measured LV pressure and cardiac output. The isovolumic LV pressure was estimated from the measured LV pressure by using a non-linear least-squares approximation technique. The measured Q m was approximated by an unknown triangular flow (Q tri ), which was generated by using a fourth-order derivative of the LV pressure. The Q tri scale was calibrated using the cardiac output. Values of E max  triQ and Q max  triQ obtained using Q tri were compared with those of E max  mQ and Q max  mQ obtained from the measured Q m . Healthy rats and rats with chronic kidney disease or diabetes mellitus were examined. We found that the LV E max and Q max can be approximately calculated using the assumed Q tri , and they strongly correlated with the corresponding values derived from Q m (P &lt; 0.0001; n = 78): E max  triQ  = 51.9133 + 0.8992 × E max  mQ (r 2  = 0.8257; P &lt; 0.0001); Q max  triQ  = 2.4053 + 0.9767 × Q max  mQ (r 2  = 0.7798; P &lt; 0.0001). Our findings suggest that the proposed technique can be a useful tool for determining E max and Q max by using a single LV pressure pulse together with cardiac output.

pflügers archiv für die gesamte physiologie des menschen und der tiere/pflügers archiv

Quantification of cardiac pumping mechanics in rats by using the elastance–resistance model based solely on the measured left ventricular pressure and cardiac output