Key result
Triangular flow single-beat elastance strongly correlates with measured aortic flow at r² ~0.83.
Why the study?
A technique to estimate maximal systolic elastance and theoretical maximum flow using only left ventricular pressure and cardiac output was evaluated to simplify cardiac pumping mechanics assessment.
Answers are grounded in this paper and cite their sources.
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 < 0.0001; n = 78): E max triQ = 51.9133 + 0.8992 × E max mQ ( r 2 = 0.8257; P < 0.0001); Q max triQ = 2.4053 + 0.9767 × Q max mQ ( r 2 = 0.7798; P < 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.
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Wang et al. (2019) studied Chronic Kidney Disease, Diabetes Mellitus (n=78). Single-beat estimation technique (assumed triangular flow, Qtri) vs. Measured aortic flow (Qm) was evaluated on Correlation of maximal systolic elastance (Emax triQ vs Emax mQ) (r2 = 0.8257, p=<0.0001). The single-beat estimation technique using an assumed triangular flow strongly correlated with the values derived from measured aortic flow for calculating maximal systolic elastance (r2=0.8257, P<0.0001).
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