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

Abstract

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.

Quantification of cardiac pumping mechanics in TAVI patients: A pilot study utilizing minimally invasive method for pressure‐volume analysis

“…Theoretically, if an isovolumic LV PV curve could be constructed, this single PV loop could describe the properties of LV. We constructed the LV isovolumic contraction from an ejecting contraction to study the PV relationship by a method proposed in our previous studies (Wang et al, 2017(Wang et al, , 2019. Two steps were needed for the construction.…”

“…Traditional PV analysis needs simultaneous measurement of LV pressure and flow over a range of load‐condition, its clinical utilization is precluded due to the invasiveness (Burkhoff, 2013 ). We proposed a novel minimally invasive method to study the VAC and LV mechanics in patients with severe AS receiving transcatheter aortic valve implantation (TAVI) (Wang et al, 2019 ).…”