Left Ventricular Systolic Resistance and Its Role in Coupling the Ventricle to the Arterial Circulation

Shroff, Sanjeev G.; Janicki, Joseph S.; Weber, Karl T.

doi:10.1007/978-1-4613-8634-6_11

Cited by 2 publications

(2 citation statements)

References 18 publications

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“…However, only the elastance–resistance model has the ability to generate the LV Q max having an inverse relationship with the LV internal resistance. At the molecular level, the LV systolic elastance can be determined by the properties of the contractile unit along with the activation process (i.e., availability of Ca 2+ ) and extramyocytic components [19]. However, the ventricular resistance seems to be related to the biochemical alterations of the myocardium, having an inverse relation with percent slow myosin [19].…”

Section: Discussionmentioning

confidence: 99%

“…If the framework of an analysis involves mean values of relevant variables (e.g., stroke volume, stroke work), the pure elastance model may be appropriate [25]. If the analysis goals are such that instantaneous behavior is of significance (e.g., coupling from the perspective of pulsatile energy generated by the left ventricle, effects of arterial wave reflection), the elastance–resistance model may be more appropriate [19].…”

Section: Discussionmentioning

confidence: 99%

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

Wang

Chang

et al. 2019

Pflugers Arch - Eur J Physiol

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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 < 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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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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

Wang

Chang

et al. 2019

Pflugers Arch - Eur J Physiol

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Late-systolic pumping properties of the left ventricle. Deviation from elastance-resistance behavior.

Campbell

Kirkpatrick

Knowlen

et al. 1990

Circulation Research

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Elastance-resistance [E(t)-R] representations of the left ventricle (LV)were evaluated for their ability to reproduce instantaneous pressure [P(t)J and outflow [Q(t)J. Experiments were performed in open-chest rats. P(t) and Q(t) were measured during steady-state ejecting beats and during a beat in which the aorta was suddenly clamped. The degree of clamping varied from partial to total occlusion. The total occlusion beat was considered an isovolumic beat that generated an isovolumic pressure [Pis,(t)J with a characteristic time to maximal P1,0(t) [Tpisomaxl. In ejecting beats, 34% of stroke volume was delivered after Tpisomax. P(t) and Q(t) from the steady-state ejecting beats and P,so(t) from the clamped beat were then used to estimate parameters of an E(t)-R model. Components of P(t) and Q(t) not accounted for by E(t)-R were identified and termed extra-pressure [Pext(t)I and extra-outflow [Qe,x(t)]. Pext(t) and Qext(t) were near-zero valued until Tpisomax; then they became systematically positive and finally negative valued after end ejection. During partial aortic occlusion, P(t) was elevated and Q(t) was reduced. However, the time of ejection was extended, and the fraction of stroke volume delivered after Tpisomax increased as P(t) was made higher. Partial occlusion also prolonged the positive phase of PeX,(t) and Qe,d(t). Elements possessing "active" and "deactive" properties were added to the E(t)-R model in an attempt to account for Pe,xt(t) and Qext(t) during partial occlusion.Optional forms of these elements were considered. These expanded E(t)-R models were fitted to basal ejecting data and then asked to predict data from a partial occlusion beat. All expanded models failed to adequately predict the partial occlusion pressure and/or outflow. It was concluded that 1) late ejection was quantitatively important to LV pumping, 2) behavior during late ejection was inconsistent with E(t)-R, and 3) ad hoc modification of E(t)-R models was not likely to yield LV pumping models that could satisfactorily reproduce instantaneous P(t) and Q(t) behavior over the entire ejection period. (Circulation Research 1990;66:218-233) It has become popular to relate instantaneous left ventricular pressure [P(t)], volume [V(t)], and outflow [Q(t)] by using mathematical models based on time-varying elastance [E(t)] and resistance (R).1-8 Such representations are appealing because, if valid, they allow identification of instantaneous left ventricular (LV) pump properties from data recorded from only one or two heart beats. In previous study,3 however, we found serious deficiencies in the performance of E(t)-R models: 1) Errors in the prediction of P(t) increased progressively as end ejection was approached. 2) E(t)-R models failed to predict P(t) and Q(t) data other than that to which these models were fitted. 3) The estimated parameter values of the E(t)-R model were unrealistic estimates of physical entities the parameters supposedly represented. 4) Interdependencies between parameters were found and resulted in nonuniq...

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Left Ventricular Systolic Resistance and Its Role in Coupling the Ventricle to the Arterial Circulation

Cited by 2 publications

References 18 publications

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

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

Late-systolic pumping properties of the left ventricle. Deviation from elastance-resistance behavior.

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