Modeling the instantaneous pressure-volume relation of the left ventricle: a comparison of six models.
Simulations are useful to study the heart's ability to generate flow and the interaction between contractility and loading conditions. The left ventricular pressure-volume (PV) relation has been shown to be nonlinear, but it is unknown whether a linear model is accurate enough for simulations. Six models were fitted to the PV-data measured in five sheep and the estimated parameters were used to simulate PV-loops. Simulated and measured PV-loops were compared with the Akaike information criterion (AIC) and the Hamming distance, a measure for geometric shape similarity. The compared models were: a time-varying elastance model with fixed volume intercept (LinFix); a time-varying elastance model with varying volume intercept (LinFree); a Langewouter's pressure-dependent elasticity model (Langew); a sigmoidal model (Sigm); a time-varying elastance model with a systolic flow-dependent resistance (Shroff) and a model with a linear systolic and an exponential diastolic relation (Burkh). Overall, the best model is LinFree (lowest AIC), closely followed by Langew. The remaining models rank: Sigm, Shroff, LinFix and Burkh. If only the shape of the PV-loops is important, all models perform nearly identically (Hamming distance between 20 and 23%). For realistic simulation of the instantaneous PV-relation a linear model suffices.
Lankhaar
Jan-Willem
JW
Department of Pulmonary Diseases, Institute for Cardiovascular Research, VU University Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands. jw.lankhaar@vumc.nl
Rövekamp
Fleur A
FA
Steendijk
Paul
P
Faes
Theo J C
TJ
Westerhof
Berend E
BE
Kind
Taco
T
Vonk-Noordegraaf
Anton
A
Westerhof
Nico
N
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D006352:Heart Ventricles; D006801:Humans; D008955:Models, Cardiovascular; D016276:Ventricular Function / Q000502:physiology*