Simulation of Left Atrial Function Using a Multi-Scale Model of the Cardiovascular System

in PLoS ONE (2013), 8(6), 65146

During a full cardiac cycle, the left atrium successively behaves as a reservoir, a conduit and a pump. This complex behavior makes it unrealistic to apply the time-varying elastance theory to ... [more ▼]

During a full cardiac cycle, the left atrium successively behaves as a reservoir, a conduit and a pump. This complex behavior makes it unrealistic to apply the time-varying elastance theory to characterize the left atrium, first, because this theory has known limitations, and second, because it is still uncertain whether the load independence hypothesis holds. In this study, we aim to bypass this uncertainty by relying on another kind of mathematical model of the cardiac chambers. In the present work, we describe both the left atrium and the left ventricle with a multi-scale model. The multi-scale property of this model comes from the fact that pressure inside a cardiac chamber is derived from a model of the sarcomere behavior. Macroscopic model parameters are identified from reference dog hemodynamic data. The multi-scale model of the cardiovascular system including the left atrium is then simulated to show that the physiological roles of the left atrium are correctly reproduced. This include a biphasic pressure wave and an eight-shaped pressure-volume loop. We also test the validity of our model in non basal conditions by reproducing a preload reduction experiment by inferior vena cava occlusion with the model. We compute the variation of eight indices before and after this experiment and obtain the same variation as experimentally observed for seven out of the eight indices. In summary, the multi-scale mathematical model presented in this work is able to correctly account for the three roles of the left atrium and also exhibits a realistic left atrial pressure-volume loop. Furthermore, the model has been previously presented and validated for the left ventricle. This makes it a proper alternative to the time-varying elastance theory if the focus is set on precisely representing the left atrial and left ventricular behaviors. [less ▲]

A Multi­‐Scale Computer Model of the Cardiovascular System Can Account for the Three Roles of the Left Atrium

in Abstract Book GIGA-Day (2013, January 28)

Model-based glycemic control in critical care

Poster (2012, December)

Insulin clearance during hyper-insulinemia euglycemia therapy

Poster (2012, December)

Cumulative Time in Band (cTIB): Glycemic Level, Variability and Patient Outcome All in 1

in Intensive Care Medicine (2012, October), 38 (Suppl 1)

structural model of the mitral valve included in a cardiovascular closed loop model. Static and dynamic validation

Conference (2012, August 31)

Interstitial kinetic parameters for a 2-compartment insulin model with saturable clearance

Conference (2012, August)

Interstitial kinetic parameters for a 2-compartment insulin model with saturable clearance

in Proceedings of the 8th IFAC Symposium on Biological and Medical Systems (2012, August)

Insulin Kinetics during Hyper-Insulinemia Euglycemia Therapy (HIET)

in Proceedings of the 8th IFAC Symposium on Biological and Medical Systems (2012, August)

Hyper-insulinemia euglycemia therapy (HIET) is a supra-physiological insulin dosing protocol used in acute cardiac failure to reduce dependency on inotropes to augment or generate cardiac output, and is ... [more ▼]

Hyper-insulinemia euglycemia therapy (HIET) is a supra-physiological insulin dosing protocol used in acute cardiac failure to reduce dependency on inotropes to augment or generate cardiac output, and is based on the inotropic effects of insulin at high doses up to 45-250x normal daily dose. Such high insulin doses are managed using intravenous glucose infusion to control glycemia and prevent hypoglycemia. However, both insulin dosing and glycemic control in these patients is managed ad-hoc. This research examines a selection of clinical data to determine the effect of high insulin dosing on renal clearance and insulin sensitivity, to assess the feasibility of using model-based methods to control and guide these protocols. The results show that the model and, in particular, the modeled renal clearance constant are adequate and capture measured data well, although not perfectly. Equally, insulin sensitivity over time is similar to broader critical care cohorts in level and variability, and these results are the first time they have been presented for this cohort. While more data is needed to confirm and further specify these results, it is clear that the model used is adequate for controlling HIET in a model-based framework. [less ▲]

Development and Pilot Trial Results of Stochastic Targeted (STAR) Glycemic Control in a Medical ICU

in Proceedings of the 8th IFAC Symposium on Biological and Medical Systems (2012, August)