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Acta Physiologica 2009; Volume 197, Supplement 675
Joint meeting of The Slovenian Physiological Society, The Austrian Physiological Society and The Federation of European Physiological Societies
11/12/2009-11/15/2009
Ljubljana, Slovenia
PREDICTING PULSATILE VARIATIONS IN FINGER ARTERIAL PRESSURE USING A NOVEL CARDIOVASCULAR SYSTEM MODEL
Abstract number: L138
de los Reyes V1 Aurelio, Kappel1 Franz
1Institute for Mathematics and Scientific Computing, Karl Franzens University, Graz, Austria
Cardiovascular modeling has been used to study the behavior of blood pressures in the peripheral and systemic compartments, cardiac output, ventricular elastance and contractility in the human circulatory system under various conditions such as constant workload and orthostatic stress. In this study we investigated, modified, and combined two existing cardiovascular models: a non-pulsatile global model (Kappel) and a simplified pulsatile left heart model (Olufsen). The non-pulsatile global model incorporates all the essential subsystems such as systemic and pulmonary circulation, left and right ventricles, baroreceptor loop, etc. This model considered the mean values of quantities over one heart cycle instead of the instantaneous values. The pulsatile left heart model utilizes a minimal cardiovascular structure to close the circulatory loop. The first goal was to integrate the pulsatile left heart model with the Kappel global model. The main objective of this study was to develop a global pulsatile lumped compartment model that predicts the pressures in the systemic and peripheral circulation and specifically the pulsatile pressures in the finger arteries where real-time measurements can be obtained. A finger artery compartment was included to reflect measurements of pulsatile pressures. Linking the average flow model with a pulsatile flow was the main difficulty. Modifications were made in the ventricular elastance to model the stiffness of heart muscles under stress or exercise state. A sigmoidal function, which is dependent on the heart rate, was used to characterize the maximum elastance of the left ventricle. Preliminary simulation results show pulsatile pressures in the systemic and peripheral compartments, including the systemic aorta and finger arteries compartment. The model parameters were estimated to obtain an average normal finger arterial pressure of 120/90 mmHg. In the simulations, a decrease in pulsatility range was observed in the arterial systemic compartment. Also, pulsatility was almost negligible in venous pulmonary and arterial pulmonary compartments. Moreover, increasing the heart rate increased the pulsatility and the blood pressures in the compartments. Our results indicate that a pulsatile cardiovascular model could be developed without excess complexity so that pulsatile information would be available and which could be incorporated into the baroreflex control loop.
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Acta Physiologica 2009; Volume 197, Supplement 675 :L138