A new hybrid (hydro-numerical) model of the circulatory system

Abstract

Abstract. The paper presents a hybrid (hydro-numerical) circulatory model built to be used as a complementary tool for clinical purposes. It was developed at the Institute of Biocybernetics and Biomedical Engineering -Polish Academy of Sciences (Poland) in co-operation with the Institute of Clinical Physiology -National Council of Research (Italy). Main advantages of the model are: 1) high accuracy and repeatability of parameters setting, characteristic of numerical solutions, 2) maximum flexibility achieved by implementing the largest possible number of the model's elements in the numerical way, 3) ability to test mechanical heart assist devices provided by special computer applications; in the model two physically different signal environments -numerical and hydraulic -are connected by special impedance transformers interfacing physical and numerical parts of the model; 4) eliminating flowmeters, as the voltage controlled flow sources embedded in the system provide information on flows.In vitro tests were performed to evaluate the circulatory model: a) modelling and simulation of physiological and pathological states parameters vs. left ventricular end-systolic elastance (E max l ) and rest volume (V o l ) variations, b) testing the effect of LVAD counterpulsation on circulatory hemodynamics and ventricular energetics; it resulted in the increase of total cardiac output (COLV tot) from pathological value 3.8 to 5.4 l·min −1 , mean aortic pressure mPas from 67.8 to 96.1 mmHg and in the decrease of left atrial pressure mP la from 15.7 to 7.7 mmHg and External Work nEW by 37.5%.The model was verified based on literature data.

Control of a Pediatric Pulsatile Ventricular Assist Device: A Hybrid Cardiovascular Model Study

“…The HCS has already been described and verified (7)(8)(9)(10). It can be connected to VADs both in atrioaortic and ventriculo-aortic connections for left and/or right ventricular assistance.…”

“…The graphical user interface presents basic information (ventricular and aortic pressures time courses, ventricular pressure-volume loops) and also gives access to full pressure, flow, and volume information in the whole system and enables simulation data storing on the hard-drive (7). The graphical user interface presents basic information (ventricular and aortic pressures time courses, ventricular pressure-volume loops) and also gives access to full pressure, flow, and volume information in the whole system and enables simulation data storing on the hard-drive (7).…”

Circulatory Modelling as a Clinical Decision Support and an Educational Tool

“…Among others, the modules sketched in Fig.1 contain a complex of simpler models of systemic and pulmonary circulation, 7-8 models of congenital heart defects 9 and of surgical procedures, 10 interfaces to respiratory models, now under development, models of heart assist devices (LVAD, RVAD, BVAD, IABP, BIV pacing), [11][12][13] models of autonomic controls (in this moment baroreflex and metabolic controls, the second one under development), 8,14 and interfaces for educational use of the platform. 8 The polymorphism of the structure has been achieved through implementation of the concept of hybrid modelling, [15][16][17][18][19] in cooperation with the Nałecz Institute of Biocybernetics and Biomedical Engineering of the Polish Academy of Science. In short, hybrid models permit to merge computational and physical models when and if necessary.…”

A hybrid (hydro-numerical) circulatory model: investigations of mechanical aortic valves and a numerical valve model

“…hybrid interfaces merging numerical (computer) and physical (hydraulic) signal environments simultaneously playing a role of impedance transformers (TR), presented in detail in [22] and in the Appendix to this paper. Thus, it is necessary to consider an exemplary scheme in Fig.…”