1. Bioingeniería Universidad Nacional de Entre Ríos COMPUTER SIMULATION OF CARDIAC MECHANICS Armando Pacher MD, Roberto Lombardo MD Facultad de Ingeniería – Bioingeniería Universidad Nacional de Entre Ríos - Paraná, Entre Ríos, Argentina Armando Pacher MD, Roberto Lombardo MD Facultad de Ingeniería – Bioingeniería Universidad Nacional de Entre Ríos - Paraná, Entre Ríos, Argentina CONCLUSIONS: A pedagogical tool was obtained to teach the cardiac mechanics. In addition, programs showing their results in real time, and simultaneously by loops of pressure/volume, loops of stress/volume, and curves of pressure, fluxes, volumes, and instant stress, along the cardiac cycle, were not detected. AIM: To design and to develop a computer simulation of the cardiovascular system behavior in order to be applied in teaching cardiac mechanics. METHODS: Automatism and conduction; cardiac chambers and valves; systemic arterial, capillary, and venous, coronary and pulmonary territories, and systemic arterial pressoreceptors were simulated using mathematical equations, and Visual Basic as programming language. All were simplified in order to allow the execution in real time. It operates in real time, and continually and simultaneously displays pressure, volume, volumetric flows, and derived curves; left ventricular stress, left and right ventricles pressure/volume loops; left ventricular stress/volume loop, arterial pressure/diameter loop, electrocardiogram, end of systole straight line, end of diastole and numerical values of significant variables function, and indexes of left ventricular diastolic and systolic function. DISCUSSION: Computer simulation allows learning and practicing without emotional and time pressures, out of situations of crisis, with a minimum cost. This makes possible a wide use of it, being, as well, a complement to conventional methodology. It is possible to access simulations in basal conditions, and when there are acute or chronic modifications: changes either isolated or related in inotropism, relaxation, distensibility, action of pericardium, action of drugs and calcium, preload, peripheral resistance, elasticity of great vessels, mitral and aortic valve diseases, isovolumic cycles with fixed and variable volumes, acute coronary occlusion, step by step simultaneous generation of curves, loops and electrocardiogram. RESULTS: The simplifications made in the design of this simulation allowed to obtain a software which works in personal computers of wide access (PC-IBM Compatible from a minimum configuration of 386 with a RAM of 4 MB), and from 3 1/2" diskettes. It was used as a pedagogical tool, which complemented teaching in pre and postgraduate courses on cardiac mechanics physiology and pathophysiology. Initial screen. Menu bars, basic curves (LV volume, pressures of aortic root, LA and LV), EKG, LV P/V loop with end-systolic straight line and end-diastolic function, numerical values chart. Basal conditions. Loop screen, with P/V of LV (black) and RV (red) simultaneous graphics in three situations: basal, moderate and severe decrease of left ventricular contractility. Numerical values chart of basal situation. Curves of LV volume, LV and LA pressure, instantaneous LV stress and EKG. P/V and stress/volume loop. Basal conditions. Angioplasty simulation: balloon into LAD coronary artery Simulation of mitral acute and severe insufficiency (3 rd and 4 th cycles and numerical values chart: basal situation) Simulation of LV isovolumic cycles Example of menu options: LV diastolic function The software can be obtained at www.fac.org.ar/modelocv Basic curves and instantaneous LV stress, P/V and stress/volume loop. LV decreased contractility and basal conditions. Numerical values chart of basal conditions.