caa a22 4500 465783856 CHVBK 20180323112002.0 cr unu---uuuuu 170327e19900901xx s 000 0 eng 10.1007/BF02441968 doi (NATIONALLICENCE)springer-10.1007/BF02441968 Force interval relationship (FIR) related to the global function of the left ventricle: a computer study [Elektronische Daten] [R. Beyar, D. Burkhoff, S. Sideman] A model which relates the left ventricular (LV) geometry, structure and sarcomere properties to its global function, recently proposed by the authors, is extended to account for contractility changes which are a function of the heart rate, prematurity of the beat and calcium transients within the cell. To characterise LV function and relate it to fibre function under varying rhythm conditions, a model of muscle force restitution, based on calcium kinetics, was used to calculate the maximum fibre stress at the optimum sarcomere length σ0 as the parameter which depends on the heart rate, the test pulse interval TPI, the action potential duration APD and the restitution time constant. The global LV force interval relationship FIR was then calculated, and by comparing the calculated FIR to the experimental measurement (in dogs) at the ventricular level, the constants of the restitution of force at the fibre level were derived. Based on these constants, the LV function under ejecting conditions at various rhythm disturbances was calculated and related to the local, distributed parameters. This approach provides a tool to describe ventricular function as well as transmural distribution of stress and sarcomere length at a wide variety of loading and rhythm conditions based on given ‘muscle level' parameters. IFMBE, 1990 Calcium kinetics nationallicence Force interval relationship nationallicence Left ventricle nationallicence Model nationallicence a 1, a 2 : constants, eqn. 1 nationallicence APD : action potential duration nationallicence b 1, b 2 : constants, eqn. 3 nationallicence c 1, c 2 : constants, eqn. 5 nationallicence C R max : maximum(dp/dt) max assuming sufficient restitution time nationallicence (dp/dt) max : maximum pressure/time derivative nationallicence (dp/dt) max, n : normalised(dp/dt) max [=(dp/dt) max /(dp/dt) max, ss ] nationallicence (dp/dt) max, ss : maximum pressure/time derivative at steady state nationallicence EF : ejection fraction nationallicence E max : maximum elastance nationallicence FIR : force interval relationship nationallicence HR : heart rate, min−1 nationallicence SL : sarcomere length nationallicence ss : steady state nationallicence TC : time of contraction, including systolic and relaxation durations nationallicence TDI : time from end of depolarisation to beginning of next depolarisation wave nationallicence TPI : time interval between the previous pulse and the test pulse nationallicence T es : time to reach point of end systole nationallicence π0 : maximum stress at optical sarcomere length nationallicence π0, n : normalised maximum stress [=π0/π0,ss] nationallicence σ R max : maximum stress at optimal sarcomere length assuming complete restitution of the contractility at the given basalHR nationallicence τ : time constant for mechanical restitution of the LV system nationallicence Beyar R. Julius Silver Institute of Biomedical Engineering, Technion-Israel Institute of Technology, 32000, Technion City, Haifa, Israel aut Burkhoff D. Department of Biomedical Engineering, Johns Hopkins Medical School, 21218, Baltimore, MD, USA aut Sideman S. Julius Silver Institute of Biomedical Engineering, Technion-Israel Institute of Technology, 32000, Technion City, Haifa, Israel aut Medical and Biological Engineering and Computing Kluwer Academic Publishers 28/5(1990-09-01), 446-456 0140-0118 28:5<446 1990 28 11517 https://doi.org/10.1007/BF02441968 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02441968 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Beyar R. Julius Silver Institute of Biomedical Engineering, Technion-Israel Institute of Technology, 32000, Technion City, Haifa, Israel aut NATIONALLICENCE 700 1- Burkhoff D. Department of Biomedical Engineering, Johns Hopkins Medical School, 21218, Baltimore, MD, USA aut NATIONALLICENCE 700 1- Sideman S. Julius Silver Institute of Biomedical Engineering, Technion-Israel Institute of Technology, 32000, Technion City, Haifa, Israel aut NATIONALLICENCE 773 0- Medical and Biological Engineering and Computing Kluwer Academic Publishers 28/5(1990-09-01), 446-456 0140-0118 28:5<446 1990 28 11517 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer