State-space representation of extended Guyton's model

E-mail: [email protected], Tel: (81)-6-6833-5012; Fax: (81)-6-6835-5403; 9 10 11 12 The work of Moller PW et al. (9), recently published in the American Journal of 13 Physiology-Heart and Circulatory Physiology, has reported that Guyton’s circulatory 14 equilibrium model qualitatively predicts the dynamic response from changing right 15 atrial pressure (RAP) and that RAP acts as back-pressure to venous return. There 16 are some debate as to these ideas (1,2,9). The Editorial Focus Article discussed 17 about these points for further understanding. 18 19 Dynamic-state applicability: In cardiovascular system, hemodynamics change 20 acutely, greatly and dynamically in response to physiological perturbations and 21 pathological stress. However, it is difficult to understand how hemodynamic 22 variables are dynamically determined. Regarding to steady-state hemodynamics, 23 Guyton et al. () pioneered major advances in understanding cardiovascular system 24 by the circulatory equilibrium model on date back to half a century ago (3-6). They 25 examined the relationship between the steady-state rate of blood flow through the 26 peripheral vasculature and RAP without the complication of changes in total 27 intravascular volume, and characterized the venous return properties of the 28 systemic vein by the venous return curve as a function of RAP (2-6). They also 29 characterized the apparent pumping ability of the cardiothoracic compartment by 30 the cardiac output curve (3-6). In the model, the intersection of the two curves 31 determines equilibrium cardiac output and RAP, indicating a concept of circulatory 32 equilibrium (3-6). However, it has been unclear whether the circulatory equilibrium 33 model is applicable to dynamic-state cardiovascular system. This is an important 34 question in circulatory physiology and clinical cardiovascular medicine. 35 36 Articles in PresS. Am J Physiol Heart Circ Physiol (June 16, 2017). doi:10.1152/ajpheart.00315.2017