Blood pressure dynamics

Ongoing work is devoted to the accurate description of the origin and spread of excitation from the natural pacemaker to the rest of the heart. Computations of ventricular pressure development are being extended to account for blood flow dynamics in adjacent blood vessels. The thorax... 

Jones RI, Hornung RS, Sonecha T, Raftery EB. The effect of a new calcium channel blocker nicardipine on 24-hour ambulatory blood pressure and the pressor response to isometric and dynamic exercise. J Hypertens 1983 l(l) 85-9. 

Predicting outcome is perilous. The penumbra is dynamic, and several factors influence its fate, including time-postictus, residual and collateral blood flow, admission glucose, temperature, hematocrit, systolic blood pressure, and treatment, including hyperoxia... 

Bakand S, Winder C, Khalil C et al (2006) An experimental in vitro model fm dynamic direct exposure of human cells to airborne contaminants. Toxicol Lett 165 1-10 Bartoli CR, Wellenius GA, Diaz EA et al (2009) Mechanisms of inhaled fine particulate air pollution-induced arterial blood pressure changes. Environ Health Perspect 117 361-366 Becker S, Soukup JM, Sioutas C et al (2003) Response of human alveolar macrophages to ultrafine, fine, and coarse urban air pollution particles. Exp Lung Res 29 29-44 Beckett WS, Chalupa DF, Pauly-Brown A et al (2005) Comparing inhaled ultrafine versus fine zinc oxide particles in healthy adults a human inhalation study. Am J Respir Crit Care Med 171 1129-1135... 

With innervation intact, the circulation at rest maintains constant ventricular stroke volume and blood pressure, on average. In addition, the regulation of cardiac output is accomplished primarily through the control of peripheral resistance. Then, the slow changes in heart rate ( ) are directly related to cardiac output (CO) and inversely to peripheral resistance (Rs), so that, fh oc CO oc 1/Rg [Berne and Levy, 1977]. This relationship is fundamental to the vascular theory of heart rate variation [Hering, 1924] and underscores the role of a time varying peripheral resistance. In this chapter, the dynamics of peripheral resistance control is examined analytically as an explanation of the very low frequency variation in heart rate. 

It is clear that the peripheral resistance decreases, while compHance increases with mammalian body size. Thus, the dynamic features of blood pressure and flow pulse transmission can be scaled through this kind of modehng. The ratio of Zq/Hs corresponds to the ratio of pulsatile energy loss due to oscillatory flow to the energy dissipated due to steady flow (to overcome R ) and has been reported to be between 5 and 10% and is an invariant for the mammalian arterial circulation [Li, 1996,2004]. 

Stephen Hales, an English clergyman and physicist, carried out a classic experiment in 1732 to determine blood pressure. He connected a U tube to the carotid artery of a mare and observed the height that blood rose in the tube. Then, using fluid dynamic principles, he calculated the velocity of blood in the aorta, force of contraction, and stroke volume. This work has been the foundation of modem hemodynamics and was used by Bernoulli in his quite accurate calculation of cardiac output in 1737. 

Hemodynamics. The human heart acts as a muscular pump that beats an average of 72 times a minute. Each of the two ventricles pumps 70 milliliters of blood per beat or 5 liters per minute. Blood pressure is measured and reported as two numbers the systolic pressure exerted by the heart during contraction and the diastolic pressure, when the heart is between contractions. Hemodynamics is the study of forces related to the circulation of the blood. The hemodynamic performance of artificial organs must match that of the natural body to operate efficiently without resulting in damage. Calculations may be made using computational fluid dynamics (GFD) relevant parameters include solute concentration, density, temperature, and water concentration. In addition to artificial hearts, which are intended to perform all cardiac functions, there is a mechanical circulatory implement called a ventricular assist... 

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