Blood-flow distribution

Smedegard G. Revenas B. Arfors KE Anaphylaxis in the monkey hemodynamics and blood flow distribution. Acta Physiol Scand 1979 106 191. 

Branston NM, Hope DT, Symon L (1979) Barbiturates in focal ischemia of primate cortex effects on blood flow distribution, evoked potential and extracellular potassium. Stroke 10 647-653... 

Laughlln, M. H. and Armstrong, R, B. (1982) Muscular blood flow distribution patterns as a function of running speed In rats. Am. J. Physiol. 243 H296-H306. 

Development of novel antianginal therapy has suffered from the lack of predictive animal models. Some of the more interesting newer approaches include direct measurement of myocardial oxygen tension.electrocardiographic analysis in normal 5.>W> and diseased hearts,4-7 regional vascular resistance studies, blood flow distribution 9>50 and functional evaluation in normal hearts5l as well as in animals subjected to chronic coronary artery occlusion.52,53 The clinical predictability of these models remains undetermined. 

Nitric oxide (NO) is a short-acting, potent vasodilator derived from the enzymatic oxidation of arginine. Its production is under control of nitric oxide synthase (NOS). This enzyme is present (expressed) in two forms a constitutive form (ecNOS) and an inducible form (iNOS). Small amounts of NO normally are produced by the vascular endothehum under the control of ecNOS for the physiologic control of vascular tone and blood flow distribution. Under pathophysiologic... 

Lassen NA, Andersen AR, Friberg H, Neirinckx RD (1987) Technetium-99m-HM-PAO as a tracer of cerebral blood flow distribution A kinetic analysis. J Cereb Blood Flow Metab 7 (Suppl 1) S535... 

Table I summarizes the important existing respiratory control models. Each model is made up of certain structural elements (1) lungs, (2) body tissues, (3) blood-gas relations, (4) ventilatory control law, and (5) blood flow and blood flow distribution control laws. The models differ mainly in the treatment of the last four elements.

Beilin, L.J. and Bhattacharya, J. (1977). The effect of prostaglandin synthesis inhibitors on renal blood flow distribution in conscious rabbits. ]. Physiol, 269, 395-405... 

Compartmental models are lumped models. The concept of a compartmental model assumes that the system can be divided into a number of homogeneous well-mixed components called compartments. Various characteristics of the system are determined by the movement of material from one compartment to the other. Compartmental models have been u to describe blood flow distribution to various organs, populatirMi dynamics, cellular dynamics, distribution of chemical species (hormones and metabolites) in various organs, temperature distribution, etc. 

The combination of the time dependent wall dimensions, the distributed energy demand parameters (which is associated with oxygen consumption) and the time dependent blood flow distribution provide the basic data needed to... 

Figure 5. Instantaneous blood flow distribution in the myocardium.

Beyar R, Sideman S (1984d) Time dependent coronary blood flow distribution in the left ventricular wall. Submitted for publication... 

FigureS.Time dependent coronary blood flow distribution with (lower) and without (upper) introduction of an algorithm for autoregulation. These calculated results are based on integrated model combing mechanical with coronary perfusionarameters (Beyar and Sideman, 1984c)...

Digital projection angiocardiography can be made in many cases less invasive (by less contrast material and radiation) than conventional techniques and can be complemented by quantitative studies of, in particular, central and regional blood flow distribution and organ perfusion. 

In general, none of these studies relates the spatial energy demand throughout the myocardium to the spatial and time dependent features of the cardiac mechanics. Obviously, knowledge of the myocardial blood flow distribution is required in order to link the energy demand to the energy supply. 

The pressure distribution within the wall, (y, t) is used as the input parameter in the calculation of the time dependent coronary blood flow distribution within the LV wall. The following assumptions are used... 

A detailed mathematical description of the model is given in Appendix C. A representation of the calculated blood flow distribution in the myocardium is given below. 

Figure 5. Time dependent coronary blood flow distributioning in the LV wall at heart rates, HR = 60, HR = 120 cycles per min.

Greater cutaneous blood flow distribution Greater percutaneous absorption... 

Ultrasound wave Essentially the density distribution of tissues in volume is here defined. However, this technique also allows to solve other parameters such as the rate of blood flow distribution in vessels... 

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