Arteries, variation

Table 20.2. Arterial variations classified according to Hiatt et al. (1994)...

Recently, amodified classification ofhepatic artery variations in two types ofhepatic arterial perfusion... 

Pre-operative radiological examinations are of major importance in order to detect hepatic artery variations in the transplant recipient or in the donor when living-related liver transplantation is considered. The current sensitivity of contrast-enhanced angio-CT or MR angiography for identification of hepatic artery variations has been recently estimated to be 91%-94% and 91%-100%, respectively (Winter et al. 1995 Carr et al. 2003 Coskun et al. 2005 Lee et al. 2003 Schroeder et al. 2006 Smith et al. 1998). 

In the setting of cadaveric liver transplantation it is more important to identify vascular anomalies of the celiac axis than hepatic artery variations. Indeed, celiac axis anomalies, such as atheromatous celiac-trunk stenosis or diaphragmatic arcuate ligament, could necessitate celiac axis revasculariza-... 

Schneiderman, G., EUis, C.G., and Goldstick, T.K., Mass transport to walls of stenosed arteries variation with Reynolds number and blood flow separation, J. Biomech., 12,869,1979. 

Peptides ng/kg i. V. Blood pressure % variation Pancreaticoduo denal artery % variation Femoral artery % variation... 

The partial oxygen pressure, p02, is particularly significant in metabolic processes of cells, and its variation from normal values often indicates pathologies (ischemic diseases, strokes, tumors). Accurate and localized measurements of the oxygen concentration are also desirable for differentiation between venous and arterial blood, or for cerebral mapping of task activation. In the past, invasive methods were used involving oxygen-sensitive electrodes which had to be placed directly in the blood or tissue and could only offer p02 from a few body points. 

Wide variations exist from individual to individual with respect to the circulatory system, the size of the respective blood vessels, and their distribution patterns. One might suppose that the main arteries arising out of the aorta, which comes directly from the heart, would always branch in about the same way and follow the same general... 

Branches of the aortic arch. Variation in the pattern of origin, a and b, Common pattern c and d, left common carotid artery from the innominate (long and short stem) e, separate origin of a thyreoidea ima artery / independent origin of a left vertebral. From Barry J. Anson, Atlas of Human Anatomy, p. 197. 

The developmental effects of 1,4-dichlorobenzene have been evaluated in New Zealand White rabbits (Hayes et al. 1985). Pregnant rabbits were exposed to 1,4-dichlorobenzene by inhalation at 800 ppm for 6 hours per day on Gd 6-18. At 300 ppm, there was a significant increase in the number of litters with resorptions and the percentages of resorbed implantations per litter however, this effect was not seen at 800 ppm and was thus probably not treatment-related. An increased incidence of retroesophageal right subclavian artery present in the offspring was noted it was not considered to constitute a teratogenic response to exposure to 1,4-dichlorobenzene, but was considered only a minor variation. Based on the NOAEL of 300 ppm, an acute-duration MRL of 0.8 ppm was calculated as described in the footnote to Table 2-1 and Appendix A (Hayes et al. 1985). 

Bacq and Fischer (11) have reported that extracts of mammalian spleen contained only noradrenaline, extracts of mammalian coronary nerves and arteries only adrenaline, but extracts of splenic nerves and sympathetic chains yield a mixture of adrenaline and noradrenaline. They have interpreted this variation as being due to the probability that the synthesis of adrenaline is through the transmethylation of noradrenaline as a final step and that this takes place slowly or not at all in some tissues. 

In general, both prediction and calibration points fall along the arterial time profile (solid line). In this particular experiment, the spectrometer-to-tissue interface remained on the animal continuously, except for a period from 13 00 to 13 45 when the interface was repeatedly removed and reset between each measurement. Clearly, resetting the interface generates a significant source of variation. Nevertheless, the PLS model appears to accurately model glucose from these noninvasive near-infrared spectra. 

Figure 13.15 Noninvasive glucose concentration predictions from the net analyte signal calibration model compared to arterial blood glucose concentrations (black line). Squares indicate spectra used to establish nonglucose-dependent spectral variations for the net analyte signal calculation.

Lauffer RB, Iron stores and the international variation in mortality from coronary artery disease, Med Hypoth 1991 35 96-102. 

The NMR methods have been used in clinical medicine for many years, and metabonomic evaluation of human samples has been conducted for at least the past 10 years (28). Classical examples include the application of NMR to the evaluation of inborn errors of metabolism (29). More recent work has applied metabonomics to the evaluation of the clinical severity of coronary artery disease and to establish a relationship between serum metabolic profiles and hypertension (30,31). Because metabonomics is highly sensitive to environmental or dietary influences (discussed under toxicological applications), concern has been raised that the natural variation in the human population would preclude the application of metabonomics to clinical problems. However, such concerns have been dealt with directly, and recently, Lenz et al. (32) demonstrated that urine and plasma could be collected from human subjects and used successfully for metabonomic analyses. Furthermore, in addition to the disease states described above, metabonomics has been shown to a potentially useful tool for describing alterations associated with dietary and nutritional practices (33). 

For normotensive rats, the typical operation point around a = 10—12 and T = 16 s falls near the Hopf bifurcation point. This agrees with the experimental finding that about 70% of the nephrons perform self-sustained oscillations while the remaining show stable equilibrium behavior [22]. We can also imagine how the system is shifted back and forth across the Hopf bifurcation by variations in the arterial pressure. This explains the characteristic temporal behavior of the nephrons with periods of self-sustained oscillations interrupted by periods of stable equilibrium dynamics. 

The posterior communicating artery offers significant variations in size and is often not sufficiently visible in MRA. If it is utilized for a collateral circulation, it can increase in signal and size, but lacking detection in MR angiography in patients with proximal stenosis does not permit an assessment of the lack of collateral flow (Hartkamp et al. 1999 Hoksbergen et al. 2003). 

Uchino A, Sawada A, Takase Y et al. (2003) Variations of the superior cerebellar artery MR angiographic demonstration. Radiat Med 21 235-238... 

Different topographical patterns of AMBI are associated with different vascular pathologies. Hemorheologic abnormalities or vascular anatomic variations may be contributing factors of AMBI in both hemispheres or in both the anterior and the posterior circulation (Roh et al. 2000). A scattered lesion pattern on DWI in patients with an initial negative CT is indicative of an arterial or embolic source and associated with favorable clinical outcome (Koennecke et al. 2001). Occlusion of the... 

Yet, since the territories of the major cerebral arteries have been shown to possibly vary considerably, lesion localization alone may not be enough to identify borderzone lesions. Van der Zwaan and Hillen (1991) described different variations of the cortical distributions in all 25 human brains obtained at autopsy through injecting different colored substances into the six major arteries of the human brain. He also noted an inter-individual difference with remarkable asymmetrical territorial distribution in both hemispheres. With the clinical use of novel MRI techniques, however, it is possible to identify acute ischemic lesions in individual hemodynamic risk zones. 

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