International audienceThe reliability of ankle—brachial index (ABI) measurements performed by different observer groups in primary care has not yet been determined. The aims of the study were to provide precise estimates for all effects influencing the variability of the ABI (patients' individual variability, intra- and inter-observer variability), with particular focus on the performance of different observer groups. Using a partially balanced incomplete block design, 144 unselected individuals aged ≥ 65 years underwent double ABI measurements by one vascular surgeon or vascular physician, one family physician and one nurse with training in Doppler sonography. Three groups comprising a total of 108 individuals were analyzed (only two with ABI < 0.90). Errors for two repeated measurements for all three observer groups did not differ (experts 8.5%, family physicians 7.7%, and nurses 7.5%, = 0.39). There was no relevant bias among observer groups. Intra-observer variability expressed as standard deviation divided by the mean was 8%, and inter-observer variability was 9%. In conclusion, reproducibility of the ABI measurement was good in this cohort of elderly patients who almost all had values in the normal range. The mean error of 8—9% within or between observers is smaller than with established screening measures. Since there were no differences among observers with different training backgrounds, our study confirms the appropriateness of ABI assessment for screening peripheral arterial disease (PAD) and generalized atherosclerosis in the primary case setting. Given the importance of the early detection and management of PAD, this diagnostic tool should be used routinely as a standard for PAD screening. Additional studies will be required to confirm our observations in patients with PAD of various severities

Regardless of the mechanisms that initiate the increase in blood pressure, functional and structural changes in the systemic vasculature are the final result of long-standing hypertension. These changes can occur in the macro- but also in the microvasculature. The supply of the tissues with oxygen, nutrients, and metabolites occurs almost exclusively in the microcirculation (which comprises resistance arterioles, capillaries and venules), and an adequate perfusion via the microcirculatory network is essential for the integrity of tissue and organ function. This review focuses on results from clinical studies in hypertensive patients, which have been performed in close cooperation with different clinical groups over the last three decades. Intravital microscopy was used to study skin microcirculation, microcatheters for the analysis of skeletal muscle microcirculation, the slit lamp for conjunctival microcirculation and the laser scanning ophthalmoscope for the measurement of the retinal capillary network. The first changes of the normal microcirculation can be found in about 93% of patients with essential hypertension, long before organ dysfunctions become clinically manifest. The earliest disorders were found in skin capillaries and thereafter in the retina and the skeletal muscle. In general, the disorders in the different areas were clearly correlated. While capillary rarefaction occurred mainly in the retina and the conjunctiva bulbi, in skin capillaries morphological changes were rare. A significant decrease of capillary erythrocyte velocities under resting conditions together with a marked damping of the postischemic hyperemia was found, both correlating with the duration of hypertension or WHO stage or the fundus hypertonicus stage. Also the mean oxygen tension in the skeletal muscle was correlated with the state of the disease. These data show that the microcirculatory disorders in hypertension are systemic and are hallmarks of the long-term complications of hypertension. There is now a large body of evidence that microvascular changes occur very early and may be important in their pathogenesis and progression.

One thousand two hundred and fifty-six subjects (apparently healthy subjects and patients with cardiovascular diseases) were registered in a prospective study including demographical and clinical data, rheological parameters (hematocrit, plasma viscosity, erythrocyte aggregation, erythrocyte deformability) as well as the erythrocyte velocity in human nailfold capillaries under resting and postischemic conditions.A multivariate regression analysis showed that under resting conditions there was no correlation between rheological parameters and erythrocyte velocity in capillaries. The blood flow regulation seemed to be so effective, that pathological changes of the blood fluidity showed no effect on the velocity of an erythrocyte passing the capillaries.During vessel paralysis in the early phase of the postischemic hyperemia following a stasis of three minutes in the vasculature distal to a pressure cuff at the upper arm a very clear correlation between the plasma viscosity and the maximum postischemic erythrocyte velocity in ipsilateral cutaneous capillaries could be observed (p < 0.0001) while none of the other rheological parameters seemed to play a role. In a subgroup of diabetic patients the erythrocyte aggregation (measured during stasis) also correlated with the erythrocyte velocity (p = 0.0175) besides the plasma viscosity.This shows that a correlation of rheological parameters with the capillary perfusion could only be found during vessel paralysis. In of diabetic patients besides the plasma viscosity also the erythrocyte aggregation correlated with the mean capillary erythrocyte velocity. Theses results are in agreement with the hypothesis from Barras that plasma viscosity determines the perfusion of microvessels. Under certain conditions e.g. diabetic disorder, also the erythrocyte aggregation plays a role.

The peripheral venous system is subdivided into a superficial (epifascial) and a deep (subfascial) system by the superficial fascia. The two systems are interconnected by the transfascial system, called perforanting veins. The blood from the superficial system (great saphenous vein and small saphenous vein) is drained to the deep system. The deep veins accompany the arteries. The direction of venous blood flow is controlled by valves. The number of valves is variable. The veins are surrounded by a venous sheath in which they are movable. The deep veins of the lower leg are arranged in three groups consisting of paired veins. The peroneal vein and the posterior tibial vein unite to form the tibioperoneal trunk. The tibioperoneal trunk is joined by the anterior tibial vein to form the popliteal vein. The superficial femoral vein which arises from the popliteal vein is joined by the deep femoral vein to form the common femoral vein. The latter vessel becomes the external iliac vein above the inguinal ligament. It unites with the internal iliac vein to form the common iliac vein. Both common iliac veins unite to form the inferior vena cava. The veins of the systemic circulation perform two basic tasks, returning venous blood to the heart and storing the blood volume that is not immediately needed. Several factors like venous valves, thoracoabdominal venous pump and peripheral venous pump are necessary to maintain venous return. The second task results from the elastic compliance of the venous system, especially the mesenteric channels.

In static or low-flow conditions erythrocytes form linear or three-dimensional aggregates with characteristic face-to-face morphology, similar to a stack of coins, often called rouleaux formation. This aggregation is reversible and shear dependent (i.e. dispersed at high shear and reformed at low shear or stasis) and caused by a variety of macromolecules present in the blood plasma. The plasma protein fibrinogen is the major plasma component promoting red blood cell (RBC) aggregation in blood, with an almost linear relationship between aggregate size and plasma fibrinogen concentration. However, other plasma proteins are also reported to increase RBC aggregation, e.g. ␣2-macroglobulin, immunoglobulin M or G. In addition, there is evidence, that plasma lipids like cholesterol or triglyceride may influence the aggregation of erythrocytes.In this study we evaluated whether there is an independent influence of proteins and lipids on the RBC aggregation. Using a regression analysis, we analyzed the correlation between the fibrinogen-, ␣2-macrogobulin-, immunoglobulin M-, Antithrombin III-, Protein C-, Factor VIII-, total cholesterol-and triglyceride concentration with RBC aggregation in blood samples from 2717 apparently healthy subjects or patients.An univariate analysis showed, that the only variable which correlates on a biologically relevant level is fibrinogen (r = 0.46). The multiple correlation coefficient corresponded to r mult = 0.589 what indicated that nearly 59% of the variation of the erythrocyte aggregation can be explained by the influencing factors used in this model. This clearly showed that there are additional factors which are involved in the process of erythrocyte aggregation and still are under discussion.