Introduction to the seventh international workshop on structure and function of the vascular system.

The Seventh International Workshop on Structure and Function of the Vascular System was held in Paris from March 12 through March 14, 2009. As with the preceding workshop (2007) the focus of the meeting shifted from large arteries toward a more integrative view on the structure and function of the vascular system, including the microcirculation. Recent insights have underlined the two-way traffic between the macroand the microcirculation. On the one hand, pulse pressure generated in the macrocirculation penetrates deeper into the microcirculation than was previously believed. Increased pulse pressure at the level of the microcirculation causes functional and structural changes in the small vessels that contribute importantly to target organ damage. This is particularly the case in the renal preand postglomerular arterioles. On the other hand, the microcirculation is an important site of wave reflections in the arterial tree. Thereby, abnormalities in the microcirculation influence the contour of the pressure wave and the height of pulse pressure in the macrocirculation. A third potential interaction between the macroand the microcirculation is the vaso-vasorum. Small arterioles have been found in the walls of larger arteries and may play a role in the structure and function of these arteries. Hypertensive disease is characterized by a “bad loop” between the macroand microcirculation that maintains elevated blood pressure and causes target organ damage. During the three-day symposium nine sessions were held. The first dealt with arterial stiffness and was opened with a lecture by Gary Mitchell. He reviewed how excessive pressure pulsatility leads to target organ damage on a microvascular level. Ian Wilkinson subsequently proposed that changes in endothelial nitric oxide production resulting from stiffness-induced alterations in local shear stress may underlie damage of the microcirculation.1 Patrick Lacolley focused on the role of integrins as mediators of stiffness-induced decrease of endothelial function. Iftikhar Kullo reviewed how abnormalities in peripheral arterial reactivity may affect the stiffness of the macrocirculation, which in turn, causes abnormalities in microvascular structure and function. The second session focused on the renal circulation. PierreLouis Tharaux stressed the role of endothelin in glomerulosclerosis. Anil Bidani presented evidence on the role of autoregulatory, myogenic responses of the preglomerular vasculature to protect against hypertensive glomerular injury. The afferent arterioles sense and respond in particular to the oscillating systolic blood pressure signal.2 Gérard London reviewed his studies on carotid pulse wave analysis in end-stage renal disease patients. He concluded that in these patients characteristic impedance of the aorta is decreased. The clinical consequence is deeper transmission of pulsatile pressure to the renal microcirculation, causing increased organ damage. The third session had a focus on molecular and hemodynamic determinants in vascular disease. Rhian Touyz gave a state-of-the-art review on oxidative stress in vascular pathobiology. The central role of various forms of NADPH oxidases was stressed. Although most clinical trials on antioxidants have been negative, therapies against NADPH oxidase may be useful in minimizing vascular injury in hypertension and diabetes.3 Chantal Boulanger discussed the increasing evidence for a role of endothelial microparticles in cardiovascular disease. In the next presentation Bruno Pannier reviewed methods to determine shear stress. It is now possible to directly evaluate the local shear rate by simultaneously recording of the changes in arterial diameter and changes in flow at the contact of the endothelium. In the next session clinical data on macroand microcirculation were presented. Tine Hansen reviewed the determinants of ambulatory arterial stiffness index in 6 different populations. This index is derived from 24-hour ambulatory blood pressure recordings. Charalambos Vlachopoulos next discussed the influence of several environmental factors, including dietary factors and smoking on arterial stiffness and wave reflections. Jean-Jacques Mourad gave a review on how vascular endothelial growth factor (VEGF) affects the microcirculation and blood pressure. He concluded on the basis of a number of clinical studies that anti-VEGF therapy for cancer led to a significant rise in blood pressure. Sébastien Czernichow concluded this session with a presentation on a recent study on the macro-and microvascular changes in patients with the metabolic syndrome. The fifth session was devoted to the ocular microcirculation. Inspection of the ocular microcirculation is one of the oldest methods to assess hypertension-induced organ damage in the clinic. Recent technological developments allow a refined measurement of the microvascular function and structure. Three speakers introduced such novel techniques and their application in hypertension research. Ronald Schmieder showed that retinal arteriolar wall-to-lumen ratio is increased in untreated hypertensive patients and is associated with other parameters of target organ damage.4 Tien Wong reviewed the recent research of his team on retinal arteriolar narrowing in hypertensive patients. Their studies show that retinal arteriolar