HOW TO ASSESS VASCULAR REMODELING IN SMALL AND MEDIUM-SIZED MUSCULAR ARTERIES IN HUMANS

The study of vascular wall changes in humans has generated great inter est with the increasing realization that, independently of the potenti al contribution to mechanisms involved in blood pressure elevation, th ese structural alterations (remodelling) or functional changes may con tribute to the complications of elevated blood pressure, Moreover, som e of these changes may be corrected partially or totally by administra tion of antihypertensive agents and other drugs, This has fuelled inte rest in the techniques used to evaluate changes in the vascular wall i n humans, which are reviewed critically here with a focus on human stu dies in hypertension, Remodelling of large and small arteries has diff erent characteristics, and is studied with different techniques. In hy pertensive patients, small arteries less than 400 mu m in diameter exh ibit a reduction in lumen diameter, accompanied sometimes but not alwa ys by an increase in media width or in media cross-section, The study of capillaries and small arteries of the skin or the eye can be perfor med non-invasively, but for the sake of obtaining the information of i nterest in hypertension, at present invasive techniques are required t o investigate small arteries, These consist of a biopsy of subcutaneou s tissue, usually from the gluteal region, and the study of vessels af ter they have been mounted on a 'wire myograph' or on a pressurized sy stem, In contrast to small arteries, large arteries from hypertensive humans present increases in media width without a significant reductio n in the lumen diameter (when studied under conditions isobaric relati ve to those in normotensive subjects), Conduit arteries may be studied non-invasively with the use of ultrasound techniques, The study of la rge elastic arteries is not addressed here, The use of echo-tracking d evices to study muscular medium-sized arteries such as the radial arte ry is described, The relative advantages and disadvantages of these te chniques, the questions which may be asked and the relevance of the in formation obtained using these approaches are discussed.