The study of vascular wall changes in humans has generated great interest with the increasing realization that, independently of the potential contribution to mechanisms involved in blood pressure elevation, these structural alterations (remodelling) or functional changes may contribute to the complications of elevated blood pressure. Moreover, some of these changes may be corrected partially or totally by administration of antihypertensive agents and other drugs. This has fuelled interest in the techniques used to evaluate changes in the vascular wall in humans, which are reviewed critically here with a focus on human studies in hypertension. Remodelling of large and small arteries has different characteristics, and is studied with different techniques. In hypertensive patients, small arteries less than 400 πm in diameter exhibit a reduction in lumen diameter, accompanied sometimes but not always 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 performed non-invasively, but for the sake of obtaining the information of interest in hypertension, at present invasive techniques are required to investigate small arteries. These consist of a biopsy of subcutaneous tissue, usually from the gluteal region, and the study of vessels after they have been mounted on a ‘wire myograph’ or on a pressurized system. In contrast to small arteries, large arteries from hypertensive humans present increases in media width without a significant reduction in the lumen diameter (when studied under conditions isobaric relative to those in normotensive subjects). Conduit arteries may be studied non-invasively with the use of ultrasound techniques. The study of large elastic arteries is not addressed here. The use of echo-tracking devices to study muscular medium-sized arteries such as the radial artery is described. The relative advantages and disadvantages of these techniques, the questions which may be asked and the relevance of the information obtained using these approaches are discussed.
1From the MRC Multidisciplinary Research Group on Hypertension, Clinical Research Institute of Montréal, Université de Montréal, Montréal, Québec, Canada
2Division of Hypertension, Centre hospitalier universitaire Vaudois, Lausanne, Switzerland.
3Requests for reprints to Dr Ernesto L. Schiffrin, Clinical Research Institute of Montréal (IRCM), 110 ouest, avenue des Pins, Montréal, Québec, Canada H2W 1R7.
Sponsorship: The authors' work was supported by a group grant from the Medical Research Council of Canada to the Multidisciplinary Research Group on Hypertension, grants from the Fondation des maladies du cœur du Québec to ELS, grants from the Swiss National Research Foundation (32–42515.94) and a career award from the Max Cloetta Foundation to D.H.
Received 25 November 1996 Revised 11 March 1997 Accepted 14 March 1997