Non-invasive ultrasound in arterial wall dynamics in humans: what have we learned and what remains to be solved.

In the past decades, non-invasive vascular ultrasound has substantially improved our insights into artery wall dynamics under normal circumstances and in disease. Although we have learned a lot, the methods in use are subject to improvement. In this review, we discuss the most important achievements in non-invasive assessment of dynamic artery wall properties in humans with emphasis on the clinical relevance of the observations. Special attention will be paid to the changes observed in aging, and in essential and borderline hypertension, because the loss of compliance (i.e. the ability to store volume thereby reducing pressure increases during ejection) of the elastic arteries in the elderly and in these patients possibly has consequences on their management. The changes in dynamic artery wall properties in diabetes and atherosclerosis are briefly discussed as well. A new approach to the determination of baroreceptor sensitivity, using artery stretch as input, is presented. The review starts with a description of the parameters most commonly used to describe dynamic artery wall properties and of the techniques employed to assess these parameters. The problems encountered in these assessments and the possible solutions to these problems are addressed as well.