Noninvasive tests of vascular function and structure: Why and how to perform them

Background Early atherosclerosis involves the endothelium of many arteries. Information about peripheral arterial anatomy and function derived from va scular imaging studies such as brachial artery reactivity (BAR) and carotid intima media thickness (IMT) may be pertinent to the coronary circulation. The prevention and early treatment of atherosclerosis is gaining more atte ntion, and these tests might be used as indications or perhaps guides to th e effectiveness of therapy, but their application in clinical practice has been limited. This review seeks to define the anatomy and pathophysiology u nderlying these investigations, their methodology, the significance of thei r Findings, and the issues that must be resolved before their application. Methods The literature on BAR and IMT is extensively reviewed, especially i n relation to clinical use. Results Abnormal flow-mediated dilation is present in atherosclerotic vesse ls, is associated with cardiovascular risk factors, and may be a marker of preclinical disease. Treatment of known atherosclerotic risk Factors has be en shown to improve flow-mediated dilation, and some data suggest that vasc ular responsiveness is related to outcome. Carotid IMT is associated with c ardiovascular risk factors, and increased levels can predict myocardial inf arction and stroke. Aggressive risk factor management can decrease IMT. Conclusions BAR and IMT ate functional and structural markers of the athero sclerotic process. The clinical use of BAR has been limited by varying repr oducibility and the influence by exogenous factors, but IMT exhibits less v ariability. A desirable next step in the development of BAR and IMT as usef ul clinical tools would be to show an association of improvement in respons e to treatment with improvement in prognosis.