Endothelial function assessment in complicated hypertension

A large body of evidence indicates that patients with essential hypertension, and even more those with complicated hypertension, are characterized by endothelial dysfunction characterized by impaired NO availability secondary to oxidative stress production. A dysfunctioning endothelium is an early marker of the development of atherosclerotic changes and can also contribute to cardiovascular events. Vascular reactivity tests represent the most widely used methods in the clinical assessment of endothelial function. In the last two decades, many studies have evaluated the endothelium in hypertensive patients, using different techniques. Several methodologies were developed to study microcirculation (resistance arteries and arterioles) and macrocirculation (conduit arteries), both in coronary and peripheral vascular districts. This review will centre on the most relevant available techniques in the research on endothelial dysfunction in essential hypertension, their advantages and limitations, focusing on available data on endothelial dysfunction which characterizes patients with complicated hypertension. No available test to assess endothelial function has sufficient sensitivity and specificity to be used in clinical practice. Therefore, the optimal methodology for investigating the multifaceted aspects of endothelial dysfunction is still under debate. Only the growing concordant results from different reproducible and reliable methods exploring endothelial function with different stimuli will support and strengthen experimental findings, thus providing conclusive answers in this area of research.