Endothelial dysfunction results in reduced compliance (increased arterial stiffness), especially in the smaller arteries. This is characteristic of patients with hypertension. However, it may be seen in normotensive patients (with normal blood pressure) before the appearance of clinical hypertension. Reduced arterial compliance is also seen in patients with diabetes and also in smokers. It is actually a part of a vicious cycle that further elevates blood pressure, aggravates atherosclerosis (hardening of the arteries), and leads to increased cardiovascular risk. Arterial compliance can be measured by several techniques. Most of them are invasive and are not clinically appropriate. Pulse contour analysis is a non-invasive method that allows easy measurement of arterial elasticity to identify patients at risk for cardiovascular events.