The Sympathetic Nervous System in Hypertension: Roadmap Update of a Long Journey

The present paper will provide an update on the role of sympathetic neural factors in the development and progression of essential hypertension by reviewing data collected in the past 10 years. This will be done by discussing the results of the published studies in which sympathetic neural function in essential hypertension and related disease has been investigated via sophisticated and highly sensitive techniques, such as microneurographic recording of sympathetic nerve traffic and regional norepinephrine spillover. First, the relevance of the pathophysiological background of the neurogenic alterations will be discussed. It will be then examined the behavior of the sympathetic neural function in specific clinical phenotypes, such as resistant hypertension, pseudoresistant hypertension, and hypertensive states displaying elevated resting heart values. This will be followed by a discussion of the main results of the meta-analytic studies examining the behavior of sympathetic nerve traffic in essential hypertension, obesity, metabolic syndrome, and chronic renal failure. The sympathetic effects of renal denervation and carotid baroreceptor stimulation as well as the possible involvement of sympathetic neural factors in the determination of the so-called "residual risk" of the treated hypertensive patients will be finally discussed.