The pathogenesis of essential hypertension, which accounts for 95% of the cases of hypertension seen clinically, is still unknown in spite of extensive clinical and laboratory studies during the past 20 years. However, these studies have indicated neurogenic, endocrine (anterior pituitary—adrenal cortex), and renal changes in pathophysiology that may have pathogenetic significance. Thus some patients with essential hypertension show evidence of increased vasomotor tone, others show mild disturbances in water and sodium chloride metabolisms, and some show increased plasma concentrations of vasoexcitatory material (VEM) and vasodepressor material (VDM), produced by the kidney and liver, respectively. Whether these changes connote several pathogenetically distinct types of hypertension or whether essential hypertension is a single clinical entity with varying degrees of alteration in different body functions remains to be determined.
Since the pathogenesis of essential hypertension is unknown, treatment is based on pathophysiology and empiricism. Moreover, information about the long-term effects of presently