Abstract
Hypertension is a heterogenous disorder resulting from either a specific cause (secondary hypertension) or some underlying pathophysiologic alteration(s) of unknown etiology (primary hypertension). In some young hypertensive patients, elevated cardiac output may be the primary pathophysiologic derangement. In most patients with established hypertension, the primary pathophysiologic alteration is elevated peripheral vascular resistance with a normal cardiac output. Explanations for the increased vascular resistance in hypertension include derangements in the central and autonomic nervous systems, renal or endocrine systems, cellular membrane or neurohumoral function, and structural vascular changes. No unifying pathophysiologic explanation can be identified as causative of primary hypertension.