Pathophysiologic mechanisms in essential hypertension: a clue to the therapeutic approach.

Essential hypertension is not a homogeneous disorder. Distinct differences with regard to systemic hemodynamics, cardiac adaptation, and volumetric and humoral factors have been identified in various patient groups. Simple clinical clues allow us to identify three main underlying pathophysiologic mechanisms. The young, lean, white patient is characterized by an elevated cardiac output, normal total peripheral resistance, and increased activity of the sympathetic nervous system. The elderly hypertensive patient is characterized by a low cardiac output, left ventricular hypertrophy, high total peripheral resistance, contracted intravascular volume, low plasma renin activity, and target organ disease. The obese patient with essential hypertension presents with a high cardiac output, expanded intravascular volume, and a normal total peripheral resistance. Each of these three models represents one extreme of a wide, overlapping continuum. Identifying the underlying pathophysiologic mechanisms and matching them with the specific pharmacological properties of an appropriate antihypertensive agent should ensure greater patient acceptance and fewer adverse effects.