Essential Versus Secondary Hypertension

Consequently, the exact cause of hypertension in the majority of patients is unknown. Many theories have been proposed to explain how blood pressure increases and eventually becomes sustained in essential hypertension. Some of the major factors that may account for the increased blood pressure in essential hypertension are presented here. 

Failure to adequately adjust fluid and electrolyte volume 

Increased cardiac output and/or increased vascular resistance 

FIGURE 21-1 Schematic diagram of the possible mechanisms in essential hypertension. Various factors interact to turn on sympathetic outflow to the kidneys, heart, and peripheral vasculature, resulting in elevated blood pressure. Hypertension also causes structural and functional changes in the vasculature that help maintain the elevated pressure. 

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