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Hypertension is defined as persistently elevated arterial blood pressure (BP). BP is the mathematical product of peripheral vascular resistance (PVR) and cardiac output (CO) and hypertension is the result of increased PVR or CO. Aberrations in the normal function of neurohormonal systems such as the renin-angiotensin-aldosterone system (RASS), sympathetic nervous system (SNS), and disturbances in sodium, calcium, and natriuretic hormones have been implicated in the pathophysiology of hypertension (Table 1-1). Hypertension is usually multifactorial; consequently, multiple antihypertensive drugs are often necessary to control BP. Cardiovascular risk reduction can occur with lower blood pressure. A reduction in systolic blood pressure (SBP) as small as 2 mm Hg reduces the risk of death from ischemic heart disease or other vascular causes by 7% and from stroke by 10%. The majority of patients with hypertension have essential hypertension because their BP is elevated for unknown reasons. Secondary hypertension accounts for less than 10% of patients (Table 1-2).

TABLE 1-1Pathophysiology of Hypertension
TABLE 1-2Secondary Causes of Hypertension


Hypertension is diagnosed when the average of two or more BP measurements are elevated at two or more clinical encounters. This BP is used to classify the patient’s hypertension. In 2013 hypertension guidelines were updated by the Eighth Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC8); the American Society of Hypertension (ASH); and the International Society of Hypertension (ISH). According to the American Heart Association (AHA) and ASH/ISH guidelines, staging at diagnosis is still appropriate and is noted in Table 1-3. The AHA has published explicit criteria for ...

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