Therapy Of Hypertension

Hypertension is the most common cardiovascular disease; its prevalence increases with advancing age. Elevated arterial pressure causes pathological changes in the vasculature and hypertrophy of the left ventricle. Hypertension is the principal cause of stroke, is a major risk factor for coronary artery disease and its complications, and is a major contributor to cardiac failure, renal insufficiency, and dissecting aortic aneurysm. Hypertension is defined as a sustained increase in blood pressure >140/90 mm Hg, a criterion where risk of hypertension-related cardiovascular disease is high enough to merit medical attention. The risk of fatal and nonfatal cardiovascular disease in adults is lowest with systolic BP <120 mm Hg and diastolic BP <80 mm Hg and increases progressively with higher systolic and diastolic blood pressures. Recognition of this continuously increasing risk provides a simple classification of hypertension (Table 32-1). Isolated systolic hypertension (sometimes defined as systolic BP >140-160 mm Hg with diastolic BP <90 mm Hg) is largely confined to people >60 years of age. At very high blood pressures (systolic >210 and/or diastolic >120 mm Hg), some patients develop fulminant arteriopathy characterized by endothelial injury and marked intimal proliferation, leading ultimately to arteriolar occlusion and the syndrome of immediately life-threatening hypertension. This is associated with rapidly progressive microvas-cular occlusive disease in the kidney (with renal failure), brain (hypertensive encephalopathy), congestive heart failure, and pulmonary edema, and typically requires emergent, in-hospital management for prompt lowering of blood pressure.

PRINCIPLES OF ANTIHYPERTENSIVE THERAPY Nonpharmacological therapy is an important component of treatment of all patients with hypertension. In some stage 1 hypertensives, blood pressure may be adequately controlled by a combination of weight loss (in overweight individuals), restricting sodium intake, increasing aerobic exercise, and moderating alcohol consumption. These lifestyle changes may also facilitate pharmacological control of blood pressure.

Drugs lower blood pressure by actions on peripheral resistance, cardiac output, or both. In patients with isolated systolic hypertension, complex hemodynamics in a rigid arterial system contribute to increased blood pressure; drug effects may be mediated by changes in peripheral resistance but also via effects on large artery stiffness.

Antihypertensive drugs can be classified according to their sites or mechanisms of action (Table 32-2). The hemodynamic effects of antihypertensive agents (Table 32-3) provide a rationale for potential complementary effects of concurrent therapy with two or more drugs. Concurrent use of drugs from different classes is an effective strategy for achieving effective control of blood pressure while minimizing dose-related adverse effects.

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