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(Circulation. 2003;107:e117.)
© 2003 American Heart Association, Inc.

Cardiology Patient Page

Beta-Adrenergic Blockers

William H. Frishman, MD

From the Department of Medicine, Division of Cardiology, New York Medical College/Westchester Medical Center, Valhalla, NY.

Correspondence to William H. Frishman, MD, Department of Medicine, New York Medical College, Westchester Medical Center, Munger Pavilion 263, Valhalla, NY 10595.

An extract of the first 250 words of the full text is provided, because this article has no abstract.

Beta-adrenergic blockers (ß-blockers) are an important class of drugs for the treatment of various heart diseases, including high blood pressure, insufficiency of blood flow to the heart muscle (angina pectoris), irregular heart beat (arrhythmias), thickened heart muscle (hypertrophic cardiomyopathy), and decreased ability of the heart to empty or fill normally (heart failure). ß-Blockers can also be used to treat migraine headache and increased pressure of the eye (glaucoma). No other class of man-made drugs has had such widespread applicability in clinical medicine.

What Is a ß-Blocker?

Hormones known as catecholamines (norepinephrine, epinephrine) activate or stimulate specific receptors on cell surfaces, known as adrenergic receptors. A receptor has a specific structure that allows a drug or hormone to bind to it, similar to a key fitting in a lock. The catecholamines are released from nerve endings of the sympathetic nervous system, an involuntary nerve network that enables the body to withstand stress, anxiety, and exercise. ß-Adrenergic receptors are found in the heart, blood vessels, and the lungs, and can be stimulated by catecholamine binding, thus increasing the activity of cells in the body. ß-Adrenergic receptor stimulation causes an increase in heart rate, heart muscle contraction, blood pressure, and relaxation of smooth muscle in the bronchial tubes in the lung, making it easier to exercise and expand the lungs.

When ß-blocking drugs are given to patients through a vein or by mouth, they will block the access of catecholamines to their receptors (Figure) so that the heart rate and blood pressure are reduced, and . . . [Full Text of this Article]