What Is the Function of a Beta Blocker?

An estimated 50 million Americans have high blood pressure. Changes in lifestyle and diet can dramatically lower blood pressure to a healthy range. However, when those changes aren't enough, physicians may prescribe medications such as beta-blockers.

Features

• High blood pressure or hypertension increases your risk of having a heart attack, experiencing heart failure, stroke, kidney disease and several other life-threatening conditions. Blood pressure is taken using a sphygmomanometer, which measures the force the heart uses to pump blood through the body. The first number (systolic) measures the force exerted against blood vessels when the heart actively pumps blood; the second number (diastolic) measures the pressure on the vascular system when the heart is in its relaxed state.

The Facts

• Although people over age 55, diabetics and those who are overweight are more likely to develop high blood pressure, anyone can get it. People can have hypertension and not know it because there are no discernible symptoms. A diagnosis of hypertension is usually made after three or more consecutive readings of 140/90 or above. Normal blood pressure is considered to be 130/85 or less, with optimal blood pressure 120/80 or below. Stage 1 (mild) hypertension is 140-159/90-99; Stage 2 (moderate) is 160-179/100-109 and severe Stage 3 hypertension is any reading 180+/110+.

Types

• There are two types of hypertension: primary or essential hypertension and secondary hypertension. Ninety-five percent of those diagnosed with hypertension have essential hypertension. This type of hypertension responds well to modifications in diet, activity level and lifestyle habits. The other five percent of hypertensives suffer from secondary hypertension, high blood pressure which results from an underlying physical cause such as kidney or adrenal disease or a history of cocaine or substance abuse.

History

• Beta-blockers were first introduced in the 1960s and are one of the most widely prescribed drugs for the treatment of high blood pressure in the U.S. They reduce the pumping intensity of the heart by binding to heart muscle cells called beta adrenergic receptors. This prevents the heart from beating harder and faster in response to adrenalin released by the body when stressed. Beta-blockers also prevent constriction of the blood vessels and retention of sodium and water in the blood, which together keep blood pressure in normal ranges.

Function

• Beta-blockers affect the entire cardiovascular system and are often used to treat angina (chest pain) and irregular heartbeat. The body responds to the drop in heart rate caused by the medication by constricting blood vessels in the upper and lower extremities, which makes hands and feet cold in some people.

Warning

• Beta-blockers may cause constriction of airways and can be dangerous for people with asthma. Those with diabetes, liver or kidney disease or other cardiovascular disorders such as congestive heart failure should discuss the use of beta-blockers with their doctors. Other drug side effects include a reduction in exercise tolerance, sleep disturbances, nightmares, lethargy and sometimes impotence.