Beta blockers such as atenolol (Tenormin) and metoprolol (Lopressor) are used to treat high blood pressure, heart failure, heart arrhythmias and angina (chest pain). They work by interfering with the action of the stress hormone adrenaline, which increases the heart rate, forcing it to work harder and raising blood pressure. By decreasing heart rate, beta blockers lower blood pressure. This means the heart works less hard, which helps to relieve angina. Beta blockers also help dilate the blood vessels, thereby improving blood flow, and block the electrical impulses that cause heart arrhythmia. Beta blockers are not typically used as a first line treatment for high blood pressure, and there is some evidence (Journal of the American College of Cardiology, Sept. 16 2008) indicating that they dont prevent development of heart failure in people with high blood pressure.