What is a beta blocker ?
Beta-blockers are a group of drugs in hematology and cardiology. They have anti-ischemic, antiarrhythmic and antihypertensive properties. That is to say that they have a beneficial effect on the blood flow, cardiac arrhythmias and high blood pressure, respectively.
When these drugs are prescribed ?
-High blood pressure (Note: the treatment of high blood pressure with only a beta blocker is outdated)
-After myocardial infarction (intravenously)
-Prevention of a heart attack after a previous myocardial infarction
-In stable and unstable angina pectoris
-In heart failure without contraindications (bisoprolol, carvedilol and metoprolol)
-With arrhythmias
-For the prevention of a cardiac arrest
-Migraine
Beta-blockers are also prescribed for essential tremor (propranolol). They use them sometimes in certain nervous situations (driving test). They mask some uncomfortable physical manifestations of stress (increased heart rate, trembling).
Action
Selected effects of blockade of alpha and beta receptor blockade. Alpha1: relaxation / vasodilation beta1: heart rate slows, and the force with which the heart contracts decreases beta2: narrowing of arteries, narrowing of the airways, goes against tremor
Blood Pressure Reduction
-Decreased activity of the heart
-Due to reduced renin is the production of angiotensin II (a substance that contributes to high blood pressure) is reduced by beta1-blockade
-Blockade of presynaptic alpha receptors, which are now no longer Releasing the pressor norepinephrine from sympathetic nerve endings
-Decrease in activity in the brains, which contributes to increased blood pressure
Anti-ischemic
-Slowing of the heart rate and decrease the force of muscle contraction the heart; by decrease in systolic blood pressure, the heart requires less oxygen.
-Extension of the relaxation phase of the heart
Improvement of the structure and function of the left ventricle
-Slowed heartbeat so the heart can fill better and better yourself by blood
-Reduced oxygen demand of the heart
-Through inhibition of catecholamines released free fatty acids
-Increase in the number of beta receptors
-Decrease of the oxygen radicals in the heart
Anti-arrhythmic
-Slow heartbeat
-Reduction of spontaneous self-discharge by pacemaker cells in the wrong places in the heart
-Delayed conduction and increased refractory period of the AV node.
Beta Blockers Side Effects
Beta-blockers are generally well tolerated. When the use of high doses may sometimes have serious side effects. By beta2-blockade reduces blood flow especially hands and feet, which consequently may feel cold, and which can occur even Raynaud's phenomenon. These side effects occur less frequently with carvedilol and selective beta1-blockers, such as atenolol, bisoprolol and metoprolol. The warning symptoms of hypoglycemia (tremor, tachycardia) in insulin-dependent type I diabetes can feel less well. The clinical benefit of treatment with beta-blockers is greater than the risks, particularly when used after a heart attack. In this setting, make selective beta1-blocker carvedilol and preferred. Exacerbation of asthma and COPD bronchospastich (not all patients with COPD). Fatigue, headaches, poor sleep, vivid dreams, and depression. These symptoms are less common in the hydrophilic agents such as atenolol. In some patients, cause, or exacerbate they impotence or decrease of libido. Beta-blockers may cause a mild form of tinnitus that usually disappears after discontinuation of the drug.
Contraindications
Patients with asthma and COPD bronchospastich (not all patients with COPD!), Should be non selective beta blockers not be used. Diabetes and intermittent claudication are not absolute contraindication to the use of beta-blockers.
Interactions
Aluminum salts, cholestyramine deteriorate the absorption of beta-blockers. Alcohol, phenytoin, rifampicin, phenobarbital and smoking reduce the effectiveness of the lipophilic beta-blocker. (The degree of effect may vary considerably). Cimetidine and hydralazine may increase the effects of propranolol and metoprolol. During concomitant use of verapamil, diltiazem, and several antiarrhythmic drugs that affect the conduction of the heart, caution is advised.
Pregnancy
There is insufficient research on the effects of beta-blockers during pregnancy. Reduce on the basis of the mechanism of action beta blockers in heart rate of mother and child, which may result in reduced placental blood flow and fetal bradycardia. Also fetal hypoglycemia is based on the mechanism of action possible. Beta-blockers increase the risk of cardiopulmonary complications in the neonate. The beta blocker atenolol can cause growth retardation. Women before pregnancy all beta blockers swallowed do not have to stop this, except for atenolol. Pregnancy induced hypertension is not treated with beta-blockers.
Doping
Beta-blockers have a calming influence on operations that require control of locomotion. Also reduces the tremor / shaking. The use is suspected in riflemen, which fire their shots between the pulsations of the carotid artery in need. A beta-blocker may correct an irregular heartbeat or an elevated heart rate. Beta-blockers are not prohibited in all sports. In amateur chess is the beta blocker no longer blacklisted.
Warning in surgery of heart patients after registration
After new international study showed the original research by Professor Don Poldermans fraudulent. He was in this respect by the Erasmus University in 2011 made inactive. As a result of the review will be revised in the course of 2014, the European directive. Beta blockers recommending changes to the discouraging start Beta blockers around surgery. British study speaks of an estimated 10,000 extra deaths in the UK through this now controversial perioperative Directive. It means the end of "Decrease". These are heart patients started with a beta blocker around surgery and not patients taking long been a beta-blocker. August 2014 it was announced that the European ESC Cardiologists Association and the American Heart Association had changed their guidelines.