These include systolic blood pressure < 110 mmHg and pulmonary edema. It is reasonable to withhold beta-blockers in patients who were previously taking them in the outpatient setting for chronic systolic heart failure when they are admitted with a heart failure exacerbation.īeta-blockers are contraindicated specifically in systolic heart failure when pulmonary edema is present, when there are signs of cardiogenic shock, severe bradycardia, hypotension or wheezing related to asthma.īeta-blockers are contraindicated during an acute myocardial infarction when there are signs of pending cardiogenic shock. Perhaps this is partially an explanation for propranolol treating migraine headaches.īeta-blockers should be initiated in patients hospitalized for acute systolic congestive heart failure prior to hospital discharge. The importance of this is not clear in clinical medicine in regards to beta-blockers. Class I antiarrhythmic drugs possess this characteristic as well. This is also the mechanism that local anesthetics work (lidocaine). Membrane stabilization: Stabilizing membranes decreases the propagation of action potentials. Examples include pindolol and acebutolol. These are commonly used in younger patients or in athletes where heart rates need to elevate (allowing overall increased cardiopulmonary effort) in order to compete in sports. ![]() ![]() Therefore, they will have some beta-blocking effects, but not to the degree of beta-blockers without ISA. Intrinsic sympathomimetic activity (ISA): Beta-blockers with ISA only partially antagonize while actually causing a small degree of activation of the beta receptors. These medications are commonly used for migraine headaches, stage fright and panic attacks for these reasons. Lipid solubility: Beta-blockers that are lipid soluble, such as propranolol or metoprolol, can cross the blood-brain barrier easily. For this reason, the cardioselective beta-blockers are safer to use in patients with asthma or reactive airway diseases. The “cardioselective” beta-blockers act upon beta-1 receptors much more than the beta-2 receptors. The chart below summarizes which beta-blockers possess each property.Ĭardioselectivity: All beta-blockers act upon both beta-1 and beta-2 receptors. intrinsic sympathomimetic activity, andĮach beta-blocker has a different amount of these properties and it is important to consider these when selecting a beta-blocker for a specific condition.The four different properties of beta-blockers are: exacerbation of systolic heart failure,. ![]() Other less common indications include anxiety, migraine headache prophylaxis and stage fright. This results in a decreased heart rate through decreased SA node activity and decreased AV nodal conduction, as well as decreased inotropy - contractility - of the heart.īeta-blockers are used to treat hypertension, tachyarrhythmias such as atrial fibrillation, and systolic congestive heart failure. Beta-blockers antagonize beta-1 and beta-2 receptors which are the usual targets of the sympathetic nervous system, including epinephrine and norepinephrine.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |