Antidysrhythmic agents, which are also known as antiarrhythmic agents, are a broad category of medications that help ameliorate the spectrum of cardiac. The ultimate goal of antiarrhythmic drug therapy is to restore normal rhythm and conduction. When it is not possible to revert to normal sinus rhythm, drugs may. Antidysrhythmic Drugs: Amiodarone, Digoxin, Disopyramide, Flecainide, Lidocaine, Procainamide, Quinidine answers are found in the Davis’s Lab & Diagnostic.
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The ultimate goal of antiarrhythmic drug therapy is to restore normal rhythm and conduction. When it is not possible to revert to normal sinus rhythm, drugs may be used to prevent more serious and possibly lethal arrhythmias from occurring.
Vaughan Williams Classification of Antidysrhythmic Drugs |
Antiarrhythmic drugs are used to:. All antiarrhythmic drugs directly or indirectly alter membrane ion conductances, which in turn alters the physical characteristics of cardiac action potentials. For example, some drigs are used to block fast sodium channels. These channels determine how fast the membrane depolarizes phase 0 during an action potential.
Since conduction velocity is related to how fast the membrane depolarizes, sodium channel blockers reduce conduction velocity.
Decreasing conduction velocity can help to abolish tachyarrhythmias caused by reentry circuits. Other types of antiarrhythmic drugs affect the duration of action potentials, and especially the effective refractory period.
By prolonging the effective refractory period, reentry tachycardias can often be abolished. These drugs typically affect potassium channels and delay repolarization of action potentials phase 3. Drugs that block slow inward calcium channels are used to reduce pacemaker firing rate by slowing the rate of rise of depolarizing pacemaker potentials phase 4 depolarization.
These drugs also reduce conduction velocity at the AV nodebecause those cells, like SA nodal cells, depend on the inward movement of calcium ions to depolarize. Because sympathetic activity can precipitate arrhythmias, drugs that block beta 1 -adrenoceptors are used to inhibit sympathetic effects on the heart.
Because beta-adrenoceptors are coupled to ion channels through defined signal transduction pathwaysbeta-blockers indirectly alter membrane ion conductance, particularly calcium and potassium conductance.
In the case of AV block, drugs that block vagal influences e. AV block can occur during beta-blocker treatment and therefore simply removing a beta-blocker in patients being treated with such drugs may normalize AV conduction. Sometimes ventricular rate is excessively high because it is being driven by atrial flutter or fibrillation.
Because it is very important to reverse ventricular tachycardia, drugs are often used to slow AV nodal conduction. Calcium channel blockers and beta-blockers are useful for this indication.
Digitalis, because of its ability to activate the vagus nerve parasympathomimetic effectcan also be used to reduce Anttidysrhythmic conduction velocity in an attempt to normalize ventricular rate during atrial flutter or antidysrythmic. Classes of drugs used in the treatment of arrhythmias are given below. Clicking on the drug class will link you to the page describing the pharmacology of that drug class and specific drugs.
Please note that many of the drugs comprising the first five listed classes have considerable overlap in their pharmacologic properties.
CV Pharmacology | Antiarrhythmic Drugs
Click here to see a table summarizing the types of drugs antudysrhythmic may be used to treat different types of arrhythmias. Cardiovascular Pharmacology Concepts Richard E. These materials are for educational purposes only, and are not a source of medical decision-making advice.