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33 Cards in this Set
- Front
- Back
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What are quinidine, amiodarone, procainamide, disopyramide?
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Class 1A antiarrhythmics
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What is the mechanism of the class 1 antiarrhythmics?
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Local anesthetics - slow or block conduction, especially in depolairzed cells; decrease slope of phase 4 depolarization and increase threshold for firing in abnormal pacemaker cells; are state dependent: selectively depress tissue that is frequently depolarized
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What do class 1A antiarrhythmics affect?
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Increase AP duration, increased refractory period (ERP), increased QT interval; both atrial and ventricular arrhythmias
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What class of antiarrhythmics are useful in reentrant and ectopic supraventricular and ventricular tachycardia
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Class 1A antiarrhythmics
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What are the toxicities of quinidine?
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cinchonism: headache and tinnitus, thrombocytopenia, torsades de pointes due to increased QT interval
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What are the toxicities of procainamide?
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reversible SLE-like syndrome
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What are the lidocaine, mexiletine, tocainide?
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Class 1B antiarrhythmics
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What does class 1B antiarrhythmics affect?
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decrease AP duration; affects ischemic or depolarized Purkinje and ventricular tissue
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What is class of antiarrhythmics are good for acute ventricular arrhythmias (especially post-MI) and digitalis-induced arrhythmias?
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Class 1B antiarrhythmics
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What are the toxicities of class 1B antiarrhythmics?
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local anesthetic - CNS stimulation/depression, cardiovascular depression
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What are flecainide, encainide, propafenone?
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Class 1C antiarrhythmics
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What class of antiarrhythmic is used for ventricular tachycaria that progress to ventricular fibrillation and intractable supraventricular tachycardia, as well as a last resort in refractory tachyarrhythmias
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Class 1C antiarrhythmics
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What are the toxicities of Class 1C antiarrhythmics?
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Proarrhythmic, especially post-MI (contraindicated), significantly prolongs refractory period in AV node.
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What is the effect of hyperkalemia on class 1 arrhythmias?
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Increases toxicity for all class 1 drugs
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What are propranolol, esmolol, metoprolol, atenolol, timolol?
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Class 2 antiarrhythmics: beta-blockers
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What is the mechanism of class 2 antiarrhythmics?
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Decrease cAMP and Ca2+ currents. Suppresses abnormal pacemakers by decreasing slope of phase 4.
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What is the clinical use of class 2 antiarrhythmics?
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Ventricular tachycardia, supraventricular tachycardia, slowing ventricular rate during atrial fibrillation and atrial flutter
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What are the toxicities of class 2 antiarrhythmics?
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Impotence; exacerbation of asthma; cardiovascular effects: bradycardia, AV block, CHF; CNS effects: sedation, sleep alterations; may mask signs of hypoglycemia
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What are sotalol, ibutilide, bretylium, amiodarone?
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Class 3 antiarrhythmics: K+ channel blockers
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What is the mechanism of class 3 antiarrhythmics?
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Increase AP duration, increase effective refractory period - prolongs QT interval
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What is the toxicity of sotalol?
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Torsades de pointes and excessive beta block
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What is the toxicity of ibutilide?
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Torsades de pointes
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What is the toxicity of bretylium?
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New arrhythmias and hypotension
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What is the toxicity of amiodarone?
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Pulmonary fibrosis; corneal deposits; hepatotoxicity; skin deposits resulting in photodermatitis; neurologic effects; constipatation; cardiovascular effects: bradycardia, heart block, CHF; hypothyroidism/hyperthyroidism
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What are verapamil and diltiazem?
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Class 4 antiarrhythmics: Ca2+ channel blockers
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What is the mechanism of class 4 antiarrhythmics?
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Primarily affects AV nodal cells - decreases conduction velocity, increased effective refractory period, increase PR interval
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What is the use of class 4 antiarrhythmics?
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Prevention of nodal arrhythmias (eg: supraventricular tachycardias)
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What is the toxicity of class 4 antiarrhythmics?
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Constipation; flushing; edema; cardiovascular effects: CHF, AV block, sinus node depression; torsades de pointes
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What is the mechanism of adenosine?
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Increase K+ out of cell which hyperpolarizes the cell
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What is the use of adenosine in arrhythmias and the duration of action?
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Drug of choice in diagnosing/abolishing AV nodal arrhythmias ~15 sec
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What are the toxicities of adenosine?
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Flushing, hypotension, chest pain
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What is the use of potassium in arrhythmias?
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Depresses ectopic pacemakers in hypokalemia (eg: digoxin toxicity)
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What is the use of magnesium in arrhythmias?
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To help resolve torsades de pointes and digoxin toxicity
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