Anti arrhythmic drugs

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Anti arrhythmic drugs
2013-03-17 00:29:21
anti arrhithmic drugs cardiac

anti arrhythmic drugs, cardiac drugs
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  1. Class I drugs
    Inhibit fast sodium channels

    Affect primarily myocardial tissue

    • Sub-classes differ by variations in drug binding to and dissociation from the channel
    • receptors
  2. Class IA
    Reduce automaticity

    Reduce conduction velocity

    Increase refractory period

    Reduce contractility
  3. Quinidine
    Class IA
    • May slow heart rate, widen QRS
    • complex, prolong QT interval
    • Cardiac monitoring when starting Rx
    • Interacts with several drugs
    • Increase risk of digoxin toxicity

    • Uses—ventricular arrhythmias
    • Supraventricular arrhythmias
    • —tachycardia, atrial fibrillation and flutter

    • Adverse effects
    • Diarrhea—up to 30% can’t tolerate
    • Cinchonism—toxicity
    • Tinnitus, ototoxicity—deafness            
    • Headache, blurred vision

    • Nursing—monitor effects and adverse effects
    •             Monitor QRS duration and rate
    • Teach—to report adverse effects
  4. Lidocaine (xylocaine)
    Class IB
    • Decrease automaticity of His-Purkinje system
    • Less effect on atria, in ischemic heart--block re-entry

    • *No decreased contractility
    • *Little  effect on BP, pulse
    • Adverse effects--CNS-- numbness, tingling        
    • Drowsiness (dose-related),
    • Toxicity--confusion, blurred vision, paresthesias, seizures, widened QRS
    • Uses: Acute Rx ventricular dysrhythmias
    • Especially in diseased heart (CHF, MI)

    IV only--bolus followed by drip

    Nursing: Requires cardiac monitoring--rhythm, observe QRS width

    • For acute therapy only
    • Observe for therapeutic and toxic effects
  5. Class II
    • Beta Adrenergic Blockers      
    • Affect sympathetic nervous system to
    • Decrease heart rate and automaticity
    • Mild inhibition of Na+ channels
    • Increase refractory period of AV node
    • Decreases contractility

    • Uses:  treat ventricular dysrhythmias
    • Prophylactically after MI

    • Digitalis-induced dysrhthmias
    • Slows ventricular rate with atrial fibrillation

    • Nursing:         
    • Monitor BP—hold for systolic  <100
    • Monitor P—hold for pulse <60 (50)
    • Observe for S/S CHF
    • Greater risk with calcium channel blockers
  6. Propranolol
    Class II
    • Beta blocker
    • Used for: tremors, angina, hypertension, dysrhythmias, and other heart or circulatory conditions. It is also used to treat or prevent heart attack, and to reduce the severity and frequency of migraine headaches.
  7. Class III
    • Blocks potassium channels, calcium channels
    • Prolong action potential
    • Slows AV conduction
    • Prolongs QT interval, widens QRS
  8. Amiodorone (cordarone)
    Class III
    • Also block Na+ channels, Ca+ channels, adrenergic receptors
    • Slow onset, long half life
    • *Primary use for ventricular tachycardia and fibrillation
    • Hypotension with IV use-give slowly
    • Bradycardia common—monitor

    • Longterm Therapy: Monitor liver enzymes, thyroid levels        
    • May cause pulmonary toxicity—pneumonitis, fibrosis

    • Monitor for dyspnea, cough, chest pain
    • High incidence of nausea, vomiting, anorexia
  9. Class IV
    Calcium channel blockers
    • Reduce AV conduction
    • *Increase AV refractory period
    • *Affects AV node – decreases automaticity
    • *Decreases myocardial contractility

    • Uses:  treat Supraventricular Tachycardias
    • Slow ventricular rate in  atrial fibrillation & atrial flutter
    • Adverse Effects: CHF, bradycardia, hypotension

    • Give slowly iv, with cardiac monitoring
    • Monitor BP—hold for systolic < 100
    • Monitor P—hold for pulse < 60
  10. Diltiazem (cardizem, ziac)
    Class IV
    • calcium channel blocker
    • It works by relaxing the muscles of your heart and blood vessels. Diltiazem is used to treat hypertension, angina, and certain disrrhythmias.
  11. Adenosine (adenocard)
    Class IV
    • Naturally occurring nucleosideàpurinergic receptor antagonist
    • Inhibits camp induced Ca++ influx
    • Depress AV nodal activity

    Use—Convert supraventricular tachycardia

    • Serum half life 1.5 – 10 seconds
    • *Give rapid IV bolus (1-2 seconds)
    • *Requires cardiac monitoring
    • May see chest pressure, nausea
    • Short term asystole (usually 5-6 seconds)