Antiarrhythmics: Nursing pharmacology

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Notes

ANTIARRHYTHMICS, PART 1
DRUG NAME
quinidine, procainamide, lidocaine, mexiletine, flecainide, propafenone
*High Alert Medications*

propranolol, esmolol, sotalol, acebutolol
*High Alert Medications*

CLASS
Class I (sodium channel blockers)
Class II (beta blockers)
MECHANISM OF ACTION
Block sodium influx, affect conduction and / or repolarization
Block catecholamines →  decreased heart contractility
INDICATIONS
Arrhythmias (e.g., supraventricular tachycardias, paroxysmal atrial tachycardia, atrial flutter, atrial fibrillation, ventricular tachycardia and ventricular fibrillation)
ROUTE(S) OF ADMINISTRATION
  • PO
  • IV
  • IM
SIDE EFFECTS
  • Arrhythmias
  • Bradycardia
  • Hypotension
  • Gastrointestinal disturbances
  • Hepatotoxicity
  • Boxed warning: cardiac toxicity
  • Quinidine: angioedema, thrombocytopenia, agranulocytosis, anemia
  • Mexiletine: acute liver injury (boxed warning)
  • Flecainide: ventricular proarrhythmic (boxed warning)
  • Procainamide: systemic lupus erythematosus, bone marrow failure (boxed warnings)
  • Dizziness
  • Fatigue
  • Bronchospasm
  • Hyperglycemia
  • Hypertriglyceridemia
  • Hyperkalemia
  • Hypoglycemia unawareness
  • Sotalol: life-threatening proarrhythmia (boxed warning)
CONTRAINDICATIONS AND CAUTIONS
  • Pre-existing hypotension, heart failure, bradycardia, heart block, torsades de pointes
  • Pregnancy and breastfeeding
  • Children and elderly clients
  • Hepatic or renal disease
  • Quinidine, procainamide: thrombocytopenia, thrombocytopenic purpura, heart block > first degree, idioventricular conduction delays (no functioning artificial pacemaker), myasthenia gravis, adversely affected by anticholinergics, quinolones that prolong QT interval
  • Lidocaine: Adam-Stokes syndrome, WPW syndrome, severe heart block (no functioning artificial pacemaker), corn allergy
  • Asthma
  • COPD
  • Diabetes
ANTIARRHYTHMICS, PART 2
DRUG NAME
amiodarone
*High Alert Medications*

verapamil, diltiazem
*High Alert Medications*

CLASS
Class III (potassium channel blockers)
Class IV (calcium channel blockers)
MECHANISM OF ACTION
Block potassium efflux, prolong repolarization, action potential duration
Block calcium influx, slow conduction velocity, decrease heart contractility
INDICATIONS
Arrhythmias (e.g., supraventricular tachycardias, paroxysmal atrial tachycardia, atrial flutter, atrial fibrillation, ventricular tachycardia and ventricular fibrillation)
ROUTE(S) OF ADMINISTRATION
  • PO
  • IV
  • IM
SIDE EFFECTS
  • Arrhythmias
  • Bradycardia
  • Hypotension
  • Gastrointestinal disturbances
  • Neurological side effects
  • Amiodarone: 
    • Thyroid problems,  bluish skin discoloration, skin rash, pruritus, toxic epidermal necrolysis; 
    • Cardiac arrhythmias, pulmonary toxicity, hepatotoxicity (boxed warnings)
  • Hyperprolactinemia
  • Contripation
  • Peripheral edema
CONTRAINDICATIONS AND CAUTIONS
  • Pre-existing hypotension, heart failure, bradycardia, heart block, torsades de pointes
  • Pregnancy and breastfeeding
  • Children and elderly clients
  • Hepatic or renal disease
  • Grapefruit
NURSING CONSIDERATIONS: ANTIARRHYTHMICS
CLASS
Classes I & II
Classes III & IV
ASSESSMENT AND MONITORING
Assessment
  • Vital signs
  • Baseline assessment; e.g., shortness of breath, palpitations, chest pain
  • Laboratory test results; e.g., CBC, electrolytes, cardiac enzymes and troponins, renal and liver function tests
  • Diagnostic test results: ECG

Monitor
  • Side effects
  • Development of arrhythmias
  • Therapeutic effect: ECG stabilization

Assessment: amiodarone

  • Chest X-ray
  • Thyroid function tests
  • Potassium, magnesium
  • Liver function tests
  • Ophthalmic exam

IV administration: amiodarone

  • Emergency equipment readily available
  • Continuous ECG monitoring
  • Correct existing electrolyte imbalances
  • Ensure correct IV catheter placement
  • In-line 2 micron filter
  • Administer bolus; titrate maintenance infusion per facility’s protocol, based on the client’s condition and response to medication

Monitor
  • Vital signs
  • Intake and output
  • ECG; watch for arrhythmias; e.g., AV block, sinus bradycardia
CLIENT EDUCATION
Quinidine
  • Take with meals
  • Dietary modifications
    • Avoid grapefruit / grapefruit juice, large amounts of foods that alkalize urine; e.g., dairy or vegetables; large amounts of fruit juice or vitamin C, low sodium diet, avoid large daily variations in salt intake
  • Side effects
    • Hypotension
  • Recognize quinidine toxicity: tinnitus, vertigo, headaches, visual changes
    • Notify their healthcare provider right away
  • Take once daily, with or without food at same time each day
  • Avoid grapefruit / grapefruit juice
  • Side effects to report immediately
    • Symptoms of pulmonary toxicity; e.g.,  shortness of breath, cough, or chest pain
    • Symptoms of cardiac toxicity; e.g., fatigue, exercise intolerance, palpitations
    • Ophthalmic symptoms; e.g., changes in visual acuity, decreased peripheral vision
    • Photosensitivity: use sunscreen, wear protective clothing, avoid tanning beds and sunlamps
  • Regular appointments for cardiac monitoring, chest X-ray and pulmonary function, measurement of thyroid hormone levels, ophthalmic examinations

Transcript

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Antiarrhythmics, also called antidysrhythmics, are a class of medications that help control arrhythmias or abnormal heartbeats, such as supraventricular tachycardia, ventricular tachycardia and ventricular fibrillation.

In general, antiarrhythmics act by altering electrical conduction pathways through the heart, and can be administered orally, intravenously, or intramuscularly. Now, based on their mechanism of action, they can be divided into four main classes.

Class I antiarrhythmics are sodium channel blockers that inhibit sodium influx into cardiac cells, and can be further subdivided into three groups depending on how they affect conduction and repolarization. Class IA antiarrhythmics, such as quinidine and procainamide, act by slowing conduction and prolonging repolarization. Class IB, like lidocaine and mexiletine, also act by slowing conduction, but they shorten repolarization. And class IC, such as flecainide and propafenone, prolong conduction but have no effect on repolarization.

Next, class II antiarrhythmics are beta-blocker medications, and include propranolol, esmolol, sotalol, and acebutolol. These medications act by preventing the catecholamines norepinephrine and epinephrine from binding and activating them; ultimately decreasing heart contractility and slowing the conduction through the atrioventricular or AV node.

Summary

Antiarrhythmic drugs are used to prevent and treat abnormal and irregular heart rhythms (arrhythmias). These drugs are classified into four major classes based on their physiological effect on the heart muscle.

First, there is Class I antiarrhythmics, which are sodium channel blockers. It includes drugs like quinidine and procainamide. Class I antiarrhythmics are subdivided into three smaller groups: class 1A, class 1B, and class 1C. Next comes class II antiarrhythmics which are beta-blockers. They include drugs like propranolol and esmolol. Class III antiarrhythmics consist of potassium channel blockers like amiodarone; and class IV antiarrhythmics which are calcium channel blockers, consisting of drugs like verapamil and diltiazem.

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