60 Questions – Multiple Choice, Select All That Apply, Multiple Sequence
Chapter 25: Antidysrhythmic Drugs
Which 3 electrolytes are involved in cardiac electrical impulses
o Sodium, potassium, and calcium
Common dysrhythmias (ventricular, supraventricular, conduction blocks)
o Ventricular
Ventricular tachycardia
Ventricular fibrillation
o Supraventricular dysrhythmias
Supraventricular tachycardia (SVT)
Atrial flutter
Atrial fibrillation
o Conduction blocks
First-degree
Second-degree (Mobitz I – Wenchebach, & Mobitz II)
Third-degree (complete heart block) – no drug therapy
Name of classification system for antidysrhythmics
o “Vaughan Williams Classification”
o Know which drug classifications slow down the heart
CCBs, Digoxin, Beta-Blockers
o Know which drugs slow the heart’s electrical impulses by blocking potassium channels
Amiodarone, Sotalol, Dofetilide
Class I: fast sodium channel blockers, negative inotropic effect (decrease contractility)
o 1a: quinidine, procainamide: 1, 5
For a fib, premature atrial contraction, premature ventricular contractions, and v
tach
Adv Eff
Quinidine – cinchonism (tinnitus, loss of hearing, slight blurring of vision,
and GI upset)
Procainamide – systemic lupus erythematosus (30%), torsades de pointes
(multiple V Tach)
o 1b: lidocaine, phenytoin: 1, 5, 12
Lidocaine is used for ventricular dysrhythmias only
o Adv Eff – CNS – twitching, convulsions, confusion, tinnitus
Phentoid is used for atrial and ventricular Tach caused by digitalis tox, and
long QT syndrome
These drugs act on ischemic myocardial tissue
Give Diulantin if seizures occur
o 1c: flecainide, propafenone: 1, 5
More pronounced sodium channel blocking effect
Used for severe Vent dysrhythmias, A fib/flutter, Wolff-Parkinson-White
syndrome, and SVT
Adv Eff – dizinness, visual disturbances, dyspnea, metallic taste with propafenone
Flecainide is first line for A Fib
, 2
Class II: Beta-Blockers (-olol): 1, 5
o Cardioprotective
25% reduction in sudden cardiac death after MI
Few are approved as antidysrhythmics (esmolol, sotalol)
o Indications – acute SVT, or vent dys
o Adv Eff – exacerbate resp disease and HF
Class III: Potassium channel blockers (QT interval)
o amiodarone: 1, 5, 6, 10, 11, 12
Adv Eff (75% of pts)
Pulmonary toxicity (progressive dyspnea and cough) secondary to
pulmonary fibrosis; gradual onset; not reversible and could be
fatal;baseline PFTs and CXR
Corneal microdeposits (visual halos, photophobia, dry eyes)
Hypo/hyperthyroidism, neuropathy with abnormal gait, numbness and
paresthesia, severe photosensitivity, rash, severe bradycardia, abnormal
liver function test
Nursing Considerations
Pulmonary function test (PFTs), liver function test, chest x-ray, eye exam,
pt teaching regarding sunscreen (blue-gray), potentiates digoxin and
warfarin, monitor QT interval (torsades de pointes)
o Very long half-life (2-3 months)
o Indications – dysrhymias that are difficult to treat, life-threatening V Tach/Fib, A
Fib/Flutter
Class IV: calcium channel blockers (CCBs)
o Reduce AV node conduction
o Indications – paroxysmal SVT, a fib/flutter (control vent rate)
o Caution in pts with – hypotension, CHF, decreased left ventricular ejection fraction,
second-degree or third-degree heart block
o verapamil, diltiazem: 1, 8
Digoxin: 1, 9, 11, 12, 13
o Slows conduction through the AV node
o Indications – paroxysmal SVT, a fib/flutter (control vent rate)
o Apical pulse prior to administration
o Monitor digoxin levels
o Monitor signs of digoxin tox
Adenosine: 1, 2, 10, 12
o For PSVT
o Causes Asystole for 6-12 seconds
o Half-life is extremely short (<10s)
All antidysrhythmics drugs: 5, 7, 11, 12
o Good to know:
Digoxin has narrow therapeutic range (0.5-2 ng/mL)
Pts with hypokalemia can develop dig tox very easily
Pt education
Do not skip doses or double up for missed doses
Contact physician for instructions if a dose is missed
Notify physician if: shortness of breath, edema, dizziness, syncope,
palpitations, chest pain
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