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OU Practice Spring 2018 > Dysrhythmia > Flashcards

Dysrhythmia Flashcards

1
Q

Autorhythmic cells

A

Cardiac cells in the heart that create their own resting membrane potential.

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2
Q

Contractile cells

A

Cardiac cells responsible for the heart’s pumping activity.

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3
Q

Automaticity

A

Relates to heart’s ability to spontaneously generate an electrical impulse.

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4
Q

Depolarization

A

Electrical stimulation or impulse that generates an action potential.

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5
Q

Repolarization

A

Movement of membrane potential to initial resting (polarized) state.

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6
Q

Conduction velocity

A

Speed in which electrical impulse is transmitted.

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7
Q

Refractory period

A

Time-frame after depolarization where cells cannot be excited again.

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8
Q

Absolute refractory period

A

In-excitable period regardless of impulse strength

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9
Q

Relative refractory period

A

Cell is partially repolarized; Strong stimulus could cause depolarization

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10
Q

Vaughan-William Classification

A
  • Class I Agents - Sodium channel blockers
  • Class II Agents - beta blockers
  • Class III Agents - Potassium channel blockers
  • Class IV Agents - Non-dihydropyridine calcium channel blockers
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11
Q

Which of the Vaughan-William Classifications can cause QT prolongation?

A
  • Class IA

- Class III

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12
Q

What are the agents in Class I?

A
  • IA: Disopyramide, Quinidine, Procainamide
  • IB: Lidocaine, Mexiletine, Phenytoin
  • IC: Flecainide, Propafenone
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13
Q

What are the agents in Class II?

A

beta blockers

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14
Q

What are the agents in Class III?

A
  • Amiodarone
  • Dronedarone
  • Sotalol
  • Dofetilide
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15
Q

What are the agents in Class IV?

A

Non-dihydropyridine calcium channel blockers

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16
Q

Class I pharmacotherapy

A
  • block Na channels (inhibit phase 0)
  • C > A > B
  • Delay automaticity
  • Slows conduction velocity
  • Varying effects on repolarization
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17
Q

Class I pearls

A
  • use dependence; work better at faster heart rates
  • need TDM
  • can be pro-dysrhythmic
  • avoid in pts with structural heart disease or CAD (linked to higher morbidity and mortality rates)
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18
Q

Class IA actions

A
  • Moderate inhibition of Phase 0
  • Prolongs absolute refractory period
  • Prolongs repolarization
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19
Q

Procainamide

A
  • Class IA
  • Ventricular arrhythmias (V. tachycardia, V. fib)
  • NAPA metabolite (acts like a Class III) which will cause more QT prolongation effects
  • 2D6 substrate
  • acute ethanol reduces serum concentraiton
  • dose adjust in renal impairment (CrCl < 50 mL/min) and hepatic impairment
  • TDM
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20
Q

Disopyramide

A
  • Norpace®
  • Class IA
  • Ventricular arrhythmias
  • dose adjust in renal dysfunction: CrCl < 40 mL/min and hepatic dysfunction
  • Substrate of 3A4
  • TDM needed
  • can induce heart failure b/c it’s a negative inotrope
  • anticholinergic side effects
  • on Beer’s list
  • administer around the clock
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21
Q

Quinidine

A
  • Class IA
  • Ventricular arrhythmias
  • Atrial fibrillation / atrial flutter
  • 3A4; eliminated by P-gp; inhibit 2D6; inhibit P-gp
  • Dose adjust if CrCl < 10 mL/min
  • Use with caution in hepatic impairment
  • TDM
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22
Q

Class IA pearls

A
  • Use has fallen out of favor due to adverse effect risk outweighing antidysrhythmic benefits
  • Notorious for QT-prolonging effects
  • Avoid in patients with structural heart disease and/or CAD
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23
Q

Disopyramide adverse effects

A
  • Hypotension
  • Exacerbate HF
  • Xerostomia
  • Constipation
  • Urinary hesitancy
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24
Q

Disopyramide patient counseling

A

take on empty stomach

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25
Q

Quinidine patient counseling

A
  • Low Na diet & food can increase rate and extent absorption
  • Fruit juice & vitamin C can increase clearance of quinidine
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26
Q

Quinidine contraindications

A
  • Thrombocytopenia
  • 2nd or 3rd degree heart block
  • Concurrent use of quinolone antibiotics that prolong QT interval
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27
Q

Quinidine adverse effects

A
  • GI distress
  • Diarrhea
  • Dizziness
  • Fatigue
  • Headache
  • Palpitations
  • Cinchoism
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28
Q

Procainamide dosing

A
  • Loading Dose: 500-600 mg IV over 25-30 minutes

- Maintenance Dose: 2-6 mg/min by continuous IV infusion

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29
Q

Quinidine dosing

A
  • 267 mg of quinidine gluconate = 200 mg of quinidine sulfate
  • Gluconate: ER: 648 mg PO q. 8 hours
  • Sulfate: IR: 200-400 mg PO q. 6 hours ▪ ER: 300 mg PO q. 8-12 hours
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30
Q

Disopyramide

A
  • Immediate release: 100-150 mg PO q. 6 hours

- Controlled release: 200-300 mg PO q. 12 hours

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31
Q

Procainamide adverse effects

A
  • hypotension (decrease dose)
  • heart failure
  • 1st degree AV block
  • lupus erythematosus-like syndrome (long term = LT)
  • blood dyscrasias (long term) ex. Agranulocytosis, Bone marrow suppression, Neutropenia, Thrombocytopenia
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32
Q

Class IB actions

A
  • Mild inhibition of Phase 0
  • shortens absolute refractory period
  • shortens repolarization
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33
Q

Class IB pearls

A
  • Used for treatment of ventricular arrhythmias (because works well on contractile cells)
  • Use with caution in patients with hepatic disease and HF
  • Relatively higher amount of CNS-related adverse effects
  • Avoid in patients with structural heart disease and/or CAD
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34
Q

Lidocaine

A
  • Xylocaine®
  • VF or pulseless VT
  • Hemodynamic monomorphic VT
  • TDM
35
Q

Mexiletine

A
  • Ventricular arrhythmias
  • must take every 8 hours to decrease variation in peaks and troughs; after dysrhythmia is controlled, could change interval to Q12h
  • 1A2, 2D6 substrate
  • Caution in patients with hepatic impairment and/or HF
36
Q

Lidocaine doses

A
  • 1 - 1.5 mg/kg bolus
  • for VF or pulseless VT: 0.5 to 0.75 mg/kg bolus every 5 to 10 minutes (maximum cumulative dose: 3 mg/kg)
  • Continuous infusion: 1 - 4 mg/minute
  • Use lower dose in patients with hepatic dysfunction (metabolized by liver)
  • 1A2, 3A4 substrate
37
Q

Mexiletine doses

A
  • 200-300 mg PO q. 8 hours

- MDD of 1.2 grams

38
Q

Lidocaine contraindications

A
  • Premixed injection may contain corn-derived dextrose and its use is contraindicated in patients with allergy to corn or corn-related products
  • Severe degrees of SA or AV block (except in patients with a functioning artificial pacemaker)
39
Q

Mexiletine adverse effects

A
  • GI effects limits people from tolerating this drug
  • Gi: GI distress, N/V
  • Dizziness
  • Ataxia
  • Hepatotoxicity
  • Blood dyscrasias
  • DRESS
40
Q

Mexiletine patient counseling

A
  • Take with food

- Avoid diets or medications that increase urinary pH

41
Q

Mexiletine patient counseling

A
  • Take with food
  • Avoid diets or medications that increase urinary pH
  • do not recommend taking with antacid b/c if you make the urine basic, it doesn’t allow medicine to be secreted in renal tubule
42
Q

Class IC actions

A
  • Major inhibition of Phase 0
  • Minimal effect on absolute refractory period
  • Minimal prolongation of repolarization
43
Q

Class IC actions

A
  • Major inhibition of Phase 0
  • Minimal effect on absolute refractory period
  • Minimal prolongation of repolarization
44
Q

Class IC pearls

A
  • Used primarily for supraventricular tachycardia
  • Commonly prescribed in the outpatient setting
  • Both agents have dietary considerations that effect plasma levels
  • TDM is not commonly performed in practice
  • Avoid in patients with structural heart disease and/or CAD
  • used for Paroxysmal atrial fibrillation and Paroxysmal supraventricular tachycardia
45
Q

Flecainide

A
  • Tombocor®
  • 2D6 substrate
  • Caution in patients with hepatic dysfunction
  • Dose adjust in patients with CrCl < 35 mL/min
46
Q

Propafenone

A
  • Rythmol®
  • monitor CBC, LFT’s, ECG
  • Use with caution in patients receiving beta-blockers (b/c has BB activity)
  • 2D6 substrate
  • inhibits P-gp
  • Dose adjust in hepatic dysfunction
47
Q

Flecainide doses

A
  • 50-100 mg PO q. 12 hours

- MDD: 300-400 mg

48
Q

Propafenone doses

A
  • ER capsule: Initial 225 mg PO every 12 hours; May increase up to maximum of 425 mg every 12 hours
  • IR tablet: Initial 150 mg PO every 8 hours; May increase up to maximum of 300 mg every 8 hours
49
Q

Flecainide contraindications

A
  • Ritonavir

- Pre-existing 2nd or 3rd degree AV block

50
Q

Flecainide counseling

A
  • Clearance may be decreased in patients following strict vegetarian (via increase in urine pH)
  • Milk may interfere with the absorption of flecainide
51
Q

Flecainide adverse effects

A
  • Dizziness
  • Headache
  • Fatigue
  • Nausea
  • Visual disturbances
  • Dyspnea
52
Q

Propafenone counseling

A

avoid grapefruit juice

53
Q

Propafenone counseling

A

avoid grapefruit juice

54
Q

Propafenone adverse effects

A
  • Unusual taste
  • Nausea
  • Vomiting
  • Dizziness
  • Fatigue
  • Blurred vision
55
Q

Class II action

A
  • Inhibit sympathetic influences on electrical activity
  • Decrease SA/AV node automaticity & conduction velocity
  • Increase action potential duration and effective refractory period
56
Q

What are the beta blockers available for dysarrhythmia?

A
  • Beta-adrenergic receptor antagonists with MSA: Propranolol, Metoprolol
  • Beta-blockers without MSA are still commonly used in practice: Esmolol
57
Q

Propranolol

A
  • Inderal®
  • Non-selective beta-blocker
  • Can be used to treat arrhythmias caused by hyperthyroidism
  • metabolized by 1A2, 2D6
58
Q

Propranolol dosing

A
  • 30-320 mg/day, divided every six to eight hours, orally (MDD of 640 mg)
  • Can transition to extended-release formulation when dysrhythmia is controlled
59
Q

Propranolol counseling

A
  • Ethanol may increase or decrease plasma levels of propranolol
  • High-protein diet can increase bioavailability
60
Q

Esmolol

A
  • Brevibloc®
  • Advantageous when patients possess tenuous blood pressure/heart rate
  • Metabolized by blood cell esterases.
  • When transitioning to oral beta-blocker therapy, infusion should be reduced by 50% thirty minutes following the first dose of the alternative agent
61
Q

Esmolol doses

A
  • Continuous infusion

- 500 mcg/kg/minute over 1 minute, then 50 mcg/kg/minute (max of 200 mcg/kg/minute)

62
Q

Class III

A
  • K channel blockers

- prolong repol -> prolong QT interval

63
Q

Which drugs are in the Class III?

A
  • Amiodarone (Pacerone®, Cordarone®)
  • Dronedarone (Multaq®)
  • Ibutilide (Corvert®)
  • Dofetilide (Tikosyn®)
  • Sotalol (Betapace®, Betapace AF®)
64
Q

Dronedarone brand name

A

Multaq®

65
Q

Ibutilide brand name

A

Corvert®

66
Q

Amiodarone

A
  • Blocks all four Vaughan-Williams classifications (protects itself from having QT prolongation)
  • Used to treat both atrial and ventricular arrhythmias
  • metabolized by 2C8, 3A4
  • inhibit P-gp, 2C9, 3A4
67
Q

Amiodarone dose

A
  • Oral: 200-1600 mg/day

- IV: 150-300 mg rapid bolus, then 1 mg/minute for 6 hours, then 0.5 mg/min for 18 hours

68
Q

Amiodarone adverse effects

A
  • hypotension
  • bradycardia
  • thyroid dysfunction (hyper- and hypo-)
  • N/V
  • Acute and chronic liver impairment
  • Skin photosensitivity
  • Pulmonary toxicity: Pneumonitis, Fibrosis
  • Peripheral neuropathy
  • Optic neuritis
69
Q

Amiodarone counseling

A

Avoid grapefruit juice

70
Q

Amiodarone contraindications

A
  • Hypersensitivity to iodine
  • Second and third-degree AV block
  • Cardiogenic shock
71
Q

Sotalol

A
  • Used to treat atrial and ventricular dysrhythmias
  • as you increase the dose, you get more anti-arrhythmic effects
  • Possesses predominantly non-selective beta-blocking properties at lower doses
  • Get baseline QTc interval prior to initiation
  • Frequency adjust in patients with CrCl ≤60 mL/min
  • Can cause life threatening ventricular tachycardia associated with QT interval prolongation
  • when dose started or changed, must be admitted to hospital for monitoring
72
Q

Sotalol dosing

A
  • Oral

- 80-160 mg twice daily

73
Q

Sotalol adverse effects

A
  • Bradycardia
  • Fatigue
  • Dizziness
  • Weakness
  • Dyspnea
  • Prolongation of QT-interval
74
Q

Sotalol contraindications

A

Contraindicated if CrCl < 40 mL/min

75
Q

Dofetilide

A
  • Tikosyn
  • Used to treat atrial fibrillation and atrial flutter
  • Measure QTc before initiation
  • Safe to use in patients with CAD or structural heart disease.
  • Dose adjust in patients with CrCl < 60 mL/min
76
Q

Dofetilide dosing

A
  • Oral

- 125-250 micrograms twice daily

77
Q

Dofetilide adverse effects

A
  • Headache
  • Dizziness
  • QT-prolongation
78
Q

Dofetilide contraindications

A
  • cimetidine
  • dolutegravir
  • hydrochlorothiazide
  • itraconazole
  • ketoconazole
  • megestrol
  • prochlorperazine
  • trimethoprim
  • verapamil
79
Q

Class iV

A
  • Non-Dihydropyridine Calcium Channel Antagonists
  • Treat supraventricular dysrhythmias
  • Atrial fibrillation/flutter
  • Paroxysmal supraventricular tachycardia
80
Q

Verapamil

A
  • Calan®
  • substrate of 3A4 and P-gp
  • Moderate inhibitor of 3A4
  • Inhibitor of P-gp
  • May need to dose adjust in hepatic/renal impairment
  • more GI effects compared to Diltiazem
81
Q

Verapamil dosing

A
  • IV
    ▪ 0.075 – 0.15 mg/kg bolus over 2 minutes
    ▪ 5 mg/hour CI
  • Oral
    ▪ 240-480 mg daily in divided doses (three times daily), initially
    ▪ Transition to extended-release formulation
82
Q

Diltiazem

A
  • Dilacor®, Cardizem®
  • substrate of 3A4 and P-gp
  • Moderate inhibitor of 3A4
  • Dose adjust in patients with liver impairment
83
Q

Diltiazem dosing

A 
- IV 
▪ 0.25 mg/kg IV bolus over 2 minutes 
▪ 5-10 mg/hour CI 
▪ Avoid exceeding 15 mg/hour
- Oral 
▪ Initially 30 mg q. 6 hours 
▪ 120-360 mg/day in divided doses or extended-release formulation

OU Practice Spring 2018 (9 decks)

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