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NAPLEX 2024 > 32. Arrhythmias > Flashcards

32. Arrhythmias Flashcards

1
Q

S/sx arrhythmias

A

Feels like “fluttering” in their chest or “skipping a beat”
Dizziness, SOB, fatigue, lightheadedness, chest pain

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2
Q

___ is used to diagnose arrhythmias

A

Electrocardiogram (ECG)

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3
Q

A ___ is an ambulatory ECG device that records electrical activity of the heart for 24-48hrs. Used to detect arrhythmias that are intermittent.

A

Holter monitor

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4
Q

Normal sinus rhythm originates in the ___

A

sinoatrial (SA) node

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5
Q

____ is the heart’s natural pacemaker

A

SA node

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6
Q

Normal HR range is ___

A

60-100BPM

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7
Q

Describe the conduction pathway

A

SA node
AV node
Bundle of His, splits to right and left branch
Purkinje fibers

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8
Q

3 reasons why arrhythmias may be occuring

A
  1. SA node can be firing at an abnormal rate or rhythm
  2. Scar tissue from prior heart attack can block and divert signal transmission
  3. another part of the heart may be acting as the pacemaker
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9
Q

The SA cells have automaticity. What does this mean?

A

Unlike other myocytes, the pacemaker cells initiate their own action potential (does not require external stimulation)

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10
Q

Describe phase 0 of the cardiac action potential

A

Heartbeat is initiated when rapid ventricular depolarization occurs in response to influx of Na
Causes ventricular contraction (represented by QTS complex on ECG)

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11
Q

Describe phase 1 of the cardiac action potential

A

early rapid repolarization (Na channels close)

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12
Q

Describe phase 2 of the cardiac action potential

A

Plateau in response to influx of Ca and efflux of K

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13
Q

Describe phase 3 of the cardiac action potential

A

Rapid ventricular repolarization in response to an efflux of K, causes ventricular relaxation (represented by T wave on ECG)

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14
Q

The most common cause of arrhythmias is __ or __

A

Myocardial ischemia or infarction

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15
Q

Non-cardiac conditions that can trigger or predispose of a pt to an arrhythmia include ____

A

electrolyte imbalances (es. potassium, magnesium, sodium, and calcium)
Elevated sympathetic states (E.g. hyperthyroidism, infection)
Drugs (illicit drugs, antiarrhythmics, and QT prolonging meds)

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16
Q

Arrhythmias are generally classified into 2 broad categories based on point of origin: _____ and ___

A

supraventricular (originating above AV node)
Ventricular (originating below AV node)

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17
Q

___ is the most common type of arrhythmia

A

Afib

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18
Q

____ are referred to as a skipped heartbeat

A

Premature ventricular contractions (PVCs)

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19
Q

A series of premature ventricular contractions (PVCs) in a row resulting in a HR of > ___BPM, is known as ___ (medical emergency)

A

> 100 BMP
Ventricular tachycardia (VTach, VT)

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20
Q

Untreated VTach can degenerate into _____ which is also a medical emergency

A

Ventricular fibrilation (VFib)

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21
Q

QTc is considered prolonged when it is > ____ milliseconds (msec) but more worrisome when it is > ____msec

A

> 440 msec
500 msec

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22
Q

Prolonged QT interval is a risk factor for ____, a particularly lethal ventricular tachyarrhythmia that can cause ____

A

TdP
sudden cardiac death

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23
Q

Drug-induced QT prolongation increases with ____

A

Higher doses
Multiple QT-prolonging drugs taken at the same time
Reduced drug clearance d/t renal/liver disease or drug interaction
Electrolyte abnormalities (hypokalemia, hypomagnesemia, hypocalcemia)
Other cardiac conditions (cardiac damage is a risk for arrhythmias, including TdP
Female gender

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24
Q

Drugs that increase or prolong QT interval

A

Antiarrhythmics - Class Ia, Ic, and III

Anti-infectives - antimalarials (e.g. hydroxychloroquine), azole antifungals (all except isavocunazonium), macrolides, quinolones, lefamulin

Antidepressants - SSRIs (highest risk with citalopram and escitalopram), TCA, mirtazapine, trazodone, venlafaxine

Antiemetics - 5-HT3 receptor antagonists, droperidol, metoclopramide, promethazine

Antipsychotics - first gen (e.g. haloperidol, chlorpromazine, thioridazine), second gen (highest risk of ziprasidone)

Onc meds - androgen deprivation therapy (e.g. leuprolide), TKIs (e.g. nilotinib), oxaliplatin

Others - cilostazol, donepezil, fingolimod, hydroxyzine, loperamide, methadone, ranolazine, solifenacin, tacrolimus

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25
Q

Prior to starting any drug for a non-life-threatening arrhythmia, ___ and ___ should be checked to identify reversible causes dominant electrophysiological effect

A

electrolytes and toxicology screen

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26
Q

The Vaughan Williams classification splits drugs into categories based on their ____

A

Dominant electrophysiological effect

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27
Q

Mnemonic for classifying drugs with Vaughan Williams

A

Double Quarter Pounder/Lettuce, Mayo/ Fries Please! Because / Dieting During Stress Is Always / Very Difficult

Class I: Na-channel blockers
Ia: Disopyramide, Quinidine, Procainamide
Ib: Lidocaine, Mexiletine
Ic: Flecainide, Propafenone

Class II: Beta-blockers
Beta-blockers

Class III: K-channel blockers
Dronedarone, Dofetilide, Sotalol, Ibutilide, Amiodarone

Class IV: Non-DHP CCB
Verapamil, Diltiazem

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28
Q

Vaughan Williams Class I MOA and Consequence

A

Na-channel blockers
Proarrhythmic (higher risk of arrhythmia), negative inotropic potential, which decreases force of ventricular contraction
Use caution in pts with underlying cardiac disease

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29
Q

Vaughan Williams Class II MOA and Consequence

A

Beta-blockers
Used primarily to slow ventricular rate in Afib

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30
Q

Vaughan Williams Class III MOA and Consequence

A

K-channel blockers
Amiodarone and dronedarone block K channels (primarily), also block Ca and Na channels,alpha- and beta- adronergic receptors
Amiodarone is useful for diff types of arrhythmias including Afib
Amiodarone and dofetilide are preferentially used in Afib in pts with HF
Sotalol blocks K channels and is a beta-blocker

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31
Q

Which Class III antiarrhythmic blocks K channels and is a beta-blocker?

A

Sotalol

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32
Q

___ and ___ are preferentially used in Afib in pts with HF

A

Amiodarone and dofetilide

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33
Q

Vaughan Williams Class IV MOA and Consequence

A

Non-DHP CCB
Used primarily to slow ventricular rate in AFib
Negative inotropic effect (decreased contraction force), can cause cardiac decompensation
Do NOT use verapamil or diltiazem in pts with HF and reduced ejection fraction (HFrEF)

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34
Q

Digoxin MOA and consequence

A

Na-K-ATPase blocker
Suppresses AV node conduction (decrease HR) by enhancing vagal tone and increased force of contraction (positive inotrope)

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35
Q

Adenosine MOA and consequence

A

Activates adenosine receptors to decrease AV node conduction
Used for supraventricular re-entrant tachycardias (formerly known as paroxysmal supraventricular tachycardias or PSVTs)

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36
Q

Which antiarrhythmic is used for supraventricular re-entrant tachycardias (formerly known as paroxysmal supraventricular tachycardias or PSVTs)

A

Adenosine

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37
Q

Guideline recommended treatment for most types of Afib involves using one of two main strategies: ___ and ___

A

rate control
rhythm control

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38
Q

Define paroxysmal afib

A

AFib that terminates spontaneously or with intervention within 7 days of onset; episodes may recur with variable frequency

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39
Q

Define persistent afib

A

Continuous afib sustained > 7 days

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40
Q

Define long-standing persistent afib

A

Continuous afib sustained >12 months

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41
Q

Define Permanent afib

A

Term sued when a joint decision has been made by the clinician and pt to cease further attempts to restore and/or maintain normal sinus rhythm (treatment choice than a characteristic of arrhythmia itself)

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42
Q

Define valvular afib

A

Afib with mod to severe mitral stenosis or with a mechanical heart valve; long-term anticoag with warfarin is indicated

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43
Q

Define non-valvular afib

A

Afib without mod to severe mitral stenosis or a mechanical heart valve

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44
Q

The goal resting HR IS <___ BPM in pts with symptomatic afib; however, a more lenient goal of <___ BPM may be reasonable in pts who are asymptomatic and have preserved left ventricular function

A

<80BPM
<11o BPM

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45
Q

___ (preferred) or ___ are recommended for controlling ventricular rate in pts with afib

A

Beta-blockers (preferred)
Non-DHP CCBs

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46
Q

Which antiarrhythmics should pts with HFrEF avoid?

A

non-DHP CCBs (verapamil, diltiazem)

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47
Q

Cardioversion has a high risk of thromboembolism. If the pt is not already using therapeutic anticoag, it should be started at least ____ before cardioversion and continued for at least ____ after successful cardioversion to NSR. If using warfarin, the goal INR should be 2-3

A

3 weeks before, 4 weeks after successful cardioversion

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48
Q

Which antiarrhythmic drugs are used for rhythm control?

A

Class Ia, Ic, or III

49
Q

If AFib is permanent, what should be avoided d/t risk > benefits?

A

Avoid rhythm-control strategy with antiarrhythmic drugs (risk outweighs benefit)

50
Q

T/F: For many patients, it is safer to remain in Afib with rate control than to try to restore NSR

A

True

51
Q

Which anticoags are preferred for stroke prevention in non-valvular Afib?

A

DOACs > warfarin

51
Q

___ is indicated for stroke prevention in pts with Afib and a mechanical heart valve

A

Warfarin

51
Q

Boxed warnings for amiodarone (Nexterone, Pacerone)

A

Pulmonary toxicity (check baseline chest X-ray, PFTs)
Hepatotoxicity (check baseline LFTs)
For life-threatening arrhythmias only; proarrhythmic, must be hospitalized for IV loading dose

52
Q

Contraindications for amiodarone (Nexterone, Pacerone)

A

Iodine hypersensitivity
Others: severe sinus-node dysfunction causing marked decrease HR, 2nd/3rd degree heart block (unless using artificial pacemaker), bradycardia causing syncope, cardiogenic shock

53
Q

Warnings for amiodarone (Nexterone, Pacerone)

A

Hyper and hypothyroidism (hypo more common) - amiodarone partially inhibits peripheral conversion of T4 to T3, optic neuropathy, photosensitivity (slate-blue skin discoloration), neurotoxicity (peripheral neuropathy), SJS/TEN

54
Q

Side effects for amiodarone (Nexterone, Pacerone)

A

Hypotension, bradycardia, corneal microdepositis, photosensitivity (sunprotection required)
Others: dizziness, tremor/ataxia, malaise/fatigue, nausea, DILE

55
Q

Monitoring for amiodarone (Nexterone, Pacerone)

A

ECG, BP, HR, electrolytes, LFTs every 6 months, thyroid (TSH and free T4) every 3-6 months
Annual chest x-ray, regular eye exams

56
Q

___ and ___ are the antiarrhythmic drug of choice in HF

A

Amiodarone, dofetilide (Tikosyn)

57
Q

Half life of amiodarone (Nexterone, Pacerone)

A

40-60 days

58
Q

amiodarone (Nexterone, Pacerone) administration notes

A

Infusions > 2 hrs require a non-PVC contained (e.g. polyolefin or glass), PVC tubing is ok

Premixed IV bags: longer stability, non-PVC, available in common conc (e.g. Nextrexone comes in non-PVC, non-DEHP GALAXY plastic container)

IV: use 0.22 micron filter, central line preferable

59
Q

What to do if hypotension or bradycardia happens when on amiodarone

A

Decrease infusion rate or d/c

60
Q

Patient needs to use Amiodarone and heparin. What are some concerns?

A

Incompatible with heparin (flush line with saline); many Y-site, additive incompatibilities

61
Q

Why is iodine hypersensitivity a contraindication for amiodarone?

A

Amiodarone chemical structure contains iodine

62
Q

Amiodarone can increase the level of many other drugs; it is an inhibitor of ____

A

CYP2C9 (moderate), 2D6 (moderate), 3A4 (weak)
P-gp

63
Q

When starting amiodarone, what should you do to the dose of digoxin, warfarin, simvastatin, or lovastatin?

A

Decrease digoxin by 50%
Decrease warfarin by 30-50%
Max dose 20mg/day simvastatin
Max dose 40mg/day lovastatin

64
Q

Additive effects can occur when amiodarone is used with other drugs that decrease HR including ____

A

non-DHP CCB, digoxin, beta-blockers, clonidine, dexmedetomidine (Precedex)

65
Q

Sofosbuvir can enhance the ___ effect of amiodarone; do NOT use together

A

Bradycardic

66
Q

Contraindications of non-DHP CCBs (Diltiazem (Cardizem, Tiazac), Verapamil (Calan SR))

A

HFrEF
Others: severe hyptoension SBP<90), 2nd/3rd degree heart block/sick sinus syndrome (unless pacemaker), caridogenic shock, Wolff-Parkinson-White syndrome with Afib

67
Q

Warnings for non-DHP CCBs (Diltiazem (Cardizem, Tiazac), Verapamil (Calan SR))

A

HF (may worsen symptoms)
Others: hypotension, 1st degree AV block with sinu s bradycardia, increased LFTs

68
Q

Side effects for non-DHP CCBs (Diltiazem (Cardizem, Tiazac), Verapamil (Calan SR))

A

Edema, arrhythmias, constipation (more with verapamil), gingival hyperplasia, HA, dizziness

69
Q

T/F: Both non-DHP and DHP CCBs can be used for antiarrhythmics (non-DHP CCBs preferred)

A

False - only non-DHP CCBs

70
Q

Additive effects can occur when non-DHP CCBs are used with other drugs that decrease HR including ____

A

amiodarone, digoxin, beta-blockers, clonidine, dexmedetomidine (Precedex)

71
Q

Non-DHP CCBs are CYP___ substrates.

A

3A4
Do NOt take with grapefruit, caution with strong 3A4 inducers/inhibitors

72
Q

Diltiazem and verapamil are substrates of P-gp and inhibitors of CYP3A4. Patients who take ___ and __ statins should use lower doses or use statin that is not metabolized by CYP3A4 such as ____

A

Simvastatin or lovastatin
Pitavastatin, pravastatin, rosuvastatin

73
Q

Digoxin (Digitek, Lanoxin) typical dose

A

0.125-0.25mg PO daily

74
Q

Digoxin (Digitek, Lanoxin) therapeutic range for Afib (lower range for HF)

A

0.8-2 ng/mL

75
Q

Pt will be switching from PO to IV digoxin. What changes need to be made to the dose?

A

Decrease dose by 20-25%

76
Q

Digoxin (Digitek, Lanoxin) if CrCl < 50

A

Decrease dose or frequency; hold in acute renal failure

77
Q

Digoxin Toxicity s/sx

A

N/V, loss of appetite, abd pain, blurred/double vision, greenish-yellow halos (or altered color perception), confusion, delirium, bradycardia, life-threatening arrhythmias

78
Q

What electrolyte imbalances increase risk for digoxin toxicity?

A

Hypokalemia, hypomagnesemia, and hypercalcemia

79
Q

Antidote for digoxin

A

DigiFab

80
Q

Digoxin is not usually given alone for rate control, used in combo with ___ or ____

A

beta-blocker of non-DHP CCB

81
Q

Digoxin is a substrate of P-gp. Levels increase with inhibitors including _____ and many other drugs.

A

Amiodarone, verapamil, diltiazem, clarithromycin, itraconazole

82
Q

Additive effects can occur when digoxin is used with other drugs that decrease HR including ____

A

Amiodarone, non-DHP CCBs, beta-blockers, clonidine, and dexmedetomidine (Precedex)

83
Q

Disopyramide (Norpace) boxed warning

A

Reserve use for pts with life-threatening ventricular arrhythmias

84
Q

Warnings for disopyramide (Norpace)

A

Proarrhythmic, myasthenia gravis (d/t anticholinergic effects)
Others: hypotension, HF, BPH/Urinary retention/narrow-angle glaucoma

85
Q

Side effects for disopyramide (Norpace)

A

Anticholinergic effects (e.g. dry mouth, constipation, urinary retention), hypotension

86
Q

Quinidine administration notes

A

take with food or milk to decrease GI upset

87
Q

Warnings for quinidine

A

Proarrhythmic, hemolysis risk (avoid in G6PD deficiency), can cause positive Coombs test

88
Q

Side effects for quinidine

A

DILE, diarrhea (35%), stomach cramping (22%), rash, lightheadedness
Cinchonism (e.g. quinidine overdose): tinnitus, hearing loss, blurred vision, headache, delirium

89
Q

___ is the drug of choice for Wolff-Parkinson-White syndrome

A

Procainamide

90
Q

What is the active metabolite for procainamide and how is it cleared?

A

N-acetyl procainamide (NAPA)
Renally cleared - decrease dose when CrCl <50

91
Q

Therapeutic levels of procainamide

A

40-10mcg/mL

92
Q

Boxed warnings for procainamide

A

potentially fatal blood dyscrasias (e.g. agranulocytosis) - monitor closely first 3 months and periodically
Long-term use leads to positive antinuclear antibody (ANA) in 50% of patients - can result in DILE in 20-30% of patients
Reserve use for life-threatening ventricular arrhythmias

93
Q

Long-term use of ____ leads to positive antinuclear antibody (ANA) in 50% of patients - can result in DILE in 20-30% of patients

A

procainamide

94
Q

Warnings for procainamide

A

Proarrhythmic

95
Q

Metabolism of procainamide to NAPA occurs by ____

A

acetylation
slow acetylators are at risk for drug accumulation and toxicity
Fast acetylators are at risk of subtherapeutic drug conc and reduced efficacy

96
Q

Class Ib antiarrhythmics are useful for ___ only

A

Ventricular arrhythmias only (no efficacy in afib)

97
Q

Lidocaine (Xylocaine) injection is used for ____

A

refractory VT/cardiac arrest

98
Q

What is a common contraindication for Class Ic antiarrhythmics (Flecainide, Propafenone (Rythmol SR))

A

HF, MI

99
Q

Boxed warning for felcainide

A

Proarrhythmic effects, esp in Afib (do not use in chronic afib)

100
Q

Warnings for propafenone (Rythmol SR)

A

Proarrhythmic

101
Q

Side effects of propafenone (Rythmol SR)

A

Taste disturbance (metallic)
others: dizziness, visual disturbances, N/V

102
Q

Boxed warning for Droneadrone (Multaq)

A

Increased risk of death, stroke and HF in pts with decompensated HF (NYHA class IV or any NYHA class with recent hospitalization d/t HF) or permanent Afib

103
Q

Contraindications with dronaderone (Multaq)

A

concurrent use of strong CYP3A4 inhibitors and QT prolonging drugs

104
Q

Warnings for dronedarone (Multaq)

A

Hepatic failure (esp first 6 months), pulmonary disease (pulmonary fibrosis and pneumonitis)

105
Q

Side effects of dronedarone (Multaq)

A

QT prolongation, increased SCr, diarrhea, bradycardia, asthenia

106
Q

Unlike amiodarone, dronedarone does not contain ___ and has little effect on ___ function

A

iodine
thyroid function

107
Q

T/F: sotalol is a selective beta-blocker

A

False - non-selective bb

108
Q

Renal dose adj for sotalol

A

CrCl < 60, decrease freq

109
Q

Boxed warning for sotalol

A

Adj dose interval based on CrCl to decrease risk of proarrhythmia; QT prolongation is directly related to sotalol concentration

110
Q

T/F: QT prolongation is directly related to sotalol conc

A

True

111
Q

Ibutilide (Corvert) formulation

A

Injection

112
Q

When using ibutilide (Corvert) for pharmacologic conversion to NSR, which electrolyte imbalances need to be corrected prior to use and during treatment?

A

Hypokalemia
Hypomagnesemia

113
Q

Boxed warning for dofetilide

A

Must be initiated in a setting with continuous ECG monitoring, assess CrCl for a minimum of 3 days, proarrhythmic (QT prolongation)

114
Q

Adenosine formulation

A

Injection

115
Q

Adenosine half life

A

less than 10 sec

116
Q

When is adenosine used for arrhythmias?

A

Supraventricular re-entrant tachycardias

117
Q

Which antiarrhythmic drugs are a/w DILE?

A

Quinidine and procainamide (recently added to amiodarone labeling but most common in quinidine and procainamide)

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