Chapter 32: Arrhythmias Flashcards by Emily Jansen

What are the 3 ways an arrhythmia can be caused

The SA node can be firing at an abnormal rate or rhythm
Scar tissue from a prior heart attack can block and divert signal transmission
Another part of the heart may be acting as the pacemaker

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What is used to diagnose arrhythmias

ECG

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A ____ monitor is an ambulatory ECG device that records the heart’s electrical activity for 24-48 hours to detect intermittent arrhythmias

Holter

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A normal sinus rhythm (NSR) beings in the ____ node

SA (the heart’s natural pacemaker)

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Which pacemaker cells have automaticity, meaning they initiate their own action potential

SA (pacemaker) cells

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In phase 0 of the action potential, rapid, ventricular depolarization initiates a heartbeat in response to influx of __, causing ventricular contraction

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In phase 2 of the action potential, there is a plateu in response to an influx of __ and efflux of ___

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In phase 3 of the action potential, there is rapid ventricular repolarization in response to an efflux of __

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The most common cause of arrhythmias

Myocardial ischemia or infarction

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Which non-cardiac conditions can trigger or predispose a patient to arrhythmias

electrolyte imbalances (esp K, Mg, Na and Ca)
elevated sympathetic states (e.g., hyperthyroidism, infection)
drugs (including illicit drugs and antiarrhythmics)

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What is the most common type of arrhythmia

AFib

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In AFib, the atria are not able to adequately contract, leading to

blood stagnation in the atria, which increases the risk of clot formation. The clot can embolize to the brain and cause a stroke

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Patients with AFib may require what medication class

Anticoagulants to reduce the risk of blood clots

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Common ventricular arrhythmias include

Premature ventricular contractions (PVCs)

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PVCs are referred to as

a skipped heart beat

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In some people, PVCs can be related to

too much stress or caffeine, nicotine or exercise

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A series of PVCs in a row, resulting in HR of > __ BPM, is known as ____

> 100 BPM

Ventricular tachycardia

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Untreated ventricular tachy can degenerate into ____

Vfib (a medical emergency)

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Which drug is used frequently for the treatment of Ventricular arrhythmias

IV lidocaine

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Which key drugs can increase or prolong the QT interval

Antiarrhythmics: Class I (especially Class Ia) and Class III
Antibiotics: Quinolones and macrolides
Azole Antifungals: All except isavuconazonium
Antidepressants: TCAs (e.g., amitriptyline, clomipramine, doxepin); SSRIs (e.g., citalopram, escitalopram) – sertraline is preferred in cardiac patients; SNRIs, mirtazapine and trazadone
Antiemetic drugs: 5-HT3 RA, droperidol, and phenothiazines
Antipsychotics (most): chlorpromazine, clozapine, haloperidol, olanzapine, paliperidone, quetiapine, risperidone, thioridazine, ziprasidone
Other drugs: Donepezil, fingolimod, methadone, tacrolimus

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Prolongation of the QT interval is a risk factor for ___, a particularly lethal ventricular tachyarrhythmia which can cause ____

TdP

sudden cardiac death

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The risk of drug-induced QT prolongation increases with:

Higher doses
multiple QT-prolonging drugs
reduced drug clearance with renal or liver disease
drug interactions that decrease clearance (with enzyme inhibitors)
with hypokalemia and/or hypomagnesemia
other cardiac conditions

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Which drugs are used in arrhythmias per Vaughan Williams Classification

Remember Double Quarter Pounder, Lettuce, Mayo, Fries Please! Because Dieting During Stress Is Always Very Difficult*
Class I
Ia: Disopyramide, Quinidine, Procainamide
Ib: Lidocaine, Mexiletine
Ic: Flecainide, Propafenone

-Class II: Beta-blockers

Class III
Dronedarone, Dofetalide, Sotalol, Ibutilide, Amiodarone (SAD KID)

-Class IV: Verapamil, Diltiazem

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What is rate control and which drugs are used for it

Patient remains in AFib and takes meds to control the ventricular rate (HR)
• BB or non-DHP CCBs (sometimes digoxin)

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What is the goal for rhythm control and which drugs are used

Goal is to restore and maintain NSR | • Class Ia, Ic, or III antiarrhythmic or electrical cardioversion

If AFib is permanent, avoid ___-control antiarrhythmic drugs

rhythm

Which anticoags are preferred for non-valvular Afib

DOACs (e.g, apixaban, rivaroxaban)

The goal resting HR is < __ BPM in patients with symptomatic AFib, however, a more lenient rate-control strategy of < __ BPM may be reasonable in patients who are asymptomatic and have preserved LV function

80 | 110

Patients with HFrEF should NOT receive which drug class

non-DHP CCB

AFib has a high rate of thromboembolism. If the pt is not already using therapeutic anticoagulation, it should be started at least __ weeks before cardioversion & continued for at least __ weeks after successful cardioversion to NSR

3 | 4

Class I antiarrhythmics are ____ blockers

Na-channel

Class II antiarrhythmics are ____ blockers

Beta-blockers (remember: 2 Bs)

Class III antiarrhythmics are ____ blockers

K-channel

Class IV antiarrhythmics are ____ blockers

Calcium-channel (non-HDP)

Digoxin is a ____ blocker

Na-K-ATPase

Na-channel blockers have _____ inotrope potential, which ↓ the force of the heart’s contraction

Negative

Which 2 potassium-channel blockers are preferentially used in AF for patients with HF

Amiodarone and dofetalide

Which medication is a beta-blocker but blocks K channels

Sotalol

MOA of digoxin

Decreases HR by enhancing vagal tone and increases force of contraction (positive inotrope)

Which drug class used for arrhythmias has a positive inotrope

Digoxin

Which drug class used for arrhythmias has a negative inotrope

non-DHP CCBs

Which drug is used for paroxysmal supraventricular tachyarrhythmias (PSVTs)

adenosine

Amiodarone brand names

Nexterone, Pacerone

Amiodarone BW

- Pulmonary toxicity, hepatotoxicity | - For life-threatening arrhythmias only; proarrhythmic, must be hospitalized for IV loading dose

Amiodarone CI

Iodine hypersensitivity

Amiodarone warnings

- Hyper- and hypothyroidism (hypo is more common) – amiodarone partially inhibits peripheral conversion of T4 to T3 - optic neuropathy (visual impairment) - photosensitivity (slate-blue skin discoloration) - peripheral neuropathy

Amiodarone SE

Hypotension, bradycardia, corneal microdeposits, photosensitivity

Amiodarone infusions > __ hours require ____

2 | non-PVC container (e.g. polyolefin or glass) - PVC tubing is OK

Which amiodarone brand comes in a premixed bag, which has advantages like longer stability, non-PVC, non-DHP, in common concentrations

Nexterone

Which antiarrhythmic is the DOC in HF

Amiodarone, dofetalide

What should be done with amiodarone if hypotension or bradycardia occurs

Decrease infusion rate or d/c

IV amiodarone: use ___ micron filter, ____ line preferred

0.22 | central

Amiodarone IV is incompatible with which drug

Heparin

Amiodarone half-life

40-60 days

Amiodarone is a CYP ___, ___, ___ and ___ inhibitor

2C9, 2D6, 3A4, P-gp

When starting amiodarone, ↓ digoxin by ___% and ↓ warfarin by ___%.

50% | 30-50%

Do not exceed __ mg/day of simvastatin or __ mg/day of lovastatin with amiodarone; statin levels will increase

20 | 40

Which drug can enhance the bradycardic effect of amiodarone and should not be used together

Sofosbuvir

Diltiazem brand names

Cardizem, Cardizem CD, Cardizem LA, Cartia XT, Tiazac

Verapamil brand name

Calan SR

Non-DHP CCB warning

May worsen HF symptoms; do not use

Side effects of non-DHP CCBs

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

All CCBs are CYP ___ substrates

3A4

Do not use ____ with any CCB

grapefruit juice

Diltiazem and verapamil are ___ substrates and ___ inhibitors

P-gp substrates | 3A4 inhibitors

Patients who take which 2 statins with non-DHP CCBs should use lower doses or use a different statin

Simvastatin and lovastatin

Digoxin brand names

Digitek, Digox, Lanoxin

Typical dose of digoxin

0.125-0.25 mg PO daily

Therapeutic range of digoxin for Afib

0.8-2 ng/mL (remember it is 0.5-0.9 for HF)

Digoxin dose should be decreased or frequency should be decreased if CrCl < ___ mL/min

When going from oral to IV digoxin, decrease the dose by __-__ %

20-25%

Initial s/sx of digoxin toxicity

N/V, loss of appetite and bradycardia

Severe s/sx of digoxin toxicity

blurred/double vision, greenish-yellow halos

Digoxin is usually given with which two drug classes for rate control (not usually given alone)

BB or CCB

Digoxin antidote

DigiFab

Which electrolyte abnormalities can increase the risk of digoxin toxicity

Hypokalemia, hypomagnesemia, and hypercalcemia

Disopyramide SE

Anticholinergic SE

How should quinidine be taken

with food

Quinidine warnings

Hemolysis risk (avoid in G6PD deficiency), can cause a positive Coombs test

Quinidine SE

DILE, diarrhea (35%), stomach cramping (22%), cinchonism (e.g., overdose; sx include tinnitus, hearing loss, blurred vision, HA, delirium)

Procainamide formulation

Injection

What is the active metabolite of procainamide and how is it cleared

NAPA | Renally

Procainamide therapeutic level

4-10 mcg/mL

Procainamide BW

- agranulocytosis | - Long-term use leads to positive antinuclear antibody (ANA), which can result in DILE

Which two drugs used for arrhythmias can cause DILE

Quinidine and procainamide

Metabolism of procainamide to NAPA occurs by ____

acetylation (slow acetylators are at risk for drug accumulation and toxicity)

Lidocaine injection is used for

Refractory VT/cardiac arrest

Flecainide, propafenone CI

HF, MI

propafenone SE

metalic tase disturbance

Dronedarone BW

Increased r/o death, stoke and HF in pts with decompensated HF or permanent AFib

Dronedarone CI

Concurrent use of strong 3A4 inhibitors and QT-prolonging drugs

Dronedarone warnings

Hepatic failure, pulmonary disease (including pulmonary fibrosis)

Dronedarone SE

QT prolongation

T/F: Dronedarone does not contain iodine and has little effect on thyroid function

True

Decrease frequency of sotalol with CrCl < __ mL/min

Which drug do you need to correct hypokalemia and hypomagnesemia prior to use and throughout treatment

Ibutilide

Which antiarrhythmic must be initiated in a setting with continuous ECG monitoring

Dofetalide

Which antiarrhythmic needs assessment of CrCl for a minimum of 3 days

Dofetilide

Adenosine half-life

less than 10 seconds