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NAPLEX - OUR cards > Arrhythmias > Flashcards

Arrhythmias Flashcards

1
Q

What tool is used to diagnose arrhythmias

A

ECG (underlined)

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2
Q

What is heart rate? Whats a normal resting heart rate?

A

Frequency of depolarization of the ventricles

Normal resting HR is 60-100 bpm

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3
Q

True or false: all patients experience symptoms of arrhythmias

A

False

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4
Q

What symptoms can occur w arrhythmias

A

Dizziness, lightheadedness, shortness of breath, chest pain, fatigue

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5
Q

Describe the 6 phases of ventricular action potential

A

Phase 0: Na channels open; rapid ventricular depolarization, initiates the heartbeat due to an influx of Na; causes ventricular contraction (QRS complex)

Phase 1: early rapid repolarization, Na channels close

Phase 2: Plateau in response to influx of Ca and efflux of K (calcium in, potassium out)

Phase 3: Efflux of K only (potassium out); rapid ventricular repolarization (T wave)

Phase 4: resting membrane potential, atrial depolarization ocurs (P wave)

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6
Q

Where do class Ia, Ib, and Ic agents work? What agents are in these classes?

A

In phase 0 where sodium influx occurs
These are sodium channel blockers

Ia: Procainamide, quinidine, dispyramide
Ib: Lidocaine, mexiletine
Ic: flecainide, propafenone

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7
Q

What are class II antiarrhythmics? How do they work?

A

Beta blockers
Rate control, slow ventricular rate
Also indirectly block calcium channels in the SA and AV node reducing automaticity and conduction velocity

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8
Q

What are class III antiarrhythmics? How do they work?

A

Potassium channel blockers
Amiodarone
Dronedarone
Sotalol

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9
Q

Define ventricular tachycardia

A

A series of premature ventricular contractions (PVCs) in a row resulting in a heart rate of greater than 100 bpm, if untreated can progress into ventricular fibrillation which is a medical emergency

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10
Q

What is Torsade de Pointes?

A

A lethal ventricular tachyarrhythmia which is commonly associated with medications and can result in sudden cardiac death

Prolongation of the QT interval (> 440 milliseconds) is a risk factor for torsades

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11
Q

Whats that stupid mnemonic for the drugs and their drug class

A

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

Ia: Disopyramide, quinidine, procainamide
Ib: Lidocaine, mexiletine
Ic: Flecainide, propafenone

II: Beta blockers

III: Dronedarone, dofetilide, sotalol, ibutilide, amiodarone

IV: Verapamil, diltiazem

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12
Q

Goal HR for patients with symptomatic Afib

A

< 80 bpm

Lenient strategy of <110 for patients who are asymptomatic and have preserved left ventricular function

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13
Q

Preferred agents for controlling ventricular rate in patients with afib?

A

Beta blockers (pref’d) and non-DHP calcium channel blockers (verapamil, diltiazem)

Do not use non-DHP calcium channel blockers in pts with HFrEF

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14
Q

What is paroxysmal afib?

A

Afib that terminates spontaneously or with intervention within 7 days of onset

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15
Q

What is persistent afib?

A

Continuous afib that is sustained > 7 days

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16
Q

What is long-standing persistent afib?

A

Continuous afib > 12 months duration

17
Q

What are class I antiarrhythmics? How do they work?

A

Sodium channel blockers
Negative inotropic effects
Boxed warning due to increased mortality compared to placebo
Drugs include flecainide, propafenone, lidocaine, mexiletine, procainamide, quinidine, and disopyramide

18
Q

Class Ia antiarrhythmics: agents, warnings/concerns

A

Disopyramide (Norpace), quinidine, and procainamide

Disopyramide = Known for strong anticholinergic effects

Quinidine = diarrhea (35%), stomach cramping (22%), cincochism, risk for drug induced lupus, anticholinergic

Procainamide = fatal blood dyscrasias, agranulocytosis, drug induced lupus, hypotension, rash
(ACTIVE metabolite is n-acetyl-procainamide, reduce dose when CrCL < 50 mL/min bc active metabolite is renally cleared (underlined)) - has therapeutic drug monitoring

19
Q

Class Ib antiarrhythmics: agents, warnings/concerns

A

Lidocaine
Mexiletine
Only useful for ventricular arrhythmias
Cross the BBB, can cause CNS adverse effects (lightheadedness, dizziness, hallucinations, disorientation)

20
Q

Which agents are only useful for ventricular arrhythmias?

A

Class Ib

Lidocaine, mexiletine

21
Q

Class Ic antiarrhythmics: agents, warnings/concerns

A

Flecainide, propafenone
Absolutely contraindicated in HF, significant left ventricular hypertrophy, or recent MI (negative inotropic, proarrhythmic properties)

Flecainide: dizziness, visual disturbances
Propafenone: taste disturbances, dizziness, visual disturbances

22
Q

Class III antiarrhythmics: agents only

A

Potassium channel blockers
Amiodarone (Pacerone, Nexterone)
Dronedarone (Multaq)
Sotalol (Betapace) - nonselective

23
Q

Amiodarone boxed warnings, warnings, side effects, notes

A

Boxed warnings: pulmonary and hepatotoxicity

Warnings: Hyper and hypothyroidism (hypo more common), amiodarone partially inhibits conversion of T4 to T3; optic neuropathy, photosensitivity (slate blue skin discoloration)

Side effects: hypotension, bradycardia, corneal microdeposits, dizziness, ataxia, N/V, constipation, tremor

Notes: Infusions longer than 2 hours must be in a non-polyvinyl chloride (PVC) container such as polyolefin or glass; premixed Nexterone comes in non-PVC containers;
Slow infusion rate of hypotension or bradycardia occur

Half-life: 40-60 days

24
Q

Antiarrhythmic of choice in heart failure

A

Amiodarone

25
Q

Dronederone contraindications, side effects, dosing

A

Multaq
Pregnancy
QT prolongation, increased SCr
Take with meals (400 mg BID)

26
Q

Sotalol dosing, boxed warnings

A

Dosing: 80 mg PO BID, increase to 160 mg BID if needed
CrCL 40-60 mL/min: decrease frequency (underlined)
Adjust dosing interval based on creatinine clearance to decrease risk of proarrhythmia
QT prolongation is directly related to sotalol concentration (underlined)

27
Q

Drug interactions amiodarone

A

Inhibitor of 2C9, 2D6, 3A4, and p-gp

When starting amiodarone, decrease dose of digoxin by 50% and decrease dose of warfarin by 30-50%

28
Q

Class IV antiarrhythmics: agents, side effects, notes

A

Calcium channel blockers
Diltiazem (Cardizem), Verapamil
Side effects: edema, headache, dizziness, hypotension, arrhythmias, HF, constipation (more w verapamil), gingival hyperplasia

Only non-DHP are used as antiarrhythmics

29
Q

Digoxin place in therapy, notes on toxicity

A

Not included in the Class I-IV classifications
Reduces heart rate but ineffective at controlling ventricular response during exercise, therefore it is not used first line for rate control

Dose: 0.125-0.25 mg PO daily
Therapeutic range for afib is 0.8-2 ng/mL
Antidote = Digifab

S/Sx toxicity include N/V, loss of appetite, and bradycardia

Hypokalemia, hypomagnesemia, and hypercalcemia increase risk of digoxin toxicity

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