32. Arrhythmias Flashcards
S/sx arrhythmias
Feels like “fluttering” in their chest or “skipping a beat”
Dizziness, SOB, fatigue, lightheadedness, chest pain
___ is used to diagnose arrhythmias
Electrocardiogram (ECG)
A ___ is an ambulatory ECG device that records electrical activity of the heart for 24-48hrs. Used to detect arrhythmias that are intermittent.
Holter monitor
Normal sinus rhythm originates in the ___
sinoatrial (SA) node
____ is the heart’s natural pacemaker
SA node
Normal HR range is ___
60-100BPM
Describe the conduction pathway
SA node
AV node
Bundle of His, splits to right and left branch
Purkinje fibers
3 reasons why arrhythmias may be occuring
- SA node can be firing at an abnormal rate or rhythm
- Scar tissue from prior heart attack can block and divert signal transmission
- another part of the heart may be acting as the pacemaker
The SA cells have automaticity. What does this mean?
Unlike other myocytes, the pacemaker cells initiate their own action potential (does not require external stimulation)
Describe phase 0 of the cardiac action potential
Heartbeat is initiated when rapid ventricular depolarization occurs in response to influx of Na
Causes ventricular contraction (represented by QTS complex on ECG)
Describe phase 1 of the cardiac action potential
early rapid repolarization (Na channels close)
Describe phase 2 of the cardiac action potential
Plateau in response to influx of Ca and efflux of K
Describe phase 3 of the cardiac action potential
Rapid ventricular repolarization in response to an efflux of K, causes ventricular relaxation (represented by T wave on ECG)
The most common cause of arrhythmias is __ or __
Myocardial ischemia or infarction
Non-cardiac conditions that can trigger or predispose of a pt to an arrhythmia include ____
electrolyte imbalances (es. potassium, magnesium, sodium, and calcium)
Elevated sympathetic states (E.g. hyperthyroidism, infection)
Drugs (illicit drugs, antiarrhythmics, and QT prolonging meds)
Arrhythmias are generally classified into 2 broad categories based on point of origin: _____ and ___
supraventricular (originating above AV node)
Ventricular (originating below AV node)
___ is the most common type of arrhythmia
Afib
____ are referred to as a skipped heartbeat
Premature ventricular contractions (PVCs)
A series of premature ventricular contractions (PVCs) in a row resulting in a HR of > ___BPM, is known as ___ (medical emergency)
> 100 BMP
Ventricular tachycardia (VTach, VT)
Untreated VTach can degenerate into _____ which is also a medical emergency
Ventricular fibrilation (VFib)
QTc is considered prolonged when it is > ____ milliseconds (msec) but more worrisome when it is > ____msec
> 440 msec
500 msec
Prolonged QT interval is a risk factor for ____, a particularly lethal ventricular tachyarrhythmia that can cause ____
TdP
sudden cardiac death
Drug-induced QT prolongation increases with ____
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
Drugs that increase or prolong QT interval
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
Prior to starting any drug for a non-life-threatening arrhythmia, ___ and ___ should be checked to identify reversible causes dominant electrophysiological effect
electrolytes and toxicology screen
The Vaughan Williams classification splits drugs into categories based on their ____
Dominant electrophysiological effect
Mnemonic for classifying drugs with Vaughan Williams
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
Vaughan Williams Class I MOA and Consequence
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
Vaughan Williams Class II MOA and Consequence
Beta-blockers
Used primarily to slow ventricular rate in Afib
Vaughan Williams Class III MOA and Consequence
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
Which Class III antiarrhythmic blocks K channels and is a beta-blocker?
Sotalol
___ and ___ are preferentially used in Afib in pts with HF
Amiodarone and dofetilide
Vaughan Williams Class IV MOA and Consequence
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)
Digoxin MOA and consequence
Na-K-ATPase blocker
Suppresses AV node conduction (decrease HR) by enhancing vagal tone and increased force of contraction (positive inotrope)
Adenosine MOA and consequence
Activates adenosine receptors to decrease AV node conduction
Used for supraventricular re-entrant tachycardias (formerly known as paroxysmal supraventricular tachycardias or PSVTs)
Which antiarrhythmic is used for supraventricular re-entrant tachycardias (formerly known as paroxysmal supraventricular tachycardias or PSVTs)
Adenosine
Guideline recommended treatment for most types of Afib involves using one of two main strategies: ___ and ___
rate control
rhythm control
Define paroxysmal afib
AFib that terminates spontaneously or with intervention within 7 days of onset; episodes may recur with variable frequency
Define persistent afib
Continuous afib sustained > 7 days
Define long-standing persistent afib
Continuous afib sustained >12 months
Define Permanent afib
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)
Define valvular afib
Afib with mod to severe mitral stenosis or with a mechanical heart valve; long-term anticoag with warfarin is indicated
Define non-valvular afib
Afib without mod to severe mitral stenosis or a mechanical heart valve
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
<80BPM
<11o BPM
___ (preferred) or ___ are recommended for controlling ventricular rate in pts with afib
Beta-blockers (preferred)
Non-DHP CCBs
Which antiarrhythmics should pts with HFrEF avoid?
non-DHP CCBs (verapamil, diltiazem)
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
3 weeks before, 4 weeks after successful cardioversion
Which antiarrhythmic drugs are used for rhythm control?
Class Ia, Ic, or III
If AFib is permanent, what should be avoided d/t risk > benefits?
Avoid rhythm-control strategy with antiarrhythmic drugs (risk outweighs benefit)
T/F: For many patients, it is safer to remain in Afib with rate control than to try to restore NSR
True
Which anticoags are preferred for stroke prevention in non-valvular Afib?
DOACs > warfarin
___ is indicated for stroke prevention in pts with Afib and a mechanical heart valve
Warfarin
Boxed warnings for amiodarone (Nexterone, Pacerone)
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
Contraindications for amiodarone (Nexterone, Pacerone)
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
Warnings for amiodarone (Nexterone, Pacerone)
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
Side effects for amiodarone (Nexterone, Pacerone)
Hypotension, bradycardia, corneal microdepositis, photosensitivity (sunprotection required)
Others: dizziness, tremor/ataxia, malaise/fatigue, nausea, DILE
Monitoring for amiodarone (Nexterone, Pacerone)
ECG, BP, HR, electrolytes, LFTs every 6 months, thyroid (TSH and free T4) every 3-6 months
Annual chest x-ray, regular eye exams
___ and ___ are the antiarrhythmic drug of choice in HF
Amiodarone, dofetilide (Tikosyn)
Half life of amiodarone (Nexterone, Pacerone)
40-60 days
amiodarone (Nexterone, Pacerone) administration notes
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
What to do if hypotension or bradycardia happens when on amiodarone
Decrease infusion rate or d/c
Patient needs to use Amiodarone and heparin. What are some concerns?
Incompatible with heparin (flush line with saline); many Y-site, additive incompatibilities
Why is iodine hypersensitivity a contraindication for amiodarone?
Amiodarone chemical structure contains iodine
Amiodarone can increase the level of many other drugs; it is an inhibitor of ____
CYP2C9 (moderate), 2D6 (moderate), 3A4 (weak)
P-gp
When starting amiodarone, what should you do to the dose of digoxin, warfarin, simvastatin, or lovastatin?
Decrease digoxin by 50%
Decrease warfarin by 30-50%
Max dose 20mg/day simvastatin
Max dose 40mg/day lovastatin
Additive effects can occur when amiodarone is used with other drugs that decrease HR including ____
non-DHP CCB, digoxin, beta-blockers, clonidine, dexmedetomidine (Precedex)
Sofosbuvir can enhance the ___ effect of amiodarone; do NOT use together
Bradycardic
Contraindications of non-DHP CCBs (Diltiazem (Cardizem, Tiazac), Verapamil (Calan SR))
HFrEF
Others: severe hyptoension SBP<90), 2nd/3rd degree heart block/sick sinus syndrome (unless pacemaker), caridogenic shock, Wolff-Parkinson-White syndrome with Afib
Warnings for non-DHP CCBs (Diltiazem (Cardizem, Tiazac), Verapamil (Calan SR))
HF (may worsen symptoms)
Others: hypotension, 1st degree AV block with sinu s bradycardia, increased LFTs
Side effects for non-DHP CCBs (Diltiazem (Cardizem, Tiazac), Verapamil (Calan SR))
Edema, arrhythmias, constipation (more with verapamil), gingival hyperplasia, HA, dizziness
T/F: Both non-DHP and DHP CCBs can be used for antiarrhythmics (non-DHP CCBs preferred)
False - only non-DHP CCBs
Additive effects can occur when non-DHP CCBs are used with other drugs that decrease HR including ____
amiodarone, digoxin, beta-blockers, clonidine, dexmedetomidine (Precedex)
Non-DHP CCBs are CYP___ substrates.
3A4
Do NOt take with grapefruit, caution with strong 3A4 inducers/inhibitors
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 ____
Simvastatin or lovastatin
Pitavastatin, pravastatin, rosuvastatin
Digoxin (Digitek, Lanoxin) typical dose
0.125-0.25mg PO daily
Digoxin (Digitek, Lanoxin) therapeutic range for Afib (lower range for HF)
0.8-2 ng/mL
Pt will be switching from PO to IV digoxin. What changes need to be made to the dose?
Decrease dose by 20-25%
Digoxin (Digitek, Lanoxin) if CrCl < 50
Decrease dose or frequency; hold in acute renal failure
Digoxin Toxicity s/sx
N/V, loss of appetite, abd pain, blurred/double vision, greenish-yellow halos (or altered color perception), confusion, delirium, bradycardia, life-threatening arrhythmias
What electrolyte imbalances increase risk for digoxin toxicity?
Hypokalemia, hypomagnesemia, and hypercalcemia
Antidote for digoxin
DigiFab
Digoxin is not usually given alone for rate control, used in combo with ___ or ____
beta-blocker of non-DHP CCB
Digoxin is a substrate of P-gp. Levels increase with inhibitors including _____ and many other drugs.
Amiodarone, verapamil, diltiazem, clarithromycin, itraconazole
Additive effects can occur when digoxin is used with other drugs that decrease HR including ____
Amiodarone, non-DHP CCBs, beta-blockers, clonidine, and dexmedetomidine (Precedex)
Disopyramide (Norpace) boxed warning
Reserve use for pts with life-threatening ventricular arrhythmias
Warnings for disopyramide (Norpace)
Proarrhythmic, myasthenia gravis (d/t anticholinergic effects)
Others: hypotension, HF, BPH/Urinary retention/narrow-angle glaucoma
Side effects for disopyramide (Norpace)
Anticholinergic effects (e.g. dry mouth, constipation, urinary retention), hypotension
Quinidine administration notes
take with food or milk to decrease GI upset
Warnings for quinidine
Proarrhythmic, hemolysis risk (avoid in G6PD deficiency), can cause positive Coombs test
Side effects for quinidine
DILE, diarrhea (35%), stomach cramping (22%), rash, lightheadedness
Cinchonism (e.g. quinidine overdose): tinnitus, hearing loss, blurred vision, headache, delirium
___ is the drug of choice for Wolff-Parkinson-White syndrome
Procainamide
What is the active metabolite for procainamide and how is it cleared?
N-acetyl procainamide (NAPA)
Renally cleared - decrease dose when CrCl <50
Therapeutic levels of procainamide
40-10mcg/mL
Boxed warnings for procainamide
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
Long-term use of ____ leads to positive antinuclear antibody (ANA) in 50% of patients - can result in DILE in 20-30% of patients
procainamide
Warnings for procainamide
Proarrhythmic
Metabolism of procainamide to NAPA occurs by ____
acetylation
slow acetylators are at risk for drug accumulation and toxicity
Fast acetylators are at risk of subtherapeutic drug conc and reduced efficacy
Class Ib antiarrhythmics are useful for ___ only
Ventricular arrhythmias only (no efficacy in afib)
Lidocaine (Xylocaine) injection is used for ____
refractory VT/cardiac arrest
What is a common contraindication for Class Ic antiarrhythmics (Flecainide, Propafenone (Rythmol SR))
HF, MI
Boxed warning for felcainide
Proarrhythmic effects, esp in Afib (do not use in chronic afib)
Warnings for propafenone (Rythmol SR)
Proarrhythmic
Side effects of propafenone (Rythmol SR)
Taste disturbance (metallic)
others: dizziness, visual disturbances, N/V
Boxed warning for Droneadrone (Multaq)
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
Contraindications with dronaderone (Multaq)
concurrent use of strong CYP3A4 inhibitors and QT prolonging drugs
Warnings for dronedarone (Multaq)
Hepatic failure (esp first 6 months), pulmonary disease (pulmonary fibrosis and pneumonitis)
Side effects of dronedarone (Multaq)
QT prolongation, increased SCr, diarrhea, bradycardia, asthenia
Unlike amiodarone, dronedarone does not contain ___ and has little effect on ___ function
iodine
thyroid function
T/F: sotalol is a selective beta-blocker
False - non-selective bb
Renal dose adj for sotalol
CrCl < 60, decrease freq
Boxed warning for sotalol
Adj dose interval based on CrCl to decrease risk of proarrhythmia; QT prolongation is directly related to sotalol concentration
T/F: QT prolongation is directly related to sotalol conc
True
Ibutilide (Corvert) formulation
Injection
When using ibutilide (Corvert) for pharmacologic conversion to NSR, which electrolyte imbalances need to be corrected prior to use and during treatment?
Hypokalemia
Hypomagnesemia
Boxed warning for dofetilide
Must be initiated in a setting with continuous ECG monitoring, assess CrCl for a minimum of 3 days, proarrhythmic (QT prolongation)
Adenosine formulation
Injection
Adenosine half life
less than 10 sec
When is adenosine used for arrhythmias?
Supraventricular re-entrant tachycardias
Which antiarrhythmic drugs are a/w DILE?
Quinidine and procainamide (recently added to amiodarone labeling but most common in quinidine and procainamide)
