Chapter 32: Arrhythmias Flashcards
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
What is used to diagnose arrhythmias
ECG
A ____ monitor is an ambulatory ECG device that records the heart’s electrical activity for 24-48 hours to detect intermittent arrhythmias
Holter
A normal sinus rhythm (NSR) beings in the ____ node
SA (the heart’s natural pacemaker)
Which pacemaker cells have automaticity, meaning they initiate their own action potential
SA (pacemaker) cells
In phase 0 of the action potential, rapid, ventricular depolarization initiates a heartbeat in response to influx of __, causing ventricular contraction
Na
In phase 2 of the action potential, there is a plateu in response to an influx of __ and efflux of ___
Ca
K
In phase 3 of the action potential, there is rapid ventricular repolarization in response to an efflux of __
K
The most common cause of arrhythmias
Myocardial ischemia or infarction
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)
What is the most common type of arrhythmia
AFib
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
Patients with AFib may require what medication class
Anticoagulants to reduce the risk of blood clots
Common ventricular arrhythmias include
Premature ventricular contractions (PVCs)
PVCs are referred to as
a skipped heart beat
In some people, PVCs can be related to
too much stress or caffeine
nicotine
exercise
A series of PVCs in a row, resulting in HR of > __ BPM, is known as ____
> 100 BPM
Ventricular tachycardia
Untreated ventricular tachy can degenerate into ____
Vfib (a medical emergency)
Which drug is used frequently for the treatment of Ventricular arrhythmias
IV lidocaine
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
Prolongation of the QT interval is a risk factor for ___, a particularly lethal ventricular tachyarrhythmia which can cause ____
TdP
sudden cardiac death
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
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
-Class IV: Verapamil, Diltiazem
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
non-DHP CCBs (sometimes digoxin)
What is the goal for rhythm control and which drugs are used
Goal is to restore and maintain NSR
or
electrical cardioversion
* Class Ia, Ic, or III antiarrhythmic
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 Calcium-channel blockers are preferentially used in HF
Amiodarone
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
50
When going from oral to IV digoxin, decrease the dose by __-__ %
20-25%
Initial s/sx of digoxin toxicity
N/V
loss of appetite
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
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
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
60
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
Dofetalide
Adenosine half-life
less than 10 seconds
