Week 2: Arrythmias Flashcards
What is the classification of anti arrhythmic drugs called?
Vaughan Williams
What are the class I drugs MOA?
block sodium channels
What are the Ia drugs of class I?
quinidine
procainamide
disopyramide
increase AP
What are the Ib medications?
lidocaine
mexiletine
decrease AP
What are Ic medications?
flecainide, propafenone
slows conduction velocity
What are the class II drugs?
beta-adrenoceptor antagonists
atenolol, sotalol
What are the class III drugs?
prolong action potential and prolong refractory period(suppress re-entrant rhythms)
amiodarone sotalol dofetiliden ibutilide
What are the class IV medications?
calcium channel antagonists
impair impulse propagation in SA & AV nodes
verapamil, diltiazem
What are the major problems with afib? (3)
atrial thrombi right atrium (pulmonary emboli) left atrium (cerebral emboli & stroke)
What is the stroke risk of patients with a fib compared to those without?
2x greater than in patients without a fib
What percentage of patients that would benefit from prophylactic anticoagulation therapy receive treatment?
only 15-44%
What should be done if a pt is not compromised and greater than 48 hours or do not know how long pt has been in a fib?
rate control and anticoagulation
conversion to SR might dislodge a thrombus
What is the safest of all the antiarrythmics?
amiodarone (Cordarone)
What is the loading dose of amiodarone (Cordarone)
150mg IV loading dose
Can you give amiodarone if the pt has an iodine allergy?
yes
What are the side effects of amiodarone?
hypothyroid hyperthyroid pulmonary fibrosis lenticular opacities blue skin discoloration
What is the rate of conversion of amiodarone?
about 60%
When is dronedarone (Maltaq) used?
for a fib/flutter who have converted
NO iodine to limit toxicity
What medication is contraindicated in NYHA class IV HF or NYHA class II-III with recent decompensation (increased HF deaths in clinical trials)?
dronedarone (Maltaq)
What is the MOA of sotalol (Betapace)?
blockers beta 1 and beta 2 receptors
When is sotalol (beta pace) mainly given?
usually used to maintain SR after conversion
When is sotalol contraindicated?
for a fib for CrCl <40mL/min
need to adjustment dose for impairment
When should sotalol dose be individualized?
In ventricular arrhythmias with CrCl <10
What is propafenone (Rhythmol) indicated for?
atrial fibrillation/flutter
How is diltiazem (cardizem) given?
IV and PO
What is the MOA of diltiazem (cardizem)?
calcium channel blocker
What form of diltiazem should be given PO?
use only the CD form
cardizem CD
What are the beta blockers that control rate?
metoprolol (lopressor)
carvedilol (coreg)
What is significant about Digoxin? (3)
works better in patients with an EF <40%
also in patients with a low BP
positive inotrope (increases force of myocardial contraction)
What is digoxin dosed?
in micrograms (mcg)
What is the half life of digoxin?
long (adults 36-48 hours)
What is the digoxin loading dose for a fib? (IVP)
500 mcg IVP x1; then 250mcg every 6 hours x 2 doses
What is the digoxin loading dose for a fib? (PO)
0.5mg once daily x 2 days
What is the Total Dizitizing Dose (TDD) of digoxin for supra ventricular tachycardia?
10-15mcg/kg
What are the risk factors listed on the CHADS2 index?
CHF, recent HTN AGE >75 DM Stroke (h/o TIA) 2 points
What should be considered a primary approach for patients with atrial fibrillation and CHF?
rate control
What eliminated the need for repeated cardio version and reduced rates of hospitalization?
rate-control strategy
___ control provided no advantage in mortality.
Rhythm
Avoidance of ______ drugs is desirable.
anti arrhythmic
When can rhythm control be abandoned?
can be abandoned early if not fully satisfactory
What is significant about pharmacological conversion of AF? (4)
simpler but less efficacious
major risk is toxicity of anti arrhythmic drugs
most effective if performed less than 7 days of developing AF
much less effective if AF onset greater than 7 days
When does Electrical vs drug conversion both carry a similar risk of thromboembolism ?
if AF greater than 48 hours
What are the drugs for AF conversion (less than 7 days) that have proven efficacy? (3)
Amiodarone (iv/po)
ibutilide (iv only)
Dofetilide (po only)
What are the drugs for AF conversion (greater than 7 days) that have proven efficacy? (3)
amiodarone (IV/po)
ibutilide (iv only)
Dofetilide (po only)
What is the most prevalent cardiac arrhythmia?
atrial fib
A fib is associated with ______ increase in stroke.
> 5 times increase
Anticoagulation with ____ has consistency been shown to reduce ischemic stroke risk compared with placebo.
warfarin
Intracranial hemorrhage risk is dependent on what? (2)
age
INR dependent
What is ventricular tachycardia (VT) often precipitated by?
electrolyte disturbances (esp severe hypokalemia)
hypoxemia
digitalis toxicity
during acute MI or ischemia (most common)
What is the drug of choice for ventricular arrhythmias?
amiodarone 300mg IV load
What is a complication of the other antiarrythmics used to treat v-tach?
all cause ventricular arrhythmias
all are potentially dangerous to use
What anti arrhythmic; diagnostic agent has a very short half life- seconds?
adenosine (adenocard)
What is the MOA of adenosine (adenocard)?
slows conduction thru AV node, interrupting re-entrant pathways, restoring sinus rhythm (SR)
What are possible complications of adenosine (adenocard)?
may cause prolonged sinus pauses
rarely prolonged systole (very rarely death)
When is adenosine (adenocard) used?
IT DOES NOT convert AF/flutter to SR, but used diagnostically if underlying rhythm is not apparent
How is adenosine (adenocard) given?
IVP over 1-2 seconds via a peripheral line
each bolus followed with 20mL NS
administer as close to the trunk as possible
Where SHOULDN’T adenosine (adenocard) be given?
do not use hand or lower arm or lower extremity
When is adenosine (adenocard) contraindicated?
2nd or 3rd degree heart block sick sinus syndrome symptomatic bradycardia (except with functioning PM) AF/flutter with underlying WPW syndrome asthma
