Arrhythmia meds Flashcards
Major problems w/ A-Fib
Atrial thrombi
Right atrium: PE
Left atrium: cerebral emboli (stroke)
How much greater risk are a-fib pts of stroke than pts w/o afib
2xs
What percent of people who could use prophylactic anticoagulation therapy recieve treatment?
15-44%
AF treatment strategy
See slide 17
How do you treat a pt who is not compromised and >48 hours (or dont know how long) pt is in a-fib?
With rate control anticoagulation
conversion to an sinus rhythm might dislodge a thrombus
Oral anticoagulation-warfarin therapeutic INR
See slide 21 for graph
What is the safest antiarrythmic?
Amiodarone
What is the IV loading dose of amiodarone?
150 mg over 10 minutes
Can you give amiodarone if you have an iodine allergy?
Yes
Side effects of amidarone
Hypothyroid Hyperthyroid Pulmonary fibrosis Lenticular opacities Blue skin discolorations
What is the rate of conversion rate w/ amiodarone?
60%
What do we use Dronedarone (amiodarone “lite”) for?
For a-fib/flutter who have converted
Is dronedarone affected by iodine?
Yes; no iodine to limit toxicity
What is the black box warning for dronedarone?
Dronedarone is contraindicated in NYHA class IV HF or NYHA class II-III HF w/ recent decomepnsation (increased HF deaths in clinical trials)
What is the MOA of sotalol?
Blocks beta 1 and beta 2 receptors
What is sotalol used for?
Used to maintain sinus rhythm after conversion
How is sotalol eliminated? Does it need an adjustment?
Renally
Yes, dose needs to be adjusted for impairment
When is sotalol contraindicated for A-Fib?
If CrCl < 40 mL/min
What is the dose adjustment for ventricular arrhythmia with a CrCL<10?
Individualize it based on pt presentation
What is propafenone indicated for?
Atrial fibrillation/flutter
What is Diltiazem?
A rate controlling calcium channel blocker (CCB)
How is diltiazem dosed?
IV and PO
What form of diltiazem do you use when giving PO?
CD form
What beta blockers can you use for rate control?
Metoprolol
Carvedilol
What populations does Digoxin work better with?
Pts w/ EF <40%
Pts w/ low BP
Pts w/ positive inotrope
What does a positive inotrope indicate
Increases force myocardial contraction
How is digoxin dosed?
Micrograms
Is the half-life of digoxin long or short? Give time
Long
36-48 hours
How do you dose IV digoxin for atrial fibrillation
500 mcg IVP x1; then 250 mcg q 6 hours x2 doses
How do you dose oral digoxin for a-fib?
0.5 mg once daily x2 days
What is the dosing of digoxin for supraventricular tachycardia?
Total dizitizing dose (TDD) = 10-15 mcg/kg
What is included in the CHADS2 index and how many points do you get for each thing?
1 point for each: CHF, recent HTN Age >= 75 DM Stroke (hx or TIA)
Stroke risk w/ non-valvular AF-CHADS2 index
see slide 44
Conclusions from study
none of the postulated benefits of a rhythm – control strategy were confirmed. The rate – control strategy eliminated the need for rerpeated cardioversion and reduced rates of hospitalization
Rate control should be considered a primary approach for patients with atrial fibrillation and congestive heart failure
Do you want to pursue or avoid anti-arrhythmic drugs?
Avoid
Is there a mortality benefit for rhythm control?
No
Is rate control the primary approach?
Yes
Can you abandon rhythm control?
Yes, early, if not satisfactory
Is pharmacological conversion as efficacious as electrical?
No, but it is simpler
Is there a risk of toxicity of antiarrhythmic drugs?
Yes, there is a major risk
When is pharmacologic conversion most effective?
If performed <= 7 days of onset of AF
When is pharmacological conversion less effective?
If AF started > 7 days ago
What risk do electrical and pharmacological conversion methods carry if AF > 48 hours?
Thromboembolism
What is the difference in thromboembolism risk between pharmacological and electrical conversion methods?
Not much, similar risk
What drugs are commonly used for AF conversion?
Amiodarone (IV/po)
Ibutilide (IV)
Dofetilide (PO)
What is the most preventable cardiac arrhythmia?
Atrial fibrillation
How much more at risk are pts w/ afib of having a stroke
> 5xs increased stroke risk
What anticoagulant has shown to reduce ischemic stroke risk?
Warfarin
What RFs are associated with intracranial hemorrhage?
Age, INR
What is ventricular tachycardia often precipitated by?
Electrolyte disturbances
Hypoxemia
Digitalis toxicity
Acute MI or ischemia (MC)
What is the drug of choice for ventricular arrhythmias (VA)?
Amiodarone!
What IV load of amiodarone do you give for VA
300 mg IV load
What are the risks of drugs used for v-tach?
All cause ventricular arrhythmias
All are potentially dangerous
What is adenosine?
An anti-arrhythmic and a diagnostic agent
How long is the half life of adenosine?
Short -> seconds
What is the MOA of adenosine?
Slows conduction through AV node -> Interrupts re-entrant pathways -> restores sinus rhythm
What is a negative SE of adenosine?
Prolonged sinus pauses
What is a rare risk of adenosine
Prolonged asystole
Does adenosine convert AF/flutter to sinus rhythm?
No
When is adenosine used diagnostically?
When the underlying rhythm is not apparent
How is adenosine delivered?
Over 1-2 seconds via a peripheral line
What do you follow each adenosine bolus with?
20 mL normal saline
Where do you want to administer adenosine?
As close to the trunk as possible
Where can you not deliver adenosine through?
Hand
Lower arm
Lower extremity
When is adenosine contraindicated
2nd or 3rd degree heart block Sick sinus syndrome Symptomatic bradycardia (except w/ functioning PM) AF/flutter w/ underlying WPW syndrome Asthma
Why do you want to avoid anti-arrhythmic drugs?
Most are pro-arrhythmic, especially when used long term
How do you classify antiarrhythmic drugs?
By the Vaughan Williams classification
What is the MOA of class 1 VW antiarrhythmics?
Sodium channel blockage
What is the MOA of class 2 VW antiarrhythmic drugs?
Beta adrenoceptor antagonists
What is the MOA of class 3 VW antiarrhythmic drugs?
Prolong action potential and refractory period
What is the MOA of class 4 VW antiarrhythmic drugs?
Calcium channel antagonists
