Atrial Antiarrhythmics Flashcards
Clinical features of A. Fib
many ectopic depolarizations from atria bombard AV node
ventricular response may be 130-180bpm
causes symptoms of palpitations, SOB, dyspnea, dizziness, fatigue or asymptomatic
if hemodynamically unstable, electrical cardioversion becomes treatment of choice
Classification and Definitions
Paroxysmal: terminates spontaneous
Persistent: sustained beyond 1 week
Permanent: continues despite treatment
Most common: chronic, idiopathic condition
Less common: Identifiable, reversible cause; Lone AFib
Management of AFib
- Control rate
- Prevent thromboembolism
- Correct to NSR and maintain in NSR (?)
Asymptomatic focus on rate control
Symptomatic focus on rhythm control
- Control Ventricular rate
Slow conduction velocity and/or increase refractory period at the AV node, decreasing the number of impulses going through the AV node to the ventricles
Drugs: BB and NDHP CCB are preferred, but digoxin and amiodarone are alternative choices
May need more than one of the above
May use IV for acute treatment to obtain HR<100bpm
CCB control what? Monitoring? Which ones do you use?
“Rate control”
Slows ventricular response to A Fib or Flutter
Monitor–
- BP because vasodilators
- Signs of HF because negative inotropic
- Rhythm-may convert to NSR
Verapimil, Diltiazem
Beta Blockers
“Rate control” (slows ventricular response) to AFib and Flutter
May prevent ventricular arrhythmias (used post MI)
May convert AV-nodal re-entry (PSVT)
Monitor:
- bradycardia, hypotension, exacerbation of CHF
- relative CI in asthma
- CNS adverse effects include fatigue, lethargy, depression, sexual dysfunction
Digoxin
Mechanism:
- **Increases vagal tone to slow conduction at AV node **
Advantageous to use in hypotension and CHF exacerbation because does not change HR or contractility
Monitor
- ventricular response (HR), blood pressure, electrolytes (Na/K)
- signs of toxicity: hallucinations, nausea/vomiting, AV block, sinus pauses, arrhythmias, vision changes
- Preventing thromboembolism
1. If plan is ot convert to NSR
Duration <48hrs, anticogulation is generally not needed
- If duration is unknown, can do an transesophogeal echo to determine if thrombus is present
If duration >48hrs, need 3 weeks warfarin anticoagulation (INR 2-3) and warfarin 4 weeks after conversion
If emergent, use IV heparin, attempt conversion, and use warfarin 4 weeks after conversion
**2. If chronic, long term Afib: **
Long term therapy (warfarin) indicated based on CHADS2
- Drugs to Convert or Maintain NSR
Agents that can be used:
- Class IA: not used much anymore
- Class IC: flecanide, propafenone (converters)
- Class III: amiodarone, ibutilide, dofetilide, sotalol
Rate vs Rhythm Control
Rate control: leave in afib, focus on controlling HR, sxs, and preventing thromboembolism. Generally better because tend to relapse
Rhythm control: Use for patients with persistent sxs, unable to control rate, CHF sxs, not an anticoagulant candidate and younger patients
Amiodarone
May convert Afib/flutter
Most effective agent in maintaining NSR
Slows ventricular rate (“rate control”) if Afib persists
Least potential for proarrhythmias
Long term effects troubling
Amiodarone Adverse Effects
Long term effects:
- Pulmonary fibrosis
- Hypothyroidism (MC)
- Hyperthyroidism
- Hepatic dysfunction
- Ocular toxicities
- Many drug interactions
Ibutilide
Dofetilide
Ibutilide is a one time IV drug used to convert A fib or flutter
Dofetilide is an oral cousin used to convert A fib to flutter and maintain NSR
Both require careful monitoring in hospital setting
Proarrhythmias
Sotalol
May maintain NSR after conversion (for atrial and ventricular arrhythmias)
Proarrhythmic
Paroxysmal Supraventricular Tachycardia (PSVT) or AV Nodal Reentry
Need to break reentry pathway in AV node to convert to NSR
Start with carotid sinus massage
Adenosine drug of choice acutely
Verapamil, diltiazem, BB also very effective
