Atrial Antiarrhythmics Flashcards Preview

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Flashcards in Atrial Antiarrhythmics Deck (16):
1

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

2

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

3

Management of AFib

 

  1. Control rate
  2. Prevent thromboembolism
  3. Correct to NSR and maintain in NSR (?)

Asymptomatic focus on rate control 

Symptomatic focus on rhythm control 

4

1. 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

5

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

6

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

7

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 

8

2. 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

 

9

3. 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 

10

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

11

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

12

Amiodarone Adverse Effects 

Long term effects: 

  • Pulmonary fibrosis 
  • Hypothyroidism (MC)
  • Hyperthyroidism 
  • Hepatic dysfunction 
  • Ocular toxicities 
  • Many drug interactions

13

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

14

Sotalol 

May maintain NSR after conversion (for atrial and ventricular arrhythmias) 

Proarrhythmic 

15

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 

16

Adenosine 

Briefly interrupts conduction at AV node to break reentry 

90-98% successful

Half life=5 seconds, very brief 

Monitor 

  • peripheral vasodilation - hypotension, flushing, SOB, chest tightness, apprehension (short duration )
  • CI-obstructive lung disease, heart transplant patients