Antiarrhythmics

Question 1

Cardiac Output and Arrhythmias

Answer 1

• ALL ARRHYTHMIAS EFFECT CO
• Symptoms of CO depend on degree of decreased CO
• AFib/AFlutter
  » Concern for blood stagnation in atrium
  » Decreased CO with increased ventricular response
  especially if exceeds 120 because not enough ventricular filling time
• VTach
  » not enough ventricular filling time
  » death possible

Question 2

Class III Antiarrhythmics

Answer 2

• sotalol
• amiodarone
• dofetilide
• dronedarone

Potassium Channel Blockers – prolonging repolarization phase

• Conduction velocity is not decreased because they do not affect sodium channels
• used for ventricular tachycardia and atrial fibrillation

Question 3

Amiodarone Monitoring

Answer 3

LFT
- Baseline and every 6 mo

PFT

• CXR baseline and annually
• PFT with DCLO: baseline and if sx develop

EKG
- baseline and when clinically indicated

Thyroid Function
- Baseline TSH, T4 and total/gree T3, then TSH q6mo

Eye Exam
- Baseline and then in event of visual changes

Question 4

Dofetilide

Answer 4

• Blocks cardiac potassium channels and delays repolarization, prolonging QT interval
• initial treatment begins in hospital
• indication:
  » highly symptomatic afib/aflutter
  »> best agent for cardioversion

BBW
- Torsades de points from QT prolongation

Avoid drugs that prolong QT
- avoid potassium-depleting diuretics

Requires Renal Dosing

Avoid with drugs that inhibit renal elimination
- verapamil, cimetidine, trimethoprim, prochlorperazine, dolutegravir, megestrol hydrochlorothiazide, ketoconazole

Question 5

Key Clinical Indications

Answer 5

Class III have are the most frequently used

- have the most toxicities