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Courses Phar 6122


ekgcircle3.gif (1164 bytes) Lecture Outlines: Diseases/Syndromes
Supraventricular Arrythmias Lecture:
Learning Objectives and Outline
General Treatment Issues
The Use of CCBA's for Afib/Aflutter
Digoxin for Afib/Aflutter
Beta-Blockers for Afib/Aflutter
Ibutilide Fumarate (Corvert®)
General Issues with Drug Selection
Management of Supraventricular Arrhythmias
Cardiac Conduction System Lecture
Antiarrhythmic Drug Tables
Ventricular Arrythmia Management Lecture



Digoxin for Afib/Aflutter

Digoxin for Afib/Aflutter:
  • Often ineffective and slow in onset of action
  • Slowed VRR can be expected after one hour but maximal effect only after 24-48 hours
  • May be superior choice for long term care of patients with systolic dysfunction (CHF)
  • Often ineffective if exercise-related increases in VRR occur

Digoxin for SVT:

  • Often used to control VRR in AF by enhancing vagal effects on the AV node
  • Limitations are in situations with vagal tone is low (exercise, thyrotoxicosis, hyperadrenergic states) or when a rapid response is desired. Several studies demonstrated chronic dig therapy alone is no better than placebo in controlling VRR during AF paroxysms
  • May be superior choice for long term care of patients with systolic dysfunction (CHF)
Dosing Digoxin:
  • LD: 10-15 mcg/kg (LBW*)
  • MD: (14 + ClCr/5) % x LD
  • Give LD 1/2 now then remainder of load as 1/4 x 2 separated by at least 6-8 hours
  • Monitor: HR, BP, EKG, K+, Ca++
  • Question need for LD in CHF
  • Reduce load and MD in renal impairment
  • V. rate is not a good measure of chronotropic effect of digoxin

*Many drugs are dosed by using lean body weight. Calculation of lean body weight (LBW) is as follows:

- LBW male = 50 + (2.3 x + # of inches > 5 ft)
- LBW female = 45 + (2.3 x # of inches > 5 ft)

Digoxin Toxicities:
  • Poorly correlated with digoxin concentrations
  • Therapeutic window 0.5-2ng/mL
  • DILS (dig. immunoreactive like substance) may cause major interferrence with interpreting normal digoxin levels in select patient populations:

  • - pregnant patients
    - patients with chronic and possibly acute renal failure
    - neonates

  • Systemic toxicities
  • Anorexia, N, V, diarrhea, yellow-green or blurred vision
  • Cardiac toxicities:

  • - Heart block (2° or 3°)
    - Ventricular ectopy
    - PAT with 2° AV block



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