The EKG in the patient treated with digitalis

Jump to navigation Jump to search
The EKG in the patient treated with digitalis

WikiDoc Resources for The EKG in the patient treated with digitalis

Articles

Most recent articles on The EKG in the patient treated with digitalis

Most cited articles on The EKG in the patient treated with digitalis

Review articles on The EKG in the patient treated with digitalis

Articles on The EKG in the patient treated with digitalis in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on The EKG in the patient treated with digitalis

Images of The EKG in the patient treated with digitalis

Photos of The EKG in the patient treated with digitalis

Podcasts & MP3s on The EKG in the patient treated with digitalis

Videos on The EKG in the patient treated with digitalis

Evidence Based Medicine

Cochrane Collaboration on The EKG in the patient treated with digitalis

Bandolier on The EKG in the patient treated with digitalis

TRIP on The EKG in the patient treated with digitalis

Clinical Trials

Ongoing Trials on The EKG in the patient treated with digitalis at Clinical Trials.gov

Trial results on The EKG in the patient treated with digitalis

Clinical Trials on The EKG in the patient treated with digitalis at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on The EKG in the patient treated with digitalis

NICE Guidance on The EKG in the patient treated with digitalis

NHS PRODIGY Guidance

FDA on The EKG in the patient treated with digitalis

CDC on The EKG in the patient treated with digitalis

Books

Books on The EKG in the patient treated with digitalis

News

The EKG in the patient treated with digitalis in the news

Be alerted to news on The EKG in the patient treated with digitalis

News trends on The EKG in the patient treated with digitalis

Commentary

Blogs on The EKG in the patient treated with digitalis

Definitions

Definitions of The EKG in the patient treated with digitalis

Patient Resources / Community

Patient resources on The EKG in the patient treated with digitalis

Discussion groups on The EKG in the patient treated with digitalis

Patient Handouts on The EKG in the patient treated with digitalis

Directions to Hospitals Treating The EKG in the patient treated with digitalis

Risk calculators and risk factors for The EKG in the patient treated with digitalis

Healthcare Provider Resources

Symptoms of The EKG in the patient treated with digitalis

Causes & Risk Factors for The EKG in the patient treated with digitalis

Diagnostic studies for The EKG in the patient treated with digitalis

Treatment of The EKG in the patient treated with digitalis

Continuing Medical Education (CME)

CME Programs on The EKG in the patient treated with digitalis

International

The EKG in the patient treated with digitalis en Espanol

The EKG in the patient treated with digitalis en Francais

Business

The EKG in the patient treated with digitalis in the Marketplace

Patents on The EKG in the patient treated with digitalis

Experimental / Informatics

List of terms related to The EKG in the patient treated with digitalis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]


Underlying Electrophysiologic Mechanisms

  1. Digoxin inhibits the transport of Na and K ions across the cell membrane
  2. It acts indirectly by increasing vagal tone
  3. Decreases the automaticity of the SA node at therapeutic doses
  4. The slowing of the sinus rate is due mostly to the vagal effect
  5. At toxic doses, it may increase the sinus rate as well as impair SA conduction.
  6. At therapeutic doses, the automaticity of subsidiary atrial pacemakers is reduced.
  7. Automaticity of subsidiary pacemakers may be increased at higher doses.
  8. At the AV node there is depression of conduction but enhancement of automaticity.
    • This depression of conduction is due to both the vagal and the direct effects of the drug.
    • The increase in the PR interval is due primarily to an increase in the AH interval and the HV interval is unchanged.
    • causes an increase in the automaticity and a decrease in the excitability of the His-Purkinje system by increasing the phase 4 slope.
  9. The effects of digitalis on ventricular repolarization are responsible for the characteristic ST segment and T wave changes associated with the administration of the drug.
  10. The recovery process is shortened and the QT interval is shortened

Effect of Digoxin on the EKG

  1. ST segment depression
  2. Decreased amplitude of the T wave, which may become diphasic (initial part is negative and the terminal positive) or negative
  3. Shortening of the QT interval
  4. Increase of the U wave amplitude (not as much as hypokalemia or quinidine)
  5. The changes are most pronounced in the leads with a tall R wave
  6. The degree of repolarization changes has no correlation with serum digoxin levels
  7. Changes are more pronounced in tachycardia
  8. One of the causes of a false positive ETT
    • A false positive test is seen in 50% of patients
  9. In LVH, the QT interval should be prolonged. If it is normal or shortened, then suspect digoxin toxicity.

Digitalis Intoxication

  1. Reported in 23% of patients on the drug in 1971, lower now
  2. Can produce all types of arrhythmias from problems with impulse conduction to problems with impulse formation
  3. Interestingly enough, it does not cause bundle branch block (the level of the block is proximal to the His bundle).
  4. Frequency of arrhythmias:
  5. A regular rhythm in the presence of atrial fibrillation suggests complete AV block
  6. In cases of enhanced impulse formation from the AV node, the rate of junctional discharge is between 70 and 130 beats per minute, and the rhythm is regular. This rhythm can be seen in patients with an MI or myocarditis
  7. Lown had reported in 1960 that 73% of cases of PAT with block were due to digoxin. The number is probably lower currently. The atrial rate is between 150 to 200 BPM.

EKG examples



Template:WikiDoc Sources