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Digitalis effect


See brief interpretation of 12 lead EKG above

Digitalis (digoxin) is a glycoside extracted from the foxglove plant. Digitalis has both anti-arrhythmic and inotropic properties. This combination makes the agent suitable in the treatment of atrial fibrillation and atrial flutter with rapid ventricular responses.

The digitalis effect is seen on the EKG as:

  • prolongation of the PR interval (AV conduction is delayed)
  • down-slope ST segment depression
  • T wave inversion
  • shortening of the QT interval

These EKG changes may be confused with myocardial ischemia. However the bowl-like down-sloped ST segment depression is characteristic for the digitalis effect.

detail digitalis Digitalis effect

The digitalis effect is normal and requires no intervention. However, in toxic blood levels digitalis causes a range of more severe EKG changes including heart blocks and tachy-arrhytmias. In these instances digitalis intoxication should always be considered – in particular when the patient is known to be in digitalis medication. Digitalis intoxication may be further evaluated with a blood test (serum digoxin).

– Mathias

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