EADs and DADs

on 7.12.08 with 0 comments

  • EAD is shown in A, B, C. action potential is prolonged; membrane fluctuations result in an extra, ectopic beat. this can lead to ventricular tachycardia, which can be dangerous

  • DAD is shown in D, E. depolarization occurs after the membrane has repolarized, but this still may cause ventricular tachycardia


  • occur before the full repolarization o the cell

  • congenital

    • familial long QT syndrome (LQTS): genetic mutations in K+ or Na+ channels prolong action potentials; this leads to EAD

    • high risk for sudden death due to torsades de pointes (vtach)

    • treat with β-blockers and implantable cardioverter-defibrillators (ICDs)

  • acquired

    • acquired long QT

    • most often due to drugs (e.g. terfenadine); also, ischemia, hypocalcemia, hypothermia

    • these patients are also at risk for VT

    • treat by remove offending cause and correct any electrolyte abnormalities


  • occur after cell repolarizes

  • example: digitalis toxicity

    • treatment involves correction of electrolytes, IV Mg, defibrillation

Category: Cardiology Notes



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