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Background

  • 82 year old female with dual chamber PPM implanted for syncope and sinus rhythm with intermittent 2nd degree AV block 

  • Initially programmed DDD 60-120

  • History of atrial tachycardias (~140 bpm) with no AF seen.

 

Routine Clinic check

  • 81 AHR episodes for a total of 3 hours

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What does the following AHR episode show?

 

Findings

  • No true AF is seen 

  • AEGM shows STc/ATc ~125 bpm with some FFRW

  • VEGM shows ventricular pacing with intermittent TWOS

 

Implications of TWOS
 

PPMs

  • Pacing below lower rate limit

    CRTs

  • withholding biventricular pacing

  • underestimating biventricular pacing percentage

    ICDs

  • Inappropriate ICD therapies

 

Troubleshooting TWOs
 

Increase V sensitivity ?

  • current settings sensitivity 0.9mV with an R wave of 12mV

  • *only a pacemaker - no concern of undersensing VF


  • Increasing blanking ?

  • Post Ventricular pace nominally 200ms

  • TWOS ~280ms post VP (probably too long to extend out)

    Change sensing vector ?

  • PPM: bipolar verse unipolar (risk of of ovsersensing in unipolar)

  • ICD: bipolar verse integrated bipolar (?effect on sensing VF)

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  • IF CRT, change BiV pacing offsets or LV pacing site?

  • May have a shorter QRS/QT or different repolarisation (different T wave)

    Reposition lead?

  • In extreme cases repositioning the lead may be warranted if TWOs cannot be avoided (particularly if an ICD lead)

 

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