Inappropriate ICD Therapies

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Raja Selvaraj MD DNB FCE (Toronto)
Professor of Cardiology
JIPMER

Definitions

Sensing

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Detection

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Confirmation

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Re-detection

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Inappropriate therapy

  • Non physiological signals
  • Physiological, non-arrhythmic signals
    • Intracardiac
      • T wave (small RR alternation)
      • QRS double counting (Na blockers, high heart rate)
      • P wave sensing (children, long PR, lead dislodgement)
    • Extracardiac
      • No relation to cardiac cycle
      • Greater signal on widely spaced electrodes
      • Lead connector problems - small part of cycle, saturates amplifier
  • Non ventricular arrhythmias

Case 1

Case

  • Young female
  • Idiopathic DCMP
  • Single chamber ICD
  • Presented with ICD shock 2 months after implant

Tracing of therapy

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Jpn Circ J 2001; 65: 685 –687

Decrease in R wave amplitude

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Autogain (sensing threshold)

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Learning points

  • Dynamic sensing thresholds
  • Inappropriate oversensing
    • Reduction in signal amplitude
    • Increase in "noise" amplitude
    • After longer pause

Case 2

Case

  • Middle aged male
  • Post MI, LV dysfunction, VT
  • Dual chamber ICD
  • Presented with shock

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Dot plot - Illustration

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"Tram track" pattern

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Patient with CRTD device

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PACE 2005;28:1322–1346

Atrial tachycardia and "double counting"

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Learning points

  • How to use dot plot
  • Tram track appearance - Physiological signal oversensing
  • Distance between tracks, sum of tracks

Case series 3 - Extracardiac noise

Diaphragmatic myopotentials

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Transcutaneous Electrical Nerve Stimulation

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Car Alternator

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Lead Fracture

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Learning Points

  • External noise usually seen in all leads
  • Not related to cardiac cycle
  • High amplitudes with amplifier saturation - Lead fracture
  • History of surroundings and activity at time of therapy

Inappropriate therapy

  • Non physiological signals
  • Physiological, non-arrhythmic signals
    • Intracardiac
      • T wave (small RR alternation)
      • QRS double counting (Na blockers, high heart rate)
      • P wave sensing (children, long PR, lead dislodgement)
    • Extracardiac
      • No relation to cardiac cycle
      • Greater signal on widely spaced electrodes
      • Lead connector problems - small part of cycle, saturates amplifier
  • Non ventricular arrhythmias