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88 year old female with dual chamber implanted for pause dependent VT
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Currently programmed DDD 70-120
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Underlying sinus rhythm
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Reprogrammed to DDI 70 (PAV 350ms) to avoid tracking noise
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Reasons for pacing faster than base rate
Atrial fibrillation pacing algorithms
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rate smoothing
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AF suppression
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post mode switch overdrive pacing
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atrial preference pacing
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Rate Response -
May only be on in a mode switch
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Ventricular based timing
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Depends on the company and the mode
Atrial verse ventricular based timing
Atrial based timing
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Pure: rate is driven by the LRI (AA interval)
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Modified: rate is driven by the LRI (AA interval), except after VPB where VA timing is used
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Ventricular sensed timing -
Rate is driven by VA interval (LRI - PAV interval)
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Ventricular/ atrial based timing are non programmable​
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Shorten AV delays ?
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this may result in higher/unnessary ventricular pacing
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*Note: no search AV/VIP in DDI mode
Back to DDD with lower UTR ?​
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still may track noise
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Decrease lower rate limit in DDI?
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avoid pacing faster than necessary
Increase atrial sensitivity to a higher number and leave in DDD ?​​
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may undersense true atrial events
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Summary of timing for DDI modes in each company
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