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Paradoxical AV delay shortening of a pacemaker
S S Barold1, H Abe, T Nagatomo
1Electrophysiology Institute, Broward General Hospital, Fort Lauderdale, Florida, USA. ssbarold@aol.com
Pacing and Clinical Electrophysiology : PACE
|November 4, 2000
Summary
Paradoxical shortening of paced AV delay (Ap-Vp) was observed in patients with CPI Vigor DR pacemakers. This occurs due to the VA extension algorithm, even at rest, impacting pacing intervals.
Area of Science:
- Electrophysiology
- Cardiovascular Technology
Background:
- DDD and DDDR pacing modes are common for managing bradycardia.
- Pacemaker algorithms aim to optimize heart rate response and prevent arrhythmias.
- The VA extension algorithm is designed to manage atrial pacing rates relative to ventricular events.
Observation:
- Paradoxical shortening of the atrial paced-ventricular paced (Ap-Vp) interval was noted at rest.
- This phenomenon occurred in patients with CPI Vigor DR pacemakers programmed with long AV delays and narrow rate differentials.
- The VA extension algorithm was implicated as the cause of the observed Ap-Vp interval shortening.
Findings:
- The VA extension algorithm, intended for sensor-driven rates, also manifests at rest.
- It can lead to variable abbreviation of paced AV delays (Ap-Vp).
- This results in variations in atrial escape intervals despite consistent ventricular pacing timing.
Implications:
- Understanding the VA extension algorithm's behavior at rest is crucial for pacemaker programming.
- This can help prevent unintended alterations in pacing intervals and optimize device function.
- Further investigation into rate- மாறுபாடு algorithms in pacemakers is warranted.