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Spontaneous endless loop tachycardia
Pacing and Clinical Electrophysiology : PACE
|May 1, 1986
Summary
Pacemaker-mediated endless loop tachycardia can occur with normally timed P waves. Shortening the atrial refractory interval after ventricular pacing effectively terminated these tachycardias.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Pacemaker-mediated endless loop tachycardia (PMELT) typically arises from P waves occurring during atrial channel sensitivity post-QRS.
- This mechanism involves retrograde atrial activation following ventricular depolarization.
Observation:
- This study details five cases of PMELT initiated by normally timed P waves.
- These P waves were either spontaneous before ventricular pacing or triggered by atrial pacing followed by ventricular pacing and QRS complex.
Findings:
- In all observed cases, the atrial refractory interval (ARI) was shorter than the retrograde conduction time.
- Prolonging the ARI post-ventricular event terminated the tachycardia in four cases.
Implications:
- These findings suggest a novel mechanism for PMELT initiation.
- Adjusting the ARI is a viable strategy for managing these specific pacemaker-induced arrhythmias.
- In challenging cases, programming to ventricular inhibited mode may be necessary.