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Ventricular fibrillation following elective cardioversion in a patient with permanent pacemaker
Z Vera1, W J Bommer, J M Desai
1Department of Medicine, University of California, Davis Medical Center, Sacramento.
Pacing and Clinical Electrophysiology : PACE
|May 1, 1990
Summary
Elective cardioversion in a VVI pacemaker patient led to ventricular fibrillation. Unsynchronized cardioverter shocks triggered by random pacemaker pulses caused the dangerous complication.
Area of Science:
- Cardiology
- Biomedical Engineering
- Electrophysiology
Background:
- Patients with VVI pacemakers undergoing cardioversion require careful management to avoid complications.
- Atrial tachyarrhythmia necessitates intervention, often involving cardioversion.
- Pacemaker modes (VVI, VOO) influence device function and interaction with external electrical stimuli.
Observation:
- A VVI pacemaker was converted to VOO mode for elective cardioversion.
- The cardioverter's energy output was inadvertently synchronized with the pacemaker's random output pulses.
- The DC shock was delivered during the ST segment of the native QRS complex.
Findings:
- Synchronization of cardioversion with random pacemaker pulses is hazardous.
- Delivery of electrical shock during the vulnerable period (ST segment) can induce ventricular fibrillation.
- This case highlights a critical risk during cardioversion in pacemaker patients.
Implications:
- Cardioversion protocols must account for pacemaker function and potential interactions.
- Pacemaker reprogramming or external device inhibition is crucial before cardioversion.
- Enhanced awareness and technical precautions are essential to prevent life-threatening arrhythmias in pacemaker patients.