ECG of the Month
presented by A/Prof Alex Voskoboinik
A 68 year old male with a long standing non-ischaemic cardiomyopathy is admitted with a NSTEMI and found to have triple vessel disease. On Day 1 post-CABGs, he complains of dizzy spells and the following is seen on telemetry:
The most likely explanation is:
- Artefact
- Ventricular tachycardia
- SVT with aberrancy
- Oversensing
- Undersensing
The most likely explanation is:
- Artefact
- Ventricular tachycardia
- SVT with aberrancy
- Oversensing
- Undersensing
Explanation
This patient has a pre-existing ICD (which remains active) and epicardial pacing wires. The beginning of the telemetry strip starts with A-V pacing from the epicardial pacing leads with a large pacing stimulus visible from stimulation of both chambers. The ICD then proceeds to deliver anti-tachycardia pacing (which appears as the wide complex ‘tachycardia’ with pacing spikes prior to each QRS complex). The haemodynamic effects of this ATP can be seen on the PAP (Pulmonary Artery Pressure) invasive waveform with flattening of the trace seen. The ICD interrogation is shown, and demonstrates oversensing of the epicardial pacing stimulus on the ICD’s ventricular channel – hence the ICD double counts both the stimulus and the ventricular paced beat and hence concludes that the patient is in VT/VF, and delivers anti-tachycardia pacing.
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