What Do You Think 14

78-year old deep sea diver with symptomatic sick sinus syndrome and an implanted pacemaker, programmed DDDR with an AV delay of 400 ms.

ECG reported as abnormal pacemaker function.

What do you think? 

Try to diagnose each complex and then put it together.

• Atrial pacing (Ap) and ventricular sensing (Vs) at a rate of 60 bpm (1000ms).
• Ventricular ectopic (red highlight) with retrograde conduction (red arrow As).
• After an AV delay of 400 ms, there is a ventricular stimulus artefact ((first blue arrow) and ventricular pacing (Vp)again with retrograde conduction setting up an endless loop, although not a tachycardia (rate ~ 90 bpm), because of the long AV delay (yellow highlight and blue arrows).

Pacemaker mediated rhythm (tachycardia) precipitated by a ventricular ectopic.

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