R-on-T Pacing

Report:

Sinus tachycardia 106/min 1

Fixed-rate ventricular pacemaker rhythm 58/min 2

R-on-pacing 3

Fusion beats 3

Nonspecific ST/T changes 1

Comment:

If the spikes go marching through another rhythm there is no way of knowing if they are atrial or ventricular unless a capture occurs. In this case there are six of them: some completely paced, some fusion beats. The fully paced beat in V2-3 starts just after the summit of a native T wave, with unpleasant possibilities.

Usually nothing happens. If it did, there would be some medico-legal considerations I’d rather not think about. One of them (anyway!) is that the patient obviously no longer needs the pacemaker in the first place.

Fig 43. 73 year old man in Casualty with chest pain.

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