Two Rhythms of Indubitably Ventricular Origin

Report:

Pacemaker rhythm

VEBs

Ventricular fibrillation

CPR artefact (end of bottom strip)

Comment:

It has been said (the actual reference eludes me) that the only two rhythms of electrocardiographically certain ventricular origin are ventricular fibrillation and the pacemaker rhythm.

The second VEB in the top strip - the one initiating the VF - looks the same as the paced beats and is almost certainly pacemaker-induced. That may have been the case with his temporary pacemaker earlier (Fig 151b).

The pacemaker continues to fire regularly throughout the VF in the top strip - a perhaps forgivable failure to sense - without any possibility of capture. In the bottom strip, it appears reset four times, probably by the onset of closed chest compressions by the alert, if somewhat sluggish, resuscitation team!

Below (Fig 151a), the VF has given way to asystole, and the team stops the cardiac massage to watch it (even when nothing much happens, as in asystole, watching it can be quite exciting). The resumed massage, perhaps surprisingly, restores the myocardial capture by the pacemaker; even more surprisingly, the patent made it eventually out of the hospital. One more surprise would be if he comes back.

In Fig 151b there is a previous episode of VF arrest, with the temporary wire. It’s not as convincing as Fig 150, but the fact remains the patient had no ventricular arrhythmias before the temporary electrode was inserted. Any arrhythmia in a paced patient must be at least considered to be pacemaker-induced. 151a. Asystole undisturbed by pacing capture or CPR movement, then more CPR resuscitating the pacemaker! 151b. Malfunctioning temporary pacemaker and VF. 152. 74 year old lady in cardiogenic shock.