Lead II ECG Interpretation

[Diptherious]

Hey all, my professor has given us some ECG's to interpret but I'm particularly stumped with this one. The pacer spikes and wide QRS complexes lead me to believe it's a ventricular demand pacemaker taking over, but as for why is the question. The pause between the normal sinus rhythm and the beginning of the demand pacing makes me think some sort of sinus arrest occured, with the pacemaker eventually taking over then discontinuing when the normal sinus rhythm returned. As for the inverted T waves that could be from any number of causes. Any thoughts?

 

[chaz90]

Demand pacing. Your thoughts seem accurate. That's exactly the purpose of an appropriately sensing and capturing ventricular pacemaker. When the SA node depolarizes properly and at the right time leading to depolarization of the ventricles, the pacemaker doesn't activate. In cases of prolonged sinus arrest (a programmable time interval that can be changed by the physician), the pacemaker takes over. When the SA node begins working again the pacemaker shuts off.

 

[STXmedic]

I would have to agree. The first paced beat after the sinus beat occurs just after the pause is long enough to be <60bpm; then the following two beats fall right at 60. Demand pacemaker indeed.