There are several reasons to be reassuring about this rhythm.

There is something regular occurring throughout the rhythm strip – in this case, there is some remnant of the sinus beat (as marked above). Also note that the O2 pleth continues undisturbed throughout the period of the questionable arrhythmia. This is a good example of artifact simulating ventricular tachycardia.

Another worrisome rhythm…

This rhythm strip is slightly more difficult to define because the O2 pleth has some artifact throughout the strip. However if you use calipers or mark R-R on a piece of paper you will again find remnants of persistent sinus rhythm through the apparent ventricular tachycardia…artifact NOT ventricular arrhythmia.