You are the resident on call and your pager goes off. It's a nurse from one of the telemetry floors and she says, " Mr X just had a run of V-Tach come quickly." You are half a sleep and say Okay after you let out a big yawn on the phone to let her no she woke you up. As you get into the elevator you flip through the sign out to see who Mr. X is. Mr. X is a 79 year old male who was admitted two nights ago for a Right sided CVA and was admitted to the telemetry floor because they where worried his heart rate might bottom out. His only medical history is HTN, and Diabetes. His hospital course since admission has been uneventful and he still has Left sided paralysis with no change on the Head CT since admission. The elevator door opens and the nurse is anxiously waiting to show you the telemtry strip. "Doctor here is the strip with the V-Tach, what should we do?". Here is the strip she shows you, what do you do?

Click Here for Better Quality Image of EKG strip

You tell the nurse. It's ok, this is not really V-Tach although it is really easy to mistake it for it if you glance at it really quickly. One tip is how irregular it is. V-Tach can be irregular but not as much as this is. This rhythm is grossly irregular. Especially between the first and second beats, compared to the next pair.

Next is the classic appearance of a "slur" between where the QRS ends a T-wave begins in v-tach is also not present. You can clearly see where the qrs ends and t wave begins.

What also adds to the clue that this is supraventricular in origin is the initial deflection of the QRS. Yes this is only a telemetry monitor strip but we can still infer that it starts off going down the same path as the sinus complexes. The complex started off in the atrium (as it is fibrillating) and got conducted fast down the His bundle most likely than hit part of the conduction system in a refractory period leading to the change in direction and length of the qrs. We cant really say which bundle is the problem here because this is not a twelve lead.

The main point also to remember is that this is a telemetry strip and localization of all this is not really possible. A twelve lead would able us to do this. Also if this rhythm where slightly more regular and a little faster, differentiating V-tach and Supraventricular Tach with abberant conduction would be virtually impossible on the surface EKG and you would need an EP study to really tell the difference.