How much can you vary ECG lead placement?

[dogman25]

Hello,

 

I am asking this question in reference to a traditional 3-lead ECG/EKG setup, where the leads are located at the RA, LA, and LL positions.

 

How much can you vary the placement of the RA, LA, and/or LL leads and still get an accurate Lead I/II/III signal? For example, I know that many systems will place the "LL" lead in the left abdominal region instead of actually on the "left leg" and still produce a reliable signal. But what if the LL lead is placed more to the left, or more to the right? What tolerance is there for these variations in placement?

[Prometheus]

In my experience quite a lot. If you're using a three-lead you're not really looking for an accurate picture, you'd be using a 12-lead in that case, but rather looking for changes. So long as you can distinguish major categories of arrhythmias the placements are fine. Can you distinguish between sinus rhythm and AF, or heart block - then you're fine. Trying to distinguish between type I and type II mobitz heart block - unlikely you'll need to distinguish these on a three lead - unless you're in cardiac intensive care maybe. I've seen LL on the sternum before.