Quote from Csizi
What if the non-conducting P wave comes later than it should be? Like 8ms-10ms-6ms. Maybe a blocked atrial escape rythm that came late?
Well, of course 8- 10- 8ms would be virtually impossible to determine in a 12 lead or even an intracardiac electrogram. Even a diagnostic ep catheter has a margin of error and at least some degree of limitation.
If however you see like.. 80ms, 100ms, 80 ms variations:
It could be escape if the morphology (shape) of the wave is different. Possibly 2nd degree avb, sinus arrest with non conducting escape. That's a possibility.
It could also be a disease superior to the AV Node and/or SSS. Conduction Disease can occur just about anywhere along the conduction pathway.
Marching out the P waves as you did is a good plan. If you have a longer strip or a long term monitor watching for patterns in the P waves can help make sense of it sometimes.
If you have a PAC or a pathway you can have concealed conduction creating the phenomenon as well. So gathering information about potential interactions between ectopics or abberency is always useful, as is a thorough understanding of patient history.
Unfortunately with situations such as these theres just so many options that it's pretty difficult to develop a concise algorithm.
Once you get the basics down and you've seen enough if these recordings to know what things look like:
The only way to advanceg with this stuff, imo, is to stop thinking about EKG criteria, and a simple block of 3 components (pri, qrs, tu) and start thinking in terms of Anatomy and Physiology and electricity. Instead of seeing a P wave and associating it with 'atria' bear in mind that the atria can be futher subdivided into inconceivably small units and that each of those units plays a role in generating an ekg complex. Not sure if that helps or not, just my 2 cents on it.