An Intriguing Rhythm: Who Belongs to Whom?

===================================MY Comment, by KEN GRAUER, MD (6/26/2023): ===================================The tracing in Figure-1 was sent to me — without the benefit of any history. How would YOU interpret this tracing?Figure-1: The initial ECG in today ' s case. (To improve visualization — I ' ve digitized the original ECG using PMcardio).MY Initial Thoughts:My attention was immediately drawn to the long lead rhythm strip in Figure-1. A lot is going on ...The rhythm is clearly irregular. All QRS complexes in this tracing are narrow — so the rhythm is supraventricular.P waves are present — and there is more than 1 P wave shape.Some P waves are too close to the QRS to conduct. That said, on initial inspection — it ' s hard to determine, " Who belongs to whom? " My Approach:When confronted with a challenging tracing consisting of multiple components, such as we see in Figure-1  — I favor starting with parts of the rhythm that I am fairly certain about.I find that the simple act of labeling atrial activity is incredibly helpful. In Figure-2  — I ' ve added RED arrows to the long lead rhythm strip in today ' s initial tracing to highlight what appears to be sinus P waves.Now look at each of these RED-arrow P waves. Which of these P waves do we know will be&...
Source: Dr. Smith's ECG Blog - Category: Cardiology Authors: Source Type: blogs