By Ken Grauer, MD
Professor Emeritus in Family Medicine, College of Medicine, University of Florida
Dr. Grauer is the sole proprietor of KG-EKG Press, and publisher of an ECG pocket brain book.
The rhythm in the figure below was diagnosed as atrial flutter with 4:1 AV conduction. Do you agree? How would you confirm your answer?
As noted in the ECG Review published in the July 15 issue, the most common ventricular response to untreated atrial flutter is with 2:1 AV conduction. But the next most common ventricular response is with 4:1 AV conduction. At first glance, the rhythm in the figure appears to be atrial flutter with this latter conduction ratio. However, close inspection reveals this is not the case.
Use of calipers demonstrates that the small upright deflections on the baseline between QRS complexes definitely are not regular. This makes it extremely unlikely that these deflections represent flutter activity, since flutter waves (by definition) should be extremely regular.
Additionally, there is a changing relationship between these small vertical deflections (seen throughout the baseline on this rhythm strip) and neighboring QRS complexes. In contrast, with atrial flutter, there is usually a constant relationship between atrial deflections and neighboring QRS complexes. This is because with the exception of the variable conduction variant of flutter, there usually will be a readily identifiable repetitive pattern of atrial activity with respect to each QRS complex that results in a predictable conduction ratio.
Finally, if one steps back a bit from this tracing, underlying upright (sinus) P waves can be seen to precede each QRS complex with a fixed (and normal) PR interval. The fact that these sinus P waves are unaffected by the smaller, irregularly occurring upright deflections proves that these smaller, pointed deflections are the result of artifact.
The best way to prove artifact is to go bedside to observe the patient as the ECG is recorded. The patient in this case suffered from Parkinson’s disease, which characteristically produces a tremor at a frequency that approximates the rate of atrial flutter.