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By Ken Grauer, MD
Professor Emeritus in Family Medicine, College of Medicine, University of Florida
Dr. Grauer reports no financial relationships relevant to this field of study.
The long lead II rhythm strip in the figure below was obtained from a middle-aged woman with syncope and hypotension. What can you say about the rhythm?
This is not an easy rhythm to interpret. That said, several statements can be made about this rhythm, and these should allow one to narrow the differential diagnosis. The five key parameters to assess when interpreting any arrhythmia can be easily remembered with the saying, “Watch your Ps, Qs, and the three Rs.” This saying serves to remind one to always look for P waves (determine if the QRS complex is wide or narrow) and assess the “three Rs” — rate of the rhythm, regularity of the rhythm, and if P waves are present, whether these P waves are related to neighboring QRS complexes. Although it may not always be possible to be certain about the interpretation of some complex arrhythmias, by addressing these five key parameters, one usually will arrive at the most likely possibilities.
Using calipers is the easiest way to measure intervals between successive P waves (i.e., the P-P interval), between successive QRS complexes (i.e., the R-R interval), and between P waves and neighboring QRS complexes (i.e., the PR interval). This instantly allows one to determine whether atrial and ventricular rates are regular and to quickly tell if at least some P waves are conducted (in which case, a similar PR interval will be seen).
Applying these five parameters to the rhythm in the figure, one could say:
Although complete interpretation of this complex arrhythmia is exceedingly difficult, consider this:
Financial Disclosure: Internal Medicine Alert’s Physician Editor Stephen Brunton, MD, is a retained consultant for Abbott Diabetes, Acadia, AstraZeneca, and Boehringer Ingelheim; and he serves on the speakers bureau of AstraZeneca, Boehringer Ingelheim, Janssen, Lilly, and Novo Nordisk. Peer Reviewer Gerald Roberts, MD; Editor Jonathan Springston; Editor Jason Schneider; Editorial Group Manager Leslie Coplin; and Accreditations Manager Amy M. Johnson, MSN, RN, CPN, report no financial relationships relevant to this field of study.