Which step helps classify the rhythm by comparing to known profiles?

• A. Compare the findings to the defining characteristics of each rhythm
• B. Rely on average heart rate
• C. Ignore QRS morphology
• D. Focus only on P wave height

Answer: (A)

Classifying a rhythm hinges on comparing what you observe to the established profiles for each rhythm. By checking the defining characteristics—how regular the rhythm is, the presence and form of P waves and their relation to the QRS (the PR interval), and the width and morphology of the QRS—you can identify which rhythm pattern matches best. Relying only on average heart rate can mislead, because different rhythms can share similar rates yet differ in how the P waves relate to the QRS or in QRS duration. Ignoring QRS morphology removes a key clue that separates supraventricular from ventricular origins, and focusing only on P-wave height ignores the timing and relationship that are essential. So, comparing the findings to known profiles is the most informative step. For example, a P wave before every QRS with a consistent PR interval and a narrow QRS points to sinus rhythm, while irregular P waves with no clear relationship to QRS suggest a different pattern.