Approach to the 12-lead ECG or rhythm analysis:

Step 1: The first step in the analysis of an ECG is to view the tracing as a whole and categorize what you see.

Step 2: The second step is to diagnose the cardiac rhythm and conduction. In order to diagnose the cardiac rhythm, I recommend the "Litany of Categorization."

In some arrhythmias with multiple abnormalities, the litany does not work. The litany has three major elements, as follows:

The "Litany of Categorization"

  1. The mean rate of the QRS complexes:
    A. Slow rate,
    B. Normal rate, or
    C. Fast (rapid) rate

  2. The duration of the dominant QRS complexes, either
    A. Narrow (normal range in adults ranges from 70-113 msec) or
    B. Wide (> 120 msec)

  3. The spacing of the R-R intervals, either:
    A. Regular or
    B. Irregular (defined as any variation in the R-R intervals)
Based upon the categorization above, one can apply Bayesian analysis to determine the most likely cardiac rhythm causing that grouping of elements.

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