A patient presents concerned about an irregular heart beat. You palpate the pulse and find indeed that it appears irregularly irregular. Can you tell at the bedside whether this is atrial fibrillation?
Possible causes of an irregular pulse include atrial fibrillation, sinus arrhythmia, and atrial or ventricular ectopy. The physical diagnosis of these conditions has been well-described but not well studied.
Sinus arrhythmia can be quite irregular. Have the patient hold the breath for 10-15 seconds. Does it become regular?
Ventricular ectopy does not reset the rhythm. Listen for the “beat” and nod your head along like it is a song. A few premature ventricular contractions should not change the original beats and your next head nod will come at just the right time.
Atrial ectopy does reset the rhythm. This one is harder to differentiate from atrial fibrillation.
You suspect atrial fibrillation based on the irregularly irregular rhythm. However, breath holding does make the rhythm regular. You check the EKG which confirms sinus arrhythmia.
Take home points:
For the patient with an irregular pulse, use breath holding to diagnose sinus arrhythmia.
PVCs do not reset the original rhythm, but PACs do