Sinus arrhythmia: The Daily PANCE Blueprint
A 26-year-old female volunteers to participate in a learning experience for PA students. The students practice putting EKG leads on her. They then obtain a 12-lead EKG on the volunteer patient. The 12-lead EKG reveals an irregular rate with an inconsistent P-P interval that tends to vary with respirations. The P waves look normal in morphology and the PR interval stays constant. Which of the following is the most likely diagnosis?
A. 2nd-degree AV block type 1
B. Atrial fibrillation
C. Sinus arrhythmia
D. Multifocal atria tachycardia
E. 1st-degree AV block
Answer and topic summary
The answer is C. Sinus arrhythmia
Sinus arrhythmia is a normal heart rhythm and is physiologically normal. It is usually seen in young, healthy people. What happens is that the heart rate varies due to vagal tone changes in the various stages of the respiratory cycle. When someone inspires, this decreases vagal tone, and thus the heart rate increase; when someone exhales the vagal tone is restored, which leads to a lowering in the heart rate. As someone ages, this sensitivity decreases, and thus the incidence of sinus arrhythmia declines. There is no need to treat it. A clue on EKG is that you will see the variation in P-P interval (of >3 small boxes) but a constant P-R interval and normal P wave morphology. Keep in mind that this does produce an irregular ventricular rate. But it’s not afib!
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Smarty PANCE Content Blueprint Review:
Covered under ⇒ PANCE Blueprint Cardiology ⇒ ⇒
