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Vanderbilt Autonomic Dysfunction Center

Sinus Arrhythmia

What is the purpose of sinus arrhythmia testing?

Sinus arrhythmia testing is used to assess parts of the parasympathetic nervous system including the vagus nerve, which is involved in the regulation of heart rate.

How is the test performed?

Normally, heart rate varies with breathing, increasing during inspiration and decreasing during expiration. This is known as respiratory sinus arrhythmia and is controlled by the parasympathetic nervous system. In this test, the patient will be instructed to take deep breaths (6 breaths/minute) and his/her heart rate will be monitored. The minimum and maximum heart rate during the breathing cycles will be determined. A difference between the minimum and maximum heart rate of at least 15 is considered normal.

What are the expected results for a patient with POTS?

Patients with POTS typically have preserved vagal function and usually have normal results for this test.

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