From the Guidelines
Postural Orthostatic Tachycardia Syndrome (POTS) is diagnosed when there is an increase in heart rate of at least 30 beats per minute (or ≥40 beats per minute in individuals aged 12-19 years) within 10 minutes of standing or head-up tilt, without orthostatic hypotension (a drop in blood pressure of >20 mm Hg reduction in systolic BP). This diagnosis is based on the criteria outlined in the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1. The guideline defines POTS as a clinical syndrome characterized by frequent symptoms that occur with standing, an increase in heart rate of ≥30 bpm during a positional change from supine to standing, and the absence of orthostatic hypotension.
Key Diagnostic Criteria
- Increase in heart rate of ≥30 bpm (or ≥40 bpm in those 12–19 years of age) during a positional change from supine to standing
- Absence of orthostatic hypotension (>20 mm Hg reduction in systolic BP)
- Symptoms of orthostatic intolerance, such as lightheadedness, palpitations, tremulousness, generalized weakness, blurred vision, exercise intolerance, and fatigue
- Symptoms should be present for at least 3 months
Diagnostic Testing
During diagnostic testing, heart rate and blood pressure are measured while the patient is lying down for at least 5 minutes, then continuously monitored for 10 minutes after standing 1. The diagnosis requires that symptoms of orthostatic intolerance accompany the heart rate increase.
Pathophysiology
The pathophysiology of POTS involves autonomic nervous system dysfunction, with several proposed mechanisms including hypovolemia, excessive sympathetic activation, and autoimmune factors affecting autonomic receptors 1.
Clinical Considerations
It is essential to distinguish POTS from other forms of orthostatic intolerance and to rule out other conditions that could cause tachycardia, such as dehydration, medication effects, or acute blood loss. A thorough history, physical examination, and eyewitness observation are crucial in making an accurate diagnosis.
From the Research
POTS Diagnosis Criteria
- The diagnosis of Postural Orthostatic Tachycardia Syndrome (POTS) is based on a symptomatic increase in heart rate upon standing, without orthostatic hypotension 2, 3.
- A typical patient with POTS experiences a heart rate increase of 30 beats per minute or more within 10 minutes of standing, in the absence of other medical conditions that may cause similar symptoms 3, 4.
- Blood pressure (BP) criteria for POTS diagnosis are less well-defined, but patients typically do not experience significant orthostatic hypotension 2, 5.
Heart Rate and BP Measurements
- Heart rate and BP measurements are typically taken in both supine and upright positions to assess for orthostatic changes 5, 4.
- The use of autonomic testing, such as heart rate variability and blood pressure monitoring, can help confirm a POTS diagnosis and exclude other causes of orthostatic intolerance 4.
- Laboratory testing and other diagnostic studies may also be used to rule out other conditions that may cause or mimic POTS symptoms 4.
Diagnostic Evaluation
- A thorough clinical history and examination are essential in evaluating a patient with suspected POTS 4.
- The diagnostic evaluation should include an assessment of symptoms, medical history, and physical examination, as well as laboratory and autonomic testing 2, 4.
- The purpose of autonomic testing is to confirm a POTS diagnosis, exclude other causes of orthostatic intolerance, and characterize POTS into neuropathic and hyperadrenergic subtypes 4.