Postural orthostatic tachycardia syndrome (POTS) is a condition that affects blood flow and heart rate. When someone with POTS stands up, their heart rate increases abnormally fast, often leading to symptoms like dizziness, lightheadedness, and fainting. This article will examine whether POTS shows up on an electrocardiogram (EKG) test.
What is POTS?
POTS is a form of dysautonomia, meaning it affects the autonomic nervous system. This system controls involuntary functions like heart rate, blood pressure, breathing, and digestion.
In POTS, the autonomic system does not respond appropriately to posture changes. Normally when we stand up, gravity causes blood to pool in the legs and abdomen. The autonomic system responds by constricting blood vessels and increasing heart rate to maintain blood flow to the brain.
In POTS, this compensatory heart rate increase is exaggerated, often rising 30 beats per minute or more within 10 minutes of standing. This criteria helps define a POTS diagnosis:
- Heart rate increase of 30+ bpm when moving from lying to standing
- Heart rate remains elevated for longer than 10 minutes upon standing
- Symptoms of lightheadedness, fainting, or fatigue with standing
- Symptoms improve with lying back down
POTS predominantly affects women, especially those aged 15-50 years. It often begins after a viral illness, trauma, or pregnancy. Some health conditions associated with POTS include joint hypermobility disorders, autoimmune diseases, diabetes, and thyroid disorders. However, many people develop POTS without any known trigger.
The hallmark symptom of POTS is an abnormally increased heart rate upon standing, along with symptoms related to reduced blood flow like dizziness, brain fog, weakness, and fatigue. Palpitations, exercise intolerance, nausea, headaches, and shortness of breath are also common. Symptoms are often worsened by warm weather, large meals, dehydration, and menstruation.
POTS is estimated to impact between 1 to 3 million Americans, though many remain undiagnosed. While there is no cure, symptoms can be managed through increased fluid and salt intake, compression garments, exercise, and medications.
What is an EKG test?
An electrocardiogram (EKG or ECG) records the electrical activity of the heart through small electrode sensors placed on the skin. The electrodes detect the heart’s electrical signals as they travel through the heart muscle to make it pump.
The EKG produces a graph of these signals in the form of wavy lines. Doctors examine the size, shape, timing and repetition of these wave patterns to identify any abnormalities in heart rhythm or damage to the heart.
EKG tests are noninvasive, inexpensive, and painless. They are routinely performed during annual checkups, before surgeries, or when cardiovascular problems are suspected. EKGs can detect heart rhythm issues like atrial fibrillation, ventricular tachycardia, heart blockages, enlarged heart chambers, or impact from past heart attacks.
Can POTS be seen on an EKG test?
An EKG performed while lying down is unlikely to detect signs of POTS. This is because the hallmark symptom of POTS is the abnormal heart rate increase that occurs upon standing up. When lying down and at rest, the EKG readings of someone with POTS will usually appear normal.
However, an EKG taken during a tilt table test may show signs of POTS. A tilt table test is often used to diagnose POTS. During this test, the patient lies flat on a table which is then tilted upright to an angle of 60 to 80 degrees, similar to standing up. Blood pressure and heart rate are continuously monitored throughout.
In those with POTS, the tilt table test will show an increase in heart rate by over 30 bpm within the first 10 minutes of tilting upright. The EKG readings during this rapid heart rate rise can help confirm a suspected POTS diagnosis.
EKG findings suggestive of POTS
While an EKG alone cannot definitively diagnose POTS, there are some EKG patterns that may be suggestive of POTS when considered along with a patient’s symptoms:
- Sinus tachycardia: This means the heart’s natural pacemaker or sinus node is signaling the heart to beat faster than normal while at rest. POTS patients often have a heart rate over 100 bpm. Rapid heart rate onset is a key feature of POTS.
- Heart rhythm disturbances: Some POTS patients have additional arrhythmias like sinus arrhythmia, sinus pauses, premature ventricular contractions (PVCs), or premature atrial contractions (PACs).
- Reduced heart rate variability: This means the time intervals between heartbeats are very consistent instead of varying beat-to-beat. Low heart rate variability indicates less adaptability.
- Tall peaked P waves: This suggests increased atrial pressure which can trigger PACs.
- QRS complex abnormalities: Some POTS patients have wide QRS complexes indicating issues with the heart’s ventricles.
- QT interval changes: Some POTS patients have elongated QT intervals which can predispose to dangerous ventricular tachycardia.
- ST segment depression: This may indicate coronary microvascular dysfunction which is sometimes seen in POTS.
However, it’s important to note these EKG findings are not definitive for POTS. An EKG alone cannot diagnose POTS – it must be used alongside patient symptoms and heart rate monitoring such as a tilt table test. Many POTS patients have completely normal EKGs even when symptomatic. An EKG alone cannot rule out POTS.
Other POTS testing
Besides a tilt table test, other tests that can aid in diagnosing POTS include:
- Active stand test – Heart rate and blood pressure are measured while lying down, then immediately upon standing.
- Heart rate and blood pressure monitoring – This can be done periodically at home to document heart rate spikes and dips in blood pressure.
- QSART – Quantitative sudomotor axon reflex test evaluates sweat responses to stress.
- Blood volume analysis – This tests for low blood volume which can contribute to POTS.
No single test definitively diagnoses POTS. Doctors make a POTS diagnosis based on the patient’s medical history, symptoms, triggers, family history, physical examination, heart rate and blood pressure responses, and results of various autonomic testing.
POTS treatment options
While no cure exists for POTS itself, many different treatments can help manage POTS symptoms. Treatment is tailored to each patient’s specific case and usually includes a combination of approaches:
- Increasing fluid and salt intake – This helps expand blood volume to prevent blood pooling.
- Compression garments – These squeeze the legs and abdomen to prevent blood pooling.
- Exercise training – This strengthens the heart and muscles and reconditions them to orthostatic stress.
- Medications – Such as beta blockers to slow heart rate, fludrocortisone for blood volume, or midodrine to raise blood pressure.
- Avoiding triggers – Such as heat, alcohol, large meals, and prolonged standing.
- Raising head of bed – This prevents overnight blood pooling while sleeping.
- Electrolyte drinks – Replenishing electrolytes like potassium and magnesium.
- Anxiety reduction – Since anxiety can worsen symptoms.
With various treatments, most patients can manage their POTS symptoms and continue daily activities. While POTS may not show abnormalities on a routine EKG, targeted POTS testing and clinical monitoring can successfully diagnose this complex syndrome.
Conclusion
POTS does not typically appear on a resting EKG when lying down. The hallmark sign of POTS – an exaggerated increase in heart rate upon standing – requires active heart rate monitoring such as with a tilt table test. While some EKG findings may point towards POTS as a possibility, POTS cannot be definitively diagnosed from an EKG alone. Confirming a POTS diagnosis requires synthesizing the patient’s medical history, symptoms, triggers, family history, physical examination, and results from autonomic testing like a tilt table test. With no single conclusive test for POTS, doctors must rule out other causes and look at the full clinical picture. While an EKG alone cannot confirm POTS, it may provide clues when paired with a complete workup. Addressing POTS requires a multifaceted approach.