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Orthostatic Hypotension and POTS: Dizziness, Palpitations, and Fainting When Standing

Assoc. Prof. Sezen Bağlan Uzunget, MD
Cardiologist

Why Do Dizziness and Palpitations Occur When Standing?

When a person stands, gravity causes some blood to pool in the veins of the legs and abdomen.

Normally, the autonomic nervous system responds rapidly by adjusting vascular tone and heart rate to maintain blood flow to the brain.

If these regulatory mechanisms do not function appropriately, standing may cause dizziness, blurred vision, palpitations, weakness, or fainting.

Two important causes are orthostatic hypotension and postural orthostatic tachycardia syndrome (POTS).

What Is Orthostatic Hypotension?

Orthostatic hypotension is an excessive decrease in blood pressure after standing.

Classic orthostatic hypotension is defined as:

  • A decrease in systolic blood pressure of at least 20 mmHg, or
  • A decrease in diastolic blood pressure of at least 10 mmHg

within three minutes of standing.

For example, a reduction from 130/80 mmHg while lying down to 105/70 mmHg after standing may indicate orthostatic hypotension under appropriate testing conditions.

Interpretation may differ in patients with high baseline blood pressure.

What Are the Symptoms of Orthostatic Hypotension?

Common symptoms include:

  • Dizziness when standing
  • Darkening or blurring of vision
  • Feeling faint
  • Weakness
  • Unsteadiness
  • Neck or shoulder discomfort
  • Syncope

Symptoms usually improve when sitting or lying down.

Some patients may have significant blood pressure reductions without noticeable symptoms.

What Causes Orthostatic Hypotension?

1. Reduced Circulating Blood Volume

Potential causes include:

  • Dehydration
  • Vomiting or diarrhea
  • Excessive sweating
  • Blood loss

2. Medications

Certain medications may contribute to orthostatic hypotension, including:

  • Diuretics
  • Alpha blockers
  • Vasodilators
  • Some antihypertensive medications
  • Nitrates
  • Certain antidepressants and psychiatric medications

3. Autonomic Nervous System Disorders

Conditions associated with autonomic dysfunction include:

  • Diabetic autonomic neuropathy
  • Parkinson disease
  • Multiple system atrophy
  • Certain peripheral autonomic neuropathies

4. Other Factors

Prolonged bed rest, physical deconditioning, and certain systemic illnesses may contribute to orthostatic symptoms.

What Are the Types of Orthostatic Hypotension?

Classic Orthostatic Hypotension

A sustained blood pressure reduction occurs within three minutes of standing.

Initial Orthostatic Hypotension

A brief, pronounced blood pressure reduction occurs within approximately 15 seconds of standing.

Continuous blood pressure monitoring may be needed for diagnosis.

Delayed Orthostatic Hypotension

The characteristic blood pressure reduction develops more than three minutes after standing.

Prolonged standing tests or tilt table testing may be useful.

How Is Orthostatic Hypotension Diagnosed?

Diagnosis is based on medical history, medication review, and blood pressure measurements.

Orthostatic Blood Pressure Testing

A typical assessment involves:

  1. Resting in the supine position for at least five minutes.
  2. Measuring supine blood pressure and heart rate.
  3. Standing up.
  4. Repeating measurements at approximately one and three minutes.

Longer monitoring may be necessary in selected patients.

Tilt Table Testing

Tilt testing may help evaluate certain forms of orthostatic hypotension and distinguish them from other orthostatic intolerance disorders.

Additional Investigations

Blood counts, electrolytes, kidney function, and other laboratory tests may be requested according to the suspected cause.

How Is Orthostatic Hypotension Treated?

Treatment focuses on identifying and correcting contributing factors.

Medication Review

Medications that may lower standing blood pressure should be assessed.

Patients should not stop prescribed medications without medical advice.

Hydration and Salt Intake

Adequate hydration is important.

In selected patients, increased fluid or salt intake may be beneficial.

However, these measures require caution in people with hypertension, heart failure, or kidney disease.

Postural Measures

Standing up gradually, especially after prolonged lying or sitting, may reduce symptoms.

Compression Garments

Abdominal compression or waist-high compression garments may help selected patients.

Medication

Midodrine or fludrocortisone may be considered in selected patients with neurogenic orthostatic hypotension.

These medications require monitoring for adverse effects, including hypertension and fluid retention.

What Is POTS?

POTS stands for Postural Orthostatic Tachycardia Syndrome.

It is characterized by an excessive increase in heart rate after standing, accompanied by chronic orthostatic symptoms.

Unlike orthostatic hypotension, POTS does not involve a diagnostic orthostatic blood pressure reduction.

What Are the Diagnostic Criteria for POTS?

General diagnostic criteria include:

  • A sustained heart rate increase of at least 30 beats per minute in adults within 10 minutes of standing
  • At least 40 beats per minute in adolescents aged 12–19 years
  • Absence of significant orthostatic hypotension
  • Symptoms that worsen when upright and improve when lying down
  • Symptoms persisting for at least three months
  • No alternative explanation for the tachycardia

An increased heart rate upon standing does not automatically establish a diagnosis of POTS.

What Are the Symptoms of POTS?

Common symptoms include:

  • Palpitations on standing
  • Dizziness
  • Presyncope
  • Fatigue
  • Exercise intolerance
  • Difficulty concentrating
  • Blurred vision
  • Tremulousness
  • Nausea
  • Heat intolerance

Syncope may occur, but it is not required for diagnosis.

What Causes POTS?

POTS is a heterogeneous condition with several possible contributing mechanisms:

  • Autonomic nervous system dysregulation
  • Reduced circulating blood volume
  • Excessive venous pooling
  • Certain peripheral autonomic disorders
  • Physical deconditioning
  • Post-infectious autonomic symptoms

Some patients develop POTS symptoms after viral infections.

However, the underlying mechanism may differ between individuals.

Who Develops POTS?

POTS is more commonly described in young adults and women.

Nevertheless, it may occur in other age groups and in men.

Diagnosis should be based on clinical findings rather than demographic characteristics alone.

Is POTS the Same as Anxiety?

No.

Palpitations, tremulousness, and discomfort associated with POTS may resemble anxiety symptoms.

However, POTS is assessed through objective orthostatic heart rate changes and the clinical history.

Anxiety may coexist with POTS, but symptoms should not automatically be attributed to a psychological cause.

How Is POTS Diagnosed?

1. Active Standing Test

Heart rate and blood pressure are measured while lying down and during the first 10 minutes after standing.

2. Tilt Table Test

Tilt testing evaluates heart rate and blood pressure responses to an upright position under controlled conditions.

3. ECG and Ambulatory Monitoring

These tests may help evaluate sinus tachycardia and exclude other arrhythmias.

4. Laboratory Tests

Anemia, thyroid disorders, dehydration, and other causes of tachycardia may need to be excluded.

How Is POTS Treated?

Treatment is individualized according to symptoms and clinical characteristics.

1. Hydration

Increasing fluid intake may help selected patients.

2. Salt Intake

Higher salt intake may improve circulating blood volume in some patients.

However, this approach may be inappropriate for people with hypertension, heart failure, or kidney disease.

3. Structured Exercise

Gradual physical conditioning is an important part of POTS management.

Initial exercises may include:

  • Recumbent cycling
  • Rowing
  • Swimming
  • Appropriate resistance training

Exercise intensity can be increased progressively as tolerated.

4. Compression Garments

Abdominal and lower body compression may reduce venous pooling.

5. Medication

Depending on individual circumstances, treatment options may include:

  • Low-dose beta blockers
  • Ivabradine
  • Midodrine
  • Fludrocortisone
  • Other selected therapies

No single medication is effective or appropriate for every patient with POTS.

Treatment should consider heart rate, blood pressure, associated conditions, and potential adverse effects.

What Is the Difference Between Orthostatic Hypotension and POTS?

  • Feature | Orthostatic hypotension | POTS |
    |---|---|---|
    | Main abnormality | Excessive blood pressure reduction after standing | Excessive heart rate increase after standing |
    | Blood pressure | Diagnostic fall is present | Diagnostic orthostatic hypotension is absent |
    | Heart rate | May rise or respond inadequately | Sustained excessive increase |
    | Common symptoms | Dizziness, blurred vision, fainting | Palpitations, dizziness, fatigue, exercise intolerance |
    | Diagnosis | Orthostatic blood pressure measurement | Active standing or tilt testing |
    | Treatment | Address underlying cause and support circulation | Hydration, salt adjustment, exercise, selected medication |

Are Orthostatic Hypotension and POTS Heart Diseases?

Both conditions affect cardiovascular regulation.

However, they do not necessarily indicate structural heart disease.

ECG, echocardiography, or ambulatory rhythm monitoring may be appropriate when symptoms suggest an underlying cardiac disorder.

When Is Emergency Evaluation Necessary?

Urgent medical assessment is important when symptoms are associated with:

  • Syncope during exercise
  • Chest pain
  • Significant breathlessness
  • Prolonged unconsciousness
  • Serious injury
  • New neurological deficits
  • Suspected dangerous arrhythmia

Can Orthostatic Hypotension and POTS Improve?

Recovery from orthostatic hypotension depends on the underlying cause.

Medication-related or dehydration-related episodes may improve when contributing factors are corrected.

POTS symptoms may improve over time in some patients, while others experience a more prolonged course.

Accurate diagnosis, appropriate lifestyle measures, and individualized treatment can help improve symptoms and daily functioning.

This content is provided for general educational purposes. Orthostatic hypotension and POTS should be diagnosed through appropriate clinical assessment, heart rate and blood pressure measurements, and evaluation for alternative causes.