12 min readBy Heart Hippo Medical Team

Why Is My Heart Racing? Understanding the Many Causes of Palpitations and When to Worry

Heart palpitations can range from harmless to life-threatening. Learn to distinguish between benign sinus tachycardia and serious arrhythmias that require immediate attention.

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That sudden racing heartbeat can be terrifying. Whether it happens when you stand up, during exercise, or seemingly out of nowhere, heart palpitations affect millions of people. But not all rapid heartbeats are created equal—some are completely harmless, while others can be life-threatening.

Understanding the different causes of palpitations is crucial for knowing when to seek immediate care versus when to schedule monitoring. This guide breaks down the most common causes and helps you understand what your racing heart might be telling you.

Understanding Palpitations: More Than Just a Fast Heartbeat

Palpitations are the sensation of your heart beating rapidly, irregularly, or more forcefully than usual. They can feel like:

  • Racing or pounding
  • Fluttering or "flip-flopping"
  • Skipping beats
  • Irregular rhythm

The key to proper diagnosis lies in understanding the underlying rhythm causing these sensations.

Benign Causes: When a Racing Heart Is Normal

Sinus Tachycardia: Your Heart's Natural Response

What it is: Your heart beating faster than 100 beats per minute, but maintaining a regular rhythm through the normal electrical pathway.

Common triggers:

  • Exercise or physical activity
  • Stress, anxiety, or emotional excitement
  • Caffeine, alcohol, or certain medications
  • Fever or illness
  • Pain or discomfort

How it feels: A steady, rapid heartbeat that gradually increases and decreases with the triggering activity.

Why it's usually harmless: This is your heart's normal response to increased oxygen demands. The electrical system is working properly—it's just working faster.

Orthostatic Changes: The Stand-Up Challenge

What it is: Heart rate changes when moving from lying or sitting to standing, sometimes called orthostatic hypotension or POTS (Postural Orthostatic Tachycardia Syndrome).

What happens:

  • Blood pools in your legs when you stand
  • Blood pressure temporarily drops
  • Heart rate increases to compensate

Symptoms:

  • Racing heart upon standing
  • Dizziness or lightheadedness
  • Temporary weakness

When it's concerning: If heart rate increases by more than 30 beats per minute or if symptoms are severe or persistent.

Potentially Serious Causes: When to Pay Attention

Supraventricular Tachycardia (SVT): The Circuit Problem

What it is: A rapid heart rhythm originating above the ventricles, often due to an extra electrical pathway in the heart.

Characteristics:

  • Sudden onset and termination
  • Very regular, rapid rate (usually 150-250 beats per minute)
  • Episodes last minutes to hours

How it feels:

  • Heart "switches on" to rapid mode suddenly
  • May feel like heart is "revving like an engine"
  • Often accompanied by chest discomfort or shortness of breath

Why it matters: While not always life-threatening, SVT can be uncomfortable and may require treatment, especially if episodes are frequent or prolonged.

Atrial Flutter: The Circular Pattern

What it is: The atria beat in a rapid, regular pattern, but the ventricles beat slower due to the heart's natural electrical system.

How it presents:

  • Regular rapid heartbeat
  • Often feels similar to SVT but may be more sustained
  • May cause fatigue or shortness of breath

The concern: Like AFib, atrial flutter can increase stroke risk and may progress to more serious rhythms.

Life-Threatening Rhythms

Atrial Fibrillation with Rapid Ventricular Response (RVR)

What it is: AFib where the ventricles are beating very rapidly (usually over 120 beats per minute), causing inefficient heart pumping.

Warning signs:

  • Irregular, rapid heartbeat
  • Chest pain or pressure
  • Severe shortness of breath
  • Dizziness or near-fainting
  • Weakness or fatigue

Why it's dangerous:

  • Severely compromises heart function
  • Can lead to heart failure
  • Increases stroke risk significantly
  • May progress to more dangerous rhythms

Ventricular Tachycardia (VT)

What it is: Rapid rhythm originating from the ventricles—the heart's main pumping chambers.

Critical characteristics:

  • Heart rate usually 150-250 beats per minute
  • May cause hemodynamic instability
  • Can progress to ventricular fibrillation (cardiac arrest)

Emergency symptoms:

  • Chest pain
  • Severe shortness of breath
  • Loss of consciousness or near-fainting
  • Severe dizziness

Red Flags: When to Seek Emergency Care

Call 911 immediately if palpitations are accompanied by:

  • Chest pain or pressure
  • Severe shortness of breath
  • Loss of consciousness or near-fainting
  • Severe dizziness that doesn't resolve
  • Symptoms lasting more than a few minutes without improvement

The Diagnostic Challenge: Why Professional Monitoring Matters

The Intermittent Nature Problem

Most palpitations are intermittent, making them difficult to capture during a brief medical visit. A normal EKG doesn't rule out serious rhythm problems—it just means your heart was in normal rhythm during those 10 seconds.

The Symptom-Rhythm Correlation

Understanding what rhythm is causing your symptoms is crucial for proper treatment. The same symptom (racing heart) can have vastly different causes and treatments.

How Extended Monitoring Provides Answers

Capturing the Culprit Rhythm

Extended monitoring with devices like the Zio® patch can:

  • Record every heartbeat for up to 14 days
  • Capture intermittent episodes you might miss
  • Correlate symptoms with actual heart rhythms
  • Distinguish between benign and concerning patterns

Real-World Detection Rates

Studies show extended monitoring detects:

  • Significant arrhythmias in 15-20% of patients with palpitations
  • AFib in 16% of patients with unexplained symptoms
  • Clinically important rhythms missed by traditional short-term monitoring

The Bottom Line: Listen to Your Heart

Palpitations exist on a spectrum from completely benign to life-threatening. The key factors that help distinguish them include:

  • Pattern: Regular vs. irregular
  • Duration: Seconds vs. minutes vs. hours
  • Associated symptoms: Chest pain, shortness of breath, dizziness
  • Triggers: Exercise, position changes, stress
  • Frequency: Rare episodes vs. daily occurrences

When in doubt, professional monitoring provides the definitive answers you need. Your heart's rhythm holds important clues about your health—don't ignore what it's trying to tell you.

This blog post is for educational purposes only and is not a substitute for professional medical advice. If you're experiencing chest pain, severe shortness of breath, or think you're having a heart attack, call 911 immediately.

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