Signals in the heart control how the heart beats. Tachycardia is caused by abnormal signals.

Risk Factors

Things that raise the risk of tachycardia are:

  • Heart problems, such as:
    • A past heart attack
    • Cardiomyopathy—heart muscle disease
    • Myocardial ischemia—poor blood flow to the heart
  • Electrolyte problems—too much or too little calcium, sodium, magnesium, or potassium in the blood
  • Hypoxemia—not enough oxygen in the blood
  • Acidosis—too much acid in the body’s fluids



Symptoms of tachycardia are:

  • Pounding heartbeats
  • Fast heartbeats
  • Lightheadedness or fainting
  • Chest pain
  • Problems breathing


The doctor will ask about symptoms and past health. A physical exam will be done.

Tachycardia is often diagnosed with an electrocardiogram (ECG). Patches are placed on the chest, arms, and legs to check heart activity.

Other tests that may be done include:

  • Holter monitor—a device worn to measure heart activity over 24 to 48 hours
  • Exercise test—to see if symptoms happen during physical activity
  • Electrophysiology study—wires are placed inside the heart to see where the abnormal rhythm starts
  • Cardiac catheterization—a tube is put through a blood vessel to check blood flow to the heart



The goal of treatment is to slow the fast heartbeats and prevent them from happening again. This includes treating any health issues that are causing the fast heartbeats.

Fast heartbeats that are life-threatening need care right away.

Care options may be:

  • Medicines to:
    • Slow the heartbeats
    • Prevent blood clots
    • Lower blood pressure
    • Treat other health issues
  • Ablation—destroys some heart tissue with cold or heat to block abnormal signals
  • Cardioversion—an electric shock reset the heart, which is used for:
  • An implantable cardiac device (ICD)—put under the skin to check heart activity and shock abnormal rhythms
Device to Correct Tachycardia
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The risk of tachycardia may be lowered by:

  • A healthful diet, daily exercise, and not smoking
  • Keeping a healthy weight
  • Avoiding or limiting caffeine and alcohol
  • Managing stress
  • Getting regular physical exams
  • Treating health problems, such as high blood pressure or high cholesterol

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.