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Electrical System and Chambers of the Heart  
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Definition  

Tachycardia is a rapid heart rate of more than 100 beats per minute. Sinus tachycardia, from the heart's sinus node, is a normal response to exercise, illness, or stress.

There are several types of abnormal tachycardias or arrhythmias . These can come from two places:

  • Atria (the two smaller chambers on the top of the heart)—called supraventricular tachycardias
  • Ventricles (the lower chambers of the heart)—called ventricular tachycardia

This condition can be life-threatening, but it can be treated. If you think you or someone you know has this condition, call for emergency medical services right away.

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Causes  

This condition is caused by abnormal electrical impulses that control the heart.

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Risk Factors  

Factors that may increase your chance of tachycardia include:

  • Heart disease, especially a prior heart attack
  • Cardiomyopathy —damage to the muscle wall of the lower chambers of the heart
  • Electrolyte abnormalities—too much or too little calcium, sodium, magnesium, and potassium in the blood
  • Myocardial ischemia—insufficient blood flow to heart muscle tissue
  • Hypoxemia—not enough oxygen in the blood
  • Acidosis—too much acid in the body’s fluids
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Symptoms  

Tachycardia may cause:

  • Heart palpitations
  • Fast heart rate
  • Lightheadedness
  • Fainting or near fainting
  • Chest pain
  • Shortness of breath
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Diagnosis  

Your doctor will ask about your symptoms and medical history. A physical exam will be done.

Tests may include:

  • Electrocardiogram (EKG) to assess electrical activity of the heart
  • Holter monitor or event monitor —an ambulatory monitor to record your heart rhythm
  • Exercise test —particularly if the symptoms occur during physical activity
  • Electrophysiology study —an invasive test where monitoring wires are placed inside the heart and the heart's conduction system is tested directly
  • Cardiac catheterization —a tube-like instrument inserted into the heart through a vein or artery (usually in the arm or leg) to detect problems with the heart and its blood supply
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Treatment  

Talk with your doctor about the best treatment plan for you. Treatment options include the following:

Medications  

Medications to treat tachycardia include:

  • Beta-blockers
  • Calcium channel blockers
  • Anti-arrhythmics

Ablation  

Ablation is done during an electrophysiology study. Radiofrequency energy or cold energy is used to destroy the abnormality and possibly cure the problem.

Cardioverison  

An electric shock is applied to the heart to stop the abnormal rhythm. This treatment may be done for life-threatening rhythms, such as ventricular tachycardia or ventricular fibrillation . It is also done for milder arrhythmias, such as atrial fibrillation .

Device to Correct Tachycardia  
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Implantable Cardioverter Defibrillator (ICD)  

An ICD can be surgically placed into your body. This device monitors your heartbeat. It can apply a shock to correct an irregular heartbeat.

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Prevention  

To help reduce your chance of tachycardia: