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Abnormal Heart Rhythms

An arrhythmia is a disorder of the heart rate (pulse) or heart rhythm, such as beating too fast (tachycardia), too slow (bradycardia), or irregularly. Alternative names include Dysrhythmias, Abnormal heart rhythms, Bradycardia and Tachycardia

Causes of Arrythmias

Arrhythmias are caused by problems with the heart's electrical conduction system. Other areas of the electrical system may also send out signals. Other times, electrical signals are not able to move as easily or at all. Problems can occur anywhere along this conduction system, causing various arrhythmias. Examples include:

  • Atrial fibrillation (AF) or flutter 
  • Atrioventricular nodal reentry tachycardia (AVNRT) 
  • Heart block or atrioventricular block 
  • Multifocal atrial tachycardia 
  • Paroxysmal supraventricular tachycardia 
  • Sick sinus syndrome 
  • Ventricular fibrillation 
  • Ventricular tachycardia -- a fast heart rate that originates in the lower chambers (ventricles) 
  • Wolff-Parkinson-White syndrome 

The risk of getting a tachycardia (beating too fast) or bradycardia (beating too slow) varies greatly, depending on:

  • Blood chemistry imbalances, such as abnormal potassium levels 
  • Cardiomyopathy -- a weakening of the heart muscle or a change in the heart muscle 
  • Heart failure 
  • Overactive thyroid gland 
  • Past heart attack 

Arrhythmias may also be caused by some substances or drugs, including:

  • Amphetamines 
  • Caffeine 
  • Cocaine 
  • Beta blockers 
  • Psychotropics 
  • Sympathomimetics 

Sometimes anti-arrhythmic medications -- prescribed to treat one type of arrhythmia -- can actually cause another type of arrhythmia.

Symptoms of Irregular Heart Rhythm Disorders

An arrhythmia may be present all of the time or it may come and go. You may or may not feel symptoms when the arrhythmia is present. Or, you may only notice symptoms when you are more active. Symptoms can be very mild when present, or they may be severe or even life-threatening.
Common symptoms include:

  • Chest pain 
  • Fainting 
  • Fast or slow heartbeat (palpitations) 
  • Light-headedness, dizziness 
  • Paleness 
  • Shortness of breath 
  • Skipping beats - changes in the pattern of the pulse 
  • Sweating 

Signs and tests

The doctor will listen to your heart with a stethoscope and feel your pulse. Your blood pressure may be low or normal. The following tests may be performed to identify arrhythmias:

  • Ambulatory cardiac monitoring with a Holter monitor (used for 24 hours), event monitor, or loop recorder (worn for 2 weeks or longer) 
  • Coronary angiography 
  • ECG 
  • Echocardiogram 
  • Electrophysiology study (EPS)