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What is arrhythmia?

An irregular heartbeat is an arrhythmia. A normal heart rate is 50 to 100 beats per minute, but arrhythmias and abnormal heart rates don’t necessarily occur together. Arrhythmia symptoms can occur with a normal heart rate, or with heart rates that are slow or rapid.

  • Atrial fibrillation (“A-fib”) – Atrial fibrillation, the most common arrhythmia in the world, causes the atria to contract abnormally. Approximately 2 to 3 million Americans suffer from this debilitating arrhythmia that often leads to symptoms of fatigue, palpitations and shortness of breath and can put the patient at risk for strokes.
  • Atrial flutter – This arrhythmia is caused by one or more rapid circuits in the atrium. Atrial flutter is usually more organized and regular than atrial fibrillation.
  • Atrial tachycardia – Atria tachycardia occurs when the electrical impulses that regulate the heartbeat originate in the wrong area of the heart.
  • Paroxysmal atrial tachycardia (PAT) – In PAT, the heart beats too fast because there is an abnormality in its conduction (electrical) system. Episodes of paroxysmal atrial tachycardia can be brief but sometimes can last for hours and be very serious.
  • Premature atrial contractions (PAC) – These contractions in the atria occur too early in the rhythm sequence, because abnormal electrical impulses signal the atria to beat prematurely. PAC are very common and can happen in a healthy patient.
  • Sick sinus syndrome (SSS) – Not a specific disease, SSS is a group of signs or symptoms indicating that the sinoatrial node (the heart’s natural pacemaker) is not functioning properly. Some patients with SSS also have rapid heartbeats, or the heartbeat alternates between too fast and too slow.
  • Sinus tachycardia – This arrhythmia has an elevated rate of impulses originating from the sinoatrial node, the heart’s natural pacemaker. Symptoms of sinus tachycardia are defined as a heart rate greater than 100 beats per minute in an average adult.
  • Supraventricular tachycardia (SVT) – This means that from time to time the heart’s electrical system doesn’t work properly and your heart beats very fast for a reason other than exercise, high fever or stress. Types of SVT include:
    • Atrioventricular nodal reentrant tachycardia (AVNRT) – This is the most common type of supraventricular tachycardia.
    • Atrioventricular reciprocating tachycardia (AVRT) – This occurs when there is an extra electrical pathway linking the upper (atria) and lower (ventricle) chambers of the heart.
    • Wolff-Parkinson-White syndrome – In this form of supraventricular tachycardia, an extra electrical pathway is present in the heart. It is one of the most common causes of fast heart rate problems in infants and children, and sometimes runs in families, but most people with this syndrome do not necessarily have other heart problems.
  • Ventrical arrhythmia – This condition involves abnormal rapid heart rhythms originating in the lower chambers of the heart (the ventricles), and include ventricular tachycardia (VT) and ventricular fibrillation (VF). Both are life-threatening arrhythmias, most commonly associated with heart attacks or scarring of the heart muscle from previous heart attacks.
  • Ventricular tachycardia (VT) – The symptoms of ventricular tachycardia are a fast heart rhythm originating in the lower ventricles. If left untreated, some forms of ventricular tachycardia may get worse and lead to ventricular fibrillation, a condition that can be life-threatening.
  • Ventricular fibrillation (VF) – This occurs when there is uncoordinated contraction of the cardiac muscle of the ventricles that makes them quiver rather than contract properly. This activity is not felt by the patient.
  • Premature supraventricular contractions – These premature contractions originate from the ventricles and occur before the regular heartbeat.


These may include fatigue, palpitations, too fast or two slow heartbeat, shortness of breath and heart attacks.


Depending on the specific condition, arrhythmias may be caused by:

  • Abnormal contractions of the atria (the heart’s upper chambers) or ventricles (lower chambers)
  • Rapid circuits in the atria
  • Electrical impulses originating in the wrong area of the heart
  • Abnormality in the heart’s conduction (electrical) system
  • Malfunction of the sinoatrial node (the heart’s natural pacemaker)
  • An extra electrical pathway is present
  • Scarred tissue from previous heart attacks

Risk factors

Arrhythmias are very common in older adults, most seriously in those over 60, and the number of incidences is increasing. One factor is that older adults often have heart disease and other health problems that can lead to arrhythmias. They may also be more reactive to the side effects of medicines, some of which can cause arrhythmias.

Some types of arrhythmia, such as paroxysmal supraventricular tachycardia (PSVT), including Wolff–Parkinson–White syndrome, are more frequent in children and young adults.

Arrhythmias are more common in people who have had heart attacks, heart failure, cardiomyopathy, abnormal heart tissue, leaking or narrowed heart vessels, congenital heart defects, high blood pressure, heart infections, diabetes, sleep apnea, thyroid problems, heart surgery, cocaine or amphetamine use, and blood chemical imbalance.


Patients who require an electrophysiology study often have symptoms of heart palpitations, shortness of breath, fainting or chest pain. In this test, insulated electric catheters are placed inside the heart to study its electrical system. A small catheter (hollow tube) is inserted through the groin or neck into the heart. This gives the physician the ability to find the origin of an arrhythmia (any abnormal electrical activity) within the heart tissue and determine the best way to treat it. Types of electrophysiology study include:

  • Holter monitor – a machine, worn for 24 to 48 hours, that continuously records the heart’s rhythms during normal activity
  • Loop recorder – a similar device that is worn for two weeks or longer
  • Tilt table studies – a test for people who experience fainting (syncope); the patient lies on a flat table and is tilted at various angles while heart rate and blood pressure are monitored closely
  • T-wave alternans study – the patient undergoes an electrocardiogram, where electrodes are placed on the body to record the electrical activity of the heartbeat, and any differences between beats are measured