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Abnormal Heart Rhythm

The heart has a built-in pacemaker that sends out electrical impulses, causing the heart’s chambers to rhythmically contract and relax in a coordinated way.

Problems with this electrical system can cause the heart to beat too slowly, too fast, in a disorganized way, or to stop suddenly.


Abnormalities of heart rate and/or rhythm are called arrhythmias. Types of arrhythmia include:

  • bradycardia: when the heart beats too slowly (fewer than 60 beats per minute) and reduces the amount of blood reaching the body and brain
  • tachycardia: when the heart beats too quickly (more than 100 beats per minute)
  • atrial fibrillation: when there is a lack of electrical coordination in the upper heart chambers. This is the most common form of arrhythmia and it increases the risk of stroke
  • ventricular fibrillation: when there is a lack of electrical coordination in the lower heart chambers. This is the rarest but more serious form of arrhythmia because it can lead to sudden cardiac arrest.

The causes of arrhythmia can also vary:

  • Some people are born with a structural abnormality in their heart that causes an arrhythmia.
  • Some people develop a heart rhythm problem due to other health conditions such as high blood pressure or heart disease.
  • Sometimes an arrhythmia has a genetic basis and affects more than one member of a family.  See theBC Inherited Arrthythmia Programfor more information.

Cardiac Services BC has developed resources and tools to help patients and caregivers.

Video Resources



Symptoms of arrhythmia vary from person to person. Some arrhythmias don't have any warning signs and are only discovered through medical or genetic testing.

Symptoms of arrhythmia may vary, depending on how healthy your heart is, the type and severity of the arrhythmia, and the frequency of arrhythmia. Some arrhythmias do not have symptoms and are discovered through medical or genetic testing.

A too-slow heartbeat can make you feel tired, short of breath, dizzy or faint. A heartbeat that is too fast can feel like a strong pulse in your neck or a fluttering, racing beat in your chest. You may also feel discomfort in your chest, weakness, shortness of breath, faint, sweaty or dizzy. If you have any of these symptoms, see your doctor immediately.



Common diagnostic tests for heart rhythm disorders include:

  • electrocardiogram (ECG or EKG)
  • exercise electrocardiogram (stress test)
  • Holter or event monitor
  • electrophysiology study
If a genetic cause for an arrhythmia is suspected, further medical or genetic testing may be done on the patient and family members. 


Treatment will depend upon the type and severity of the arrhythmia. Many arrhythmias are treatable with lifestyle changes, medications, and non-surgical techniques. For some people, invasive or surgical procedures offer the best option to restore a normal heart rhythm.


In BC, specialized programs and clinics provide heart rhythm patients with access to healthcare teams, treatment plans, education and counselling. See a list of Clinics here.


A number of procedures are used to treat heart rhythm problems. These procedures are performed in hospital and may involve either surgical or minimally-invasive techniques (e.g. catheterization).

An implantable cardiac rhythm device is used to regulate an irregular heartbeat by sending electrical signals to the heart to alter its rhythm. 

These devices are surgically implanted under the skin, typically just below the collarbone. A small, battery-operated computer generates the electrical signal (pulse generator), which is transmitted to the heart via one or more electric wires (leads).

There are three main categories of implantable cardiac rhythm device.

Permanent pacemakers 

These deliver specifically timed, low-energy electrical impulses to the heart. Pacemakers help maintain adequate heart rate when the heart rate is not fast enough (bradycardia) or there is a block in the heart's electrical conduction system (heart block).

Cardiac resynchronization therapy (CRT) pacemakers 

Also called biventricular pacemakers, these have at least two leads implanted in the heart to simultaneously stimulate both the left and right lower chambers (ventricles) to make them contract at the same time. A third lead may be implanted to coordinate the upper (atria) and lower chamber contractions.

Implantable cardioverter-defibrillators (ICD) 

These act as a permanent safeguard that corrects sudden, life-threatening arrhythmias with high-energy pulses (cardioversion or defibrillation). ICDs are used in people who are at high risk for having a potentially life-threatening heart rhythm (ventricular tachycardia or ventricular fibrillation) or who have survived such an event. Some CRT pacemakers have additional ICD capacity to provide additional protection if required.


Catheter ablation is an invasive procedure that targets faulty electrical tissue in the heart. It is used primarily to treat people with atrial fibrillation or rapid heartbeat. In most cases, the diagnostic test (electrophysiology study) and the treatment (cardiac ablation) are performed as part of the same procedure.

During the diagnostic electrophysiology study, special catheters (thin flexible tubes) are inserted through a vein in your arm, groin or neck and guided to your heart. The procedure involves triggering certain heart rhythms and mapping the electrical activity of the heart cells. This helps pinpoint the abnormal tissue causing the arrhythmia. Based on this information, doctors will decide whether catheter ablation would be useful to treat the arrhythmia. If so, the treatment will proceed immediately.

During catheter ablation treatment, a special catheter is placed in the dysfunctional area identified by the electrophysiology study. The catheter then uses heat or cold to damage the tissue. The resulting scar (ablation) creates a barrier that isolates the faulty electrical section from healthy heart tissue. This prevents abnormal electrical signals from traveling to the rest of the heart and causing arrhythmias.


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