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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.

Arrhythmias

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 can have a genetic basis. Some of the most serious types of arrhythmia are inherited and affect more than one member of a family. See the BC Inherited Arrhythmia Program for more information.

Because there are so many different types and causes of arrhythmia, this heart condition varies in its effects: some types of arrhythmia are not very serious, while others may be life threatening.

 

Cardiac Services BC's heart rhythm has developed a number of resources and tools to help patients and caregivers learn more about their condition and self-manage it effectively.




Symptoms

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.

Your symptoms may depend on how healthy your heart is and the type of arrhythmia you have, including how severe it is, how often it occurs and how long each episode lasts.

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.

Treatment

Diagnosis

Common tests for heart rhythm disorders include an electrocardiogram (ECG or EKG), an exercise electrocardiogram (stress test) and a Holter or event monitor. These tests are non-invasive: information is gathered about your heart by attaching electrodes onto the skin. 

In some cases, your physician may also order an electrophysiology study. This invasive diagnostic test, performed under local anesthesia in a hospital setting, helps determine the type of arrhythmia and the best treatment options, including catheter ablation. Both electrophysiology study and catheter ablation procedures are coordinated provincially by Cardiac Services BC.

If doctors suspect a genetic cause for an arrhythmia, further medical and genetic testing may be done. In this case, testing is also offered to family members. See the BC Inherited Arrhythmia Program for more information.

Treatment

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.

Programs

In BC, there are specialized programs and clinics for certain heart rhythm conditions. They provide patients with comprehensive services, including specialist consultation, individualized treatment plans, and patient education and counselling.

  • Patients with atrial fibrillation may be referred to one of BC's atrial fibrillation clinics, where a specialist team (cardiologist, nurse and pharmacist) will work with them and their primary care provider to manage and treat their condition.
  • The BC Inherited Arrhythmia Program is a provincial program of Cardiac Services BC that brings together specialist expertise in adult and pediatric cardiology with medical genetics to identify, screen and manage patients and families affected by an inherited heart rhythm condition.

Procedures

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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SOURCE: Abnormal Heart Rhythm ( )
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