The normal heart rate is 60 to 100 beats heart minute, regularly. It is also normal for the number of heartbeats to accelerate in response to physical exertion or in the event of disruption of the thyroid gland, for example. An arrhythmia occurs when the heart irregular beats or if he beats less than 60 heartbeats or more than 100 heartbeats per minute, without any justification.
Arrhythmia is the most common heart condition. In an arrhythmic heart, the electrical impulses that control the heartbeat occur disorderedly or do not pass through the usual electrical circuits.
The duration of an arrhythmia varies greatly from one individual to another and also depends on the type of arrhythmia.
Note. There are a multitude of forms of arrhythmia, and not all of them are described in this chart.
How does the heart beat?
Normally, the signal of a heartbeat starts from a point called a sino-atrial node, located at the very top of the heart’s right atrium (see diagram). This signal causes the auricles to contract and pump blood into the ventricles. The electrical signal then goes to the atrioventricular node, located between the atria, then to the His bundle, a type of cardiac fibers located between the ventricles and thence to the ventricles, which then contract and pump blood into the arteries. It is the contraction of the ventricles that produces the pulse.
The different types of arrhythmia
The arrhythmias are categorized depending on where they originate the atrium or ventricle depending on the effect they produce or the acceleration or deceleration of the heartbeat. The tachycardia corresponds to an increased heart rate, bradycardia a decrease.
- Tachycardias or increased heart rate
- It is called tachycardia when the heart beats at a rate greater than 100 beats per minute.
Some Tachycardias occur in the atria. The most common forms are:
Atrial fibrillation. It is the most common type of arrhythmia. It occurs most often after age 60 in people with high blood pressure or a heart condition. It is usually due to wear of the conductive tissue of the heart. Up to 10% of people aged 80 and over suffer from it. Atrial fibrillation periods can last from minutes to hours. Often, fibrillation is even permanent. A fibrillating atrium can contract at the rate of 350 to 600 times per minute (fortunately, the ventricles do not beat as quickly as some of these disordered impulses are stuck en route). This type of arrhythmia can be dangerous. The blood is no longer circulating properly. If he stagnates in the atrium, ablood clot can form, migrate to the brain and risk causing a stroke;
Atrial flutter. This type of arrhythmia is similar to atria fibrillation, although the heartbeat is more structured and a little slower in this case, at about 300 per minute;
Supraventricular tachycardia. There are several forms. It usually causes 160 to 200 contractions per minute and can last from a few minutes to a few hours. It occurs more in young people and does not usually put life at risk. The most common is paroxysmal supraventricular tachycardia or Bouveret’s disease (a kind of short circuit is created and stimulates the ventricles very quickly and regularly). The Wolff-Parkinson-White syndrome is another form. It occurs when electrical impulses pass from the atrium to the ventricle without passing through the atrioventricular node;
Sinus tachycardia. It is characterized by an increase in heart rate beyond 100 beats per minute. Sinus tachycardia is normal in a healthy heart after physical exertion, in case of dehydration, stress, consumption of stimulants (coffee, alcohol, nicotine, etc.) or certain medications. It may, however, be a sign of a major health problem in the heart, such as pulmonary embolism or heart failure;
Extrasystole auricular. An extrasystole is a premature contraction of the heart, usually followed by a longer break than normal. The extrasystole sometimes slips between normal pulsations, without altering their succession. It is normal to have some of them a day. With age, they are more common, but often remain harmless. However, they can be caused by a health problem (heart or other). The atria extrasystole originates in the atrium, while the ventricular extrasystole (see below) originates from the ventricles.
Other tachycardias occur in the ventricles, that is, in the lower chambers of the heart:
Ventricular tachycardia. This is a regular but very fast beating of the ventricles, ranging from 120 to 250 contractions per minute. It often occurs at the site of a scar left by previous surgery or weaknesses due to heart disease. When the periods last several minutes, they can degenerate into ventricular fibrillation and require emergency intervention;
Ventricular fibrillation. These rapid and disorganized contractions of cardiac ventricles constitute a medical emergency. The heart cannot pump anymore and the blood is no longer circulating. Most people lose immediate knowledge and require immediate medical assistance, including cardiopulmonary resuscitation. The heart rate must be restored with a defibrillator; otherwise the person dies in minutes;
Long QT syndrome. This problem refers to the length of the QT space on an electrocardiogram (ECG), the time between charging and electrical discharge of the ventricles. It is often caused by a genetic disorder or a congenital malformation of the heart. In addition, the side effects of several drugs can cause this syndrome. It causes accelerated and irregular beats of the heart. It can lead to loss of consciousness and even sudden death;
Extrasystole ventricular. Premature contraction may occur in the ventricles. The ventricular extrasystole is more common than the atria one. As for the atria extrasystole, it can be innocuous in a healthy heart. However, it is necessary to explore further when it is very common.
Bradycardia or decreased heart rate
There is bradycardia when the blood circulates at less than 60 beats per minute. A slower heart rate than normal does not necessarily put life at risk. It can even be a sign of excellent heart health. Some athletes, for example, have a resting heart rate of 40 beats per minute and are physically fit.
On the other hand, in cases where the heart cannot adequately supply the organs with oxygen, it is called symptomatic bradycardia. The following forms are the most common:
Dysfunction of the sino-atrial node. This usually causes a heartbeat less than 50 per minute. The most common cause is scar tissue that disrupts or replaces the sinoatrial node;
Atrioventricular block. This lacks of transmission of electrical impulse (slowing down, occasional interruptions or complete interruption) between the atria and the ventricles causes a slowing of the heartbeat.
Causes of Heart Rhythm Disorder
The causes of cardiac arrhythmia are multiple and include the following:
- Normal aging;
- Abuse of tobacco, alcohol, coffee or any other exciting thing; cocaine use;
- Arteriosclerosis and atherosclerosis;
- Taking certain medicines;
- Broncho-pneumopathies (problems of the respiratory system);
- Pulmonary embolism;
- Coronary insufficiency leading to a lack of oxygenation of the heart tissue.
- Possible complications
Certain types of arrhythmia increase the risk of complications such as:
- A cerebrovascular accident (CVA);
- Heart failure
- A loss of consciousness (rarely, some types of arrhythmia only).
When to consult a doctor?
Contact emergency services immediately if you experience symptoms such as palpitations, chest pain or shortness of breath, unexpectedly and unexplained.
Symptoms of Arrhythmia
Heart arrhythmia does not always cause symptoms. On the other hand, experiencing symptoms does not necessarily mean that the problem is serious. Some people have several signs of arrhythmia without having serious problems, while others have no symptoms, despite significant heart problems:
- Loss of consciousness;
- Irregularity of the pulse, slow or fast pulse;
- Drop in blood pressure;
- For certain types of arrhythmia: weakness, shortness of breath, chest pain.
People at risk
People suffering from a genetic abnormality, a heart disorder, diabetes, hypertension, a thyroid problem or sleep apnea;
- People under certain medications;
- People who suffer from obesity;
- People abusing alcohol, tobacco, coffee or any other exciting.
Can we prevent?
To keep a healthy heart, it is essential to adopt a healthy lifestyle: eat healthy, do physical activity (the benefits of light to moderate physical activity, such as walking and gardening, even has been demonstrated in people aged 65 years and older1), refrain from smoking, consume alcohol and caffeine (coffee, tea, soft drinks, chocolate and some over-the-counter medications), reduce the level of stress.
Note that it is better to consult your doctor before starting any new physical activity or to make major changes in your lifestyle.
To learn more about how to preserve a healthy heart and blood vessels, see our Cardiac Disorders and Hypertension fact sheets.
To better diagnose an arrhythmia and understand its origin, several tests may be useful.
Electrocardiogram: recording of the electrical activity of the heart;
Cardiac Holter: A portable device that continuously records the electrocardiogram for at least 24 hours;
Exercise test: recording of the electrocardiogram during a period of physical exercise;
Echo cardiogram: ultrasound of the heart. Sound waves are used to obtain an image of the structures of the heart.