Inside the heart there is a cluster of cells called the sinus node*A cluster of cells located in the heart. Its depolarization controls normal cardiac rhythm (sinus rhythm)., which functions like a metronome: its electrical impulses dictate the rhythm of cardiac contractions. Basically, an arrhythmia occurs when these electrical discharges do not originate exactly from the sinus node or do not follow the usual circuit.
The most common cardiac rhythm disturbance, atrial fibrillation*A common cardiac rhythm disturbance that occurs when the atria and the ventricles of the heart beat irregularly and non-synchronously., is characterized by an irregular, even chaotic, heartbeat which is usually too rapid. More detailed explanations about this specific pathology can be found on this website in a series of four videos.
When the arrhythmia accelerates the heart rate, it is called tachycardya*A cardiac rhythm disturbance characterized by a rhythm that is too fast. (from the Greek, tachy = rapid); if the heart rate slows, it is called bradycardya*A cardiac rhythm disturbance characterized by a rhythm that is too slow. (brady = slow).
Symptoms of Cardiac Arrhythmia
Sometimes the problem goes unnoticed. When symptoms appear, they generally include palpitations, dizziness, discomfort in the chest (pressure), shortness of breath, unusual sweating, and a feeling of weakness, alongside a reduction in physical performance. In some cases, people can also lose consciousness.
The severity of symptoms and point at which they are noticed can vary greatly from person to person. In addition, cardiac arrhythmia can manifest in a temporary or intermittent fashion (for several days or longer).
Causes of Heart Rhythm Disturbances
The causes are often difficult to pinpoint as this is a group of complex conditions. There is often an underlying cardiovascular issue (for example high blood pressure, coronary artery disease*Heart disease, also called coronary artery disease or coronary heart disease, is a disease of the coronary arteries, the arteries that transport blood to the heart., a previous heart attack*Heart attacks occur when there is a partial or complete obstruction of a coronary artery. The part of the heart connected to this artery stops receiving oxygen, and so can necrotize and die. Heart attacks are also known as myocardial infarctions., or heart failure*A general term that refers to disorders that affect how the heart works.), that requires targeted treatment. In young patients, a genetic cause or even heightened anxiety may be suspected. In some cases, the arrhythmia may be linked to a hormone disorder, in particular abnormal function of the thyroid gland (hyperthyroidism*Hyperthyroidism is when the thyroid gland produces too much of the thyroid hormones.).
Finally, arrhythmia can also be caused by drinking too much caffeine or alcohol, taking too many drugs or medications (such as laxatives), obesity, and sleep apnea.
It is difficult to identify specific risk factors for cardiac arrhythmia because of the wide variety of different causes. We know that one of the most common forms of the disease, atrial fibrillation, occurs more frequently in men. In our industrialized societies, a link has also been demonstrated between cardiac arrhythmia and old age, in addition to leading a sedentary lifestyle leading to obesity. It also seems that consuming tobacco and/or alcohol and stress can make you more likely to experience a heart rhythm disorder.
Traitements de l’arythmie cardiaque
Defibrillation*A medical technique used to treat certain cardiac rhythm disorders. Two electrodes placed on the patient’s chest administer a set electrical current that “resynchronizes” the heart’s normal activity. is a common treatment technique. Two electrodes are either stuck to the patient’s chest or held there manually to administer a set level of electrical current that “resynchronizes” the heart’s normal activity. This treatment doesn’t address the initial cause of the arrhythmia however, and the patient may experience a relapse if other steps are not taken.
Antiarrhythmic*Drugs used to treat heart rhythm problems (cardiac arrhythmia). drugs can be prescribed to regulate the heart rhythm. In cases of atrial fibrillation, other drugs are used to quickly dilate the vessels or thin the blood (anticoagulants).
In some cases, the focus of the cardiac arrhythmia needs to be destroyed. This operation is performed using an electrode catheter that sends a high-voltage current to the exact location in the heart where the arrhythmia originated. This is called radiofrequency ablation*A medical technique used in cardiology to treat certain cardiac rhythm disorders..
Progression and Possible Complications
Although it may not have any serious consequences, cardiac arrhythmia often affects quality of life. In some cases, without treatment a vicious circle can occur. The activity of the heart’s muscle fibers is no longer coordinated, and so the entire mechanism of the heart can become progressively weaker, potentially leading to heart failure.
One possible complication of atrial fibrillation, the most common form of cardiac arrhythmia, is reduced blood flow, which can cause coagulation and therefore clotting. If a blood clot becomes detached, it is released into the blood flow and can obstruct a vessel. This is called an embolism*The obstruction of the blood flow by a clot, which can cause a stroke. and can trigger a stroke. Atrial fibrillation increases your risk of a stroke fivefold.
Most symptomatic cardiac arrhythmias can however be treated using medication or a cardiology procedure using a cardiac catheter.
Preventing Heart Rhythm Disorders
There are some simple things you can do to bring your heart rhythm back to normal, for example if you experience supraventricular tachycardia*Abnormal acceleration of the heart rhythm that originates in the upper chambers of the heart (atria).. Referred to as vagal maneuvers*A set of actions you can take to stimulate the vagus nerve (for example performing carotid massage, applying eyeball pressure, or yawning)., they stimulate the vagus nerve which, among other things, helps regulate the cardiac rhythm. These maneuvers include carotid*The artery located in the chest and neck that supplies blood to most of the head and part of the neck. massage and a forced exhalation (Valsalva*Manœuvre d'équilibrage permettant d'équilibrer la pression entre l'oreille externe et l'oreille moyenne elle implique de se boucher le nez, de fermer la bouche et de faire monter la pression pulmonaire. maneuver). You can also simply apply pressure to your closed eyes, or drink a large mouthful of cold, ideally sparkling, water.
Maintaining a healthy lifestyle, in particular through physical activity (but not to excessive levels), keeping coffee and alcohol consumption at moderate levels, and limiting exposure to stressful situations, is the key to preventing cardiac arrhythmia in general.
When Should You Contact the Doctor?
It is important to distinguish between increases in heart rate with rational, harmless causes (such as physical exertion) and those accompanied by unusual and significant symptoms in addition to the palpitations.
A temporary loss of consciousness (syncope*Syncope is a brief loss of consciousness due to reduced blood flow to the brain. Syncope is often accompanied by a fall.) can occur when your pulse drops below 30 beats per minute or, in the opposite case, when your heart rate speeds up significantly. The person normally regains consciousness quickly when placed in a horizontal position (with their feet raised, if possible). If they do not regain consciousness this constitutes a medical emergency and first aid is required immediately.
Care at Hôpital de La Tour
Firstly, the patient’s pulse will be taken. Their medical history will be consulted for additional information and an electrocardiogram*A test that uses electrodes and studies the electrical activity of the heart, can detect whether the patient has had a heart attack, and if there is insufficient blood supply to the heart. (ECG) should help determine a diagnosis.
To perform an ECG, the doctors place ten electrodes on the patient’s chest, arms, and legs. The electrical signals from the heart are recorded in the form of lines that can be interpreted.
Temporary arrhythmias are not always detected using this method, so an ECG can be performed continually over a 24- or 48-hour period using a connected portable ECG monitor or, only very recently, widely available smart devices such as watches. Other examinations can be performed if needed, including:
- Exercise ECG*A test used to observe variations in heart activity, heart rate, and blood pressure while the patient exercises on a treadmill or bike. (on a stationary bike or treadmill),
- Electrophysiological study*A test that aims to determine the exact nature of the cardiac rhythm disorder. (a catheter equipped with a probe is inserted into a vein in the groin),
- Echocardiogram*A medical imaging technique that uses ultrasound to perform a scan of the heart. (an ultrasound medical imaging technique),
- Magnetic resonance imaging*Technique d'imagerie médicale permettant d'obtenir des vues en deux ou en trois dimensions de l'intérieur du corps. (MRI).