Heart rhythm disorders

The heart has a pump function; it allows the maintenance of blood circulation, which is essential for the proper functioning of our body. The contraction of the heart muscle, which will perform this pump function, is triggered by an electric wave. Researchers and doctors at Liryc specifically study this electrical activity of the heart.


Under the effect of an electrical impulse, at a regular sinus rhythm, a heart beats between 60 to 100 beats per minute when at rest.


When we talk about heart rhythm disorders or arrhythmias, the electrical activation of the heart is abnormal. It beats too fast, too slowly or haphazardly. Arrhythmias are not always dangerous, but can be very serious. Liryc teams mainly focus on the study of three heart rhythm disorders with a high prevalence:

  • Atrial fibrillation, responsible for 20% to 30% of strokes worldwide.
  • Ventricular fibrillation, responsible for 350,000 sudden cardiac deaths in Europe or the United States.- Heart failure, responsible for 150,000 hospitalizations a year in France.

Atrial fibrillation

What is atrial fibrillation?

Atrial fibrillation is the most common arrhythmia. It affects more than 11 million people in Europe, with a projection of 14 to 17 million by 2030.


It is characterized by irregular and rapid heartbeats, caused by anarchic electrical activation of the heart. The result is an inefficient contraction of the atrium, the upper chamber of the heart (400 to 600 beats per minute), which promotes blood stagnation in the atria and the formation of blood clots.


Atrial fibrillation can occur in episodes, sometimes lasting several days, between which the rhythm of the heart is regular or permanent.


Clinicians at Liryc identified the sources of atrial fibrillation in the pulmonary veins several years ago, enabling the development of a non-pharmacological treatment.

Atrial fibrillation is very debilitating; its impact on the quality of life of those affected is as significant as that of coronary artery disease (myocardial infarction). It is the main culprit of strokes and is a risk factor for heart failure and dementia.


Atrial fibrillation manifests differently in different people, with the most common symptom being that of an irregularly felt beat.


Other symptoms to watch out for are a rapid heartbeat, chest pain, shortness of breath, severe fatigue or weakness, dizziness or fainting. Talk to your doctor if you experience any of these symptoms.

Atrial fibrillation can occur without an established apparent cause, but certain criteria may be evident:

  • Age; the risk of developing atrial fibrillation increases with age.
  • Family predispositions, in particular first-degree relatives (father or mother, brother or sister).
  • Obesity, diabetes and metabolic syndrome.
  • Cardiovascular diseases, such as high blood pressure, heart valve abnormalities, artery diseases or the after-effects of a myocardial infarction.
  • Pulmonary or respiratory diseases (embolism, pneumonia, obstructive sleep apnoea).
  • Hyperthyroidism.
  • Factors from a poor lifestyle: smoking, excessive alcohol consumption, taking drugs, excessive intensive physical activity.

The diagnosis of atrial fibrillation is made by carrying out an electrocardiogram (ECG). If atrial fibrillation is diagnosed, the patient is referred to a cardiologist to complete the assessment (blood tests, exercise ECG, polysomnography). In case of brief and inconstant heart rhythm disturbances, a “Holter ECG” may be recommended. This is an electrocardiogram involving recordings over 24 hours.

Atrial fibrillation is treated based on a diagnosis and a personalized assessment conducted by health professionals to relieve symptoms, restore sinus rhythm and prevent the risk of a stroke.


If the episode of atrial fibrillation is brief, with little or no discomfort and no risk of embolism, the doctor may decide that no treatment is required. Nevertheless, it is advisable to adopt a healthy lifestyle to limit the cardiovascular risk.


Conversely, if the patient’s medical situation requires it, the doctor will propose a treatment including:

  • Anticoagulants to prevent the formation of clots.
  • Anti-arrhythmics or cardioversion (an electric shock is sent to the heart) to regulate the heart rate.
  • Ablation of arrhythmogenic foci responsible for atrial fibrillation.


This treatment was established by clinicians at Liryc. It consists of cauterizing the areas involved in triggering fibrillation around the pulmonary veins in the heart with a catheter, introduced from the femoral vein, to exclude these sources of arrhythmia. This treatment has become the reference treatment: to date, more than 700,000 patients worldwide benefit from it each year.

Ventricular fibrillation

What is ventricular fibrillation?

Ventricular fibrillation is the most serious cardiac arrhythmia, responsible for 50,000 sudden deaths in France each year, or one death every 10 minutes.


Ventricular fibrillation manifests itself with a hyper rapid and disorganized electrical activation of the ventricles (lower chamber of the heart), with the immediate consequence of the loss of all effective cardiac contraction. The absence of intervention within three minutes is most often fatal (sudden cardiac death) or leads to irreversible brain damage.

Ventricular fibrillation causes loss of consciousness within seconds. In the absence of defibrillation, the person usually suffers a brief seizure and becomes limp and listless.

Nearly 40% of sudden deaths occur as a complication of heart disease, the most common cause being acute myocardial infarction.


Some risk factors may be:

  • Heart failure
  • The presence of a scar on the heart muscle, following myocarditis (inflammation of the myocardium) or an infarction
  • Cardiomyopathies
  • Coronary artery disease
  • A hereditary rhythm disorder (long QT syndrome, Brugada syndrome and other channelopathies)

Ventricular fibrillation is diagnosed by electrocardiography (ECG) as the cause of cardiac arrest.


Unfortunately, a large majority of people who will die suddenly do not know they are sick. The major challenge, on which Liryc’s research teams focus, is to find a way to identify them in the general population.

During an episode of ventricular fibrillation, cardiopulmonary resuscitation should be performed within a few minutes and should be followed by defibrillation, an electric shock delivered to the chest, to restore normal heart rhythm.


People successfully resuscitated after ventricular fibrillation are at high risk of having another episode. An implantable cardioverter-defibrillator (ICD) is surgically implanted in most patients to correct the arrhythmia, if it recurs. ICDs continuously monitor the heart’s rate and rhythm, automatically detect ventricular fibrillation, and deliver a shock to convert the arrhythmia back to a normal rhythm.


Liryc clinicians have located the sources of idiopathic sudden death, i.e. without known cause, in the electrical system of the heart, called the Purkinje network, enabling the implementation of an innovative curative treatment by thermo-ablation destruction of these sources of arrhythmia with a catheter introduced from the femoral vein/artery.

Heart failure

What is heart failure?

Heart failure affects nine million people in Europe, including one million in France, or one in 10 hospital admissions. It has a very strong impact on the long-term quality of life.


Heart failure is a failure of the heart pump, which becomes unable to properly ensure the propulsion of blood in the body and therefore the necessary supply of oxygen and nutrients (blood flow) for the proper functioning of the organs.


This disease results from damage to the heart muscle or its irrigation by the coronary vessels, an alteration in energy metabolism or cardiac desynchronization. An out of sync heart is a heart that has lost harmony in the propagation of electrical impulses and therefore the resulting contraction. As such, one wall can contract while another is at rest, resulting in a major loss of efficiency and progressive exhaustion.

At the onset of heart failure, the patient has no symptoms.


However, when the heart isn’t pumping well and congestion occurs, some of these symptoms can occur:

  • Increased shortness of breath, especially extensive.
  • Sudden weight gain.
  • Continuous sensation of swelling.
  • Cough or cold symptoms that last longer than a week.
  • Fatigue, loss of energy and extreme exhaustion.
  • Loss or change in appetite.
  • Increased swelling in the ankles, feet, legs, sacrum (base of the spine) or abdomen (around the stomach).
  • Need to urinate more frequently at night.
  • Cold extremities.
  • Confusion and difficulty thinking clearly.


Talk to your doctor if you experience any of these symptoms.

Heart failure mainly concerns people aged 65 or over, but it can also affect children and pregnant women.


Several causes or risk factors can cause heart failure:

  • Coronary heart disease, itself resulting from a lack of oxygenation of the heart due to a narrowing of the coronary arteries.
  • Arterial hypertension (i.e. too high blood pressure) poorly controlled by treatment.
  • Cardiac rhythm and conduction disorders, including atrial fibrillation.
  • Abnormalities of the heart valves (narrowing or insufficient sealing).
  • Diseases of the heart muscle (or myocardiopathy), genetic diseases, sometimes consecutive to an infection.
  • Lung diseases, such as obstructive pulmonary disease, pulmonary arterial hypertension.
  • Hyperthyroidism.
  • Factors of a poor lifestyle: excessive consumption of alcohol or drugs, poor diet, smoking, lack of physical exercise.
  • Obesity and diabetes.
  • Exposure to chemotherapy

The medical check-up allows the doctor to confirm heart failure, to assess its seriousness and to look for the cause.


This is both a blood and cardiac assessment: chest X-ray, electrocardiogram, cardiac ultrasound, cardiac MRI, cardiac catheterization (exploration of the heart using a probe) or coronary angiography and cardiac CT scan.

Heart failure is treated based on a diagnosis and a personalized assessment conducted by health professionals to improve quality of life, avoid episodes of cardiac decompensation (complication that occurs when the body is no longer able to compensate for heart muscle failure) and slow the progression of the disease.


The treatment includes rules of healthy eating and physical activity, as well as lifelong drug treatment.


If the heart failure is severe, with a very weakened contraction of the ventricles and an insufficiently effective drug treatment, the medical team can propose surgical interventions. Liryc clinicians have contributed to the development of cardiac resynchronization in heart failure.


This therapy consists of implanting stimulation probes in the ventricular cavities. Its purpose is to specifically correct electrical desynchronizations, so as to harmonize the contraction of the ventricles and ensure better cardiac output. Applied at an early stage of disease, it can prevent its development and worsening, and would have a major clinical and socio-economic impact.


An implantable automatic cardiac defibrillator can also be offered to monitor the rhythm of the heart and, if necessary, in the event of serious cardiac rhythm disorders, to produce an electric shock.

UN MATIN, LE COEUR DE JULIETTE, 14 ANS, S’EST ARRÊTÉ…

Juliette a été victime d’une mort subite cardiaque provoquée par un dysfonctionnement de son coeur. Grâce aux découvertes et aux innovations scientifiques de l’Institut Liryc, elle a pu être sauvée. Ne laissons pas les maladies du rythme cardiaque emporter des vies.

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