I’cardiac arrest is defined by a cessation of mechanical activity of the heart which leads to the suspension of blood circulation as well as the interruption of the supply of blood (and therefore oxygen) to vital organs. In the absence of treatment, cardiac arrest leads to death with 90% mortality when no emergency action is taken quickly.

Cardiac arrest is a absolute medical emergency which requires rapid treatment (within minutes of the first symptoms) by cardiovascular resuscitation. The occurrence of such an event in a hospital environment (30% of cases) or in the presence of at least one witness who can provide first aid treatment are good prognostic factors.

A heart attack is a term generally used to designate a myocardial infarction. The latter is caused by a circulatory problem (blockage of a vessel that supplies blood to the heart) which can cause irreversible heart damage. It is most often the consequence of a coronary disease linked to atherosclerosis.

On the other hand, cardiac arrest refers to the mechanical arrest of the heart that has an electrophysiological origin (electrical heart rhythm dysfunction). It may be related to heart or respiratory disease.

Here again, the sudden death and cardiac arrest have different definitions. Indeed, sudden death corresponds to a natural death occurring suddenly and unexpectedly within 24 hours of the first signs. It is the first and last symptom of the underlying disease (if there is one). Sometimes it remains totally unexplained. Sudden death involves cardiac arrest. In the vast majority of cases, it is the consequence of a ventricular heart rhythm disorder (most often related to coronary artery disease).

THE causes of cardiac arrest are different in adults, children and infants

In adultscardiac arrest can be the result of:

• A myocardial infarction in a context of coronary heart disease in 15% of cases (most often linked to atherosclerosis);
• A heart rhythm disorder (ventricular fibrillation, bradycardia…);
• A malformation of the heart Or cardiomyopathy (enlarged heartr, arrhythmogenic dysplasia of the right ventricle, dilated cardiomyopathy, etc.);
• congenital heart disease ;
• Acute myocarditis ;
• A pulmonary embolism;
• A digestive haemorrhage ;
• A trauma ;
• Acute respiratory distress syndrome (ARDS);
• A metabolic or electrolyte disorder (such as hypokalaemia for example);
• Various respiratory disorders such as airway obstruction, drowninga infectiona smoke inhalation…;
• An intoxication (like a medication overdose).

In infants and children, cardiac arrest is rarer. It is most often the consequence of:

• Respiratory failure due to various disorders of the respiratory system such as airway obstruction, drowning, infection, sudden infant death syndromesmoke inhalation…
• A arrhythmiaresulting from a channelopathy or a cardiac abnormality underlying structure.

Some people are at higher risk of cardiac arrest such as patients who:

• have ever had a heart attack (myocardial infarction) or cardiac arrest;
• suffer fromheart failure ;
• have a family history of cardiac arrest(s);
• have a heart or respiratory disease that could lead to cardiac arrest. People who have severe heart failure (with a particularly low ejection fraction) or those with advanced coronary disease (with angina at rest particular) are particularly at risk.

Cardiac arrest can be manifested by the following symptoms:

• Signs of myocardial infarction: intense pain in a “vice” behind the sternum or even intermittent pain in the chest radiating to the neck, jaw, or armfeelings of oppression, nausea and digestive disorders…;
• A shortness of breath which intensify until cardiac arrest;
• A difficult breathing even a lack of breathing ;
• A faintnessdizziness, vertigo…;
• A hiccup;
• Sweats;
• Of the palpitationsand the racing heart.

These warning signs can be followed by a loss of consciousness.

THE first signs of cardiac arrest can be painful and intense (pains in the chest, palpitations, nausea…). Nevertheless, thereafter the patient does not suffer any more. Indeed, the drop in blood pressure (low blood pressure) results in a gradual decline in consciousness leading to loss of consciousness and coma.

After the crisis, each minute without treatment decreases the victim’s chances of survival by 10%. Beyond 5 minutes of heart failure, brain damage are irreversible. Beyond 12 minutes, if no action (cardiac massage or defibrillation) is performed, the risk of death is maximal.

The survival rate for cardiac arrest in France is 5% ; it is 4 to 5 times higher in countries where public places are equipped with automated external defibrillators and the population trained in lifesaving gestures. Since May 2007, the law authorizes any citizen to use a defibrillator.

During a cardiac arrest, oxygen is no longer supplied to the body’s cells (due to the cessation of blood circulation). The tissues become necrotic and the vital organs no longer function (we speak of ischemia). The main consequence is cellular suffering and the formation of particularly harmful edemas in the brain, which swells and becomes compressed in the cranial box (intracranial hypertension). As a result, a significant proportion of successfully resuscitated patients suffer from significant brain dysfunction in the short, medium and sometimes long term. It can be vigilance disorders as well as convulsions.

In the event of a heart attack, you must adopt 3 first aid gestures in order to increase the chances of survival :

1- CALL 15 (SAMU)

The first thing to do is to call the emergency services by dialing 15 where the 112.

The first resuscitation maneuver consists of immediately performing a heart massage.

Look around you if you see a defibrillator. Ask other people if necessary. If you find a defibrillator use it as soon as possible.

In case of cardiorespiratory arrest, ECG Or electrocardiogram shows a flat trace, which means that there is no more electrical activity in the heart and therefore no more heartbeat.

Several examinations are used to assess the risk of cardiorespiratory arrest (electrocardiogram (ECG), echocardiogram, chest X-ray, stress test, etc.).

In the event of cardiac arrest, the patient should be admitted to cardiopulmonary resuscitation as quickly as possible to increase the chances of survival. The purpose of intensive care is to restart the beating of the heart in order to compensate for the stoppage of blood circulation. They may include:

• defibrillation (by electric shock) for “shockable” rhythm disorders (ventricular fibrillation or ventricular tachycardia).
• Early administration of adrenaline for non-shockable rhythms.
• When possible, the primary cause treatment. Complementary examinations can be carried out in order to detect this cause (such as a coronary angiography because of myocardial infarction).
• Care after resuscitation.