Sudden Cardiac Arrest

Sudden cardiac arrest is a life-threatening emergency in which the heart suddenly stops pumping effectively. The person rapidly loses consciousness, cannot breathe or is not breathing normally, and no pulse can be felt; immediate CPR and, if available, an AED can be lifesaving.

What is sudden cardiac arrest?

Sudden cardiac arrest is the abrupt loss of the heart’s ability to pump effectively because of a disruption in its electrical system. As a result, blood flow to the brain and other organs stops. A person may lose consciousness within seconds. This condition is different from a heart attack; in a heart attack, the problem is usually blockage of a vessel supplying the heart muscle, although a heart attack can sometimes lead to sudden cardiac arrest. If untreated, sudden cardiac arrest can be fatal within minutes. ^[1][2][3]

What are the symptoms?

The most typical signs are sudden collapse, unresponsiveness, abnormal breathing or no breathing, and absence of a detectable pulse. In some cases, chest pain, palpitations, dizziness, shortness of breath, or fainting may occur just before the event, but there may be no warning signs at all. For this reason, if a person is unresponsive and not breathing normally, emergency help should be called and CPR should be started immediately. ^[1][2]

Causes and risk factors

The most common mechanism is a life-threatening rhythm disturbance such as ventricular fibrillation. Coronary artery disease, a prior heart attack, cardiomyopathies, heart failure, certain congenital rhythm disorders, and severe electrolyte imbalances may increase risk. However, it can also occur in some people without previously known heart disease. ^[3][4]

What should be done in the first minutes?

In sudden cardiac arrest, time is the most critical factor. If the person is unresponsive, help should be called, the emergency response system activated, and CPR started immediately. If an automated external defibrillator (AED) is nearby, it should be used as soon as possible. According to the American Heart Association, early CPR and early defibrillation can significantly improve survival. ^[1][2]

Diagnosis and treatment in the hospital

Once a heart rhythm has been restored, ECG, blood tests, imaging, and rhythm evaluation are performed to identify the underlying cause. In appropriate patients, medications, procedures, or an implantable cardioverter-defibrillator (ICD) may be considered to prevent recurrent rhythm disturbances. Treatment is individualized according to the cause of the event. ^[3][4]

How is it different from a heart attack?

A heart attack develops when blood flow to the heart muscle is reduced or blocked. Sudden cardiac arrest, by contrast, is an electrical failure in which the heart stops or becomes ineffective. During a heart attack, the person may remain conscious; in sudden cardiac arrest, consciousness is usually lost quickly. Still, because a heart attack can trigger sudden cardiac arrest, the two are closely related. ^[2][3]

When is emergency help needed?

This condition is, by itself, an emergency. If a person suddenly collapses, is unresponsive, and is not breathing normally, emergency help must be called immediately, CPR started, and an AED used if available. ^[1][2]

Brief conclusion

The first minutes are lifesaving in sudden cardiac arrest. If unresponsiveness and abnormal breathing are present, rapid action with CPR and an AED is required instead of waiting. ^[1][2]

For safe assessment, symptoms should be considered together with personal risk factors; particularly if emergency warning signs are present, individualized medical evaluation should not be delayed. ^[1][2]