Health and Fitness

Sudden Cardiac Arrest: Symptoms, Causes, And Consequences

Sudden cardiac arrest (ACI) is a condition in which the heart suddenly and unexpectedly stops beating. When it occurs, blood stops reaching the brain and other vital organs.

ACI typically causes death if left untreated within a few minutes.

To understand cardiac arrest, you first need to understand how the heart works. The heart has an electrical system that controls the speed and rhythm of the heartbeat. Problems with the electrical system can cause irregular heartbeats, called arrhythmias.

There are various types of arrhythmias, but basically, the heart can beat

  • Too fast ( tachycardia ),
  • Too slowly ( bradycardia ),
  • Or irregularly.

Some arrhythmias make the heart-pumping action ineffective and these arrhythmias cause ACI.

Patients with heart disease are the people at greatest risk of sudden cardiac arrest, which however can also affect apparently healthy individuals with no known heart disease or other risk factors.

Most ACI victims die, often within minutes. In some cases, prompt treatment with a defibrillator can be life-saving (a defibrillator is a device that sends an electric shock to the heart in an attempt to restore a normal rhythm).

Differences between cardiac arrest and heart attack

It is good to clarify immediately that cardiac arrest is not synonymous with a heart attack: a heart attack occurs when the blood supply to part of the heart muscle is blocked ( heart attack ). Generally, the heart does not stop beating suddenly during a heart attack, but it can still occur after or during recovery from a heart attack.


Ventricular fibrillation (VF), a specific form of arrhythmia, is the cause of most cases of sudden cardiac arrest.

During ventricular fibrillation, the ventricles (the lower chambers of the heart) do not pulse normally. Rather they tremble very quickly and irregularly. In these cases, the heart is practically unable to pump blood into the circulation. This is a fatal arrhythmia unless treated within minutes.

Other problems with the heart’s electrical system can also cause it to stop suddenly. For example, an extreme slowdown in electrical activity can lead to arrest and cause ACI, which can also depend on the heart muscle’s failure to respond to electrical impulses.

Certain diseases and conditions can cause electrical problems that lead to ACI. I am an example of this

  • Coronary heart disease,
  • Severe physical stress,
  • Some congenital disorders
  • And structural changes of the heart.

Several research activities are underway in an attempt to establish the exact causes of cardiac arrest and how to prevent it.

Coronary heart disease

Coronary heart disease is a disease marked by the accumulation of a waxy substance, the so-called plaque, inside the coronary arteries, the vessels that carry oxygenated blood to the heart muscle.

The plaques narrow the coronary arteries and reduce blood flow to the heart. Part of the plaque can then split, causing the formation of a free clot capable of partially or totally blocking the flow of oxygenated blood to the part of the heart muscle fed by the artery, thus triggering a heart attack.

During a heart attack, some muscle cells die and are replaced by scar tissue. Scar tissue damages the heart’s electrical system. As a result, electrical signals can be distributed abnormally. These heart changes increase the risk of life-threatening arrhythmias and ACI.

Coronary heart disease appears to be the leading cause of ACI in adults, but many people have no signs or symptoms of coronary heart disease prior to cardiac arrest.

Physical stress

Certain types of physical stress can cause disturbances in the heart’s electrical system, such as:

  • Intense physical activity, which involves the release of a hormone, adrenaline, capable of inducing aci in people with heart problems,
  • Very low blood levels of potassium or magnesium, minerals that are crucial for heart electrical signals,
  • Massive bleeding,
  • Severe oxygen deficiency.

Hereditary disorders

Some arrhythmias tend to have a family pattern. The tendency is hereditary, that is, it is transmitted from parents to children through genes. Members of these families may have increased risks of sudden cardiac arrest.

An example of an inherited disorder that puts you at risk for arrhythmias is long QT syndrome. It is a disorder of the electrical activity of the heart, caused by tiny pores on the surface of the heart’s muscle cells. Long QT syndrome can cause sudden, uncontrollable, and dangerous arrhythmias.

Individuals with inherited structural heart problems may also be more at risk for ACI. Often, this kind of problem is the cause of ACI in children.

Structural changes in the heart

Changes in the size or structure of the heart can affect the electrical system. Examples are cardiac dilatation resulting from arterial hypertension or severe heart failure. Heart infections can also alter the structure of the heart.

Sexual intercourse

Unlike what is commonly thought, sexual intercourse does NOT generally cause cardiac arrest; sexual activity is an important aspect of the life of many couples and the data available in the literature make it possible to reassure patients today, even in the case of previous cardiovascular episodes. Obviously, from this point of view, it is still advisable to always address the discussion with your specialist, to evaluate the individual case.

Risk factors

The risk of sudden cardiac arrest increases:

  • With age,
  • In males.

However, the main risk factor is coronary heart disease. Many people with ACI have some degree of coronary heart disease, although they may not be aware of it until the onset of arrest. Typically, their coronary heart disease is “silent”, ie it does not show signs or symptoms, thus not allowing it to be identified.

Numerous cases of ACI also have silent or undiagnosed heart attacks before full arrest. They have no obvious signs of a heart attack and are not even aware that they have suffered it. It is important to know the risk factors for coronary heart disease.

Other risk factors include:

  • Personal history of arrhythmias,
  • Personal or family history of aci or inherited disorders that expose arrhythmias,
  • Drug or alcohol abuse,
  • Heart attacks,
  • Heart failure.


Typical symptoms of cardiac arrest are:

  • Loss of consciousness ( fainting ),
  • Absence of heartbeat (pulse not detectable).

In some cases, in the hour before the ACI appears

  • Chest pain,
  • Breathlessness,
  • Nausea (stomach discomfort) or vomiting.

Some people may feel a rush of racing heart, dizziness, or confusion just before passing out.


Sudden cardiac arrest occurs by definition without warning and requires emergency treatment.

It is rare to resort to instrumental examinations during arrest, more often the diagnosis is made later.

The diagnostic approach is by excluding other causes of sudden collapse.

People at high risk of ACI may need to see a cardiologist. A cardiologist is a doctor who specializes in the diagnosis and treatment of heart diseases and conditions. It is the professional figure who will evaluate the possible opportunity for preventive treatment.

A branch of cardiology specializes in problems with the electrical system of the heart. They are electrophysiological cardiologists.

These specialists have various tests to identify risk factors for ACI.

  • Electrocardiogram,
  • Echocardiography,
  • Mri of the heart,
  • Cardiac catheterization,
  • Electrophysiological study,
  • Blood tests (potassium, magnesium, and other blood electrolytes, which determine the heart’s electrical signals).


Emergency treatments

Sudden cardiac arrest is a medical emergency.

The person with ACI should be treated immediately with the defibrillator. This device sends an electric shock to the heart, which can restore a normal rhythm in a heart that has stopped beating.

To be effective, defibrillation must be delivered within minutes of stopping. Every minute that passes rapidly decreases the chances of survival.

Public safety personnel, emergency medical technicians, and other rescue workers are typically trained and equipped to use the defibrillator. Call 911 immediately if anyone has any signs or symptoms of ACI. The sooner the call occurs, the sooner the life-saving treatment will begin.

Automated external defibrillators

Automated External Defibrillators (AEDs) are special defibrillators that can also be used by untrained passers-by. These portable devices are often available in public places, such as shopping malls, sports fields, convention centers, airports, airplanes, game rooms, hotels, gyms, and schools.

They are programmed to deliver an electric shock when they detect a life-threatening arrhythmia, such as ventricular fibrillation. This allows people who are unconscious but not in cardiac arrest to avoid the shock.

The individual on ACI should undergo cardiorespiratory resuscitation until a defibrillator is available.

Individuals at risk of ACI may possibly equip themselves with AEDs in their own homes. A 2008 study by US institutes (National Heart, Lung and Blood Institute and National Institutes of Health, respectively, National Heart, Lung and Blood Institute National Institutes of Health) found that equipping homes with AEDs are safe and effective.



However, it is a good idea to discuss the possibility of equipping your home with AEDs with your doctor.

Treatment in the hospital

Those who survive cardiac arrest are likely to be hospitalized for continued care and treatment. Cardiac activity will be carefully monitored. Eventually, drugs will be given in an attempt to reduce the risk of relapse.

During hospitalization, the possible causes of the ACI episode will be investigated. In case of coronary heart disease, it is possible to undergo percutaneous revascularization operations ( coronary angioplasty ) or coronary artery bypass grafting. These procedures help restore blood perfusion through narrowed or blocked coronary arteries.

Often, those affected by ACI are treated with the implantation of an internal defibrillator (ICD, from the English Implantable Cardioverter Defibrillator). It is a small device that is inserted through surgery under the skin in the chest or abdomen. The ICD uses electrical pulses or shocks to try to control dangerous arrhythmias.


The preventive approaches to death from sudden cardiac arrest (ACI) differ depending on whether:

  • It is a relapse.
  • It is the first attack in a high-risk individual.
  • It is the first attack in a person with no known risk factors.
  • In survivors of sudden cardiac arrest

The risk of ACI is high in people who have already survived an arrest. Research shows that ICD reduces the chances of dying from a second ACI attack. The device is inserted via surgery under the skin in the chest or abdomen. It features wires with electrodes on the terminals that connect with the heart chambers. The ICD monitors the heart rate.

When it detects a dangerous rhythm, it delivers an electric shock to restore normal rhythm. Drugs may be given to reduce abnormal heartbeats which can activate the ICD.

The device is not the same as the pacemaker. These are similar devices, but with some important differences. The pacemaker delivers low-energy electrical pulses. They are often used to treat less dangerous heart rhythms, such as those that occur in the upper chambers of the heart. Most of the latest generation ICDs work as both a pacemaker and an ICDs.

In subjects at high risk of a first episode of cardiac arrest

Carriers of severe coronary heart disease are at high risk for ACI. This is especially true shortly after a heart attack.

Your doctor may prescribe a type of medicine known as a beta-blocker to reduce the risk of ACI. Statin treatment in people with a high risk of heart disease or stroke may also be considered.

Typically, statins are prescribed in people with:

  • Diabetes,
  • Heart disease or previous stroke,
  • High levels of LDL cholesterol.

Medicines may also be indicated for:

  • Reduce the risk of heart attack or sudden death.
  • Lower blood pressure.
  • Preventing blood clots , possible causes of heart attack or stroke.
  • Prevent or delay the need for a percutaneous or surgical procedure, such as angioplasty or coronary artery bypass grafting.
  • Reduce the workload of the heart and relieve the symptoms of coronary heart disease.

It is obviously very important for survival:

  • Take medicines as prescribed, regularly.
  • Do not change quantities or skip doses unless your doctor prescribes it.

Even if in drug therapy, a healthy and adequate lifestyle must still be observed.

Other treatments for coronary heart disease, such as percutaneous revascularization procedures (coronary angioplasty) or coronary artery bypass grafting, can also decrease the risk of ACI. There may be indications of an ICD in individuals at high risk for ACI.

In people with no known risk factors for cardiac arrest

Coronary heart disease appears to be the cause of most ACI in adults, as well as being a major risk factor for angina (chest pain), heart attack, and other ailments.

Following a healthy lifestyle can help lower the risk of coronary heart disease, ACI, and other heart problems. A healthy lifestyle includes:


Adoption of a healthy diet ,

Achieving an adequate body weight ,

Stress containment ,

Physical activity ,

Abolition of smoking .

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