Sudden Cardiac Arrest – Symptoms and Causes  

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Sudden cardiac arrest occurs when the heart stops beating suddenly. Heart attack and cardiac arrest are used synonymously, but they do not mean the same. A heart attack arises when there is a block in the blood supply to the heart. When the heart experiences a dysfunction, it can result in sudden cardiac arrest.  

SCA (Sudden cardiac arrest) is an “electrical” issue, whereas a heart attack is a “circulation” problem.  

Heart attack   

A heart attack arises when an artery becomes clogged, preventing oxygen-rich blood from getting to a certain area of the heart. The area of the heart ordinarily supplied by the blocked artery starts to deteriorate if it is not quickly unblocked. More damage occurs when the person stays longer without treatment.  

What is sudden cardiac arrest?   

Sudden cardiac arrest results when the heart suddenly stops pumping blood. Sudden cardiac death (SCD) occurs when the person does not survive. The person may or may not be known to have heart disease.  

Sudden cardiac arrest can occur in anyone at any age. SCA and SCD, which are uncommon, have a terrible effect on families, careers, and the community.  

What is sudden cardiac death?

A sudden, unexpected death is known as sudden cardiac death (SCD). It is brought on by a lack of heart function (sudden cardiac arrest). The leading cause of natural mortality is sudden cardiac death. Half of all deaths from heart disease are caused by sudden cardiac death.  

Adults in their mid-30s to mid-40s are the age group most frequently affected by sudden cardiac death.   

Difference between heart attack and cardiac arrest   

While experiencing a sudden cardiac arrest,   

  • Unexpected irregularities occur in the electrical circuitry of the heart.  
  • There is a rapid heartbeat.  
  • Ventricular fibrillation causes the heart to quiver or flutter.  
  • The heart is unable to pump blood effectively due to these electrical changes, and blood cannot get to the rest of the body. If emergency care is not started immediately, this condition will result in death.  

The biggest concern in the initial minutes is that there won’t be enough blood getting to the brain, which could cause unconsciousness.  

Heart attack (myocardial infarction) does not apply to sudden cardiac arrest.  

  • A person may experience a heart attack when the coronary arteries get blocked. The heart cannot get enough oxygen-rich blood as a result.   
  • One can sustain heart damage if the blood’s oxygen cannot reach the heart muscle.  

Causes of sudden cardiac arrest   

Ventricular fibrillation (VF), an irregularity in the heart’s electrical circuit, is usually the cause of sudden cardiac arrest. Blood supply to the body and brain stops as a result of VF, and the heart begins to flutter.   

VF and heart attacks are not the same. A coronary artery blockage leads to heart muscle damage, which in turn causes a heart attack. SCA can develop after a heart attack.  

A rapid cessation of all electrical activity in the heart, commonly known asystole, may also be related to SCA. It may also be connected to pulseless electrical activity (PEA), a disorganised electrical activity affecting the heart’s ability to beat and pump blood.  

The following conditions are more likely to result in SCA/SCD in adolescents:  

  • Hypertrophic cardiomyopathy – A form of heart muscle disease that results in the thickening (hypertrophy) of the heart muscle. This thickening usually takes place in the left ventricle, the lower left chamber of the heart.   
  • Congenital heart disease – It is characterised by a change in the heart’s structure present from birth. Aortic stenosis, mitral valve prolapse, and anomalous coronary arteries are a few examples of structural heart defects that make up 10 to 15 per cent of SCD cases.  
  • Heart muscle disorder – Arrhythmogenic cardiomyopathy affects the heart muscle. Over time, this illness results in heart muscle breakdown, raising the risk of arrhythmia and premature death.  
  • Arrhythmia – Any deviation from the regular rhythm of the heartbeat or heart rate is referred to as an arrhythmia. Long QT syndrome and catecholaminergic polymorphic ventricular tachycardia are two of the more frequent inherited heart rhythm disorders linked to SCA/SCD.  

Symptoms of Sudden Cardiac Arrest   

Sudden cardiac arrest occurs in nearly half the cases with no warning signs.  

Symptoms of a sudden cardiac arrest include:  

  • Fainting  
  • Dizziness  
  • Chest pain  
  • Tachycardia  
  • Lightheadedness.  
  • Breathing difficulty  
  • History of high blood pressure  
  • Palpitation  
  • Restriction on activities due to heart condition.  
  • Extreme tiredness or breathlessness during exertion  
  • Unexplained fainting (syncope), especially with or immediately after activity.  

People at risk for of Sudden Cardiac Arrest   

The two main risk factors are   

  • Heart attack history – There is an increased risk of sudden cardiac death during the initial six months post a heart attack.  
  • Coronary artery disease – A family history of CVD, smoking, and high cholesterol are risk factors for coronary artery disease linked to sudden cardiac death.  

Diagnosing sudden cardiac arrest   

The doctor can diagnose a sudden cardiac arrest if the patient,  

  • Isn’t breathing  
  • Is unconscious  
  • Has no pulse  

Since sudden cardiac arrest frequently results in death, many cases are identified after death.  

The healthcare professional will want to run tests to diagnose the cause of cardiac events and stop further sudden cardiac arrest.   

Tests include,  

  • ECG or EKG (electrocardiogram)  
  • Cardiac MRI 
  • Blood tests examine the electrolytes necessary for the electrical conduction of the heart 
  • Echocardiogram 
  • Catheterisation of the heart  

What to do during sudden cardiac arrest?   


During a sudden cardiac arrest, CPR (cardiopulmonary resuscitation) keeps the blood and oxygen flowing to the brain and other essential organs. Start performing proper CPR immediately and continue doing so until trained emergency medical personnel arrive.  

Unless the injured individual experiences a return of normal circulation (either spontaneously or after receiving an AED shock), is awake (moving and breathing), conscious, and talking, CPR should be continued until emergency medical services (EMS) arrive and take over. Trained medical personnel are advised to utilise rescue breathing as part of CPR.  


In the event of a sudden cardiac arrest, an AED (Automated external defibrillator) can restore a regular heartbeat. AEDs can be found in public locations such as schools, malls, businesses, hotels, airports, and sports areas. AEDs include audio step-by-step instructions and are simple to use.  

An AED can give an electrical shock through the chest (that travels to the heart) to stop the irregular rhythm when the heart is in sudden cardiac arrest. This permits the heart to return to its regular rhythm.   


Doctors may implant a defibrillator to prevent SCD in children and adolescents who have experienced an SCA or are believed to be at risk for experiencing one. An implantable cardioverter defibrillator is a tiny computerised gadget with an energy source for defibrillation or pacing.  

The child’s heart chambers are connected to an ICD by wires with electrodes on the ends. It is capable of identifying a rhythm that poses a severe risk to life and administering an electrical shock to restore the rhythm to normal.  

Children who have survived an SCA or who are at high risk for such a cardiac event undergo an ICD implant according to the recommended procedures. It is possible to discharge ICDs given to children for either of these reasons to prevent SCD.  

Prevention of sudden cardiac arrest   

Primary prevention describes measures taken to stop sudden cardiac arrest. Finding a disease that predisposes people to sudden cardiac death and acting early on is necessary to reduce the incidence and prevalence of the illness.  

Evaluation of persons who exhibit warning signs, symptoms, or family history is part of primary prevention. Early treatment with medicine, lifestyle modifications, and the use of defibrillation devices are made possible by the identification of a cardiac problem or other risk factors.  

After a person has gone through a sudden cardiac arrest, efforts used to prevent sudden cardiac death are known as secondary prevention. These procedures include automated external defibrillators (AEDs), implantable cardioverter defibrillators (ICDs), and cardiopulmonary resuscitation (CPR).  

When to see a doctor?   

While recovering from a sudden cardiac arrest, there will be several follow-up check-ups with healthcare professionals. On visiting a doctor after an SCA, the patient will receive procedures or treatments that help prevent experiencing another unexpected cardiac arrest.  

Keep the doctor informed while experiencing any new symptoms or if the symptoms don’t improve.  


Surviving a sudden cardiac arrest marks the beginning of a long recovery. There may or may not be brain damage, depending on how long the brain was oxygen-deprived. This implies that the ability to perform everything daily task is hindered. Additionally, there could be struggles with mental health issues, including stress and depression. According to research, the quality of life for those who survived sudden cardiac arrest improved after six months. 


What is the most common cause of sudden cardiac arrest?   

Coronary artery disease causes nearly 80 % of the cases of sudden cardiac death.  

What are the four signs of sudden cardiac arrest?   

The most common early signs of sudden cardiac arrest are
Back pain  
Extreme fatigue  
Nausea, vomiting and stomach pain  
Chest pain  

What is an early warning of cardiac arrest?   

Chest pain, dizziness, palpitations, shortness of breath, fainting, nausea, and vomiting are the most common warning signs.  

How long can cardiac arrest last?   

It may be deadly if cardiac arrest lasts longer than 8 minutes without CPR. Brain damage occurs when the arrest lasts for 5 minutes. 


The Information including but not limited to text, graphics, images and other material contained on this blog are intended for education and awareness only. No material on this blog is intended to be a substitute for professional medical help including diagnosis or treatment. It is always advisable to consult medical professional before relying on the content. Neither the Author nor Star Health and Allied Insurance Co. Ltd accepts any responsibility for any potential risk to any visitor/reader.

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