Cardiac Arrest: Symptoms, causes and how it is different from a heart attack

Cardiac arrest is a serious heart condition. The term arrest means to stop or bring to end. The heart ceases to beat in cardiac arrest. It is also called sudden cardiac death. It is an immediate loss of heart function, breathing, and consciousness in which the heart stops to beat. The heart is controlled by electrical impulses. The condition often results from an electrical disturbance in the heart that disrupts its pumping mechanism and stops the blood flow. When these electrical impulses change their pattern, the heartbeat becomes irregular. This is also known as arrhythmia.


Cardiac arrest is an emergency that requires fast & appropriate medical care. If left untreated, it can lead to death. Using a defibrillator, giving cardiopulmonary resuscitation (CPR), or even just giving chest compressions can improve the chances of survival until the ambulance arrives.


Heart attack and cardiac arrest

People often think that a heart attack and cardiac arrest are the same things. However, that is not true. To understand the difference between a cardiac arrest and a heart attack, it is first important to know what happens in both of these processes.


Heart attack - The heart is a muscular organ, and like all muscles, it requires an oxygen-rich blood supply.  The heart receives its own oxygen-rich blood supply with the help of coronary arteries. A heart attack usually occurs when there is a blockage in the coronary arteries. This is generally caused by a blood clot or plaque deposition. The blockage can partially or entirely halt the blood flow. Such a blockage, if not treated timely, can cause parts of the heart muscle to begin to die.


Cardiac arrest - A cardiac arrest is totally different from a heart attack. In a cardiac arrest, all of a sudden, the heart stops beating, whereas, in a heart attack, the heart continues to beat even though the blood supply to the heart is disrupted.


Symptoms of cardiac arrest

Sign and symptoms of sudden cardiac arrest are quick and drastic and include:


  • Sudden collapse
  • No pulse
  • No breathing
  • Loss of consciousness


Sometimes other signs and symptoms occur before an episode of sudden cardiac arrest. These might include:


  • Chest discomfort
  • Shortness of breath
  • Weakness
  • Palpitations


Usually, a sudden cardiac arrest often occurs with no warning.



A problem in the heart rhythm or electrical system of the heart is the usual cause of sudden cardiac arrest. An electrical system controls the heart rate and rhythm of the heartbeat. If there is any problem with the electrical activity, the heart can beat too fast, too slowly or irregularly (arrhythmia). Most of the time, these arrhythmias are short and harmless, but some of them can lead to sudden cardiac arrest.


The most known heart rhythm at the time of cardiac arrest is an arrhythmia in a lower chamber of the heart (ventricle). Rapid, irregular electrical impulses cause the ventricles to tremble or shake uselessly instead of pumping blood (ventricle fibrillation).


Some heart conditions that can lead to sudden cardiac arrest

Cardiac arrest can occur in individuals who have no known heart disease. However, a life-threatening arrhythmia can develop in a person with a pre-existing heart condition. These conditions are as follows:


Coronary artery disease: Most cases of cardiac arrest occur in individuals who have coronary artery disease, in which the arteries become jammed or choked with cholesterol and other depositions that ultimately reduces the blood flow to the heart.


Heart attack: A heart attack can trigger cardiac arrest and ventricular fibrillation. Also, a heart attack can leave damaged tissue in the heart. Electrical short circuits around the damaged tissue can result in abnormalities in the heart rhythm.


Enlarged heart (cardiomyopathy): The disease of the heart in which the heart's muscles become enlarge or thicken. This makes it quite difficult for the heart to pump blood to the rest of the body.


Congenital heart disease: The sudden cardiac arrest which occurs in children or adolescents can be due to a heart defect that may be present since birth (congenital heart disease). Adults who had gone surgery for a congenital heart defect still have a higher risk of cardiac arrest.


Valvular heart disease: Leaking or narrowing of the heart valves can lead to stretching or thickening of the heart muscle. When the heart's chambers become enlarged or weakened as stress caused by a stiff or leaking valve, there is an increased risk of developing arrhythmia.


A problem in the electrical activity of the heart: In some people, there is a problem in the heart's electrical system instead of a problem with the heart muscle or valves. These are known as primary heart rhythm abnormalities and include conditions such as Brugada's syndrome and long QT syndrome.


Risk factors

Because a sudden cardiac arrest is often linked with coronary artery disease, the same factors that can put an individual at threat of coronary artery disease can also put them at risk of sudden cardiac arrest. These include:


  • A family history of coronary artery disease
  • Smoking
  • High blood pressure
  • High blood cholesterol
  • Obesity
  • Diabetes
  • A sedentary lifestyle


Other factors that might increase the possibility of sudden cardiac arrest include:


  • A previous episode of cardiac arrest
  • A previous heart attack
  • A family history of other forms of heart disease
  • Increasing age
  • Being male
  • Nutritional imbalance, such as low levels of potassium or magnesium
  • Obstructive sleep apnea
  • Chronic kidney disease


If an individual survives sudden cardiac arrest, the doctor will try to catch the cause to prevent future episodes. To diagnose a cardiac arrest, the following tests may be recommended:


  • Electrocardiogram (ECG)
  • Blood tests to analyse the levels of potassium, magnesium, hormones, and other chemicals that can affect the heart's ability to function.
  • Imaging tests like Digital Chest X-ray, Echocardiogram, MRI, CT Scan or Nuclear scan.
  • Other test includes Coronary catheterization (angiogram).


These are just suggestions. Consult the doctor before taking any tests.



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