Cardiac Arrest: Causes, Symptoms, Diagnosis, and Treatment

Cardiac arrest (CA) occurs when the heart suddenly and unexpectedly stops pumping. If this happens, blood stops flowing to the brain and other vital organs. 

What causes CA?

Abnormal, rapid impulses abruptly override the normal electrical impulses responsible for a regular heartbeat. These abnormal impulses are known as arrhythmias. The most common life-threatening arrhythmia is ventricular fibrillation. This is an erratic, disorganized firing of impulses from your heart’s ventricles (lower chambers). When this happens, your heart can’t pump blood.

Conditions and situations that can lead to these abnormal heart rhythms are the underlying causes of sudden cardiac arrest. These include: 

• Cardiomyopathy
• Drugs for other medical conditions
• Heart attack
• Heart failure
• Recreational drugs like cocaine
• Brugada syndrome
• Long QT syndrome
• Severe illness or injury (trauma) with major blood loss

Other CA causes include:

• Coronary artery disease
• Congenital heart conditions
• Changes to your heart structures because of disease or infection
• Extreme physical activity or blood loss
• Infectious diseases
• Respiratory conditions
• Severe injury (trauma)
• Toxins (eating or drinking poisonous substances)

What are the risk factors for CA?

The following conditions increase the likelihood of having CA:

• Having a history of sudden CA previously, or a history of CA in the family
• Have a personal or family history of abnormal heart rhythms, like long QT syndrome and ventricular tachycardia
• Had certain arrhythmias after a heart attack
• Have had heart or blood vessel issues since birth
• Have heart valve disease
• Have a history of fainting
• Have heart failure from conditions like dilated cardiomyopathy
• Have hypertrophic cardiomyopathy
• Have major changes in the amount of potassium and magnesium in your blood
• Obesity  
• Diabetes

Take recreational drugs or drugs that can increase the risk of life-threatening arrhythmias [1]

What are the symptoms of CA?

• Fatigue
• Dizziness
• Shortness of breath
• Nausea
• Chest pain
• Heart palpitations
• Sudden collapse or loss of consciousness
• The person is not responsive to shouting or shaking
• Loss of pulse [2] 

How is a CA diagnosed?

Symptoms are predominantly the key to identifying CA. Cardiac arrest symptoms begin suddenly, leaving little time for tests. The condition can become fatal within minutes. This is why a quick diagnosis and medical intervention are essential to save a life!

When a person is experiencing symptoms of CA and is attended by an emergency medical professional, the following tests can help detect issues:

• Blood tests: To detect protein leakage after a heart attack or electrolyte imbalance.
• Electrocardiogram: Can detect the abnormal electrical activity of the heart.
• Echocardiogram: Can show blood flow, heart muscle, and valvular damage.
• Ejection fraction: It is a measurement of the percentage of blood leaving the heart during each ventricular contraction. The normal range of ejection fraction is 50% to 70%. An ejection fraction of less than 40% increases the risk of sudden cardiac arrest.
• Chest X-ray: Shows the size and shape of the heart and lungs. It might also show whether you have heart failure.

Other tests like nuclear scan or cardiac catheterization, can be done to detect coronary artery and heart blood flow; however, these are often always kept for screening at a later stage. In the event of sudden CA, immediate treatment is always recommended based on the appearance of indicated symptoms.

How is CA treated? 

• In the presence of unconsciousness, loss of pulse, and/or breathing, immediate Cardio-pulmonary resuscitation or automated external defibrillator (AED) is used to prevent death. 
• Anti-arrhythmic drugs are often the first line of pharmacotherapy to restore normal heart rhythm. Other medicines that may lower the risk of sudden CA may include beta-blockers, angiotensin-converting enzyme (ACE) inhibitors, and calcium channel blockers. 
• Surgical options are considered to correct an irregular heartbeat, open a blockage, or place a device to help the heart work better. They may include:
  • Implantable cardioverter-defibrillator: To check and restore normal heart rhythm. 
  • Coronary angioplasty: To open blocked or clogged heart arteries, it can be done at the same time as a coronary catheterization, a test that doctors do to find narrowed arteries to the heart.
  • Coronary artery bypass surgery: Creates a new pathway for blood to flow around a blocked artery to the heart.
  • Radiofrequency catheter ablation: Heat, called radiofrequency energy, on the end of the catheter is used to create small scars in the heart. The scars block the irregular heart signals. 
  • Corrective heart surgery: To treat birth defects, valvular dysfunctions or diseased heart muscle. [3] 

How can one prevent getting a CA?

• Have a balanced and nutritious diet keeping cholesterol and weight under control/check. 
• Stay hydrated to prevent losing excess body salts, water. and electrolytes.
• Get adequate sleep.
• Stay active on a regular basis by indulging in any form of exercise, which can be as simple as walking or cycling. If you have an arrhythmia, talk to your healthcare provider to determine the right type and dosage of exercises.
• Manage stress by practicing yoga, meditation, or mindfulness. Seek help from mental health professionals if you`re struggling to cope on your own.
• Quit smoking.
• Limit alcohol intake.

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