Sudden Cardiac Arrest & CPR

The terms heart attack and cardiac arrest are often used interchangeably to describe the same medical condition. They are in fact, not the same thing. Let’s break this down.

Cardiac arrest is defined as a situation where the heart suddenly stops pumping blood due to an irregular heart rhythm.

A heart attack happens when blood flow to a part of the heart muscle is interrupted due to a blockage. If blood flow is not restored, then that part of the heart muscle will die.

Sometimes a heart attack can cause an irregular heart rhythm and cardiac arrest. However, there are other potential causes as well.

Let’s review some of the details about sudden cardiac arrest and more importantly, introduce the basics of Cardiopulmonary Resuscitation or CPR. This lifesaving skill can be performed by anyone and potentially save somebody’s life, maybe even a loved one.

As described, sudden cardiac arrest can often happen without any warning signs or symptoms. People typically collapse and lose consciousness. Without immediate medical treatment sudden cardiac arrest can be fatal. Sometimes people can have symptoms prior to collapsing. These may include chest pain, shortness of breath, weakness, dizziness, or palpitations like a fluttering or pounding heart. If you are feeling unwell and are having these symptoms, it is important to call 911 to seek emergency medical attention.


A number of heart conditions can potentially lead to sudden cardiac arrest. As mentioned above, a heart attack which is a complete blockage in one of the coronary arteries which interrupts blood flow to the heart muscle, could lead to a serious arrhythmia resulting in sudden cardiac death. After a heart attack, the scar tissue that is formed as a result of the heart damage can also put you at risk of sudden cardiac arrest in the future.

Sometimes, severe but not complete blockages in the coronary arteries that greatly reduce blood flow can also trigger serious arrhythmias in the heart even though they don’t cause an actual heart attack.

Other heart conditions that increase the chances of sudden cardiac arrest are:

  • Cardiomyopathy – stretched out (dilated) or thickened (hypertrophic) heart muscle that can interrupt the heart’s electrical system
  • Heart valve disease – leaking or narrowing of heart valves that can lead to stretching or thickening of heart muscle
  • Congenital heart defects – structural heart problems that you are born with
  • Previous heart surgery – scar tissue from surgery can increase the risk
  • Long QT syndrome – a problem with the heart’s electrical system
  • Other inherited electrical heart issues (eg. Brugada syndrome)

Risk Factors:

In addition to these heart specific issues, there are other risk factors or conditions that increase the risk of sudden cardiac arrest. These include the traditional risk factors for coronary artery
disease such as:

  • Age
  • Family history of coronary artery disease
  • Smoking
  • High blood pressure
  • High blood cholesterol
  • Obesity
  • Diabetes
  • Physical Inactivity

As well as other risk factors that are linked with increased risk of sudden cardiac arrest such as:

  • Previous heart attack
  • Previous episode of sudden cardiac arrest
  • Family history of sudden cardiac arrest
  • Illicit drug use (cocaine or amphetamines)
  • Kidney disease
  • Electrolyte imbalances, especially potassium or magnesium
  • Obstructive sleep apnea


If you have had a sudden cardiac arrest or have a condition that puts you at high risk, your cardiologist may recommend implanting an Internal Cardioverter Defibrillator (ICD) which can recognize a serious arrhythmia and attempt to shock you back into a normal rhythm.

Unfortunately, many people are not aware that they may be at risk of a sudden cardiac arrest.

If someone’s heart stops pumping blood to your body, immediate and appropriate medical treatment is critical. There are two basic things that need to happen to help save someone’s life:

  1. Blood needs to continue to be pumped around the body in order to preserve the vital organs until a normal heart rhythm is re-established. This is exactly what CPR does. The basics of CPR will be introduced below.
  2. Re-establishing a normal heart rhythm. There are now many places that have a device called an Automated External Defibrillator (AED) that can identify a potentially fatal heart arrhythmia and deliver a shock to attempt to restore a normal rhythm. Otherwise, CPR would need to be performed until Emergency Medical Services arrive to take over.

CPR or Cardiopulmonary Resuscitation

The best way to learn CPR is to take an accredited course. The more you know, the better. Hopefully you will never have to use this skill but you never know when the situation may arisethat you could help save someone’s life. Often CPR is done on family members and friends because you are around them most often. If your see someone who is unconscious and not breathing there are basically 2 steps:

  1. Call 911 or whatever number activates emergency medical services. You can also
    instruct someone to retrieve the AED if there is one close by.
  2. Start CPR (if it is safe to do so)
    a. If you are not trained in CPR then all you should do is perform chest compressions. These are done in the middle of the chest, hard and fast. Ideally at least 2 inches in depth and about 100-120 per minute which is about the pace of the BeeGee’s song “Staying Alive”
    b. If you are trained in CPR then you would open their airway and give 2 rescue breaths after every 30 compressions.
    c. Continue this until help arrives

If you have any questions about Sudden Cardiac Arrest – please don’t hesitate to contact us.