Sudden Cardiac Arrest or Sudden Death

What is it? How can you deal with it?

When a person suffers from a sudden cardiac arrest (SCA), his/her heart suddenly stops beating due to a problem in the electrical system of the heart.

Sometimes, an arrhythmia –irregular heart beat– can cause the heart rate to increase dramatically, this is called ventricular tachycardia (VT). If the heart rate goes too fast, it can become unstable and irregular and turn into something much more dangerous called ventricular fibrillation (VF). With VF, the heart quivers rapidly and cannot pump blood to the whole body.

The person becomes unconscious fast and stops breathing, and if he/she does not receive immediate treatment with a defibrillator, he/she might suffer brain damage.

SCA is a serious and life threatening medical emergency. The chances of surviving SCA decrease by 7-10% with every minute that passes without a life-saving shock. After the first 10 minutes, few attempts at resuscitation are successful. In more than 90% of cases, death comes abruptly and unexpectedly.

In contrast, with a heart attack, there is a “connection” problem caused by one or more obstructions in the heart’s blood vessels, preventing proper flow. Part of the heart muscle dies, but the patient remains conscious and breathes.

Why does SCA happen?

SCA can be caused by a coronary artery disease or other heart problems. It can happen to people of all age, gender and race, even those who seem to enjoy good health. There are cases of professional athletes with optimum levels of fitness that have suddenly died during a sporting event due to a SCA.

Which are the risk factors of SCA?

Most heart and blood vessel diseases can lead to sudden cardiac arrest. Among the factors that increase the risk of suffering SCA, we find: a history of heart diseases in the family, hypertension, high cholesterol, obesity, diabetes, sedentary lifestyle, smoking, excessive alcohol intake, and age.

Other aspects that might influence a SCA are personal or family history of arrhythmias or SCAs, heart attacks or heart failure problems, drug abuse.

What are SCA symptoms?

Even though there are no warning signs before a SCA, it’s possible that some symptoms appear, such as fatigue, weakness, or difficulty breathing. Also, a person might faint, feel dizzy, lightheaded, and suffer from heart palpitations and/or chest pain.

But the first and often only symptom of SCA is loss of consciousness – from lack of blood to the brain.

How is SCA diagnosed?

Sudden cardiac arrest is diagnosed after the event, and may appear as ventricular fibrillation on an electrocardiogram (ECG).  If a person presents any of the risk factors indicated above, the doctor can suggest some tests, such as the ECG, which evaluates the heart’s electrical system, or an echocardiogram, which controls the way the heart pumps blood through ultrasound, to create an image of the heart when it beats. There are also some tests that check how electrical impulses travel through the heart muscle.

What does SCA treatment involve?

Once a cardiac arrest occurs, cardiopulmonary resuscitation (CPR) and defibrillation are required within the first minutes to restore electrical activity to the heart and revive the heart’s pumping function.

  • CPR: consists of chest compressions together with assisted breathing. This is an important step prior to successful external defibrillator therapy.
  • Defibrillation: the usage of a device (defibrillator) that sends a strong electrical shock to the heart to stop the arrhythmia and restore a normal heartbeat. There are two types of defibrillators: external defibrillators, which use paddles to deliver a shock to the outside of the body; and implantable cardioverter defibrillators, that are implanted pacemaker-like devices that can sense arrhythmias and deliver lifesaving shocks.


Doctors recommend a healthy lifestyle, having a diet low in fat and high in fiber, not smoking, among others. But defibrillator therapy has been shown to effectively stop 95% or more dangerously fast heart rhythms. On the other hand, only 1 in 20 people usually survives a sudden cardiac arrest event. With a defibrillator, the proportion is exactly inverted: 19 to 20.