Cardiac arrest is when the heart ceases to function. A heart attack, which is the blockage of a vessel supplying a heart muscle, can cause the heart to stop. But nearly 80% of cardiac arrests are not caused by a heart attack. Instead, they are what EMT’s call “shockable arrests.” That is when the heart’s electrical signals have gone haywire, but can be reset by the delivery of a powerful electric shock. Most people die within minutes from cardiac arrest; the survival rate is an abysmal eight percent. But an individual’s chance to recover is significantly higher if the arrest occurs in public. That’s because people trained in CPR, meaning cardiopulmonary resuscitation, are more likely to be around. Better yet the little machine designed to provide that critical electric shock could be nearby, too. Minutes and even seconds are critical in rescuing somebody from cardiac arrest.
“Shockable Arrests”
Electrical signals from the brain tell the heart when to beat. Similar to the action of a timing belt, these signals control which parts of the heart does its job and when. For a variety of reasons, the heart goes into what’s called ventricular tachycardia or VT. This is when the heart goes into hyper-drive, beating from 120 to over 200 times a minute. A normal heart rate at rest is 60 to 80 beats per minute. The lower heart chambers, or ventricles, begin to beat blood out faster than they can fill. If VT continues, the heart can then advance to deadly VF, or ventricle fibrillation. VF is when the ventricles can only twitch uselessly, stopping the blood flow to the brain. This is the point of no return. Unless electric shock is applied within less than five minutes, asystole, better known as flat line, follows. Usually after then even electric shock has no effect because the heart has died. If cardiac arrest happens at home, chances are slim that machine and those trained people are available.
Automated External Defibrillator
That little machine is a godsend to people who have gone into VF. Designed to be used by anybody able to follow a few brief directions, the automated external defibrillator, or AED, delivers that critical shock to restore normal rhythm. Leads are simply and easily attached to the chest. They then inform the machine if indeed the heart has arrested and it it’s because of VF. If it determines the need for shock it can be delivered immediately. The shock actually stops the heart completely. It then rests momentarily before it hopefully resumes beating at a more normal rhythm. The AED can confirm this.
These life-saving machines are found in more and more locations every day. They’re in many places; airports, office buildings, restaurants, courthouses, schools and even bars are stocking them. There’s good reason for this. More than a third of people who suffer cardiac arrest in public and treated with an AED survived. That’s much better odds than the national average of only eight percent.



