What is sudden cardiac arrest (SCA)?

Sudden Cardiac Arrest (SCA) is a life-threatening emergency that occurs when the heart suddenly stops beating. It strikes people of all ages who may seem to be healthy, even children and teens.

When SCA happens, the person collapses and doesn’t respond or breathe normally. They may gasp or shake as if having a seizure.

SCA leads to death in minutes if the person does not get help right away. Survival depends on people nearby calling 911, starting CPR, and using an AED (if available) as soon as possible.

Is SCA the same as a heart attack?

No. Both the heart attack (myocardial infarction) and a sudden cardiac arrest have to do with the heart, but they are different problems. SCA is an electrical problem; a heart attack is a “plumbing” problem. Sometimes a heart attack, which may not be fatal in itself, can trigger a sudden cardiac arrest.

What is the recommended treatment for SCA?

Defibrillation is the only treatment proven to restore a normal heart rhythm. When used on a victim of SCA, the automated external defibrillator (AED) can be used to administer a lifesaving electric shock that restores the heart’s rhythm to normal. AEDs are designed to allow non-medical personnel to save lives.  

How much time do I have to respond if someone has a sudden cardiac arrest?

Only minutes. Defibrillate within three minutes and the chances of survival are 70 percent. After 10 minutes, the chances of survival are very slim. 

How does an AED work?

Two pads, connected to the AED, are placed on the patient’s chest. A computer inside the AED analyzes the patient’s heart rhythm and determines if a shock is required to save the victim. If a shock is required, the AED uses voice instructions to guide the user through saving the person’s life.  

Why are AEDs important?

AEDs make it possible for more people to respond to a medical emergency where defibrillation is required. Because AEDs are portable, they can be used by nonmedical people (lay-rescuers). They can be made part of emergency response programs that also include rapid use of 9-1-1 and prompt delivery of cardio pulmonary resuscitation (CPR). All three of these activities are vital to improving survival from SCA.

Who can use an AED?

Non-medical personnel such as police, fire service personnel, flight attendants, security guards and other lay rescuers who have been trained in CPR can use AEDs.

Although formal training in the use of an AED is not required, it is recommended to help the rescuer increase their comfort and level of confidence. However, AEDs are intended for use by the general public. Most AEDs use audible voice prompts to guide the user through the process.

Are AEDs safe to use?

AEDs are safe to use by anyone. Some studies have shown that 90 percent of the time AEDs are able to detect a rhythm that should be defibrillated. This data suggests that AEDs are highly effective in detecting when (or when not) to deliver a shock.

Where should AEDs be placed?

All first-response vehicles, including ambulances, law- enforcement vehicles and many fire engines should have an AED.

AEDs also should be placed in public areas such as sports venues, shopping malls, airports, airplanes, businesses, convention centers, hotels, schools and doctors’ offices. They should also be in any other public or private place where large numbers of people gather or where people at high risk for heart attacks live. They should be placed near elevators, cafeterias, main reception areas, and on walls in main corridors.

Why do we need AEDs?

AEDs save lives. When a person has a sudden cardiac arrest, the heart becomes arrhythmic. Every minute that the heart is not beating lowers the odds of survival by 7-10 percent. After 10 minutes without defibrillation, very few people survive.  

Is an AED complicated to use?

AEDs are very easy to use. An AED can be used by practically anyone who has been shown what to do. In fact, there are a number of cases where people with no training at all have saved lives.  

Can a non-medical person make a mistake when using an AED?

AEDs are safe to use by anyone who has been shown how to use them. The AED’s voice guides the rescuer through the steps involved in saving someone; for example, “apply pads to patient’s bare chest” (the pads themselves have pictures of where they should be placed) and “press red shock button.” Furthermore, safeguards have been designed into the unit precisely so that non-medical responders can’t use the AED to shock someone who doesn’t need a shock.  

Can I be sued if I help someone suffering from SCA?

State and federal “Good Samaritan” laws cover users who, in good faith, attempt to save a person from death. To date, there are no known judgments against anyone who used an AED to save someone’s life.  

What is Hypertrophic Cardiomyopathy?

Hypertrophic cardiomyopathy (HCM) is a complex, yet relatively common, genetic heart disease that occurs in approximately 1 in 500 individuals. It affects both genders and all races. The disease results in excessive thickening of the heart muscle—referred to as “hypertrophy”—which occurs most commonly in the septum (i.e. the muscular wall that separates the left and right lower chambers of the heart).  In the majority of patients, this thickening begins during puberty, with little to no change in the thickness beyond early adulthood.  However, symptoms from HCM can develop or worsen at any age, but most commonly occur during mid-life.

What is Obstructive Hypertrophic Cardiomyopathy?

Almost two-thirds of HCM patients have the obstructive form of the disease. This means their mitral valve moves abnormally, causing it to come in contact with the thickened septum, and therefore partially obstructing flow of blood out of the heart. This obstruction of blood creates higher pressure in the left lower chamber of the heart, which can be reliably measured with an echocardiogram.  In some patients, this obstruction to blood flow is present at rest. In other patients it occurs only during exercise, requiring an exercise stress test be performed at the time of the clinical evaluation.

The obstruction to blood flow and the resulting increase in pressure in the heart is responsible for what we call “limiting” symptoms, that include: shortness of breath with activity, exertional fatigue, chest pain (or “heart pounding”) and occasionally lightheadedness.  These symptoms can often be managed with appropriate medications. However, when medications are not effective, patients can then become candidates for invasive treatment options to relieve the obstruction—via either surgical myectomy or alcohol ablation.

How did I get Hypertrophic Cardiomyopathy? 

Hypertrophic cardiomyopathy is a genetic heart disorder. You were born with an abnormal gene that caused your heart muscle to thicken. Your heart muscle did not thicken due to poor lifestyle habits or anything else you may have done to yourself over the years. However, although you did nothing to cause it, maintaining a healthy lifestyle through weight and diet will absolutely benefit you in the long-run with respect to your symptoms and overall energy levels.

What is my life expectancy with Hypertrophic Cardiomyopathy?

Most patients with hypertrophic cardiomyopathy are able to maintain an active lifestyle and have a normal lifespan. Mortality rates for HCM alone is only about 0.5% per year—which is no different than the general population for all causes. Most patients have near-normal life expectancies and live highly satisfying and productive lives.

Can I exercise with Hypertrophic Cardiomyopathy?

YES. There are many psychological and physical benefits to a regular exercise routine. Having HCM does not make you immune to developing coronary artery disease or having a heart attack (or other disease related to leading a sedentary lifestyle). However, there are definitely activities to avoid. Intense physical exertion increases your heart rate and releases a rush of adrenaline that can predispose some individuals to heart arrhythmias. This places HCM patients at additional risk for passing out or sudden cardiac death. Exercise counseling should be individualized. Remember to talk to us before starting any exercise program.


American Heart Association

Parent Heart Watch


Tufts Medical Center

Additional Resources

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