Heart Attack vs. Sudden Cardiac Arrest: Understanding the Difference

Mary M. Newman

Image result for heart spaceshipAwake or Not Awake. That Is the Question.

October is National Sudden Cardiac Arrest Awareness Month. Understanding the difference between heart attack and sudden cardiac arrest could help save lives. One way to understand the difference between the two conditions is this distinction: The heart attack victim is awake and the heart is beating. In contrast, the sudden cardiac arrest victim is not awake and the heart is not beating. To survive sudden cardiac arrest, the victim needs immediate CPR and treatment with a defibrillator. [1]

Sudden unexpected cardiac arrest is the third leading cause of death in the U.S. [2], affecting 326,200 people each year, including 6,000 youth [3]. On average, about 10 percent of victims survive, though nearly 40 percent survive when bystanders call 911, start CPR, and use automated external defibrillators, or AEDs, before emergency medical services (EMS) arrives at the scene. [4]

It’s a common misconception that heart attack and sudden cardiac arrest are the same thing. In reality, the two conditions are quite different.

Heart attack, or myocardial infarction, occurs when part of the heart’s blood supply is reduced or blocked, causing the heart muscle to become injured or die. Victims may complain of various symptoms including:

• Mild intermittent chest discomfort that lasts a few minutes and comes and goes over a period of days

• Pain or discomfort in one or both arms that spreads to the shoulders, upper back, neck or jaw

• Shortness of breath

• Nausea, sweating, lightheadedness

• A general sense of anxiety

• A tendency to deny that anything serious is happening.

Women sometimes experience additional symptoms including:

• Stomach or abdominal pain

• Weakness and overwhelming fatigue

• Swelling of the ankles and lower legs.

When someone has a heart attack, he or she is awake and the heart is beating. It’s important to act right away to maximize the odds of survival and minimize permanent damage to the heart. Bystanders should call 911 and have the person lie down and rest until EMS arrives.

While heart attack is often described as a “plumbing problem,” sudden cardiac arrest is more of an “electrical problem” that prevents the heart from functioning effectively. Heart attacks can lead to sudden cardiac arrest, but there are many other causes as well, including congenital and electrophysiological abnormalities, severe heart failure, electrocution, and drug overdose.

In contrast, when sudden cardiac arrest occurs, the heart stops beating altogether. As a result, blood is no longer pumped throughout the body, including the brain. The person suddenly passes out, loses consciousness, and appears lifeless — except for abnormal gasping, which may last several minutes. Sometimes victims experience seizure activity at the onset of the event.

The sudden cardiac arrest victim is not awake and the heart is not beating. If no one provides immediate help, the victim will die within minutes.

When sudden cardiac arrest occurs, it is critically important for bystanders to call 911, give CPR, and use the nearest AED.

This is lifesaving care that anyone can provide. While it is best to be trained in CPR and the use of AEDs, even without formal training, bystanders can call 911, follow dispatcher instructions, push hard and fast on the center of the victim’s chest, and follow the directions on the AED while waiting for EMS to arrive.

Sometimes people hesitate to help because they are afraid they might do something wrong and hurt the victim. But since the cardiac arrest victim is clinically dead and cannot get any worse, bystander actions can only help. In addition, state and federal Good Samaritan laws provide protection to bystanders who render aid to sudden cardiac arrest victims in good faith.

Risk factors for sudden cardiac arrest include:

• A previous heart attack

• A previous episode of cardiac arrest

• A low (<35 percent) ejection fraction (the heart’s ability to pump blood)

• Underlying heart conditions such as coronary artery disease, congenital heart disease (e.g., hypertrophic cardiomyopathy), electrophysiological abnormalities (e.g., long QT syndrome, Wolff-Parkinson-White disease, Brugada syndrome)

• Severe heart failure

• Marked changes in electrolytes in the blood

• A tendency to faint

• Hyperthyroidism

• Electrocution

• Drug abuse

• A family history of heart disease or stroke, especially having relatives who died suddenly before age 50.

If your loved ones have one or more of these risk factors, they may be at risk for sudden cardiac arrest. If this is the case, they should see a cardiologist or heart rhythm specialist (electrophysiolgist) for an evaluation. The physician may recommend implantable cardioverter defibrillator therapy, medications, or other measures to prevent sudden cardiac death.

In summary, heart attack victims are awake and typically experience discomfort or pain. While they do not need CPR or treatment with a defibrillator, it’s essential to call 911 so they can be transported immediately to the hospital. In contrast, sudden cardiac arrest victims are not awake and need immediate CPR and treatment with a defibrillator. You can save a life by learning to recognize these conditions and being prepared to take appropriate action.




Arkyd 3 Reflight Deploys From The ISS

NASA via Planetary Resources

Planetary Resources, a company that wants to mine asteroids for precious materials, has just launched a demonstration vehicle to test out its asteroid mining technologies. The breadbox-sized Arkyd 3 Reflight (A3R) is so-named because the original Arkyd 3 died a fiery death in the Orbital Sciences explosion in October. This one survived its launch to the International Space Station in April, and today, astronauts booted it out of an airlock to see how it fares in low Earth orbit.

The vehicle’s mission is to test out components that the company later plans to send into deep space to visit resource-rich asteroids, with the goal of extracting water, which can be broken down in to hydrogen and oxygen for rocket fuel, and valuable metals, including platinum.

Over the next 90 days or so, the little spacecraft will test out its avionics and control systems–it won’t actually be doing any drilling anytime soon. While low Earth orbit isn’t a perfect facsimile to deep space, it will give the components a taste of the harsh environments they would face on the job—including extremely cold temperatures, radiation, and the vacuum of space. By pinpointing the components’ weaknesses in low Earth orbit, the company can hopefully fix any problems before sending spacecraft further beyond Earth.

The test is going according to plan so far, a Planetary Resources spokesperson told Popular Science.

Arkyd 3

Planetary Resources

About the size of a loaf of bread, the Arkyd 3 Reflight launched today from the International Space Station.

Later this year, Planetary Resources plans to launch another demonstration vehicle, the Arkyd-6. Twice the size of the A3R, the A6 will test out avionics, attitude control, power, and communications systems. (Notably, the robo-prospectors will eventually use LASERS to communicate with Earth.)

Onboard the A6 will also be an infrared imaging system, which will eventually scan asteroids for water and minerals. A Planetary Resources press release says “the system will first test targeted areas of our own planet before being deployed to near-Earth asteroids on future missions.”

The Arkyd-6 Test Vehicle Will Launch Later This Year

Planetary Resources

Later on, the company will figure out the best way to extract the resources from asteroids. But here’s one way it could be done, from a Planetary Resources video:


China has had a telescope on the moon for the past two years

China has had a telescope on the moon for the past two years

China has had a telescope on the moon for the past two years
Point a telescope at the moon, and you might just see one looking back. Chinese researchers have reported that their robotic telescope, the first of its kind, has been operating flawlessly ever since it landed on the moon in 2013.

The 15-centimetre telescope is mounted on the Chang’e 3 lander, which touched down on the lunar surface in December 2013. Chang’e 3 (pictured above) carried the Yutu rover, which repeatedly struggled to survive the lunar night and ceased working in March this year – but the lander is still going strong.

The telescope sees in ultraviolet light, making it particularly suited for observations that aren’t possible here on Earth. “There is no atmosphere on the moon, so unlike Earth, the ultraviolet light from celestial objects can be detected on the moon,” says Jing Wang of the National Astronomical Observatories in Beijing, China, who is in charge of the telescope. And since the moon rotates 27 times more slowly than the Earth, the scope can stay fixed on the same star for a dozen days without interruption, he says.

Snapping Earth
In a paper published this week, Wang and his colleagues detail the first 18 months of the telescope’s operation, during which it has observed for 2000 hours and monitored 40 stars. The team also captured a picture of the Pinwheel galaxy, shown below.

China has had a telescope on the moon for the past two years

Astronauts on the Apollo 16 mission had a manually operated UV telescope, which they used to take pictures of Earth, stars and the Large Magellanic Cloud. But the Chinese telescope is the first to be operated remotely from Earth.

That’s a challenge, because the moon is a hostile environment, full of charged and abrasive lunar dust that can get into equipment and destroy electronics, as Yutu’s troubles demonstrate. To counter this, the telescope is stowed within Chang’e 3 during sunrise and sunset on the moon, when dust is thought to be at its worst, and has survived much longer than its expected one year life. Wang says the scope is still working today, and the team are awaiting a decision to continue its mission past the end of this year.

Journal reference: arxiv.org/abs/1510.01435

Image information (from top): The Chang’e 3 lander (credit: Xinhua/Corbis); Picture of the Pinwheel galaxy captured by the telescope on the moon lander (credit: Chinese Academy of Sciences/The Bruce Murray Space Image Library/The Planetary Society)

By Jacob Aron