Preventing Sudden Cardiac Arrest

Every two minutes, someone collapses and dies from a malfunction in the heart’s electrical system—a condition called sudden cardiac arrest or SCA—and most of the victims have no idea they are at risk for the tragic event.

“That’s absolutely true,” says Dr. Richard Page, immediate past president of the Heart Rhythm Society and chair of the Department of Medicine at the University of Wisconsin School of Medicine and Public Health. “While a single individual’s chance of dying suddenly is quite small, there are so many people out on the street with some risk that the overwhelming majority of SCA victims have not ever demonstrated cardiac disease.”

The challenge for SCA researchers is two-fold, according to Dr. Page, who recently took time to discuss with us the latest findings on SCA risk factors and symptoms, as well as advances in preventing the heart emergency and saving lives.

“It comes down to two questions,” explains the heart rhythm specialist. “How can we better identify those at risk? And, given the fact we can’t identify all (or even most) of the potential patients: How do we address sudden cardiac arrest when it does happen?

Post: About 250,000 Americans die of sudden cardiac arrest every year. Who is at most at risk?

Dr. Page: Ongoing research confirms that heart structure is an important risk factor. People with an enlarged heart, or heart damage from a prior heart attack, are at higher risk for SCA than those with normal heart structure.

Remember, a heart attack isn’t a sudden cardiac arrest; a heart attack is death of heart tissue due to a blockage in an artery. A person who has a heart attack doesn’t lose consciousness, unless they have a cardiac arrest on top of that.

But it is clear from large, multi-center, randomized studies that many patients with prior injury to the heart or enlargement of the heart are better off with an implanted cardioverter defibrillator (ICD) than without one.

More recently, we have identified certain families who are at higher risk because of cardiomyopathy (a condition in which the heart is enlarged or thickened) or an electrical abnormality called long Q-T syndrome that can be seen on the EKG test. In addition, investigators are identifying the genetic abnormalities that underlie these conditions, as well as some genetic traits that may put one at higher risk of sudden cardiac arrest that are less subtle than abnormal heart structure or function.

Post: Is genetic screening for SCA risk available yet?

Dr. Page: Genetic tests for the general population are not ready for primetime because the genes don’t predict risk adequately. An abnormal EKG, for example, may or may not represent a significant risk to the individual. But we may have genetic tests for general screening five or ten years from now.

Likewise, there continues to be some debate as to the proper way to screen athletes. In Europe (particularly in Italy) everyone who participates in sports is screened with an electrocardiogram. The American Heart Association doesn’t yet recommend that. But they do advise that people be examined and asked about personal and family history. If someone has family members who died suddenly, he or she is clearly at higher risk for SCA and should be evaluated further.

Post: You mentioned that Italy recommends EKGs. Don’t we use echocardiograms (Echos) to screen U.S. athletes?

Dr. Page: We do both in some cases—but according to the risk. The most aggressive method of screening athletes is an exam, a history, an EKG, and an Echo. The echocardiogram defines heart structure. It provides a two-dimensional moving picture that shows chamber size and wall thickness. An EKG provides indirect evidence of structure. For example, alterations in electrical activity may suggest hypertrophy, or a prior heart attack. It doesn’t necessarily tell you if the heart is enlarged or damaged the way an Echo does, but it’s a simple and less expensive test.

Another point about universal screening: Some might say, “Well, let’s just screen everybody.” Well, the problem is that the tests aren’t perfect. If you screen a low-risk population, there will be some false positive results. I am concerned that the Italian protocols have excluded too many athletes. So universal screening of athletes might cause undue concern, and even cause some athletes at low risk to stop competing. Universal screening of low-risk individuals is a double-edged sword.

Are there any symptoms or warning signs of SCA?

Dr. Page: There may be symptoms in some cases. An important warning is passing out, or fainting. Most episodes of passing out are not a cause for alarm. But people should get checked out if they pass out while exercising, or if they experience palpitations and feel close to passing out. In addition, those with a history of heart attack or heart failure need to know their ejection fraction—a number that reflects the percentage of blood that is pumped from the left ventricle with each heartbeat. A good, efficient heartbeat pumps out more than half the blood in that chamber. When the heart is enlarged or scarred, however, the ejection fraction can drop below 35 percent or less. These people are at higher risk of SCA, and may be candidates for an ICD. A patient ought to be able to ask a doctor, “Is my heart enlarged, and if so, is there a number that would suggest I should have a defibrillator implanted?”

Post: What type of test is used to determine the patient’s ejection fraction?

Dr. Page: The most common test used to determine the ejection fraction is the echocardiogram. As I mentioned earlier, this test is basically a two-dimensional movie. Geometric calculations of the chamber volume just before and after the left ventricle squeezes suggest how much blood is pumped from the heart. For example, if the volume was a hundred before it squeezes and 50 after it squeezes, that’s an ejection fraction of 50 percent, which is good. But if the volume was 100 squeezing down to 75, that’s an ejection fraction of 25 percent, which is bad, and adds risk for sudden cardiac arrest.

Post: What should people do to lower their risk of SCA?

Dr. Page: If you have a personal or family history of recurrent pass-out spells, see a doctor. But all of us (whether or not we have heart disease) should care of our hearts. Discuss your cardiovascular risk factors with your doctor. Then, stop smoking, eat properly, exercise, control diabetes, and keep blood pressure and cholesterol in check to protect your heart and blood vessels.

Minimizing the risk of developing heart disease lowers the risk of heart damage and sudden cardiac arrest. Every day, I tell patients they ought to exercise. I don’t want to be a hypocrite, so I work out between 4:30 and 5:30 each morning, and then go to the office. I wish I ate a perfect diet, but I am trying!

Click here for more on SCA and an animation of the life-threatening emergency from The Heart Rhythm Society.

Watch for more from Dr. Page about saving lives with automated external defibrillators (AEDs) in a future Medical Update posting.

Preventing Sudden Cardiac Arrest The Saturday Evening Post

Pat later learned that gasping, also called agonal breathing, is relatively common in victims of cardiac arrest. Since her daughter’s death, Pat has become a CPR instructor and is now sharing her story to help educate and save lives.

“I don’t want people to have to go through the pain or guilt of losing a loved one because they weren’t sure what to do,” Pat explains. “Get trained in CPR, and don’t be afraid to act if you see someone who is unresponsive and gasping. It’s critical that you act quickly—seconds count.”

Gasping indicates that the brain is functioning, yet it is not normal respiration. If someone collapses and is unresponsive, the American Heart Association recommends calling 911 and getting an AED (automated external defibrillator), if available. Then, check whether the victim is breathing normally. If not, start CPR immediately.

Agonal breathing may also be mistaken for snorting, moaning, or labored breathing. For a video reenactment of how agonal breathing may look and sound, visit americanheart.org/agonal.

Neighborhood Heart Watch, the brainchild of Dr. Douglas Zipes, is a grass roots initiative to place AEDs in homes and neighborhoods.

Neighborhood Heart Watch: Remembering Maggie The Saturday Evening Post

Helping Hearts

Given that heart disease is the leading cause of death in the country for both men and women, it’s no surprise that researchers are always looking for better procedures and devices to assist people with heart trouble. From the University of Michigan comes the recently approved HeartMate II, a device that’s implanted in the chest to help a failing heart pump blood and keep patients alive until they can receive a transplanted heart. The new device is smaller—about the size of a D-cell battery —than earlier versions of heart-assisting implants, making it more suitable for people with smaller bodies, like women and adolescents. According to research published in The New England Journal of Medicine, the HeartMate II helped 75 percent of 133 patients stay alive —and improved heart function and quality of life—for at least six months or until a donor heart became available. One patient even recovered to the point where a transplant was no longer needed.

Cool It

Folks in cardiac arrest need to be cooled down —and quickly—to improve their chance of recovery and to avoid brain damage. But how? Methods such as packing unconscious patients in ice can take hours, which makes survival dicey. Now, emergency medical personnel have the Thermosuit, a plastic suit filled with cold water that reduces body temperature in approximately 30 minutes. Survival rates have improved in the hospitals where the Thermosuit is in use; a National Institutes of Health-sponsored trial will soon be underway to test the device further.

Get Your Own Cells

The heart muscle tends to become weaker after a heart attack because it doesn’t regenerate itself well. One day, heart patients may be able to use their own skin cells to repair their hearts, using a new type of stem cells called induced pluripotent stem cells (iPS). Like embryonic stem cells, iPS cells have the potential to develop into any type of cell in the body. A team of scientists at University of California, Los Angeles has grown functioning cardiac cells in the lab using cells from mouse skin reprogrammed with iPS cells. Scientists hope that this will lead to heart patients using their own skin cells to create iPS lines that will repair and regenerate.

Suit Smarts

Fabrics are a basic human need. And now, “smart textiles” do more than the ancient functions of protecting us from the environment and making us look good. They can sense certain stimuli and adapt or respond accordingly, explains Tushar K. Ghosh, Ph.D., a textiles professor at North Carolina State University in Raleigh. Among the many purposes are: protective gear for firefighters; garments that monitor patients’ vital signs like blood pressure and temperature; the delivery of drugs; and to serve as antibacterial or artificial skin for people with severe burns. In the works are fibers that mimic human muscle fibers, which hold promise for prosthetics and robotics. Ghosh and his team are researching a “heatingcooling garment, with fibers that get smaller or larger,” he says. “The idea is to create a piece of clothing that can let the wind come through or tune it closed if it gets too windy or cold.”

“No-Stick” Bandages

In the same vein, an electrical engineering researcher at Mississippi State University has developed a “smart” adhesive bandage that can check cholesterol, insulin, and blood chemistry without needles—a boon to people with diabetes who are used to sticking themselves many times per day. The bandage reads people’s biochemistry right through their skin. The inventor, Ray Winton, expects the bandage to be commercially available in one or two years.

Mag-netting Cancer Cells

Magnets: not just for science fair projects anymore! Scientists at the Georgia Institute of Technology have found a way to use magnets to catch cancer cells in the bodies of mice with ovarian cancer. They hope that this will be useful in diagnosing or slowing the spread of this deadly cancer in women. The way it may work: A peptide (a protein-like molecule) designed to attach to ovarian cancer cells is fastened to very tiny magnetic particles and injected into the abdomen. The peptides latch on to the cancer cells, and a magnetic filtering device outside the body pulls them out. Other researchers have developed magnetic nanoparticles that show promise for spotting and getting rid of harmful.

Crafty Solutions

Gas prices of late have convinced just about everyone that we need better ways to get around. For Leik Myrabo, Ph.D., an engineer-ing physics professor at Rensselaer Polytechnic Institute, one answer is the Lightcraft. “The Light-craft will move goods and people around the planet in more environmentally friendly ways, using power from renewable energy sources, such as the sun or wind,” he explains. The Lightcraft doesn’t carry its own energy or fuel, instead moving by energy beamed to it from remote laser or microwave power plants, either on Earth or in space (hence the name Lightcraft, a hyperenergetic craft flying on a powerful beam of light). That means it can weigh significantly less than conventional vehicles, such as jet planes and rockets with their massive fuel loads. Myrabo has been working on the concept for more than 30 years, but only in the last few years have power-beaming sources become cheap enough to make the Lightcraft feasible. He estimates that in three to five years, his company, Lightcraft Technologies, Inc., will be able to launch something to the edge of space; moving people will follow within a few more years. “This is species-changing technology,” he says, “sustainable global mobility that will enable you to go anywhere on the planet in 45 minutes or to the moon in a few hours.”

The Future of Medicine is Now The Saturday Evening Post

A: Leading cardiologist Dr. Douglas Zipes replies: Premature ventricular contractions are extra heartbeats coming from the bottom chambers of the heart (ventricles). In the vast majority of people, these beats are completely benign and nothing to fear. They are the commonest cause of palpitations affecting all age groups, and generally increase in number as one ages. I spend a lot of time in my practice reassuring patients that the palpitations they are feeling are nothing to worry about. Be happy you don’t sense them, because they can be a nuisance. I feel them occasionally, focus on what I am doing, and forget about them.

Question (and Answer) About Extra Heartbeats The Saturday Evening Post