Wooziness hit Greg Wooldridge just as he and his wife were about to drive home from shopping. Seconds later, the 61-year-old Portland, Ore., man slumped forward in the passenger seat, his heartbeat lapsed into an ineffective chaos.
His wife, Anita, pounded the car horn to summon help from store employees, who called 9-1-1. She then pulled her 6-foot-3, 200-pound husband out of the car to begin life-saving chest compressions in a desperate race to keep him from dying. Eight minutes later, firefighter paramedics arrived and delivered electric shocks from a defibrillator to jolt his stalled heart back into action.
Against long odds, Wooldridge survived. But cardiologists never found an explanation for his near-death experience on that December day in 2008.
"Every time I go in for a checkup, I ask: Why did I have this?" Wooldridge says. "They don't know."
Sudden cardiac arrest -- killer of 180,000 to 250,000 people each year in the U.S. -- remains one of medicine's most intractable problems.
Despite years of intense research, refinements in resuscitation and widespread placement of automated defibrillators in public places, 90 percent of victims never regain consciousness.
Since 2008, four large-scale clinical trials of potential new treatments for out-of-hospital cardiac arrest have failed to show improvement in survival.
In the struggle to understand sudden cardiac arrest, Portland, Ore., residents are among the most closely watched populations in the world. Since 2002, researchers have gathered every relevant detail they can find on every case of sudden cardiac death that occurs in Multnomah County, Ore. "We want to identify people before they experience sudden cardiac arrest, not after," says Dr. Jonathan Jui, an emergency medicine physician at Oregon Health & Science University and one of the leaders of the Oregon Sudden Unexpected Death Study. Collaborators include researchers at Cedars Sinai Medical Center in Los Angeles, ambulance and fire-and-rescue teams, the state Medical Examiner's Office, and hospitals across the county. The years of effort are starting to pay off with tantalizing clues in the search for strategies to prevent sudden cardiac arrest. Among them: Women are about half as likely as men to show an important warning sign -- decreased heart pumping ability -- before cardiac arrest, researchers reported in November. That means that women at risk are probably less likely than men to receive protective implantable defibrillators.Contrary to long-held assumptions, vigorous physical activity seldom triggers cardiac arrest; an analysis last year of 300 cases in the Oregon study found that people were sleeping or engaged in light activities at the time of their cardiac arrest. Vigorous exercise was a potential factor in only 5 percent of cases.Residents of poor neighborhoods face a much higher risk of sudden cardiac arrest than those in higher income areas, the Oregon study revealed in 2006. Researchers say the findings should guide decisions where to target anti-smoking programs and place automatic defibrillators. "It's one of the most comprehensive looks at this condition ever conducted," says Dr. Mickey Eisenberg, a medical professor at the University of Washington and director of emergency medical services for King County, renowned for its cardiac arrest survival rate. Eisenberg, who is not involved with the Oregon study, says it is giving researchers the means to root out the underlying causes of cardiac arrest.
As long as the medical response remains limited to desperate resuscitation measures, Eisenberg says, "We're never going to have full success. But if you go after the causes, the triggers, then you can talk about making a major attack on this problem." Beyond Belief The tragedy of sudden cardiac arrest made a searing impression on Dr. Sumeet Chugh in 1993. He was a second-year medical resident at Hennepin County Medical Center in Minneapolis when a19-year-old girl arrived at the emergency room after collapsing on a dance floor. "We couldn't bring her back," says Chugh, now a cardiologist at Cedars Sinai Medical Center in Los Angeles and a medical professor at UCLA. An autopsy revealed no cause. "It was, to me, beyond belief," Chugh says. "She was 19, at the peak of her health." Chugh went on to specialize in cardiology. He began organizing the Oregon Sudden Unexpected Death Study shortly after landing a position at OHSU in 1999. Coronary artery disease plays a role in many cases of sudden cardiac death. In eight out of 10 cases doctors find clogged and hardened heart arteries. But the majority of people with coronary artery disease -- more than 80 percent -- will never experience cardiac arrest, so the diagnosis is not a reliable way to detect those at highest risk of sudden death.
Researchers also have known for years that a heart with a measurably weak pumping ability is a risk factor. "But it turns out that less than a third of people who have a cardiac arrest have that sort of weak pumping ability," Chugh says, based on findings in the Oregon study. Last year, the researchers found evidence that a slight alteration in heart rhythm, a lengthening of the so-called QT interval, increased sudden death risk by a factor of five in patients with coronary artery disease. The alteration was different from "long-QT" syndrome, a widely known inherited disorder that puts people at risk of sudden death. Chugh's group and others are pursuing genes that may predispose people to the rhythm alteration. Soon, the researchers hope to have enough evidence to improve estimates of individual risk by combining information about heart rhythm, pumping ability, genetics and other factors. No Warning Wooldridge, a former U.S. Navy aviator, had no reason to suspect heart problems before his cardiac arrest. Annual physical exams required for his job as a commercial pilot included cardiac EKG tests, which showed no abnormalities. His blood pressure and cholesterol levels were exceptionally healthy. "I didn't have any problems at all," says Wooldridge, who now has a surgically implanted defibrillator to protect him from a repeat cardiac arrest. Patients with seemingly normal hearts account for about 5 percent of sudden cardiac deaths.
At this point, experts have no idea how to stop these unpredictable deaths. If the cause is an inherited trait, the Oregon study could help researchers find the genes that put people such as Wooldridge at risk. "We have more than 2,500 cases, and DNA on at least half of them," Chugh says. He considers the problem of sudden cardiac death his life's work. "We have this opportunity to prevent so many deaths," he says. How to Help Someone in Cardiac Arrest Recognize it: If you see a person collapse for no apparent reason and that person is unresponsive and not breathing, assume it is cardiac arrest. Gasping or gurgling breath sounds may last up to several minutes after a cardiac arrest and should not be mistaken for normal breathing, experts say.Get help: Call 9-1-1 or get someone else to call before attempting cardiopulmonary resuscitation. CPR only works as a desperate holding action until rescuers arrive. Staving off death requires a jolt from a defibrillator.Start chest compressions: Position the patient on the floor, face up. Place the heel of one hand on the center of the chest with the heel of the other hand on top of the first. Lock both elbows in a straight-arm position and position your shoulders directly above the patient's chest so that you can put your weight into it. Press with enough force to compress the chest about two inches and fast enough to do 100 compressions per minute (the same rhythm as "Stayin' Alive" by the Bee Gees, the American Heart Association tells its CPR classes). Lift hands after each compression to let the chest spring back.Mouth-to-mouth: Skip it if you're unsure of the technique and the patient is an adult in cardiac arrest. A child who collapses is more likely to have experienced respiratory arrest and require mouth-to-mouth breathing, which also is crucial for adults after near-drowning, drug overdose or carbon monoxide poisoning, according to the American Heart Association.Don't stop: Continue chest compressions without pause until rescuers arrive. If another bystander is present, take turns doing the compressions to make it easier to keep up.Be prepared: Take a CPR class to learn more details and gain confidence in lifesaving skills. Find a course by contacting the American Heart Association (www.americanheart.org).