April 6, 2006 -- A ringing alarm clock marked the beginning of a medical mystery for the Shockley family.
It was August 1996, and Linda Shockley heard the alarm, but her daughter Casey, a 16-year-old lacrosse player, didn't get out of bed.
When she went to Casey's room, Linda realized something was wrong and called to her husband, Bill. "I think she said, 'Bill, she's not breathing,'" he said. "It was one of the most frightening sounds I've ever heard."
For 30 minutes, Bill and Linda, who are both doctors, administered CPR, frantically fighting unsuccessfully to save their daughter's life.
"As a mother, you just don't kiss your child goodnight and put her to bed, and for her to die and not know," Linda said. "I wanted to know why. What happened?"
How does a seemingly healthy, active teenager suddenly die? As doctors later discovered, a heart abnormality, one that could have been triggered by something as benign as an alarm clock, killed Casey.
And the same defect may be to blame for more than half the sudden, unexplained deaths in teenagers and young adults, killing as many as 4,000 young people a year.
Adrenaline Rush Can Be a Trigger
Casey had never been seriously ill, though she had fainted a couple of times and once complained that she felt her heart racing. Taking no chances, Bill and Linda took her for some tests. The results came back normal.
Just a day before her death, Casey had an electrocardiogram and was given a clean bill of health.
Dr. G. Michael Vincent, a cardiologist at LDS Hospital in Salt Lake City and a pioneer in the study of sudden cardiac deaths, was able to uncover the mystery for the Shockleys. He looked at Casey's EKG from the day before she died and noticed something that many doctors might miss.
Casey's EKG showed a much longer interval between the Q and T waves than what is considered normal. The teenager had died of something called long QT syndrome, a primarily genetic glitch in the heart's electrical system that can trigger a fast, irregular and lethal heartbeat.
Unfortunately, it's something that doctors often miss.
"It is very disappointing to know how many physicians still have never heard of this," said Dr. Michael Ackerman, a pediatric cardiologist at the Mayo Clinic.
Casey's fainting spells and her complaints of a racing heart are classic symptoms of long QT syndrome that had gone undiagnosed, as it often does.
"The end point is either 80 years symptom-free -- never an episode of long QT misbehavior -- or an episode in which the long QT heart suddenly spins out of control," Ackerman said.
Researchers believe long QT syndrome affects about one in 3,000 people in the United States, and Ackerman said it may explain the sudden deaths of some young athletes.
"The triggers are the thrill of victory, the agony of defeat. So, the adrenaline rush, doorbells, alarm clocks, the buzzers at games, the game, 'boo' where you can be startled," he said.
One thing doctors do know about long QT is that it is inherited. That was a difficult thing to hear for the Shockleys, who worried that their younger daughter Lindsey was also at risk.
"I was terrified," Linda said. "I mean, I thought Lindsey would die. We took the alarm clock out of her room. We took the phone out of her room. I think I watched her sleep every night."
Stress Test Can Ease Minds
Luckily, long QT can be easily diagnosed.
Like Casey, Karen Doust had fainted once as a child and again in college, never suspecting anything was seriously wrong. Then on a beach vacation with her two children, Karen, who was 33, went into cardiac arrest and collapsed. In her case, CPR brought her back.
"I'm very lucky," Karen said. "I honestly didn't realize the greatness of this and that itcan choose to do it whenever it wants. And I just really didn't know what I really had."
A simple stress test, used to generate a picture of the heart's electrical system, was all it took to confirm Karen's diagnosis. Her EKG was clearly abnormal, said Vincent.
And there was a 50-50 chance she'd passed the long QT genes to her children. "And you just go, 'Please, don't let them have it,' you know?" she said.
Her two sons were tested and came up negative for the abnormality.
Once diagnosed, long QT syndrome is treatable, usually with beta blockers, commonly prescribed heart medication that help keep the heart's rhythm in check.
"Once properly treated, the vast majority of people lead not only a normal lifestyle but a normal life span," Vincent said. "The risk is in not knowing who has it and, therefore, not treating them."
Back in Chapel Hill, N.C., the Shockleys flew to Salt Lake City to get stress tests from Vincent.
"We'll never forget his words," Linda said. "They were, 'Let's talk about Lindsey first, because she is perfectly normal.' And we'll never forget that day."
The moment was bittersweet. Although he'd never exhibited a symptom his entire life, Bill learned it that he had passed the gene to Casey.
"Certainly, I feel, you know, guilty, but I don't know that I feel that I could feel any worse than I do about losing her," Bill said.
Since Casey's death, the Shockleys have been trying to take the mystery out of long QT syndrome and other heart abnormalities by educating others through the Sudden Arrhythmia Death Syndromes Foundation, founded by Dr. Vincent. For more information (visit sads.org).
"I really think none of us will rest until parents, teachers, nurses, coaches, until everyone knows about this," said Linda.