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Inherited heartbeat disorders are taking a toll on our teens

Inherited heartbeat disorders are taking a toll on our teens

Diana Swift


©2011 Thinkstock
A seemingly healthy 16-year-old boy is found dead in his bed by his father. An ace high-school hockey player collapses on the ice and dies. A 17-year-old girl dies after being sent home and told to "learn how to breathe properly.” Welcome to the world of inherited pediatric heart arrhythmias.

On a spring night in 2008, 16-year-old Taylor Allan was hanging out at a friend’s house not far from her home in Kingston, Ont. As Taylor, a Grade 11 student and soccer star, went to join her friends in the hot tub, she collapsed and was soon pronounced dead at a local hospital. Taylor’s heart had gone into spasm and stopped beating —the result of an undetected genetic defect known as arrhythmogenic right ventricular cardiomyopathy (ARVC).

An estimated 700-plus young Canadians under age 35 die annually of sudden cardiac death. Of these, about 50% are thought to have displayed at least one warning sign
In ARVC, healthy muscle cells in the heart’s right pumping chamber are gradually replaced with fat and fibrous tissue.

Sudden Cardiac Deaths

ARVC is one of a cluster of inherited cardiac conditions that cause the heart to beat dangerously faster or slower than normal, or to flutter helplessly in an uncontrolled manner (fibrillation) — sometimes leading to sudden death. Each year in Canada, an estimated 35,000 to 40,000 people die of sudden cardiac death (SCD), and an unknown but significant percentage of these deaths — especially in younger individuals — are due to inherited arrhythmias rather than arrhythmias caused by lifestyle and aging. An estimated 700-plus young Canadians under age 35 die annually of SCD. Of these, about 50% are thought to have displayed at least one warning sign. (See "Know the Warning Signs and Risk Factors,” below)

Firm figures on the inherited arrhythmias are hard to come by, says Dr. Joel Kirsh, a pediatric cardiologist at Toronto’s Hospital for Sick Children. "These disorders are moving targets, but a rough guesstimate is that as many as one in 500 people could have one.” That means that in a large high school of 1,000 students, two kids could potentially have one of these disorders.

Taylor’s father, Ken, believes his daughter would be alive today if there was wider recognition of the warning signs of such conditions, both in the general population and in the medical community, and he’s devoted himself for the past three years to doing that. Many doctors agree. "It’s time for these treatable conditions to be at the front of physicians’ minds — not at the back of a textbook,” says Kirsh.

Taylor had suffered at least one episode of fainting, including one during a soccer match, but had been discharged from the hospital with a clean bill of health after routine tests and an electrocardiogram (ECG). But exercise-related fainting is, in fact, one of the warning signs of cardiac arrhythmias.

Until recently, little was known about the prevalence and genetics of these difficult-to-diagnose arrhythmias. Detected early enough, however, these silent killers can be managed with drugs such as beta-blockers, which prevent vulnerable hearts from going into spasm, or with implantable cardioverter defibrillators (ICDs), devices that can shock an irregular heartbeat back into a normal rhythm. In certain cases, defective heart tissue can be zapped electrically or removed surgically, but some stress-worn hearts may eventually need transplants.

More Young Victims

While it’s young athletes dying on the field that grab headlines, SCDs can also occur at rest. Back in 1990, for example, Pam Husband’s then 16-year-old son, Greg, died in his bed. "He wasn’t particularly athletic, but at about age nine or 10, he started passing out at the sound of his alarm clock going off,” says Pam, a Mississauga, Ont., retired accountant and executive director of the Canadian Sudden Arrhythmia Death Syndromes (SADS) Foundation.

Greg was originally diagnosed with idiopathic (cause unknown) epilepsy. At age 14, he had had an apparently normal ECG, but after his death, a reanalysis of the original ECG by an expert electrophysiologist- cardiologist clearly showed he had long QT syndrome (LQTS) — an abnormal lengthening in part of the heart’s pumping cycle, which can lead to a dangerously rapid heartbeat. "The medical community couldn’t give us any answers,” says Pam, "because with LQTS, the heart tissue looks normal in an autopsy.” In 1995, Pam founded the Canadian SADS Foundation to provide support and raise public awareness and research (www.sads.ca).


Jessica Barnett died at age 17 after being misdiagnosed with epilepsy
"And two decades after Greg’s death, young people are still dying of these undetected disorders,” says Pam. She points to the case of Jessica Barnett of Wolfville, N.S., who, after a long history of fainting that began at age 12, died of LQTS in 2007 at age 17 after being misdiagnosed, like Greg, with epilepsy.

Fortunately, there’s some proactivity around these genetic conditions. Ontario has updated its autopsy standards for investigating unexplained sudden deaths in people ages two to 40. These require pathologists to assess the hearts of young suddendeath victims and store their heart tissue for genetic testing. "It is hoped that other jurisdictions will follow suit,” says Dr. Shubhayan Sanatani, director of cardiac pacing and electrophysiology in the Children’s Heart Centre at the BC Children’s Hospital in Vancouver.

According to Sanatani, diagnosing these inherited abnormalities is challenging, "even when you have a heightened index of suspicion,” since MRI and ECG results can all appear normal. But if these rhythm disorders can be identified in children before age 18, there’s a greater chance they won’t die as young adults.

Ginelle Johnston, 20, a Queen’s University engineering physics student from Calgary, is one of the fortunate ones. Diagnosed at age 12 with LQTS after her 48-year-old father died while water skiing, Ginelle was placed on a high-dose betablocker and later implanted with an ICD. Her ICD allows her to maintain an active lifestyle — but at a price. "I collapsed at a skating rink after being shocked three times,” she says. "It feels like a stick of dynamite has exploded in your chest.” Others liken the phenomenon to being kicked in the chest by a horse.

New Research

At St. John’s Memorial University researchers are studying 16 extended kinships of some 1,200 people — all thought to be genetically linked to a common 18th-century ancestor. Their family bibles are full of the names of people who, over the generations, died inexplicably at young ages — likely from ARVC. "We’d all meet at the funeral of some 19-year-old relative who just dropped dead and whisper about the family curse,” says Deborah Roberts of Miramichi, N.B., who grew up in Mount Pearl, N.L. The 48-year-old mother of a son with ARVC was herself diagnosed with the abnormality after a blood test and a heart biopsy in 1999 and later implanted with a defibrillator.

Knowing that you’ve passed a defective heart gene on to a child can leave a parent carrying a heavy burden of guilt. Two of Deborah’s sons have normal hearts, but her middle son, Adam, was diagnosed with ARVC at age 15 and implanted with a defibrillator. Now 23, Adam wants to stamp out this family curse for good. "He’s talking about having in vitro fertilization and pre-implantation genetic embryo testing with his future wife so the defect won’t be passed on to their children,” says Deborah.

Ontario has updated its autopsy standards for investigating unexplained sudden deaths in people ages two to 40. These require pathologists to assess the hearts of young sudden-death victims and store their heart tissue for future genetic testing
Clinicians stress the importance of testing the kin of affected patients since, for every one person who dies with an identified inherited arrhythmia, as Ginelle’s dad likely did, the odds are that several first-degree relatives will also have it, says Kirsh.

Screening

"We’ve made huge strides since the 1980s in our ability to detect and treat these elusive disorders, and there’s much greater public awareness now,” says Kirsh. It costs money to test a patient, he concedes,"but $5,000 spent on testing to save 50 or 60 years of life for a young person is not much, considering the amounts spent on renal dialysis and coronary bypass surgery for older people.”


Cardiac arrhythmias are investigated with electro -cardiogram, ultrasound, magnetic resonance imaging and genetic testing.
©2011 Thinkstock
So, should we also be spending scarce health-care dollars on mass screenings of young people? Certainly, screening can help identify at-risk people, notes Kirsh. In northern Italy, for example, a program of screening older children and young adults about to enter organized sports leagues markedly reduced sudden deaths. Similar programs in Nevada have picked up at-risk high-school athletes, and, in Japan, all kids going into junior high and high school are screened.

Dampening enthusiasm — apart from the price tag per year of life saved — is the thorny issue of who will read the massive volume of ECGs. "If you’re a cardiologist who is an expert in long QT syndrome, you’ll pick this up more reliably than a general cardiologist or a family doctor,” says Kirsh. A recent study by Kirsh found that among family doctors, cardiologists and electrophysiologists, only electrophysiologists did well at spotting LQTS on ECGs.

Jessica’s mother, Tanya Barnett, thinks doctors need a lot more training in spotting arrhythmias on ECG. "An ECG done at a small regional hospital found that Jessica had long QT, but the results were not confirmed by ECG at a large pediatric centre and the earlier, accurate test was dismissed,” she says. She has since become a strong advocate for better training of doctors in reading pediatric ECGs.

Training for Emergencies


Automated external defibrillators can save young lives.
Photo courtesy of philips.com
Many public buildings now have automated external defibrillators (AEDs), and there is growing support for placing AEDs in schools and training all students how to use them. "If we’re going to give teenagers vaccines to protect against STDs and teach them how to avoid pregnancy, then we can take the three to five hours needed to teach them how to save someone’s life,” says Kirsh. "We can’t bring back those who’ve died of these arrhythmias, but we can honour their memory by helping those who are still living with them.”

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