When she was four, Sara Dumas' parents took her to the emergency room. The girl had been vomiting frequently and her parents could not figure out why.
Doctors discovered a heart murmur. When they performed an ultrasound, called an echocardiogram, to look at the function and structures of the heart, they realized it was worse than a mere murmur: Sara had hypertrophic cardio-myopathy (HCM), a congenital heart disease.
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With HCM, the heart muscle becomes thick, making it difficult for blood to pump out of the heart and forcing the organ to work harder to pump at all. The disease can cause shortness of breath and severe chest pain.
In the worst cases, about 5 percent of the time, HCM sufferers need heart transplants.
Sara, at 16, learned that she was among the 5 percent, a group she would jokingly call the "lucky ones."
HCM is a genetic condition. When one family member is diagnosed with the disease, typically immediate family members are also tested.
Doctors discovered that Sara's father passed down the disease. He tested positive. So did Sara's brother, Ian, who is two years her junior.
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At first, the Dumases did not understand the seriousness of what they were dealing with.
Most children with HCM can live normally, but are not allowed to exercise strenuously, according to Dr. Elizabeth Blume, Sara's cardiologist. Team sports are usually off-limits, because of the risk of sudden death.
When young athletes suddenly suffer heart attacks on the field, undiagnosed cases of HCM is a common cause.
High-spirited and curious, Sara always tried to cope with her disease as best she could, pursuing the things she loved -- and was allowed to do, such as pursuing her passions for music and science. She also likes shopping with her friends, just like any other teenager.
"As far as I can remember, I've always been limited,'' said Sara. "I don't know anything different."
When Sara was 12, the Dumas family relocated and learned just how serious the disease could be.
"When we moved to Connecticut, and started going to Yale-New Haven Hospital," said Sara's mother Lisa Dumas, "and they were like 'Oh boy, they aren't on any medication? This is really serious. This is really dangerous.'"
Both Sara and Ian immediately were put on medication and became regulars in the office of cardiac specialists.
And as Sara got older, her condition worsened. In July 2008, both Sara and Ian were referred to Children's Hospital Boston in Massachusetts. On a family vacation that year, Sara was in so much pain, she dissolved into tears, her mother said.
"We were doing a lot of walking and even with frequent stopping, she was in a lot of pain," said Lisa Dumas.
By November, both siblings had small life-saving devices, known as implantable cardioverter defibrillators (ICDs). installed in their chests. ICDs instantly shock the heart to restore normal rhythm when any abnormality occurs.