What makes a young heart stop beating?

Sudden Infant Death Syndrome (SIDS) takes the life of more than 2,000 babies in the United States every year. The diagnosis is synonymous with not only unfathomable tragedy, but mystery too; it’s given for any death of a child under 12 months of age for which there is no known cause.

Sudden Cardiac Arrest (SCA) is a leading cause of death among people under 25. It’s also the number one killer of student athletes, mainly basketball players and track stars. Both of these syndromes stop the hearts of young people in the blink of an eye, with seemingly no warning.

When Darren and Phyllis Sudman lost their 7-week-old son Simon, the initial diagnosis was SIDS. But their family physician also insisted the couple have their own hearts checked as soon as possible.

That’s when Phyllis was diagnosed with Long Q-T Syndrome, an arrh...