YUMA, Ariz. - A 17-year-old girl is alive thanks to a newly-approved device that gives the wearer a shock when it detects heart failure.

Gisselle Castro was talking to her sister when "everything went black." Her wearable defibrillator detected the arrhythmia and delivered a shock that restored her normal heart rhythm while her family got help. Minutes later, Giselle's heart slipped back into ventricular fibrillation, and the LifeVest delivered three more shocks that saved her life.

"I had three heart attacks and died and came back," Gisselle told 12 News.

Eleven days earlier, Gisselle had been prescribed the LifeVest with instructions to wear it all the time. Gisselle, at just 17, had a diagnosis of dilated cardiomyopathy, or heart failure.

The LifeVest was approved for pediatric patients December 2015.