one you may recognize, val chmerkovskiy.since first grade. until she started passing out during her vigorous tap routines at age 11. >> i'm holding her and she was nonresponsive. it was the scariest thing to see and to go through. >> reporter: after five incidents in three years, her parents knew it was something more than exhaustion and dehydration. >> the condition that she has is the second most common cause of sudden death among young people when they exercise. she actually had a small heart attack. >> reporter: after doctors discovered a malfunction in her heart, gianna underwent open heart surgery in long island in march of 2014. what were her first words after surgery? >> can i dance? >> reporter: within four months gianna was back on the dance floor, even winning a national championship. >> to see such a courageous young star to go through this struggle and defeat wit the strength of dance, is awesome. >> reporter: she thinks she's at a press conference to celebrate her miraculous recovery and perform. little does sh

one you may recognize professional dancer val chmerkovskiy. >> dancing with the stars. >> the other an 14-year-old gianna schupler, dancing since first grade. until she started passing out during her vigorous tap routines at age 11. >> the condition that she has is the second commonist cause of sudden death among young had people when they exercise. she had had a small heart attack. >> after doctors discovered a malfunction in her heart, she underwent complex open heart surgery at a medical center in long island in march of 2014. >> what were her first words after surgery. >> can a dance? >> within four months, she was back on the dance floor. >> she's amazing. >> even winning a national championship. >> to see such a courageous young lady go through the struggle and defeat it with the strength of dance is awesome. >> she thinks she's at val's studio dance with me for a press conference so celebrate her miraculous recovery and perform. little does she know this pro is about to bust through that door. >> gianna. mwah. hi. >> hi. >> i'm val. >> i'm gianna. >> a hug. >> how amazing is she