Record-setting swimmer Dana Vollmer opted against an implanted cardiac defibrillator to treat her potentially deadly heart rhythm disorder.

American swimmer and record-setter Dana Vollmer's mother doesn't just cheer her on from the stands during competitions - she's on alert, external defibrillator in tow, in case her daughter's heart condition takes the spotlight during the races.

Diagnosed at 15 with a potentially deadly heart rhythm defect called long Q-T syndrome, Vollmer and her family opted against an implanted defibrillator that would have monitored her heart rhythms and provided a life-saving shock should she suffer a heart attack.