The family of a Missouri teen, who died unexpectedly while swimming with friends, said the girl was "a competitor and lively spirit."
Emma Aronson, of Lee's Summit, Missouri, died this week after collapsing at a swimming pool with her friends, according to her father Jason Aronson.
The 17-year-old rising senior was with her boyfriend and other friends at local pool where they were racing against each other in the pool.
"She was done racing and she just resting on edge of pool," Jason Aronson told ABC News. "She said I feel so tired...then she just passed out."
Aronson said his daughter's friends and others tried to revive the teen but that the medical attention did not save her.
"We believe that her heart gave out," said Jason Aronson, who said she had no current history of cardiac problems.
He told ABC News that Emma Aronson had always been athletic and had recently been on her high school varsity basketball team.
"She was a tomboy at heart and hung out with the boys and gave them a run for her money," he told ABC News.
An autopsy has been scheduled with the Jackson County Medical Examiner's Office to try and determine a cause of death.
Dr. Sahil Parikh, a cardiologist and director of the Interventional Cardiology Fellowship Program at University Hospitals Case Medical Center Harrington Heart & Vascular Institute in Cleveland, said that cases of sudden death in teens are extremely rare but that they can sometimes be related to cardiac issues including pumping function, electrical function of the heart or artery blockages.
"There are patients born with a wiring problem and [others] born with predisposition of arrhythmia (irregular heartbeat)," said Parikh, who said congenital defects can sometimes show symptoms only as the heart fails.
Parikh, who did not treat Aronson, said even young seemingly healthy teens can have physical issues with their heart that shows up only in cases of cardiac arrest. Some teens or young adults have cardiac myopathy, which is a thickening or thinning of the heart muscle that can lead to heart failure.
Screening all young athletes for heart disease has been controversial. Parikh said there are some tests that can be done to check for cardiac problems such as an EKG or echocardiogram, but that it is likely impractical to test every single young athlete for heart disease. Last month the American Heart Association announced in their blog they expect the NCAA to recommend heart screening for their athletes.
Parikh said it makes sense to do testing if there is a history of heart disease or cardiac abnormalities in the family.
"In the absence of family history, we’re left with doing usual which is a medical history and having a history of any kind of chest pains or fainting spells or blood pressure problems to look for obvious abnormalities," said Parikh.