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Bronny James, who suffered cardiac arrest during basketball practice at the University of Southern California on Monday, had a cardiac screening several months ago as part of a program for prospective NBA players, a source familiar with the matter told CNN Wednesday.

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According to the source, James had two screenings – a transthoracic echocardiogram and an electrocardiogram (EKG) – and both showed normal results.

A transthoracic echocardiogram looks at blood flow through the heart, while an EKG records the heart’s electrical activity.

Normal results of such tests would likely point doctors to look for another cause of the cardiac arrest James suffered on Monday, CNN’s Dr. Sanjay Gupta said Thursday. Cardiac arrest happens when the heart suddenly and unexpectedly stops pumping blood through the body.

The test results could also mean that Monday’s issue is not related to a structural problem with the heart.

Because of the care the 18-year-old received at USC and the fact he did not spend a long time in the intensive care unit is a good sign, Dr. Jonathan Drezner told CNN. Drezner specializes in sports cardiology at the University of Washington Medical Center

“The longer someone is down from cardiac arrest, the more potential damage to their heart tissue, to their brain tissue, to their body,” Drezner told CNN.

“A quick stay in the ICU and then a transfer to a lower level of care in a short period of time suggests that there was very little damage and is definitely a good sign.”

Dr. Celine Gounder, a CBS News medical contributor, said James is likely in for several rounds of tests to determine what may have happened.

Gounder is a clinical assistant professor of Medicine and Infectious Diseases at NYU Grossman School of Medicine.

James is likely to have an MRI of the heart, rhythmic monitoring and possibly genetic testing to explore other potential causes before returning to training and play, Gounder told CBS.

“You’re talking about probably a couple of months at least of testing, follow-up, trying to assess does he have a recurrence before easing back into training and play,” Gounder said.

James, a 6′3′’ guard, is an incoming freshman at USC. His father has said he has put off retiring in the hopes the two could play together in the NBA. Bronny James would be eligible to enter the NBA draft after one year at USC.