Hiba Jelahej was standing in her kitchen in Chandler, Arizona, last summer when everything around her started spinning. She blacked out and fell to the ground. When she came to, she brushed it off.

She was in the middle of training for a marathon and figured it was from the added stress on her body. Maybe she was dehydrated, she thought. Then 30, she'd never dealt with any major health issues.

She'd always been fairly active and ate a healthy diet. She even studied nutrition in college. But then she fainted again while at work just days later.

And then again. After a fourth fainting spell within one month, Jelahej was rushed to the emergency room. The ER doctor looked at her bloodwork and said, "Something is going on with your heart.

It's critical you get evaluated by a cardiologist." An invasive cardiologist put her through a series of stress tests on a treadmill to see how her heart responded. She had a test to examine the electrical signals from the heart.

Then he did a type of test that involved putting a probe down her esophagus to get a clearer image of her heart through sound waves. It was that final test that found the source of the problem: an extremely rare heart condition called a quadricuspid aortic valve. A normal heart has three cusps, or leaflets, in the aortic valve.

Some people are born with two cusps; that condition is called bicuspid aortic valve and it's among the most common congenital heart defects. Far more unusual is what Jelahej has: four cusps, known.