Credit: Danny Feld/ABC Television Group © 2010 Disney Photo: Meredith on Grey's Anatomy, February 17, 2011

Teddy and Meredith fought valiantly to save Oliver's life on this week's episode of Grey's Anatomy (Season 7, Episode 15), but it was all for naught: the damage to his aorta was too severe. What happened? How can someone go from chest pain to death in under an hour? Here's what you need to know.

As we stated last week, an aorta is a major blood vessel responsible for carrying blood from the heart. An aortic dissection usually occurs because of a tear in the wall of the aorta. Such a tear creates two channels within the aorta: one in which blood is moving and one in which the blood is still. The latter channel can cause the aorta to swell and even rupture, as was the case with Oliver. Chances of survival decrease dramatically at that point: less than half of patients whose aortas have ruptured survive. But aside from those more dire scenarios, the main symptom is indeed chest pain. No one knows what brings aortic dissections about, though atherosclerosis — or hardening of the arteries — and high blood pressure are known risk factors.

Source: PubMed Health

Original Air Date: February 17, 2011

MORE FROM THIS EPISODE:

"You Know What's Perky? My Boobs" and More Quotes From Grey's Season 7, Episode 15

The Meredith Grey Episode: Grey's Season 7, Episode 17