Her aorta tore while in Ireland. She turned her drama into a cabaret act.

When Shana Pennington-Baird signed up for a summer conference in Ireland to enrich her voice acting career, she was excited to tack on some family vacation time. Her husband had always wanted to visit the country, and their daughter, then 8, was old enough to appreciate the sights.

A couple weeks before they left, Pennington-Baird experienced a tiny popping sensation in her chest while walking. That evening, she had what felt like heartburn up to her jaw. She was fine the next day, but the burning sensation returned a couple times, then disappeared completely. Although she'd never had heartburn, the then-45-year-old thought maybe it was something that comes with age.

After two weeks touring Iceland, Scotland and Ireland, Pennington-Baird's family returned to their home in Seattle, while she hit the road for a couple days before the start of the conference. As a former touring musical theater performer, Pennington-Baird was comfortable with solo adventures. On her first day, she hiked 8 miles in Northern Ireland. Then she was off to the remote Dingle Peninsula on the western coast for more sightseeing.

As she pulled into the driveway of her vacation rental, everything went gray. She started sweating profusely, like nothing she'd experienced. She knew she needed help. After looking up what emergency number to dial (999), she called an ambulance.

The hospital was a 90-minute ride away on twisting roads. Pennington-Baird kept the mood as positive as possible by cracking jokes. Once there, it took doctors several hours and a CT scan to find the problem.

Pennington-Baird had experienced an aortic dissection, a life-threatening condition where the wall of the aorta – the main artery carrying blood away from the heart – tears. She needed open-heart surgery, and it would have...