Ever since she was 5 years old, Southland native Jenny Thompson has been fascinated with killer whales. She landed her dream job as a trainer at SeaWorld San Diego in 2004, when she was only 23 years old. She relished the physically demanding gig, but a decade later, she began having sharp pains in the center of her chest.

"I was diving off high boards and playing with these huge animals," says Jenny. "I figured my sternum was just inflamed from the physical stress."

The daughter of a scientist and a radiologist, Jenny told her parents about the pain. She also visited a local emergency room, an urgent care clinic and her primary care doctor. No one could identify the source of her symptoms, and her heart appeared normal and healthy on imaging.

A single mom, Jenny left her job at SeaWorld to pursue higher paying but less personally fulfilling work as a corporate recruiter. The job was less physically demanding, but her symptoms didn't abate. Instead, they got worse. Her chest pains began to radiate through her back and jaw, and she found herself short of breath when she made her bed in the morning.

"When I went to urgent care or the hospital, doctors ran blood tests and listened to my heart. Sometimes they did an electrocardiogram," Jenny says. "But since my heart seemed to be functioning as it should, they sent me home."

Over time, Jenny's pain became so severe she could barely function. She was tired all the time, struggled to speak during work calls and frequently felt like she was gasping for air. What's worse, doctors from San Diego to Orange County were dismissing her at every turn.

Read: Women and Heart Disease: What We Know Today

Desperate for answers, Jenny began doing her own research and kept a log of her symptoms. When she learned that endometriosis can infiltrate different organ systems and realized her pains coincided with her period, she thought she had an answer.

Her gynecologist did a laparoscopic procedure and found no evidence of disease. She went to a gastrointestinal specialist, who conducted a similarly fruitless sigmoidoscopy. Eventually, she underwent a CT scan, which revealed plaque in her left anterior artery. That didn't explain the pain, so she underwent an angiogram.

"When I woke up from that exam and the doctor said my arteries looked great and the plaque wasn't that bad, I started crying," Jenny says. "I didn't want him to give me some devastating diagnosis, but I needed an explanation for my pain."

That's when Jenny put Cedars-Sinai cardiologist Dr. C. Noel Bairey Merz on the case. 

Rread: Matters of the Heart: C. Noel Bairey Merz, MD

Dr. Bairey Merz, who holds the Irwin and Sheila Allen Chair in Women's Heart Research, is one of the world's foremost experts in heart disease in women. As director of the Barbra Streisand Women's Heart Center in the Smidt Heart Institute at Cedars-Sinai, she has devoted much of her career to unraveling the unique ways in which heart disease presents in women.

Doctors were puzzled by Jenny's symptoms, particularly since she appeared healthy and fit and was only 37 years old. Jenny's quality of life was at its worst by the time she met Dr. Bairey Merz. Her pain was so debilitating—sometimes knocking her out for weeks at a time—that she was forced to quit her job.

Dr. Bairey Merz put Jenny on three medications to reduce the burden on her heart: baby aspirin, a statin and a calcium-channel blocker. Then she decided to dig deeper with a second angiogram at Cedars-Sinai.

The test uncovered coronary microvascular endothelial dysfunction, a disease of the small blood vessels that impairs blood flow to the heart—a disease that Dr. Bairey Merz holds close to her heart. In fact, Dr. Bairey Merz has served as the principal investigator for several groundbreaking multiyear, multicenter research studies showing that women's heart attacks are frequently caused by microvascular dysfunction.

"Microvascular dysfunction produces symptoms that are similar to those recognized for heart disease—such as shortness of breath and chest pain," Dr. Bairey Merz says. "But it's really good at hiding, since there's often little to no narrowing in the main arteries."

Thanks to Cedars-Sinai's sensitive testing methods and the highly skilled team of experts at the Barbra Streisand Women's Heart Center, with their deep understanding of how heart disease manifests in women, doctors were able to spot the dysfunction in Jenny's small vessels to further identify treatment targets to relieve her symptoms and prevent future heart attacks.

While the reduction in pain was a welcome change, just getting the diagnosis changed everything for Jenny.

"For five years, from the onset of pain until I got diagnosed, was the most frustrating road I've ever been on," she says.

Read: Solving Johanna's Heart Attack Mystery

To help Jenny resume her usual activities, Dr. Bairey Merz prescribed cardiac rehab three times a week so Jenny could regain strength and endurance in a safe and stepwise progression.

"It's like relearning to exercise," Jenny says.

Just as important, Jenny learned to advocate for herself. The sensations she was feeling in her chest were real; she just had to find an expert who believed her and could uncover the culprit.

"The symptoms of microvascular disease are slightly different from a heart attack, so it's important for patients to know what to watch for," Dr. Bairey Merz says.

Some telltale signs include:

• Chest pain or discomfort
• Shortness of breath
• Sweating
• Nausea and dizziness
• Pain that spreads beyond your chest to one or both of your arms or neck
• Swollen feet (where you can't put on a shoe)

Every now and then, Jenny still gets a sharp pain in her chest. She starts wondering what steps to take if anything happens. But now she knows she'll be taken seriously if she has to walk into an emergency room.

"The nice thing now is I can walk in and say, 'I have microvascular disease,'" Jenny says. "Then I'm in and out in 30 minutes."

Over time, Jenny has become stronger and more fit. In fact, just last month she rejoined SeaWorld as a full-time supervisor.

"I know it will be challenging for me, but I want to give it a shot and get back to what I love," Jenny says.

Dr. Bairey Merz has given her the tools she needs to pull it off.

Read: Heart Attacks in Women Could Be Flying Under the Radar