USC medical students publish breakthrough case report on rare heart anomaly

For first-year medical student Justin Wang, uncovering something never before seen wasn’t on the agenda when he showed up for his gross anatomy lab. Instead, he and his peers were there to learn about the human form’s visible internal structures by examining donated bodies. This type of coursework provides them with hands-on knowledge of human anatomy — an important early milestone in medical education.

But then Wang encountered a medical mystery. As he and his group examined their donated body, they found themselves both intrigued and puzzled. The heart and its associated vessels didn’t look like what their lab guide predicted.

“I saw this unique structure,” said Wang, now in his third year at the Keck School of Medicine of USC. “We just could not figure out what it was.”

They consulted with their faculty instructor, Kristian Carlson, PhD, and other anatomy faculty on hand. Textbooks were scoured. Still, the answer was unclear.

“I knew there was something new here,” Wang said. “If it surprised all the anatomy professors, it must be really fascinating.”

With Carlson’s guidance, the students diligently analyzed the anatomy of the odd-looking heart. They discovered it had a condition known as persistent left superior vena cava (PLSVC). This is characterized by an extra vein that flows into the heart, but their example had an accompanying constellation of features that had not yet been documented. 

“It’s not often that a basic science class focused on training gives students the chance to publish research,” said Carlson, a professor of clinical medical education at the Keck School of Medicine. “Seeing new variations that you haven’t encountered before is always a high point. It was such a thrill to see the uncommon tenacity that Justin and his colleagues exhibited, pursuing this until we finally documented how unique the alteration was.” 

The result was a case report recently published in the European Journal of Anatomy, with Wang as the first author and Carlson as the senior author. This contribution to medical literature not only constitutes a rare discovery of new anatomical structures in a first-year gross anatomy course, but also helps educate surgeons and other clinicians about a variation that can complicate standard medical procedures. The study may even inform new scientific understanding of a PLSVC.

Seldom symptomatic, but potentially dangerous if undetected

PLSVC takes shape before birth. Normally, what begins as two veins in a fetus eventually transitions into one major tributary draining into the right side of the heart. In PLSVC, that union of pathways for blood is never fully realized.

Although usually harmless on its own, the anomaly sometimes appears alongside health conditions such as irregular heartbeats. PLSVC can be detected incidentally during careful review of imaging, but is often missed. 

The lack of easy visibility leads to risk. Procedures including heart surgery, defibrillation and the placement of a cardiac catheter can go awry in a patient with PLSVC if they’re conducted based on typical heart anatomy.

With the case report, Wang and his colleagues bring clinicians’ attention to a never-before-seen anatomical variation.

“In our case, there were other alterations to the anatomy of the veins,” Wang said. “It would be hard to diagnose with imaging alone — the sort of thing that could surprise surgeons when they have to work on the fly. So it’s not just an interesting anomaly. It’s something that affects patients’ lives.”

The case report also raises questions about the developmental origin of PLSVC. The specific alterations seem to contradict the two prevailing explanations for how the condition comes to be.

“What we found doesn’t fit into the textbook picture of PLSVC,” Wang said. “It suggests new questions to ask in basic embryology research.”

Getting the most out of a rare opportunity

Identifying the unique anomaly in a donated body provided research opportunities that are not always possible with a standard case report. 

The team employed a research-grade instrument for high-resolution 3D X-ray imaging called micro-computed tomography (micro-CT). It allowed for detailed, isolated examination of the heart. They also used a 3D rendering of the heart to perform clinical imaging analysis. Ultimately, they gained further insight by dissecting the organ and the surrounding thoracic cavity.

The keen curiosity and hard work paid off with an unexpected honor: the micro-CT images from their case report were chosen for the cover of that journal issue.

“We used some cardinal and gold in the images, for USC,” Wang said with a laugh. “It was fun to see them right there on the front of the journal.”

Working on creating the case report was also personally meaningful for Wang. He and his classmates first noticed the puzzling anomaly the same week that he got his start in trauma surgery investigations. The twin research experiences have shaped his aspirations to become a surgeon and influenced his approach to biomedical science.

“I really learned the mindset of a physician-scientist,” he said. “And to me, medicine is about having a concrete positive impact on people’s lives, every day I go to work.”

At the end of their paper, where advisers and funders are typically acknowledged, Wang and his colleagues included a sincere tribute to those who choose to donate their bodies for medical training and research. 

“This is such a selfless thing to do, and it’s extremely impactful for students,” Wang said. “We’re learning medicine with these donors. In a way, they are our first patients. Their generosity will help us save lives in the future.”

Learn more about the Keck School of Medicine of USC MD program.