Faculty Spotlight: Thomas Dewland, MD

Solving Puzzles of the Heart

A lifelong athlete, Thomas Dewland, MD, found himself drawn to cardiology in medical school. “I’ve been a runner and cyclist most of my life, and have always had an interest in the physiology of exercise,” he said.

Dr. Dewland grew up in northern Virginia, earned his bachelor’s degree in biophysical chemistry from Dartmouth College, and his medical degree from Yale University School of Medicine. He came to UCSF, where he completed his internal medicine residency, general cardiology fellowship, and cardiac electrophysiology fellowship.

He enjoys the challenge of diagnosing and treating arrhythmias, or heart rhythm disorders. “Cardiac electrophysiology is a niche field of cardiology, and when you’re in the EP (electrophysiology) lab, you’re trying to figure out a puzzle,” said Dr. Dewland. “We know there’s a problem, but we have to get in there and do a lot of measurements and testing to figure out the specifics. You have to think on your feet.”

Once he and his team pinpoint the problem, they can interrupt abnormal electrical patterns in the heart that cause the arrhythmias through ablation. This involves strategically destroying areas of heart tissue to short-circuit the arrhythmia. In other cases they may implant a pacemaker or defibrillator.

Coming Full Circle

After completing his training at UCSF, Dr. Dewland joined the faculty at Oregon Health Sciences University. In addition to treating patients at his busy clinic in Portland, Ore., and learning about some of the latest devices and technologies, he also staffed an outreach clinic in Coos Bay, about a four-hour drive south. “It was interesting practicing medicine in a rural hospital,” he said. “It’s a four-hour ambulance trip or a long helicopter ride to Portland if any problems were to occur, so you’ve got to get it right.”

That distance from Portland also meant that he would spend the night, go for runs after work, and eat dinner in town, giving him a better understanding of the community in which his patients lived. “Coos Bay was once the largest lumber port in the world, but the local economy has declined in past decades, and many residents are struggling financially,” said Dr. Dewland. “I developed an appreciation for why some patients might have difficulty getting their medications, or might not think it’s important to take them.”

In 2020, Dr. Dewland was recruited back to the UCSF faculty. “I was drawn by the opportunity to work with people I trained with, who are among the best electrophysiologists in the world,” he said. “It’s a bit intimidating, but I knew it would make me better from an intellectual and academic standpoint. It was also appealing to work under very good leaders like [Chief of the UCSF Division of Cardiology] Jeff Olgin and [Chief of the UCSF Cardiac Electrophysiology and Arrhythmia Service] Ed Gerstenfeld.”

He also appreciates being back in the Bay Area, a hub of innovation in cardiac electrophysiology. For example, Dr. Dewland is working with Dr. Gerstenfeld, collaborating with companies that are pioneering a new technology called pulsed field ablation. This approach allows an electrophysiologist to use high-voltage energy for very short periods of time in a way that selectively targets heart tissue, minimizing the risk of collateral damage to nearby organs such as the esophagus or lungs.

“I’ve helped test this out in large animal models, which has allowed me to work side by side with the engineers who developed the technology,” said Dr. Dewland. “It’s fun to watch their reaction when they realize their hard efforts have resulted in a catheter that works! This partnership is fairly unique to the Bay Area, and we are fortunate that many of these startup companies find value in partnering with UCSF.”

Exercise and Arrhythmias

Dr. Dewland also continues to collaborate on research projects with his fellowship mentor, Gregory Marcus, MD, Endowed Professor in Atrial Fibrillation Research. “I’m interested in learning more about the intersection between exercise and arrhythmia,” said Dr. Dewland. “For example, there is a very strong association between long-term exposure to endurance exercise and arrhythmias, especially atrial fibrillation. We all know that we should exercise, but we don’t understand why or at what point long bouts of endurance exercise become unhealthy.” 

This is a difficult thing to study. “It’s not feasible to randomize people to run 100 miles a week versus doing nothing, and then follow them for five years,” said Dr. Dewland. “People who engage in extreme forms of exercise probably have other health and lifestyle habits that are different from the average American, so it is a challenge to sort out.”

Dr. Dewland is also beginning to investigate how exercise may promote arrhythmias in patients with known rhythm abnormalities. “After we implant a defibrillator, patients always ask us, ‘Can I exercise?’” he said. “I’d like to know whether exercise mitigates or contributes to the risk of future arrhythmias in these patients, both in the short term and over the long term. With defibrillators and the explosion of self-monitoring with wrist-worn devices, there’s a growing opportunity to better understand the relationship between arrhythmia and exercise.”

For example, Dr. Dewland and his collaborators recently published a paper describing how patients with atrial fibrillation tend to have lower daily step counts, and the more severe their disease, the lower their step counts. “It’s tough to know if exercise is impacting their arrhythmia or vice versa, and we’d like to learn more,” he said. In one creative approach, their group is studying whether COVID-19-related shelter-in-place orders may have affected the arrhythmia burden in the population. “Rather than someone saying, ‘I’m going to stop exercising,’ there’s a third party telling you that you can’t go outside,” he said. “It may be an interesting way to study it.” 

“Dr. Dewland was one of the most outstanding cardiology and cardiac electrophysiology fellows we’ve had the pleasure to train, and we were very fortunate to recruit him back to UCSF,” said Dr. Marcus. “Tommy is a brilliant clinical investigator who substantially heightens the quality, sophistication and impact of every research project he touches. He’s also an extraordinarily conscientious clinician with impeccable technical skills as a proceduralist.”

Caring for the Whole Patient

Dr. Dewland enjoys the dynamic nature of the EP lab. “There’s a lot of thinking on your feet, not only to make a diagnosis, but as things change or new arrhythmias emerge,” he said. “That makes it fun, but I recognize the risks.” For example, ventricular tachycardia (VT) is a potentially lethal arrhythmia, and to successfully ablate it, electrophysiologists often need to deliberately trigger it in the EP lab to understand where it originates and how to fix it. “You’re stirring the hornet’s nest, and you have to be able to rescue the patient from that and also know when to stop,” he said. “Those are hard things to learn, and it takes time and experience.”

He also relishes the complexities of caring for the whole patient during a procedure. “While we’re treating the arrhythmia, we also need to recognize that these arrhythmias may result in very substantial hemodynamic effects,” said Dr. Dewland. 

“We have to think about the patient’s blood pressure and their level of sedation. It’s always a challenge to manage all aspects of the patient’s care, while still focusing on what can be really nuanced and subtle findings.”

As an educator, he encourages fellows to do their homework. “In EP especially, the details matter,” he said. “We try to impress upon them the need to be fastidious about looking at all the preoperative data, including the electrocardiogram [EKG] tracings, the echocardiogram, and the MRI [magnetic resonance imaging], because that can all be important for how to safely and effectively perform procedures. The fellows here are really outstanding, and are focused on learning.”

Dr. Dewland’s passion for biking has also led him to have encounters with UCSF on the patient side. During his first month of residency, he crashed his bike and ended up as a patient at Zuckerberg San Francisco General Hospital and Trauma Center. “You know that nightmare people have where they are at work and they’re naked?” he said with a wry laugh. “That happened to me, because they brought me to the hospital where I worked and had to cut all my biking clothes off.” He had a bad concussion but made a full recovery.

Outside of medicine, Dr. Dewland enjoys trail running and road biking. He sometimes bikes to work from Marin County, passing coyotes and seeing the sunrise illuminate Mount Tamalpais before biking over the Golden Gate Bridge. He is married to Ilse Larson, MD, medical director of the Newborn Nursery at UCSF Benioff Children’s Hospital San Francisco; together they have two children, Solveig and Soren.

– Elizabeth Chur