Meet Our Team

Karen "Kate" Isselbacher M.D.

FOUNDER & CEO

Karen T. Isselbacher, M.D., is the founder and CEO of Exceptional Health. With a strong lineage of physicians in her family, medicine is an inherent part of her life. Dr. Isselbacher’s unwavering dedication to patient care has earned her a reputation for establishing profound personal connections with those she treats. Many of her patients speak of the comfort, security, and trust they feel under her compassionate care.

Dr. Isselbacher graduated with honors from Harvard University, earning an A.B. Degree in 1981. Subsequently, she obtained her Medical Degree from Boston University School of Medicine in 1985. She completed her medical internship and residency at Mount Auburn Hospital, a prestigious Harvard teaching hospital in Cambridge, MA, in 1989. Additionally, she holds the esteemed title of diplomate of the American Board of Internal Medicine.

From 1991 to 2001, Dr. Isselbacher served as an active member of the medical staff at Mount Auburn Hospital, where she practiced primary care medicine. In 2001, she joined the Department of General Internal Medicine at Brigham and Women’s Hospital in Boston, continuing to provide exceptional primary care until 2006 in a bustling group practice situated in Newton Corner.

Throughout her tenure from 1991 to 2012, Dr. Isselbacher also served as a respected faculty member at Harvard Medical School. She took great pleasure in mentoring students and resident doctors, offering her expertise and guidance. While she has a particular interest in women’s health, Dr. Isselbacher wholeheartedly cares for both men and women.

With over 30 years of experience in primary care, Dr. Isselbacher’s commitment to improving & maintaining health of each patient remains unparalleled. The quality of medical care she provides continues to surpass expectations, establishing her as a true leader in the field.

Kevin Heaton, M.D.

CLINICAL INSTRUCTOR OF MEDICINE HARVARD MEDICAL SCHOOL

Dr. Kevin Heaton graduated from Columbia University’s post-baccalaureate premedical program. He then earned his medical degree from The University of Chicago School of Medicine, where his peers inducted him into the Gold Humanism Honor Society. Dr. Heaton completed his internal medicine residency at Massachusetts General Hospital and practiced there for over a decade.

Throughout his career, Dr. Heaton has taken on notable teaching roles at both Harvard Medical School and Massachusetts General Hospital. He actively fosters clinical reasoning and promotes a deep understanding of patient care across both ambulatory and inpatient settings. As an Associate Program Director in Internal Medicine, he taught primary care in diverse clinical environments. He also joined the Ambulatory Core Educators, a select group of primary care physicians dedicated to teaching outpatient medicine. Additionally, he chaired the Clinical Competency Committee, where he oversaw resident evaluations and developed expertise in clinical reasoning and learner support. His dedication to teaching ultimately earned him The Primary Care Teaching Award.

As a concierge physician, Dr. Kevin Heaton currently serves as an Instructor of Medicine at Harvard Medical School, where he has taught in the residency program since 2015. His clinical interests include preventive medicine, cardiology, endocrinology, complex and rare diagnoses, and musculoskeletal and sports medicine. Dr. Heaton values a patient-centered approach. He takes time to truly listen and adapt care plans to each patient’s unique health journey. Dr. Heaton fosters trust and open communication, carefully tailoring medical guidelines to meet individual needs and wellness goals.

Outside of medicine, Dr. Kevin Heaton is married with two children. He enjoys spending quality time with his family, exploring rigorous types of exercise, and reading on diverse topics, including literature, philosophy, history, and the science of exercise. His commitment to continuous learning drives him to stay current with the latest clinical evidence. This dedication ensures he provides the highest quality care to his patients.

Christine Harrington M.D.

INTERNAL MEDICINE SPECIALIST

Dr. Christine Harrington graduated Magna Cum Laude from Brown University with a B.A. in Cognitive Science. She earned her medical degree from the Perelman School of Medicine at the University of Pennsylvania. After earning her degree, she completed her residency in internal medicine at the University of Pennsylvania Hospital.

Dr. Harrington worked at Beth Israel Deaconess Medical Center for 16 years. There, she served as a Harvard University Instructor, educating and mentoring medical students in primary care. She worked passionately to improve high-quality healthcare delivery. She served on the Affiliated Physicians Group (APG) Provider Advisory Board and the Clinical IT Leadership Committee. In these roles, she played a pivotal role in implementing a new electronic medical record system for APG.

Following three years spent establishing a new primary care practice at Atrius Health, Dr. Harrington joined Newton Wellesley Hospital in 2019. Since then, she has remained a committed member of the Department of Internal Medicine.

Dr. Harrington’s clinical interests include preventive medicine, women’s health and the long-term care of cancer survivors. She is also certified in Lifestyle Medicine. This field focuses on evidence-based methods like diet, exercise, sleep, and stress reduction. These methods help prevent, treat, and reverse chronic diseases.

Outside of medicine, Dr. Harrington lives by her advice. An avid runner, biker, swimmer, skier, and hiker, Dr. Harrington loves spending time outdoors with her dogs. In addition to her active lifestyle, she is a passionate cook and an even better baker. Confident in her balanced approach to nutrition, she enjoys tofu and chickpeas. However, she will never give up her home-baked M&M cookies.

Dr. Christine Harrington is passionate about helping her patients not only live longer but also healthier lives. She looks forward to working with each patient in a concierge setting. Together, they will create a personalized plan. This plan will address both current and future health care needs.

Li Tso M.D.

ASSISTANT PROFESSOR OF MEDICINE HARVARD MEDICAL SCHOOL

Li Tso, M.D. graduated magna cum laude from Harvard University with a degree in chemistry. He then earned his medical degree from SUNY Stony Brook School of Medicine, graduating first in his class and joining Alpha Omega Alpha, the National Medical Honor Society.

Dr. Tso completed his residency and fellowship in nephrology at Massachusetts General Hospital. After his training, he practiced there for nearly 30 years and also served as co-director of Bulfinch Medical Group. At Bulfinch, he focused on advancing patient care and developing best practices. Over the years, Dr. Tso has aimed not only to diagnose and treat but also to educate and empower his patients through empathy and understanding.

Recognizing his dedication to patient care, Mass General Brigham honored Dr. Tso with the Partners in Excellence Award. This award celebrates healthcare professionals who go beyond expectations to support the healthcare system’s mission and values.

In addition to his clinical practice, Li Tso, M.D., serves as an Assistant Professor of Medicine at Harvard Medical School. For many years, he has shared his expertise with students and residents, helping shape the future of medicine. Since 2010, he has also served as a team physician and internist for the New England Patriots, a role that underscores his knowledge in sports medicine and preventive health.

Dr. Tso’s clinical interests span preventive medicine, renal disease, cardiology, and sports medicine. He believes strongly in the patient-doctor relationship, seeing it as essential to good care. Dr. Tso listens carefully to each patient’s unique needs, fostering trust through open communication and mutual respect.

Outside of medicine, Dr. Tso is married with two children. In his free time, he enjoys running, reading, especially history and science, and traveling. He remains committed to lifelong learning, always striving to expand his knowledge and provide exceptional patient care.

Dr. Li Tso looks forward to partnering with each patient in a concierge setting, where they will work together to create a personalized health plan that meets both current and future needs.