About Thor Sundt, MD

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I have been the chief of cardiac surgery at the Massachusetts General Hospital since February 2011. Since that time the division has evolved significantly with a focus on enhancing our ability to deliver patient centered care of the highest quality. We have improved access to our caregivers by redesigning workflow in the office in a manner that we hope is seamless for our patients.

My personal clinical practice is broad and based on my experience and training at MGH and elsewhere. After attending Princeton University for my undergraduate education, I attended medical school at Johns Hopkins University. My general surgery training was here at the Mass General followed by training in cardiac surgery at Washington University in St. Louis. After an additional year of training in London, I returned to St. Louis where I practiced the full range of adult cardiac surgery including the use of arteries rather than veins for bypass grafts in the treatment of coronary artery disease. This technique offers greater durability and superior freedom from the need for subsequent operations or procedures. I have also developed a great interest in the treatment of thoracic aortic aneurysm disease. In 2001 I moved to the Mayo Clinic where I remained on staff for 10 years. At Mayo Clinic, my principal focus was on valvular heart disease including mitral and aortic valve repair as well as treatment of thoracic aortic aneurysm disease. In particular I have had an interest in bicuspid aortic valve disease an the associated aortic dilatation. I have published quite a bit on the topic and am frequently asked to deliver talks on this topic nationally and internationally. While at Mayo Clinic I  developed a research interest in Human Factors and Patient Safety.

Since returning to Mass General, I have maintained a broad clinical practice ranging from the use of arterial conduits for coronary bypass, to aortic and mitral valve repair and complex valve reoperations as well as treatment of aortic valve disease. I also perform septal reduction for hypertrophic obstructive cardiomyopathy and have found my experience in pericardiectomy for pericardial constriction and recurrent relapsing pericarditis to be a unique strength.


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Clinical Interests:



Mass General Heart Center: Cardiac Surgery
55 Fruit St.
Boston, MA 02114
Phone: 617-643-9745

Medical Education

  • MD, Johns Hopkins University
  • Residency, Massachusetts General Hospital
  • Fellowship, Barnes Jewish Hospital
  • Fellowship, Harefield Hospital
  • Fellowship, National Cancer Institute

American Board Certifications

  • Thoracic and Cardiac Surgery, American Board of Thoracic Surgery

Accepted Insurance Plans

Note: This provider may accept more insurance plans than shown; please call the practice to find out if your plan is accepted.


The focus of my research has been on the genetics and clinical aspects of aneurysmal disease associated with bicuspid aortic valve.  In addition my research team has explored fundamental aspects of medical error with a particular emphasis on Human Factors and communication.


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