Our Practice

I am Mary B. Callahan, DO FACC and I welcome you to the website for my cardiovascular practice. After working in other practices I wanted to create a place to provide high-quality care in a comfortable and relaxed outpatient setting. I believe that we have achieved that here at our office in Sandwich, MA conveniently located at 68A Route 6A across from Stop & Shop and CVS.

As a native New Englander, I grew up near Boston and spent summers on Cape Cod. I graduated from the University of New Hampshire with a Bachelor’s degree in Biochemistry and a Master of Science degree in Animal and Nutritional Sciences. After graduation I worked in physiologic research at Brigham and Women’s Hospital, in Boston, studying vascular disease and hypertension. During that time, I became interested in medicine so I applied to and was accepted at the University of New England College of Osteopathic Medicine in Biddeford, Maine. With my studies completed, I continued {my New England travels} with a Residency in Internal Medicine at Brown University in Providence, Rhode Island. {During that time I was encouraged to apply for a fellowship in cardiology to advance my training.} For my Fellowship in Cardiovascular Diseases I went to Albany Medical Center in Albany, New York. When my studies were {finally} completed, I returned to Massachusetts and have been affiliated with several hospitals – Boston Medical Center, Quincy Medical Center, Jordan Hospital and Cape Cod Hospital.

Currently, I reside in Plymouth with my husband, Michael, our son Daniel and our dog Skipper. We have two grown daughters, Andrea and Jessica. When I am not working I enjoy spending time with my family, cooking, being outdoors, walking in the woods, sailing, bicycling and beaching. I feel fortunate to live in this beautiful area and try to enjoy it as much as possible.

Lisa is our Cardiac Nurse Practitioner.  I look forward to leveraging Lisa's extensive clinical experience and strong assessment and communication skills to benefit patients of our practice.  She is a self-motivated professional who is committed to providing quality care and adept and managing complex patients.

Tonya Lindsey is my long-time and dependable assistant. She will answer your calls and emails, schedule appointments, fill prescriptions, and answer all your questions. Tonya has years of cardiology experience and she has lived on Cape Cod for many years with her husband and children.

Adrienne Souza is our Billing Manager and comes to us with a wealth of experience.  With her assistance, this October we will be implementing Healow Payment Services (HPS).  HPS will enable you to utilize state of the art, PCI Compliant features which will streamline the billing and payment process for you, our valued patient.

Glenn Davis is a Registered Diagnostic Cardiac Sonographer with 23 years of experience performing over 40,000 adult echocardiograms in hospitals and doctor’s offices.