Professor Jahangiri is a Cardiothoracic Surgeon who works at the Wellington Hospital and Harley Street Clinic. She is the first female Professor of Cardiac Surgery appointed in the UK and Europe. She was appointed as Consultant Cardiac Surgeon and Senior Lecturer in 2001 at St. George’s Hospital, University of London. She was appointed Professor of Cardiac Surgery at University of London in 2007. Her major interests in the field of clinical cardiac surgery include: heart valve surgery, minimally invasive aortic valve procedure, coronary artery bypass graft surgery with arterial revascularisation, surgery of the aorta, including aneurysms, especially major and major complex cases and beating heart surgery.

She regularly performs coronary artery bypass graft surgery using minimally invasive techniques. She has pioneered minimally invasive aortic valve surgery in the UK. Marjan Jahangiri operates on approximately 250 cases per annum. This is one of the largest cardiac surgical services in the UK. Her overall mortality for all cases including complex and major complex heart operations is 1.5 – 3%. She graduated in medicine from University College Hospital, London. Subsequently, she completed her cardiac surgical training at the Royal Brompton and St. Bartholomew's Hospitals and Children's Hospital, Harvard University. She has been the author of more than 250 peer-reviewed publications, book chapters and manuscripts in addition to several abstracts and communications.

She is the associated editor and regular reviewer for several academic journals. She has successfully supervised more than 26 higher research degrees, including 11 PhDs and 15 Masters. She is a regular invited speaker at national and international conferences. She has chaired multi-disciplinary guidelines on management of coronary artery disease, aortic valve (minimally invasive) and aortic disease. Including Heart Valve Disease Guidelines of NICE (National Institute for Health and Care Excellence) as well as the surgical lead and coauthor for several European and American guidelines. She has received several awards for excellence in clinical care and surgical training.