Dr Bilal Mustafa, Consultant Cardiologist, Akbar Niazi Teaching Hospital Barakahu, Ali Medical Center, Islamabad. Cardiology is the study and treatment of disorders of the heart and the blood vessels. A person with heart disease or cardiovascular disease may be referred to a cardiologist. Cardiology is a branch of internal medicine. The cardiologist will carry out tests, and they may perform some procedures, such as heart catheterizations, angioplasty, or inserting a pacemaker. Heart disease relates specifically to the heart, while cardiovascular disease affects the heart, the blood vessels, or both.