A heart specialist is called a cardiologist. Cardiologists are doctors who specialize in the treatment of the cardiovascular system, which includes the heart and blood vessels. They diagnose and treat heart diseases, such as heart attacks, heart failure, heart valve disease, arrhythmia, and high blood pressure. They can also perform procedures such as implanting a pacemaker or inserting a cardiac catheter. There are many types of cardiologists, including clinical cardiologists, heart failure specialists, interventional cardiologists, and congenital heart specialists.