Cardiology is the term applied to physicians who are internists trained in the diagnosis and management of diseases of the heart and blood vessels. Diseases of the heart can include all aspects of the heart structure, including the electrical system. Electrophysiologists are subspecialists within cardiology who deal almost exclusively with the electrical abnormalities of the heart. This includes the diagnosis and management of arrhythmias, including the insertion of pacemakers and sophisticated defibrillator devices. Many times, medical therapy is an important part of the treatment. Electrophysiologists also have the capability of manipulating the electrical system by a process called ablation so that certain types of fast heartbeat abnormalities of the heart can be fixed permanently.