Electrophysiologists are those Cardiologists who gain expertise in treatment of arrhythmias like atrial fibrillation, Supraventricular tachycardia, Premature beats with medicines and catheter based procedures like ablation. They also implant devices like pacemakers and defibrillators to treat slow heart rate, cardiac arrest.

Emergency medicine is a subspecialty that focuses on patients who need immediate and often intensive care. These physicians must be able to handle medical problems quickly to avoid potential complications with their patients. With their knowledge of emergency medicine comes knowledge about many other types of medicine, as they must be able to respond to patients who present a variety of symptoms and problems. They will also have a thorough understanding of emergency medical devices.