An electrophysiologist is a cardiologist who specialises in a type of cardiology called electrophysiology. Electrophysiology entails the diagnosis and treatment of irregular heartbeats, or arrhythmias of the heart.
Electrophysiologists complete all the training requirements of a cardiologist, (medical school, residency, and fellowship), plus additional years of training in electrophysiology.
Electrophysiologists study the electrical properties of biological cells and tissues. They measure the voltage change or electrical current flow on a great variety of scales. They might work with single ion channel proteins or whole organs such as the heart. In neuroscience, electrophysiologists measure the electrical activity of neurons, as well as action potential activity.
There are two main divisions of electrophysiology: extracellular recording and intracellular recording. Intracellular recordings are usually (but not in every case) made from cells “in vitro” (in a glass or plastic tube), while extracellular recordings are usually “in vivo” (in living animals or organisms). Intracellular recording devices include the voltage clamp and the current clamp. Extracellular recording involves field potential recording, single unit recording, single channel recording, and amperometry.