An electrocardiograph is a representation of a heartbeat based upon natural electric signals emitted from the body. The word itself comes from three words: "electro" (dealing with electricity), "cardio" (relating to the heart), and "graph" (which is a writing), so quite literally an "electrical drawing of the heart". The earliest recordings of this nature were made around the 1870s. Today electrocardiographs are a standard for measuring a heartbeat.
The data is recorded and displayed by a piece of medical equipment known as an electrocardiogram; usually shortened to "ECG". ECG machines consist of several wires which are attached to a box which records and analyzes the data and then transmits it back simultaneously in the form of a graph. Some ECG machines have this graph printed out on paper, while others use a digital screen to display the electrocardiograph.
What ECG machines essentially do is record the tiny electrical changes made to the human skin that are caused by the heart depolarizing on each beat. These changes are picked up by little wires with nodes at the end which are attached (using weak adhesive) to the skin at certain positions. The number of wires used with this piece of medical equipment is dependent on what type of reading is needed. For a more complex reading, which is printed out and checked by a specialist, there are usually ten wires attached to the precise points in the arms, legs and chest. This is called a twelve-lead ECG and it is used for determining if there is any problem with a patient's heart, as other symptoms of heart trouble may be caused by stress or anxiety or even indigestion.
However, the main usage of these ECG machines is usually to monitor the critical status of a patient without having to use a stethoscope or other medical equipment. In this case, only three or five wires are attached, the electrocardiograph is displayed on a digital screen, and it can be monitored by a nurse or hospital orderly. The graph measures several different specifications of a heart beat per beat, such as intervals and intensity. In the case that a patient's heart ceases to work, the electrocardiograph will display a flat line. Getting high quality medical equipment that is capable of measuring and relaying an electrocardiograph consistently and accurately is vital to running an effective hospital or private practice.