Analysis of an E.C.G.

Abstract

It has been said that the best discoveries and the most exciting advances are often made when two disciplines overlap, and the dark ground can be illuminated from two sides. This is so when the science of electrical engineering touches the science of biology and the art of medicine. This multidisciplinary activity is called biomedical engineering. This section of engineering is mostly important in modern technology and in the last 25 years application of the engineering theory has been used in the design of various devices which served to improve the processes of measurement, providing greater precession, and the ability to measure many more parameters. One of the first discoveries in the biomedical engineering was the electrocardiograph (e.c.g.). This is an instrument used to display electrical potentials at the surface of the body which are clearly associated with the heart beat. It was first invented by Enthoven in 1903 when he applied a string galvanometer to display these electrical potentials. The electrocardiogram (e.c.g.), as the displayed picture is called, is used by doctors to diagnose faulty functioning of the heart and by correlation any other part of the bod¥ which may, by its malfunctioning affect the heart. Heart diseases are, perhaps, the most common diseases nowadays and many deaths occur because of heart attacks. So, an electrocardiograph is needed immediately to save lives after a heart attack. For diagnostic purposes the e.c.g. is invaluable. In addition to indication irregular heart action it can show conditions of heart enlargement, .and where this occurs, or the site of a coronary occlusion. Many other conditions such as blood pressure, thyroid disease, and some forms of malnutrition can be determined from an e.c.g. pattern. But the primarily need of the e.c.g. signals is in the treatment and care of patients. Deviations from the normal heart rate rhythm, known as arrhythmias, may vary from the relatively unimportant sinus-arrhythmia, where the heart beat varies over the breathing cycle, to the serious condition, ventricular fibrillation in which the ventricle muscle fibres contract convulsively: without very rapid treatment an attack of this kind usually ends in death. This shows the importance of the e.c.g. since every case has a different e.c.g. pattern and a different treatment is needed. The reason for monitoring the functioning of the heart falls mainly under three categories:- 1. For research into the heart's activity when subjected to unusual stresses e.g. astronauts, athletes, etc. 2. For diagnosis of malfunctioning in hospital patients who are suspected of having heart trouble. 3. For monitoring the heart of a patient who is undergoing or has undergone major surgery or who has recently recovered from heart trouble. Each of these separate categories has different requirements. Although a system which could perform all the requirements necessary for the three categories is technically possible, such a system would not only be too expensive but would also be two complex for the user and would provide each such user with much irrelevant information. […]