Upon seeing a patient with a possible heart problem the doctor would obtain a history and perform a physical examination. Then laboratory work would be done as well and radiographic examination of the heart(chest x-ray or CAT scan) and a 12 lead electrocardiogram, known as an EKG or an ECG would be done The electrocardiogram was initiated about a century ago and has been increasing in popularity ever since - and is performed on virtually all known or suspected cardiac patients.
Towards the end of the 18th century an Italian professor of anatomy Luigi Galvani by accident one day made a remarkable observation. When his assistant was dissecting a frog on a laboratory table nearby, he noticed contractions of the muscle when metallic contact occurred. He realized it was an electric current, and he developed a method for recording such phenomenona. Some time later another Italian Carlo Mattenucci made similar observations. Eventually a method was devised for recording electrical signals using a capillary electrometer. Eventually a major breakthrough occurred when Willem Einthoven invented a string galvanometer -- a method for analyzing and recording electrical phenomena. His paper was published in 1903 and, in his initial publication, he demonstrated that his method was superior to the capillary one. Credit also goes to Sir Thomas Lewis with his utilizing the electrocardiogram to study patients; and he largely accounted for its clinical success at that time. Dr. Einthoven was awarded the Nobel Prize in medicine in 1924 for his seminal work in developing the string improving galvanometer and its adaptation to clinical use for studying the human heart and actually improving patient care as a result.
At that time all the electrical current was recorded from the extremities. This method was excellent for analyzing the cardiac rhythm or arrhythmias (heart rate too fast, too slow or too irregular) but was not adequate to show muscular damage, enlargement of chambers, heart attacks and other important information. Considerable research was done culminating in the development of six “chest leads” on precordial locations. This gave more anatomic information and was particularly helpful in the diagnosis of myocardial infarction (ie heart attack). It was ironic in that at the same time a large hospital was being built in New York City and was quite modern; and that it used three channels to transmit the electrical information to the heart station -- a system that was almost immediately outmoded by the addition of the six new chest leads.
After about another quarter-century the computer came of age -- and then it too was adapted to electrocardiography. I found this particularly interesting since I was involved as a consultant to IBM for 28 years. They IBM system had over several hundred thousand employees in its data base The United States Public Health Service was the leader in computer electrocardiography with IBM in second place, as the the Public Health service had a 5 year head-start. The IBM program was successful in that for the normal EKG it was correct in about 99% of those recorded.. For the borderline or abnormal EKG there was an error rate above 10%. And all borderline or abnormal ones had to be interpreted by a cardiologist.
So much for the technical development of the electrocardiogram. Human initiative, being what it is, accounted for greater sucess and innovation. During that time of World War II, Dr. Masters developed the two-step stress test. The patient would walk up 2 steps and down 2 steps. The patient's pulse, blood pressure and electrocardiogram were recorded prior to the exercise and after the exercise was completed. For example, if the patient had a normal EKG at rest which became abnormal following exercise, it was considered a positive test, which often indicated a coronary disorder. Somewhat later a treadmill was used but otherwise the methodology was the same. In Europe, where individuals were more accustomed to bicycle riding it often was more practical to use a stationary bike. As time went on radioisotopes were added to the protocol -- this increased the sensitivity as well as the specificity of the test -- and also the cost!
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