It is possible, by listening to the beat of the heart and by feeling the pulse, to tell whether or not the beat is taking place satisfactorily, and whether or not the blood is being pushed through the blood vessels and back to the heart as it ought to be. Such measurements are, however, loose determinations. A device called the electrocardiograph measures, by photographing waves on a photographic plate, the changes in the beat and any disturbance of the mechanism of propelling the heart beat through the organ itself. Such methods are far more accurate than the use of the unaided human senses.

One may feel the pulse in the wrist with the finger, or one may attach to the wrist a device called the sphygmo-graph, which records the variations in a pulse beat on a moving strip of paper in such a way that the various changes may be determined. The machine is far superior to the human finger in detecting changes.

There was a time when it would have been considered equivalent to murder to push a needle into the sacs around the heart. To-day the physician frequently extracts the fluid accumulated in that sac, on the basis of his studies of the heart condition by the methods that have been mentioned. He does not hesitate to insert a needle and to withdraw the fluid.

The beat of the heart was first heard by an investigator who placed his ear directly on the chest. Then came the discovery of the method of listening to the heart through a solid rod. Later more delicate devices were discovered which had a bell for collecting the sound, a membrane for amplifying it, and rubber tubes to carry the tone of the sound to the ear. With the development of electric translation of sound and new means of amplification, it now becomes possible to step up the sound so that tiny variations may be determined.

Through examination after death from a known disease, it is possible to correlate all the observations made before death with the actual appearance of the heart and to learn the significance of each of the procedures used in diagnosis. Of special interest to the patient as well as to the doctor is the question of how capable the heart may be of carrying on its work. To the specialist in heart disease a dozen or more functional tests are known whereby he can measure the capacity of the organ to withstand unusual effort.

Heart disease is, to-day, the most frequent cause of death, its rate being at least twice that of the next nearest cause. Hence, the number of men giving special attention to diseases of the heart is increasing by the old law of supply and demand; though there are as yet few, if any, physicians who devote themselves exclusively to this branch. Diseases of the heart is a special department of internal medicine.

It is known to the specialist in heart disease that this organ may become inefficient and degenerate for many reasons. For instance, the acute infectious diseases may leave a weakened heart in their wake; and infections of the throat and of the teeth may be transferred to the valves of the heart and to the lining of the heart with disastrous results. Venereal disorders sometimes produce strange changes in tissues of the heart. As man grows older, the strain on this muscle becomes greater and greater. It attempts to compensate for the strain by enlarging and by stretching, and its function is modified. There are many unsolved riddles yet to be answered before diseases of the heart will be brought fully under medical control.

No one knows exactly why the germs from the throat or teeth tend to localize in the heart in certain cases and to produce distinctive changes. This has to do, perhaps, with the constitution or hereditary stock of the individual. It may be concerned with the fact that the patient lives in a damp basement or near a river. It may be due to the fact that he is undernourished and has not had sufficient sunlight. It may be a certain form of a general group of germs that does this deadly damage rather than all of the germs of that group. It may be a combination of any such circumstances. Only when all of the facts are known and when the non-essential information is discarded will it be possible to prevent this type of heart disease and to supply proper treatment early enough to secure control. It is, of course, exceedingly important that patients come to the diagnostician soon enough to permit him to give proper advice. If the patient comes too late, such significant changes have already taken place that it is impossible to be of any real service. Education of the public is increasingly necessary to bring about frequent and careful examination of the condition of the heart.

In the past, patients with heart disease merely took to their beds and waited for the inevitable death, or continued their occupations until some too severe strain brought fatality. Modern study attempts to establish the exact capacity of the heart and to find for the individual an occupation suited to his condition.

With the heart, as with other portions of the body, it is extremely difficult to separate the effects that are purely mental from those that are physical. Associated with the shock of the World War were many cases of neurocirculatory asthenia, or weakness of the heart and of the nervous system, in which patients suffered from palpitation and pains and weakness without any detectable physical change being present. It is an extremely difficult diagnostic task to separate such cases from actual cases of heart disease.