Size And Shape Of The Heart
( Originally Published 1921 )
The determination of the size and shape of the heart has always been a matter of much concern to physicians. It seems a simple matter, but .is really difficult. If this appears doubtful, put some familiar object underneath a thick carpet and see how many people can recognize it by thumping it and feeling of it through the carpet. The examination of the heart is much more difficult than this, because the heart is enclosed between the two lungs and comes to the surface only over a small space.
When X-ray pictures were invented, it was supposed that a definite method had been discovered, but it was found almost immediately that the X-ray picture did not give the correct knowledge of the size and shape of the heart. This is because the- X-ray is a shadow picture, and shadows are vastly distorted according to the way the light rays strike the object, the distance of the object from the source of light, and the screen on which the shadow is thrown. In proof of this, put a candle on the floor and stand close to it, and see what a giant you seem by the shadow on the wall. But walk toward the wall and the shadow gradually shrinks in size until finally it is the same size as you are.
Elaborate machinery was devised to overcome the defects of the X-ray picture, the most interesting of which was the orthodiagraph. In this instrument, by an intricate arrangement, the X-ray tube was moved so that it always stood directly behind the part of the heart that was being drawn on the screen. In this way there was no slanting of the rays of light, they always came directly from the tube to the screen. This was a tedious process and exposed the operator to the X-rays over long periods of time, and for that reason was dangerous to him.
As the X-ray machines were improved in strength and the photographic plates were made more sensitive, it became possible to do with the heart what you do with yourself when you walk from the candle toward the wall. In other words, it was possible to put the source of light a long distance away and the plate right near the heart. This process received the terrible name of teleoroentgenography. With a powerful machine and sensitive plates it gives a picture that is a correct outline of the heart with little distortion, if any.
The best, procedure is to have this kind of picture made, and then to study the heart with a fluoroscope, and after having identified the various chambers, to draw them on the picture with a red pencil. While it is not necessary that this should be done with every one who has heart trouble, still it furnishes so much in-formation and is so valuable a record that we recommend it wherever possible. Certainly, a definite record of the size and shape of the heart should be made by some means.
The heart is sensitive to many influences which tend to change its-shape, so if we know what> the shape of a heart is at any given time, we can tell whether changes are taking place in it.
The shape of the heart, as shown by its correct outline, is often sufficient to indicate the kind of trouble that exists within that organ. So, after looking at the heart as shown on the screen of the fluoroscope, one can often tell what sounds would be heard when the heart is examined with the ear. When the valves at the top of the heart, or the aortic valves, are defective, the heart enlarges to the left, lies down flat on the diaphragm, and assumes approximately the shape of a golf club. This is a trouble that affects mostly older people. When the mitral valve is involved, the heart is enlarged in the region of the left auricle, and the shadow of the heart is round, like the shape of a tennis racket. This is often seen in young people. One can connect these two facts with the other two facts that older people play golf and young people play tennis.
When the lungs are obstructed by asthma or disease, the burden falls on the right side of the heart, and we find the heart enlarged toward the right. This is best proved by the electrocardiogram, which tells us the relative functional activity of the different regions of the heart.
The accompanying diagrams show the shape of the heart under various conditions.