First and foremost we wish by percussion to learn the actual size of the heart, in other words what is ordinarily called the relative cardiac dullness. With the absolute dullness we are not concerned. That irregular area represents, as has been said, actually the limits of lung resonance. The heart may or may not be covered with lung; there may or may not be the incisura cardiaca. What I wish to insist upon is that the size of the area of absolute dullness can give us no data in regard to the size of the heart. What we must endeavor to learn is the actual size of the heart as nearly as our crude means will permit.
Light, very light, almost inaudible percussion, what Goldscheider called "Schwellungsperkussion," must be practiced. Use the middle finger of the right (left) hand as the hammer and the last joint of the middle finger of the left (right) hand pressed firmly against the chest, as pleximeter. I believe it is better to place the pleximeter finger parallel to the boundary to be limited although some place the finger perpendicularly, that is, pointing toward the boundary. Now and then it helps to bend the pleximeter finger at the second joint, hold it perpendicularly to the chest wall, and strike the joint directly in line of the finger. This in my hands has been of great assistance in percussing the limits of the heart dullness. Pottenger's "light touch palpation" is a modification of the light palpation and, to my mind, has no very special advantages. Auscultatory percussion is of great value at times. The bell of the stethoscope is placed over the portion of heart uncovered by lung (should such be the case), and with this point as a center the chest is lightly and quickly tapped along radii converging toward the stethoscope. One soon learns to recognize the change of pitch as the tapping reaches the border of the heart. It is well to use all methods, especially in difficult cases, and to compare the results. Personally I have found that by light percussion I can limit with much accuracy the upper, right, and left borders of the heart.
There is much to be gained by using light percussion. Strong blows set in vibration not only the underlying structures, but also more or less of the chest wall. We wish to avoid this source of error, we do not wish to differentiate by pitch alone. Finally one's pleximeter finger becomes, after long practice, so sensitive to changes in the resonance of structures lying below it, that there is actual feeling of impairment to the slightest degree. This delicate touch is what we should endeavor to cultivate.
It is at times of advantage to use immediate percussion. This is done by bending the fingers of the striking hand, bringing the tips in a line and striking the chest lightly with the four fingers as one finger. Some find it easier to percuss the dullness due to the heart in this way than by mediate percussion.
The little hammer and hard rubber, celluloid, bone, or ivory pleximeter does not seem to me to be nearly as good as the fingers. Moreover, one always has his hands, but may forget his hammer and pleximeter.
Auscultation
In auscultating the heart I prefer the binaural stethoscope of the Ford pattern. The recent substitution of an aluminum bell for the hard rubber bell is an improvement. Personally I do not favor the phonendoscope or any of the new patent non-roaring instruments now for sale by urgent instrument makers. The phonendoscope has its uses, for example in auscultating the back when a patient is lying in bed or in listening to the heart sounds when a patient is under an anesthetic; but for differentiating the murmurs and for heart diagnosis, I much prefer the regular bell stethoscope.
In arteriosclerosis the two places over which it is important to listen are the apex and the second right cartilage, the aortic area. Over the former, one gains data in regard to the strength of the heart as indicated by the first sound, over the latter point, one learns of the tension in the aorta by the character of the sound produced when the aortic valves close.
The hypertrophy of the heart in arteriosclerosis is invariably due to the enlargement and thickening of the left ventricle. From the nature of the position which the heart assumes in the thorax, this enlargement is downward and to the left. The apex beat will therefore be found in the fifth or sixth interspace, and definitely at an increased distance from the midsternal line. As stated above, it is most important that this distance be accurately measured and put down in the notes of the case for future reference. No satisfactory prognosis can be given unless this is done, for the gradual increase or the decrease under treatment in the size of the heart can thus be definitely known, and, knowing the other factors, a prognosis may be given which will be of some value to the patient.