This section is from the "Impaired Health: Its Cause And Cure" (Volume 1) book, by John H. Tilden. Also available from Amazon: Impaired health its cause and cure: A repudiation of the conventional treatment of disease
There are two sounds: The systolic, or first, sound is caused by contraction of the ventricles. Then there might be a short silence, followed by the diastolic, or second, sound, which is caused by the closing of the semilunar valves on the arteries. These sounds may be represented graphically as follows: The first sound (venticular) may be represented by the following figure: "u" . Then there is a brief silence, followed by a second sound, which is diastolic and longer, and may be represented by -- Then silence, and the sounds are repeated.
The attention must be educated to distinguish slight variations in these sounds. Many normal hearts must be examined to become familiar with the normal sounds. The first deviation from normal may be said to be that of emphasis on the sounds--they are more pronounced. To get the sound, have someone with a normal heart exercise vigorously for a few minutes; then, if the ear is placed to the heart, the sounds will be louder and faster. When this occurs without exercise, it must be caused by stimulation. The stimulation may be from fear or some other emotions, or from the use of stimulating foods or drugs.
An increase of the second sound may be heard at the pulmonary orifice (left third intercostal space), indicating nothing more than a disturbed circulation in the lungs.
A weakened sound may be caused by an accumulation of fat in the thorax, and it may be due to weakness of the heart. If so, it is the first sound that grows dull and finally disappears. This symptom is not so significant as a weakening of the second sound.
When there is an effusion in the pericardium, the heart sounds are muffled and sometimes extinguished.