AUSCULTATORY PHENOMENA - In very many instances these alone are sufficient to determine the existence of dime& in an early stage, before any change has occurred in the actual dimensions of the organ; in other instances they explain the 'causes of the change. They may be divided into modifications of normal sounds, and morbid sounds—" bruits" or" murmurs," as it seems better to call them, to distinguish them from those which, par excellence, are called the sounds of the heart. These bruits, again, comprise those formed in the pericardium and those formed within the heart, sometimes classed as exocardial and endocardial : the only pericardial bruit is friction ; the endo cardial, on the other hand, are divisible into the systolic and diastolic. We shall attempt to show what deductions may be drawn from their presence, and how the student may best refer the sound heard to one or other of these classes.
Much confusion is created by unnecessarily increasing the nomenclature of various sounds. It is quite allowable to employ a particular name to desig nate any unusual bruit, such as "purring," or "musical," but its exact cha rooter is now known to be of far less importance than its position and time of • occurrence with reference to the rhythm of the heart's action. It seems quite unnecessary to introduce such a name as exocardial : if it mean to include sounds formed in the pleura, and not in the pericardium, the classification is objectionable ; if it be restricted to the pericardial bruit, we need employ no other name than friction ; creaking is but a form of friction, and the name "to and fro" sound which has been sometimes need, is only applicable to cer tain cases—a majority, truly, but not all. With regard to endocardial mur murs, again, the introduction of the word regurgitant perplexes the student: either a systolic or a diastolic bruit may be regurgitant; and regurgitation may take place at any of the sets of valves ; it merely expresses the fact of the ordinary current being reversed—a fact which is quite ae explicitly stated when the bruit is named according to its time and place. If during the dias tole the left ventricle be filled from the aorta as well as from the auricle, there is regurgitation : if during the systole the blood pass out into the auricle as well as into the aorta, there is also regurgitation ; but any one who understands the mechanism of the heart's action knows that the expressions diastolic aortic, and systolic mitral murmurs imply these facts, and have the great advantage of being definite statements regarding disease.
§ 1. Modifications of Normal Sounds.
a. They may have a ringing distinctness in consequence of nervous excitement: this is no indication of disease ; it is tran sient, and when the palpitation subsides, the sounds resume their ordinary characters.
b. The first sound especially tends to become short and sharp in thinning of the walls of the heart : the chief distinction between this and the preceding condition is its permanence, and its inde pendence of excitement and palpitation.
c. They become dull and indistinct, though loud, in hypertro phy. The prolongation and indistinctness of the 1st sound in particular, is the reason why they are often spoken of as being weaker than the sharp flapping sound of dilatation.
d. Distance and obscurity of sound is produced by the inter position of fluid in the pericardium or overlapping of the lung, especially in emphysema.
e. The rhythm, or proportionate duration of each sound, is very liable to be altered in the commencement of an inflammatory attack : this condition is very generally the precursor of some more definite evidence of change of structure ; but it is associated with other forms of disease, and is also occasionally casual and transitory, the sounds returning to those of health.
f. Either 1st or 2d sound may be reduplicated. Each stroke of the pulse is repfesented by three or even four sounds heard in the prEecordial region. It is generally the 2d sound which is reduplicated, the 3d following close upon it, and occupying the pause which in health intervenes between the end of the 2d and the commencement of the 1st sound. When the 1st sound is reduplicated, it causes of necessity reduplication of the 2d. This modification does not always imply disease : it seems to be due to irregular muscular action, and we can only decide from other circumstances whether the defect be in the muscle itself, in the nervous system, or in the mechanism of the circulation.