\ T ARIATIONS Otf THE HEART-SOUNDS. 95 



54. Variations of the Heart-Sounds. 



An increase of the first sound of both ventricles indicates a more energetic con- 

 traction of the ventricular muscle and a simultaneously greater and more sudden 

 tension of the auriculo- ventricular valves. An increase of the second sound is a 

 sign of increased tension in the interior of the corresponding large arteries. 

 Hence, increase of the second (pulmonary) sound indicates overfilling and excessive 

 tension in the pulmonary circuit. 



Feeble weak action of the heart, us well as abnormal want of blood in the heart, 

 causes weak heart-sounds, which is the case in degenerations of the heart-muscle. 



Irregularities in structure of the individual valves may cause the heart-sounds 

 to become "impure." If a pathological cavity, filled with air, be so placed, and 

 of such a form as to act as a resonator to the heart-sounds, they may assume a 

 "metallic"' character. The first and second sounds may be "reduplicated" or 

 "divided." The reduplication of the lirst sound is explained by the tension 

 of the tricuspid and that of the mitral valves not occurring simultaneously. 

 Sometimes a sound is produced by a hypertrophied auricle producing an audible 

 presystolic sound, i.e., a sound or " murmur, 7 ' preceding the first sound. As the 

 aortic and pulmonary valves do not close quite simultaneously, a reduplicated 

 second sound is only an increase of a physiological condition (Landois). All con- 

 ditions which cause the aortic valves to close rapidly (diminished amount of blood 

 in the left ventricle) and the pulmonary valves to close later (congestion of the 

 right ventricle both conditions together in mitral stenosis), favour the production 

 of a reduplicated second sound. 



Cardiac Murmurs. If irregularities occur in the valves, either in cases of stenosis 

 or in insufficiency, so that the blood is subjected to vibratory oscillations and friction, 

 then, instead of the heart-sounds, other sounds arise or accompany these murmurs 

 or bruits, which, when combined, are always accompanied by disturbances of the 

 circulation. It is rare that tumours ur other deposits projecting into the ventricles 

 cause murmurs, unless there be present at the same time lesions of the valves and 

 disturbances of the circulation. The cardiac murmurs or bruits are always related 

 to the systole or diastole, and usually the systolic are more accentuated and 

 louder. Sometimes they are so loud that the thorax trembles under their irregular 

 oscillations (fremitus, fremissement cataire). 



In cases where dlastoltc murmurs are heard, there are always anatomical changes 

 in the cardiac mechanism. These are insufficiency of the arterial valves, or stenosis 

 of the auriculo-ventricular orifices (usually the left). Systolir murmurs do 

 not always necessitate a disturbance in the cardiac mechanism. They may 

 occur in the left side, owing to insufficiency of the mitral valve, stenosis of 

 the aorta, and in calcification and dilatation of the ascending part of the aorta. 

 These murmurs occur very much less frequently on the right side, and are due to 

 insufficiency of the tricuspid and stenosis of the pulmonary orifice. 



Systolic murmurs often occur without any valvular lesion, although they are 

 always less loud, and are caused by abnormal vibrations of the valves or arterial 

 walls. They occur most frequently at the orifice of the pulmonary artery, less 

 frequently at the mitral, and still less frequently at the aorta or the tricuspid 

 orifice. Anaemia, general mal-nutrition, acute febrile affections, are the causes of 

 these murmurs. 



Murmurs also occur during a certain stage of inflammation of the pericardium 

 (pericarditis) from the roughened surfaces of this membrane rubbing upon each 

 other. Audible friction- sounds are thus produced, and the vibration may even be 

 perceptible to touch. [These are "friction-sounds," and quite distinct from sounds 

 produced within the heart itself.] 



