VENOUS MURMURS. 193 



cases where no source of external pressure is discoverable, and when no aneurism 

 is present, the spontaneously occurring sounds are favoured, when at the moment 

 of arterial rest (cardiac systole) the arterial walls are distended to the slightest 

 extent, and when during the movement of the pulse (cardiac diastole) the tension 

 is most rapid (Traube, Weil) i.e., when the low systolic minimum tension of the 

 arterial wall passes rapidly into the high maximum tension. This is especially the 

 case in insufficiency of the aortic valves, in which case the sounds in the arteries 

 are audible over a wide area. If the minimum tension of the arterial wall is 

 relatively great, even during diastole, the soiiuds in the arteries are greatly 

 diminished. 



In insufficiency of the aortic valves, characteristic sounds may be heard in the 

 crural artery. If pressure be exerted upon the artery, a double blowing murmur is 

 heard; the first one is due to a large mass of blood being propelled into the artery 

 synchronously with the heart-beat, the second to the fact that a large quantity of 

 blood flows back into the heart during diastole (Duroziez, 1861). If no pressure 

 be exercised two sounds are heard, and these seem to be due to a wave propagated 

 into the arteries by the auricles and ventricles respectively (Landois) compare 

 73, Fig. 62, III. In atheroma a double sound may sometimes be heard ( 73, 2). 



98. Venous Murmurs. 



1. Bruit de Diable. This sound is heard above the clavicles in the 

 furrow between the two heads of the sterno-mastoid, most frequently 

 on the right side, and in 40 per cent, of all persons examined. It is 

 either a continuous or a rhythmical murmur, occurring during the 

 diastole of the heart or during inspiration ; it has a whistling or 

 rushing character, or even a musical quality, and arises within the 

 bulb of the common jugular vein. When this sound is heard without 

 pressure being exerted by the stethoscope, it is a pathological phe- 

 nomenon. If, however, pressure be exerted, and if, at the same time, 

 the person examined turns his head to the opposite side a similar 

 sound is heard in nearly all cases (Weil). The pathological bruit de 

 diable occurs especially in ansemic persons, in lead-poisoning, syphilitic 

 and scrofulous persons, sometimes in young persons, and less frequently 

 in elderly people. Sometimes a thrill of the vascular wall may be felt. 



Causes. It is due to the vibration of the blood flowing in from the 

 relatively narrow part of the common jugular vein into the wide 

 bulbous portion of the vessel, and seems to occur chiefly when the 

 walls of a thin part of the vein lie close to each other, so that the 

 current must purl through it. It is clear that pressure from without, 

 or lateral pressure, as by turning the head to the opposite side, must 

 favour its occurrence. Its intensity will be increased when the velocity 

 of the stream is increased, hence inspiration and the diastolic action 

 of the heart (both of which assist the venous current) increase it. The 

 erect attitude acts in a similar manner. A similar bruit is sometimes, 

 though rarely, heard in the subclavian, axillary, thyroid (scrofula), facial, 

 innominate and crural veins and superior cava. 



13 



