Wm. J. Kerr 



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and the ventricles, aorta, and pulmonary artery provide the channel through 

 which the blood is flowing during systole. The pulse w^ave travels through 

 the aorta at the rate of about 15 m. per sec. If the carotid vessels or the aorta 

 are palpated in the neck or through the chest over the upper sternum, a 

 systolic thrill appears on the crest of the pulse wave. If one chest piece of the 

 symballophone is applied over the aortic area (second right intercostal space 

 near the sternum) and the other above the course of the carotid artery or even 



1\/Iur>mur> ^pavelsl)'. 

 vvitVi the pulse 

 wave 



EddiGS in the 

 blood slr^eam 



Coar-ciaiion 

 of aoT>ia 



Aor-iic stenosis 



A^ 



Fig. 9. The transmission of the systolic uuuniin forward in the direction of the blood flow 

 from the stenosed aortic vahe and backward along the walls of the left \entricle is shoAvn 

 diagrammatically. At the point X in the descending aorta two types of congenital lesion are 

 encountered. In each instance the timing of events depends upon the arrival of the pulse \va\ e 

 at this point bet\\een 1/20 and 1/10 sec. following the first or svstolic sound at the apex. In 

 coarctation of the aorta a systolic miuiinu' is heard over the left upper chest dorsad, and in 

 patent ductus arteriosus (Botalli) the systolic accentuation of a continuous nrurmur is heard 

 over the pulmonary artery ventrad, chiefly to the left of the sternimr and below the clavicle in 

 the second and third intercostal spaces. 



over the sternum at a point cephelad to the other chest piece, the systolic mur- 

 mur heard appears first at the point nearer the aortic valve and later at the 

 more distant point. After a simple auditory demonstration of the sensory effect 

 of blowing across the two chest pieces, the natural perception of a sound in 

 motion can quickly be recognized. The sounds heard appear to be "alive" in 

 contrast to the rushing noise heard with the ordinary stethoscope. The systolic 

 murmur over the carotid arteries appears about 0.05 sec. after the first sound 



