To Mark out Heart 163 



and even the basic impulse, are drowned in the case of abundant peri- 

 cardial effusion. When, as the result of old adhesions, the apex clings 

 to the hinder part of the pericardium, there may be no upheaval of the 

 fifth space during systole, but, with each contraction of the heart, the 

 space may actually recede, to thrill again or throb with ventricular 

 relaxation. Thus the apex-beat is synchronous with diastole a some- 

 what rare phenomenon. 



Displacement of apex-beat. The apex-beat is raised when the 

 diaphragm is thrust up, as in ascites, tympanites, or abdominal tumour ; 

 it is depressed when the diaphragm is thrust down by emphysema, or 

 by fluid in the left pleura : in these circumstances also it is displaced 

 to the right, but the heart becomes more vertical as it sinks from the 

 left side. When the right pleura is full the displacement is to the left. 

 When the left lung is contracted the diaphragm is raised, and with it 

 of course, the apex-beat, which is manifested more to the left. 



Even in the healthy subject there is a considerable amount of fat 

 about the grooves between the auricles and ventricles. When its 

 deposit is greatly increased it is spoken of as a fatty encroachment, 

 a much less serious condition than that in which muscular elements 

 have passed into fatty degeneration. 



To mark out the heart upon the chest, first make a dot corre- 

 sponding with the apex, two inches below the left nipple and one inch 

 to the sternal side ; it is over the fifth space. Then draw a line to it 

 from the right side of the xipho-sternal joint ; this defines the flat side 

 of the right ventricle, which rests on the diaphragm ; it should be 

 slightly convex downwards, as the margin of the heart bulges a 

 little, as shown on p. 166. 



From the right end of this draw another line, bowing outwards 

 half an inch from the right side of the gladiolus, to the top of the third 

 chondro-sternal joint. This shows the bulge of the right auricle. 



From the top of the last line draw another horizontally across the 

 sternum and extending an inch to the left of the sternum ; this marks 

 the top of the auricles and the beginning of the great vessels. 



It now remains to make a fourth mark from the left end of the 

 superior horizontal line to the dot which is over the apex ; this mark 

 must be bowed so as to indicate the left convex border of the heart. 

 The left and the flat borders must not meet at a point, but 

 should be well rounded off, like the apex itself, which their junction 

 represents. 



The situation of the heart varies only slightly with change of 

 position of the subject, but when the diaphragm descends with in- 

 spiration the heart must, of course, descend also, though, resting on 

 the central tendon of the diaphragm which moves less than do the 

 muscular domes the change of position is not very great. The 

 elevation with inspiration is not so extensive as it seems to be, be- 

 cause in that act the thoracic cage is raised in front of the heart. 



M2 



