298 THE VASCULAR SYSTEM 



seen. Instead, there is a visible indrawing of the fourth and 

 fifth intercostal spaces on the left side during systole, and this 

 pulsation is similar in character to the pulsation in the 

 epigastrium. This condition must be distinguished from the 

 sucking in of the same interspaces caused by adherent peri- 

 cardium (p. 291). 



Enlargement of the right ventricle is usually accompanied 

 by an increase in size of the right atrium (auricle). Such an 

 increase can be determined by percussion since it results in 

 displacement of the right border to the right side, the left 

 border remaining normal or being displaced to the left. 



It must be remembered that the heart may be thrust bodily 

 over to the right by the pressure of a left-sided pleural effusion 

 or pneumo-thorax, but in these cases the apex-beat is not 

 found in its normal position and the left border of the heart 

 is displaced medially. 



Enlargement of the left ventricle is indicated by displace- 

 ment of the apex-beat downwards and to the left, while the 

 distance of the left border of the heart from the sternum is 

 found, on percussion, to be greater than normal. In this case, 

 also, it must be remembered that the heart may be thrust over 

 to the left by a right-sided pleural effusion or pneumothorax, 

 but, under these circumstances, the position of the right 

 border will be similarly altered. 



Dilatation of the left atrium (auricle) does not enlarge the 

 area of cardiac dulness, unless the left auricle (auricular 

 appendix) is affected, and, in that case, cardiac dulness may 

 be discovered on percussion over the sternal end of the 

 second left intercostal space. 



Unless coincident with pulmonary emphysema, the enlarge- 

 ment of any of the chambers of the heart, except the left 

 atrium, results in an increase of the area of superficial cardiac 

 dulness, since the enlarging chamber pushes the lungs aside. 



In mapping out the antero-superior surface of the heart in 

 the child, the methods indicated above may be followed, due 

 allowance being made for the difference in size. Although, 



