162 



The Heart 



The heart is lowered in the cases of pulmonary emphysema, left 

 hydrothorax, large mediastinal tumours, and aneurysm of the aortic 

 arch ; also when the stomach and intestines are collapsed, as in 

 cesophageal stricture. It is raised in ascites, tympanites, and in the 

 case of ovarian, hydatid, or of other large abdominal tumours. It is 

 pushed to the left in the case of effusion into the right pleura, and 

 when the left pleura is water-logged the apex-beat may be found even 

 to the right of the sternum (p. 189). It maybe dragged to either 

 side by a contracting lung or by pleural adhesions. 



The anterior part of the heart is chiefly the right ventricle, the left 



ventricle being posterior. 

 The left ventricle has 

 much more work to do 

 than the right ; indeed, 

 its wall is of treble thick- 

 ness, and bulges into the 

 right ventricle ; thus, 

 when the heart is re- 

 moved from the body the 

 ventricles may be distin- 

 guished by gently pinch- 

 ing each between the 

 finger and thumb. Hav- 

 ing comparatively little 

 to do, the free border of 



i, Wall of right vent., and 2, 3, wall of left. 



the right ventricle is thin and sharp (margo acutus], whilst that of the 

 left ventricle is thick and rounded (margo obtusus). The left ventricle 

 extends beyond the right and forms the apex of the heart. 



The apex-beat appears, ' two inches below the left nipple and one 

 inch to the sternal side,' as a gentle upheaval of the tissues of the fifth 

 space. In children the impulse is sometimes in the fourth space ; and 

 in the aged, on account of the stiffness of the large arteries, it may be 

 found in the sixth space. 



The distinctness of the manifestation of the heart's impulse is due 

 to the great strength of the left ventricle (which forms the apex), to the 

 tilting of the heart forwards during systole, to the lengthening of the 

 aorta as the blood is impelled into it (causing the heart to descend 

 somewhat), and to the fact that there is no lung between the apex and 

 the chest-wall. 



The impulse of the apex-beat is felt as the ventricle discharges its 

 contents into the large vessel, and resembles the ' kick ' of the rifle. 

 The impulse which is felt over the base is due to the energetic con- 

 traction of the thick ventricular mass. When the apex is covered with 

 lung, as in emphysema, the apex cannot reach the chest-wall, and the 

 cardiac impulse which is felt by the hand is then due to the contrac- 

 tion of the right ventricle. And, as remarked above, the apex-beat ; 



