Displacements  of  the  Impulse  of  the  Heart. — Displacements  due
to  Changes  in  the  Heart  Itself, — The  impulse  is  displaced  downward  and
toward  the  left  in  hyi)ertrophy  and  dilatation  of  the  heart,  and  the  combi-


PHYSICAL   DIAGNOSIS:     INSPECTION.  71

nation  of  these  conditions  is  the  most  common  cause.  Enlargement  of
the  left  ventricle  tends  to  displace  the  visible  impulse  downward,  enlarge-
ment of  the  right  ventricle  tends  to  displace  the  impulse  to  the  left,  and
both  of  these  conditions  tend  to  increase  its  extent.
Pressure  Displacements  are  next  in  Order  of  Frequency, — The  heart  is
dislocated  upward  in  pressure  from  below  the  diaphragm,  as  in  excessive
tympany,  ascites,  massive  tumors,  large  cysts,  and  pregnancy.  In  any  of
these  conditions  the  impulse  may  be  seen  in  the  fourth  interspace  and  to
the  left  of  the  midclavicular  line.  The  heart  in  pleural  effusion,  pneumo-
thorax, or  rapidly  growing  malignant  tumors  of  the  pleura,  is  displaced
towards  the  opposite  side.  When  these  conditions  are  left-sided  the
impulse  may  disappear  behind  the  sternum  or  become  visible  at  its  right
border,  or  in  extreme  cases  in  the  right  nipple  line.  In  large  right-sided
effusions,  on  the  contrary,  the  impulse  may  be  displaced  as  far  left  as  the
line  of  the  anterior  axillary  fold.  Cysts  and  abscess  in  the  right  lobe  of
the  liver  may  displace  the  heart  somewhat  to  the  left  and  shift  the  impulse
to  a  corresponding  extent.
The  heart  may  be  displaced  downward  by  an  aneurism  of  the  arch  of
the  aorta  or  a  mediastinal  tumor.  Under  those  circumstances  the  impulse
is  not  only  lower  than  normal  but  it  is  also  somewhat  further  to  the  left.
