90 



VARIATIONS OF THE CARDIAC IMPULSE. 



causes the heart to heave, so that a part of the left chest- wall may be raised and 

 also vibrate during systole. 



A falling in of the anterior wall of the chest during cardiac systole occurs in the 

 third and fourth interspaces, not unfrequently under normal circumstances, 

 sometimes during increased cardiac action, and in eccentric hypertrophy of the ven- 

 tricles. As the heart's apex is slightly displaced, and the ventricle becomes slightly 

 smaller during its systole, the empty space is filled by the yielding soft parts of 

 the intercostal space. When the heart is united with the pericardium and the 

 surrounding connective tissue, which renders systolic locomotion of the heart 

 impossible, a falling in of the chest-wall during systole takes the place of the 

 cardiac impulse (Skoda). During the diastole a diastolic cardiac impulse of the 

 corresponding part of the chest- wall may be said to occur. 



Changes in the cardiac impulse are best ascertained by taking graphic repre- 

 sentations of the cardiac impulse, and studying the curves so obtained. This 

 method has been largely followed by many clinicians. 



In all the following curves, a, b, means auricular contraction ; b, c, ventricular 



Fig. 30. 



Various forms of curves obtained from the cardiac impulse a, b, Contraction of 



auricles ; 6, c, ventricular systole ; d, closure of aortic, and e of pulmonary 

 valves; e,f, diastole of ventricle ; P, Q, hypertrophy and dilatation of the 

 left ventricle ; E, stenosis of the aortic orifice ; F, mitral insufficiency ; G, 

 mitral stenosis ; L, nervous palpitation in Base.dow's disease ; M, case of 

 so-called hemisy stole. 



