7o 



VARIATIONS OF THE CARDIAC IMPULSE. 



Clinically, changes in the cardiac impulse are best ascertained by taking graphic representa- 

 tions of the cardiac impulse, and studying the curves so obtained (fig. 49). 



In curve P (much reduced), from a case of marked hypertrophy with dilatation the ven- 

 tricular contraction, be, is usually very great, while the time occupied by the contraction is not 

 much increased. P and Q were obtained from a case of marked eccentric hypertrophy of the 

 left ventricle, due to insufficiency of the aortic valves. Curve Q was taken intentionally oyer 

 the auriculo-ventricular groove, where retraction of the chest-wall occurred during systole ; 

 nevertheless the individual events occurring in the heart are indicated. 



Fig E is from a case of aortic stenosis. The auricular contraction {ab) lasts only a short 

 time the ventricular systole is obviously lengthened, and after a short elevation {be) shows a 



Hi 1*1 



i 



wn 



Fig. 49. M 



Curves of the cardiac impulses, a b, contraction of auricles ; be, ventricular systole ; d, closure 



of aortic, and e, of pulmonary valves ; ef. diastole of ventricle ; P, Q, hypertrophy and 



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



(i, mitral stenosis ; L, nervous palpitation in Basedow's disease ; M, so-called hemisystole. 



series of fine indentations (c, e) caused by the blood being pressed through the narrowed and 

 roughened aorta. 



Fig. F, from a case of insufficiency of the mitral valve, shows (ab) well marked on account 

 of the increased activity of the left auricle, while the shock (d) from the closure of the aortic 

 valves is small, on account of the diminished arterial tension. On the other hand, the shock 

 from the accentuated pulmonary sound (c) is very great, and is in the apex of the curve. On 

 account of the great tension in the pulmonary artery, the second pulmonary tone may be so 

 strong, and succeed the second aortic sound (d) so rapidly, that both almost merge completely 

 into each other (H and K). 



The curve of stenosis of the mitral orifice (G) shows a long, irregular, notched, auricular 

 contraction (ab), caused by the blood being forced through an irregular narrow orifice. The ven- 

 tricular contraction (be) is feeble because the ventricle is imperfectly filled. The closures of the 

 two valves, d and e, are relatively far apart, and one can hear distinctly a reduplicated second 

 sound. The aortic valves close rapidly, because the aorta is imperfectly supplied with blood, 

 while the more copious inflow of blood into the pulmonary artery causes its valves to close later. 



