PATHOLOGICAL DISTURBANCES OF THE CARDIAC IMPULSE. 89 



contraction the auricles relax, or whether the ventricles are contracted 

 while the auricles still remain slightly contracted, so that the whole 

 heart is contracted for a short time at least. The latter view was 

 supported by Harvey, Bonders, Schiflf, and others, while Haller and 

 many of the more recent observers support the view that the action of 

 the auricles and ventricles alternates. In the case of Frau Serafin, 

 whose heart was exposed, v. Ziemssen and Ter Gregorianz obtained 

 curves from the auricles, which showed that the contraction of the 

 auricles continued even after the commencement of the ventricular 

 systole. In Marey's curve (Fig. 29) the contraction of the ventricle is 

 represented as following that of the auricle. 



52. Pathological Disturbances of the Cardiac 



Impulse. 



Change in the Position of the Apex-beat. The position of the cardiac 



impulse is changed (1) by the accumulation of fluids (serum, pus, blood) or gas 

 in one pleural cavity. A copious effusion into the left pleural cavity compresses 

 the lung, and may displace the heart towards the right side, while effusion on the 

 right side may push the heart more to the left. As the right heart must make 

 a greater effort to propel the blood through the compressed lung, the cardiac 

 impulse is usually increased. Advanced emphysema of the lung, causing the 

 diaphragm to be pressed downwards, displaces the heart downwards and inwards, 

 while conversely the pushing or pulling up of the diaphragm (by contraction of 

 the lung, or through pressure from below) causes the apex-beat to be displaced 

 upwards (even to the third intercostal space), and also slightly to the left. 

 Thickening of the muscular walls and dilatation of the cavities (hypertrophy with 

 dilatation) of the left ventricle make that ventricle longer and broader, while the 

 increased cardiac impulse may be felt to the left of the mammary line, and 

 in the axillary line in the sixth, seventh, or even eighth intercostal space. 

 Hypertrophy, with dilatation of the right side, increases the breadth of the heart, 

 while the cardiac impulse is felt more to the right, even to the right of the 

 sternum, and at the same time it may be slightly beyond the left mammary 

 line. In the rare cases where the heart is transposed, the apex-beat is felt on 

 the right side. When the cardiac impulse goes to the left of the left mammary 

 line, or to the right of the parastemal line, the heart is increased in breadth, and 

 there is hypertrophy of the heart. A greatly increased cardiac impulse may 

 extend to several intercostal spaces. 



The cardiac impulse is abnormally weakened during atrophy and degeneration 

 of the cardiac muscle, or by weakening of the innervation of the cardiac ganglia. 

 It is also weakened when the heart is separated from the chest-wall owing to the 

 collection of fluids or air in the pericardium, or by a greatly distended left lung ; 

 and, indeed, when the left side of the chest is filled with fluid, the cardiac impulse 

 may be extinguished. The same occurs when the left ventricle is very imperfectly 

 filled during its contraction (in consequence of marked narrowing of the mitral 

 orifice), or when it can only empty itself very slowly and gradually, as during 

 marked narrowing of the aortic orifice. 



An increase of the cardiac impulse occurs during hypertrophy of the walls, as 

 well as after the influence of various stimuli (psychical, inflammatory, febrile, 

 toxic) which affect the cardiac ganglia. Great hypertrophy of the left ventricle 



