PATHOLOGICAL CARDIAC IMPULSES. 69 



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 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 the contraction of the ventricle is represented as following that 

 of the auricle (fig. 48). 



[(2) Rolleston used a special apparatus which was connected with the interior of the heart, 

 and he finds that there is no distinct rise of pressure in the dog within the ventricles corre- 

 sponding to the auricular systole such as was obtained by Marey in the horse. During the 

 ventricular diastole in certain cases the pressure falls below the atmospheric pressure, and may be 

 equal to- 20 mm. mercury or more in the left ventricle ( 48). It is probably caused by 

 the elastic expansion of the ventricle continuing after the blood in the auricle at the moment 

 of the cessation of the ventricular systole has entered the ventricle, i.e., the quantity of 

 blood in the auricle is not sufficient in all cases to distend the left ventricle to the point at 

 which its suction action ceases. Magini, operating on dogs with a trocar which perforated 

 the cavities of the heart, found none of the secondary elevations obtained by Marey with his 

 sound.] 



A. Fick regards the alternating contraction as a means whereby the pressure in the large 

 venous trunks is kept nearly constant. At the moment of ventricular systole the auricles 

 relax, and the venous blood flows freely into the latter, while if the auricles remained contracted, 

 the blood in the veins would be kept back. Further, at the moment of ventricular diastole 

 the auricles contract, so that there is not an abnormal diminution of the pressure in the veins. 

 Thus the pressure in the auricle is more equable, while the current in the terminal parts of the 

 veins is kept more constant. 



52. PATHOLOGICAL CARDIAC IMPULSES. 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 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, 

 and also slightly to the left. Thickening of the muscular walls with dilatation of the cavities 

 of the left ventricle makes that ventricle longer and broader, while the increased cardiac 

 impulse may be felt in the axillary line in the sixth, seventh, or even eighth intercostal 

 space to the left of the mammary line. Hypertrophy, with dilatation of the right side, 

 increases the breadth of the heart, so that the cardiac impulse is felt more to the right, even 

 to the right of the sternum. 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 parasternal line, the heart is increased in breadth, and there is 

 hypertrophy of the heart. A greatly increased cardiac impulse may extend to several inter- 

 costal spaces. 



The cardiac impulse is abnormally weakened in cases of 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 under 

 the influence of various stimuli (psychical, inflammatory, febrile, toxic) which affect the cardiac 

 ganglia. Great hypertrophy of the left ventricle causes the heart to heave, so that a part of the 

 left chest-wall may be raised and also vibrate during systole. 



A pulling in of the anterior wall of the chest during the cardiac systole occurs in the third 

 and fourth interspaces, not unfrequently under normal circumstances, sometimes during in- 

 creased cardiac action, and in eccentric hypertrophy of the ventricles. 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, retraction 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. 



