PRACTICAL CONSIDERATIONS: THE HEART. 713 



collapse of the lung. Enlargement of the right auricle seems to be the basis of the 

 frequently occurring right-sided hydrothorax of valvular heart disease. Compression 

 of the azygos vein and perhaps of the veins and lymphatics at the root of the right 

 lung by the enlarged auricle accounts for the occurrence of one-sided hydrothorax 

 (Stengel). 



ijiupture of the heart is usually secondary to fatty degeneration of the cardiac 

 muscles. It may follow a complete embolic obstruction of one of the branches of 

 the coronary arteries. Arterio-sclerosis with slow obliteration of one or both of 

 these arteries may result in such atrophy of the myocardium as to favor rupture, and 

 this atrophy is hastened by the fact that there is no direct anastomosis between the 

 branches of these vessels (page 703). With any of these predisposing conditions 

 present, rupture may follow unusual exertion, or a heavy fall, or direct violence to 

 the precordium, or may occur spontaneously. The right side of the heart is the 

 more frequently involved, the right auricle especially ; but the cavities implicated, in 

 order of frequency, are the right auricle, left ventricle, left auricle, right ventricle. 

 This order probably results from the facts that (a) the right auricle is the weakest 

 part of the heart ; (<5) the left ventricle, though normally the strongest part, stands 

 second because it is specially liable to the myocardial degenerations that result from 

 coronary arterio-sclerosis ; (r) the left auricle and the right ventricle, though weaker 

 than the left ventricle, are less frequently affected because they are not so liable to 

 such degeneration. 



Wotuid of the heart is not necessarily fatal. A stab wound may be followed by 

 little or no hemorrhage owing to the anatomical arrangement of the muscular fibres, 

 some of which, whatever the direction of the wound, escape division. The thicker 

 the cardiac wall at the site of the wound the more numerous the fibres and the 

 more effective their action in preventing hemorrhage ; hence wounds of the auricles 

 are more certainly and more rapidly fatal than wounds of the ventricles, and wounds 

 of the right ventricle are graver than those of the left. Pain and syncopal attacks 

 are almost always present. Hemorrhage into the pericardium will be attended by 

 great precordial oppression, there will be increase of the area of cardiac dulness, 

 and indistinctness or feebleness of all the heart sounds. 



The anterior surface of the heart is most frequently wounded. The overlapping 

 of the pleura (page i860) leads to its usual involvement in wounds of the heart or peri- 

 cardium, except those that reach the latter through those areas of the sternum with 

 which they are in direct relation. Accordingly, in most heart wounds a pleural cavity 

 — commonly the left — is found to contain blood. As the anterior margin of the lung 

 is also apt to be involved, except when the wound is within the bounds of the area 

 of cardiac dulness, the blood in both the pleural and pericardial cavities may be frothy. 

 The right auricle and ventricle and the left coronary vessels — running in the 

 anterior interventricular groove — are most frequently wounded ; the right auricle if 

 the wound passes through the inner end of the right third, fourth, or fifth intercostal 

 space ; the right ventricle if it passes through a corresponding space to the left of the 

 sternum. 



As 40 per cent, of the reported cases operated upon for heart- wounds ha\e 

 recovered, it may be well to associate the study of the normal heart with that of the 

 best method of gaining access to it for surgical purposes. 



The heart should be exposed by a flap, the lower border of which corresponds 

 to the sixth interspace, the inner border to the left border of the sternum, and the 

 upper border to the third or, if the wound is high up, to the second interspace. 

 The cartilages of the corresponding ribs are divided and the flap is raised, separated 

 if possible from the pleura, and turned outward by fracturing the ribs. The pleura 

 is separated from the pericardium, to which it does not adhere very closely, 

 beginning towards the middle line. The pericardium is then incised and the accu- 

 mulated blood evacuated, which is often a great relief to the heart, to which the pulse 

 quickly responds. Two fingers are now inserted below and behind the apex and 

 the heart tilted forward and sutured. If a second wound — that of exit — is suspected, 

 it may be found by twisting the heart gently to the right or left. The sutures should 

 go down to the endocardium, but should not enter the cavities of the heart. The 

 pericardium is then closed, the pleura replaced, and the flaps sutured in position. 



