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monary artery on its left; it then passes in front of the trachea, just above its bifurcation, arches over the left bronchus, and, passing still further backwards, lies upon the left lung and the oesophagus, until ultimately it rests against the left side of the bodies of the fifth and sixth dorsal vertebræ, having the esophagus on its right side and the lung on its left.
The pulmonary artery rises from the right ventricle, just behind the left edge of the sternum, opposite the third sterno-costal articulation, and ascends inclining slightly backwards until it bifurcates opposite the second costal cartilage.
The arteria innominata springs from the transverse portion of the arch of the aorta, whilst it lies behind the right side of the sternum, and, passing upwards and to the right in front of the trachea, it bifurcates behind the right sterno-clavicular articulation. The spot at which any sounds which may arise in it can be heard in greatest intensity is the first costal cartilage on the right side.
The left carotid artery arises from the arch of the aorta, behind the sternum, nearly in the mesian line, and, passing in front of the trachea, it tends upwards and outwards to the left sterno-clavicular articulation.
The left subclavian artery arises from the most depending part of the transverse portion of the arch of the aorta, and thence ascends almost perpendicularly to the first rib, where it turns suddenly outwards. Throughout the first portion of its course it lies close to the spine and parallel with the æsophagus.
The superior vena cava passes nearly vertically from opposite the cartilage of the first rib on the right side to the cartilage of the third rib, lying along the outer edge of the ascending portion of the arch of the aorta near the right border of the sternum.
The boundaries of the space within which the heart lies are subject to variation, even when the organ is perfectly sound and the patient healthy. This results partly from the change of form which the heart undergoes in systole and diastole, partly from the change of its position occasioned by alteration in the posture of the body, and partly from the change in the size of the chest and in the position of the thoracic organs consequent on the acts of inspiration and expiration. Thus, during systole the heart twists spirally round its longitudinal axis from right to left, and its long diameter is shortened; the base is drawn downwards and backwards, the ventricles assume a globular form, and the apex is tilted forward and passes from right to left. During diastole the converse takes place. Again, when the body is raised from
a recumbent into an erect posture, the heart comes forward, and at the same time sinks downwards to the extent of an inch or even more; and it shifts in like manner from right to left, or from left to right, according as the patient lies on one side or the other. And, once again, the act of inspiration, by depressing the diaphragm, lowers the heart; whilst, conversely, expiration raises it. These various circumstances, therefore, alter the position of the valves of the heart in their relation to the walls of the chest, and consequently produce a corresponding change in the points at which the various sounds are heard in greatest intensity. For this, due allowance must be made whilst conducting a physical examination of the heart and great vessels.
HAVING determined the position of the heart and great vessels, and their relation to the walls of the chest, we may proceed to discuss the means at our disposal for the examination of the circulatory apparatus within the thorax. These are- Firstly, inspection; secondly, palpation, or the application of the hand; thirdly, percussion ; fourthly, auscultation.
Inspection informs us of the shape of the chest walls in the cardiac region, the condition of the integuments, and the existence or nonexistence of visible pulsation, whether in the chest walls or in the larger vessels in the neck.
Without stopping to investigate the various alterations in the form of the chest which are compatible with a healthy condition of the heart and great vessels,* it may be stated generally that in a healthy person, with an ordinarily well-formed chest, the præcordial region does not differ materially from the corresponding portion of the chest on the right side, except in the fact that in the fifth intercostal space, about midway between the sternum and the left nipple, a gentle heaving or pulsation may usually be seen. This accompanies each systole of the heart, and being due to the forcible impulse of the apex of the heart against the chest walls is regular in rhythm and single—not double. The area of visible impulse seldom exceeds a square inch; and in stout persons, with broad, capacious chests, and in persons in whom the heart is weak and does not contract forcibly, it often happens that no impulse can be detected. In some individuals who have a short sternum the impulse is seen in the epigastrium; and in all persons change of posture, distension of the abdomen, tight lacing, and the alteration produced in the size and form of the chest, by full inspiration and full expiration, lead to corresponding changes in the position which the heart occupies, and therefore of the surface over which pulsation is visible. The heart and large vessels are all lowered during full inspiration by the descent of the diaphragm, and are all raised by its ascent during expiration. In thin persons, with narrow chests, the area over which the impulse is visible is greater than in stout persons, with broad capacious chests, and in males it is usually more extensive than in females. Cæteris paribus, the impulse is more forcible and therefore more plainly visible in persons of an excitable, nervous temperament than it is in those of a sluggish disposition, and it is also augmented by flatulent distension of the abdomen, and by whatever leads to an upward pressure of the diaphragm, and so to the tilting upwards and forwards of the apex.
* For details respecting the causes of these deviations from the normal shape of the chest see part i, chap. ii, pp. 9-11, of my treatise on · Diseases of the Chest.'
In disease, material alterations may be observed in the form and condition of the chest walls, in the character and position of the cardiac impulse, and in the condition of the larger vessels of the neck. It frequently happens that in a state of health there is nothing to be observed in the præcordial region indicative of the presence of any organ which does not exist in a corresponding portion of the opposite side of the chest. But in disease this region may be unusually prominent or retracted, or may be the seat of pulsation of an abnormal character; or bulging and pulsation, or either of them may be observed in other parts of the chest where such phenomena ought not to exist; or the integuments may be ædematous, or covered with swollen, tortuous veins, such as are not seen in a state of health; or the larger vessels in the neck may be observed to pulsate, and to be abnormally swollen.
Abnormal prominence of the præcordial region may be due to causes acting either within or without the pericardium. Amongst the former may be mentioned hypertrophy, and dilatation of the heart; exudations of all kinds, whether serous, plastic, purulent, or hæmorrhagic, into the pericardial sac; and deposits, whether tuberculous or cancerous. Amongst the latter abscesses, aneurismal, cancerous, and other tumours in the anterior mediastinum.
The liquid effusions, more especially when copious, push forward the sternum, elevate the costal cartilages, and produce widening and bulging of the second, third, fourth, fifth, and sixth intercostal spaces ; the more solid exudations, aneurismal and other tumours, and hypertrophy and dilatation of the heart, increase the prominence of the chest walls, and cause widening, but not bulging of the intercostal spaces—a fact of some importance in a diagnostic point of view. It should be added, that considerable mischief of all kinds may occur either within or outside the pericardium, without producing prominence of the chest walls, or bulging of the intercostal spaces, and that the prominence under the conditions mentioned is most marked when the chest walls are very elastic and yielding, as in childhood or early youth.
Retraction of the chest walls in the præcordial region is stated by Dr. Walshe* to be due sometimes to absorption of pericardial effusion. But my observations do not correspond with his in this particular. It is just within the range of possibility that apparent retraction, limited to a small extent of surface, may be observed occasionally in consequence of adhesion having taken place over one portion of the heart, whilst, as yet, the remainder of the pericardial sac remains distended with fluid, but such retrạction is apparent only, and referable to the abnormal prominence of the adjacent parts; and it is difficult to conceive how any real retraction can possibly take place in the præcordial region from an uncomplicated attack of pericardițis. In every instance in which I have noticed retraction, and have had the opportunity of examining the parts after death, the pericardial mischief has been accompanied by pleurisy, to which, doubtless, and not to the pericarditis, the retraction of the chest walls has been referable—the only exception being in cases which have been referred to by Skoda, in which the heart has become adherent to the anterior surface of the chest, and slight retraction of the intercostal spaces is observed consequent on its action.
The condition of the integuments is also a subject for remark in some instances, inasmuch as in cases of aneurismal, malignant, and other tumours, they are often more ædematous over the seat of mischief than in other parts of the chest. Further, the presence of swollen or distended tortuous veins may afford evidence of deep-seated pressure.
* "On Diseases of the Lungs and Heart,' p. 181.
The variations which occur in the impulse of the heart, under the influence of disease, are very remarkable. Not only may the position of the impulse be shifted, but its whole character and rhythm, and the extent of surface over which it can be seen may also undergo alteration.
The apex of the heart may be visibly displaced in one of four directions, either upwards, downwards, to the right, or to the left.
The heart will be forced upwards, and its apex, therefore, must be displaced upwards, and will pulsate higher than usual in the chest, when the abdominal viscera are enlarged, the stomach or intestines distended with air, or the abdomen with fluid. Ascites, and enlargement of the left lobe of the liver are especially prone to produce this result, and so is pericarditis, with copious effusion, when the patient lies very flat in bed. In such a case the pericardium undergoes distension upwards with the greatest readiness, and the base of the heart and the great vessels are thus dragged upwards and backwards as the fluid increases, and the apex of the heart is tilted upwards and outwards, so that it may even beat in the fourth intercostal space outside the nipple. *
When the heart is hypertrophied and dilated, the apex may be lowered to such an extent that sometimes it may be felt as low as the eighth rib. Again, when a patient maintains an erect or semi-erect posture during the existence of extensive effusion into the pericardial sac, the heart, by reason of its gravity, will sink to the lowest part of the fluid, and may be seen pulsating below, and usually to the left of its usual place. Aneurismal dilatations of the arch of the aorta, or of the pulmonary artery, will also depress the heart, and lower the position of its apex beat, and so also may extensive emphysema of the lungs, which serves to depress the diaphragm, to which the organ is attached.
Displacement may take place either to the right or to the left, according as disease occurs on the right or left side of the chest, or on the right or left side of the heart. Ordinarily it results from the
* Dr. H. Davies describes displacement of the heart downwards as the invariable result of pericarditic effusion, and Dr. Walshe, on the other hand, speaks only of its displacement upwards under the same circumstances. Neither description is strictly correct. I have often seen it displaced upwards, and as often downwards, by pericarditic effusion, the result in either case being due simply to the posture of the patient, and the direction in which the fluid gravitates and distension of the pericardium