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protrudes through the thoracic wall. In subclavian murmur, the firm application of the stethoscope will itself check the exhibition of the phenomenon.
In aneurism, movements of the arm do not influence the sound. In subclavian murmur, the sound can invariably be modified by merely raising the arm, and changing the angle of the limb to the body.
In aneurism, there will commonly be present dul. ness on percussion over the seat of the pulsation; such dulness being independent of tubercular disease of the lungs. In subclavian murmur, if in the region of the murmur there is any dulness on percussion, the stethoscopic and other physical signs will, in the majority of cases, perhaps in all, show that the deficient resonance is due to tubercular deposition.
In aneurism approaching the surface there may be fremitus; but the fremitus is permanent under all conditions. In subclavian murmur there may be fremitus; but this can be made to disappear by movement of the arm on the side affected, and also by a deep expiration, or a very deep and sustained inspiration.
In aneurism of any of the three great vessels I have named, there will be, as a general rule, symptoms of dyspnoea and respiratory oppression. Subclavian murmur is not, per se, accompanied with any such complication.
Finally, as a diagnostic difference between subclavian murmur and subclavian aneurismal murmur, this may be observed; that, if simple subclavian murmur be present on one side, it can usually be detected on the other side; and when the two sounds
are traced downwards, towards the sternum, they are found to be lost, showing that they have no common point of origin, but an origin purely local in each artery. Now, whilst double subclavian aneurism is not an impossible, it is an unrecorded phenomenon, and in common experience is so rare, that the fact of double murmur may be considered as affording direct evidence against aneurism as the cause of the abnormal sounds.
The diagnosis as between subclavian murmur and cardiac murmur is comparatively easy. By carrying the stethoscope from the subclavian region to the cardiac region, it will be detected in pure cases of subclavian murmur, that the heart-sounds are both distinct, and that the bruit in the upper part of the chest is entirely unheard at the heart. However loud it may be in its own region, subclavian murmu never intrudes itself on the cardiac music. This line of diagnosis is therefore direct. But there are cases, and I have seen two such, where, together with subclavian murmur, there was systolic cardiac murmur from mitral disease. But here again I had no difficulty in distinguishing the two morbid sounds; for the mitral murmur was permanent, while the subclavian murmur was intermittent; the mitral murmur was prolonged, while the subclavian was short and sharp; and lastly, on carrying the stethoscope from the subclavian space downwards, towards the heart, an intermediate point was found, where the subclavian murmur was lost and the cardiac murmur began to be heard ; and on the contrary, on carrying the stethoscope upwards, from the heart towards the subclavian artery, an intermediate point was found, where the cardiac murmur was lost and the subclavian murmur began to be heard. There were thus distinctive evidences of two seats for the two murmurs; and the same evidences would, I presume, be present in all similar complicated cases. I had, again, another example, where subclavian murmur existed with loud aortic murmur, and this latter murmur was in truth reflected nearly into the subclavian region. But several differences were detected on careful inquiry, by which the diagnosis was determined. For example, the two murmurs had each a different sound; the subclavian murmur could be stopped by inspiration, by the movement of the arm, and by pressure of the stethoscope; while the aortic murmur was persistent in all these conditions; and a last but excellent point was, that the radial pulsation, which was synchronous with the subclavian murmur, followed the aortic murmur. I do not think there could be two better marked examples of subclavian murmur, complicated with aortic and mitral murmurs, than those above given. Without further comment, they supply in themselves all the differential diagnostic points to which it is necessary to call the attention of the reader.
Pleural friction-sound may be mistaken for subclavian murmur, or the murmur may be mistaken for friction-sound, but not if care is taken. One of my
pupils once showed me a patient who had, he believed, the subclavian murmur; but, on re-examination, the sound proved to be frictional. The character of the sound was certainly closely analogous to a sharp subclavian whiz, and the position was right for such an occurrence. But the diagnosis was clearly in favour of pleuritic friction: for (a) the sound heard was only present during inspiration, and was but one sound in the full period of inspiration; the arterial sound would have been repeated as frequently as the pulse. (6) The sound heard was not modified by the position of the arm. (c) The sound was still heard when the stethoscope was applied with sufficient firmness to stop the arterial pulsation altogether, and to check the radial pulse.
These three distinctions were in themselves suffi. cient, as physical signs, to indicate the nature of the case. To them, nevertheless, were added other general symptoms; viz., pleuritic pain increased by a deep breath, a small irritable pulse, and feverish exacerbations. Such symptoms, truly, were compatible with subclavian murmur and tubercle ; but, coupled with those which are already named, they completed the evidence, and rendered an almost perfect diagnosis quite perfect. In any other analogous case, similar diagnostic rules would be afforded, in part at least, if not in the whole.
I have met with one case in which, together with subclavian murmur, there was, with chronic bronchial inspiration in the right subclavian region, a sharp bronchial coo immediately behind the artery. The patient was young, twenty-three years old, had suffered long from bronchial cough, and at the time of my first seeing him had been losing flesh and spitting blood. I was undecided as to the concurrent existence of tubercle; for a sharp bronchial coo at each inspiration covered the physical indications, even if present, of this deposit. At the point under the clavicle where the bronchial sound was heard, there could also be brought out during a deep inspiration a sharp subclavian murmur. But the distinction between the murmur and the bronchial whistle was clearly to be distinguished. In tone and timbre they were nearly the same, but in time they were different; for while the bronchial sound was as one to an inspiration, the subclavian ran on to three, both kinds of sound being heard as distinctly as two parts in a musical scale; added to this, there was the influence of differing positions of the arm, which modified the subclavian murmur, and did not modify the bronchial coo: while, again, the effects of firm stethoscopic pressure stopped the arterial, but in no way affected the bronchial sound.