In the systolic murmur at the base, the history of previous rheumatic fever, or of nervous or hysterical symptoms ; the complaint of palpitation, or of cough and dyspncea ; and the aspect, whether pallid or florid—help in the determination of what is the value of the bruit. Only it must be remembered that, begun by actual alteration of the valve, it may be exaggerated by changes in the condition of the blood. We should be mistaken in looking always for a thrill in the pulse, though this be not unfrequent ; because in place of its being firm as it generally becomes, in consequence of hypertrophy in very marked aortic disease, it may be rendered weak by dilatation or fatty degenera tion : the coexistence of arms aenilis, as already observed, affords some con firmation to the latter hypothesis.
In decided anaemia we are apt to overlook the actual coexistence of valvular lesion. In hypertrophy and dilatation we are apt to assume its presence when there is merely imperfect closure and no positive disease : but the latter is of =Itch less moment as an error in diagnosis than the former.
The absence or presence of a hammering pulse may at once decide the ques tion whether a diastolic murmur be produced in the mitral or in the aortic valves.
When a double sound is heard, the history, the pulse, and the aspect of the patient ought never to permit the existence of a doubt whether it be endocar dial or exocardial, even in cases in which the character of the sound is not sufficient to determine the question; and here, again, as between a double sound produced in the aortic and a double sound produced in the mitral aper ture, the pulse is one of the best aids to forming a correct opinion.
When all has been done that can be done towards forming an accurate diagnosis, many cases will remain in which the judg ment is perplexed and the decision uncertain, many in which the conclusion has been absolutely false ; but the mind best trained to examining and weighing the facts of each case, and the ear most accustomed to discriminate and individualize the sounds, will be least frequently in error in obscure cases—will also be most often right in those of every day experience, which, even in their simplest form present to the careful physician so perplexing a problem. We need pnly here allude to some of those loud musical sounds heard at times some distance from. the patient, which, from their very intensity, cannot be localized at all ; for them the stethoscope need not exist., they must be judged of solely by general symptoms. Cases, on the other hand, occasionally t themselves which are too few to be made the basis of any diagnostic rules, and yet too curious to be passed over ; these are cases in which the arterial and venous currents get mixed through some congenital malformation, the circulation of the foetus being to a certain extent continued after birth. The blueness of the
akin, without appreciable obstruction to the respiration, and the long continuance of the symptom—its persistence, in fact, from birth, or at least childhood—serve sufficiently to mark them off as a set of cases standing alone.
Disease of the mitral valve may be traced in a large number of cases to rheumatic fever. This seems to be the point on which endocarditis, accompanying that disease, most readily fastens in the first instance ; when the first seizure is severe, or subsequent attacks occur, the aortic valves are usually also implicated. The systolic murmur is so readily produced, that very slight changes in the form of the mitral valve are indicated, though the pulse be for a long time scarcely affected, and the circulation undis turbed; when the change is originally greater, or repeated attacks of inflammation have seriously damaged the valve, the circulation is impeded, because the whole contents of the ventricle are not propelled through the aorta : and the current is, consequently, both smaller and weaker ; but, besides this, the blood which escapes through the mitral orifice is driven back upon the lungs, produc ing congestion, and giving rise to imperfect oxygenation ; hence we have the two symptoms of feeble pulse and dusky complexion.
In the further progress of disease the left side of the heart becomes dilated, and its wall hypertrophied : sometimes the one, and sometimes the other condition prevailing, but, as a general rule, the dilatation exceeding the hypertrophy. The diastolic mitral murmur is usually developed when the hypertrophy is greater than the dilatation. The heart's action becomes irregular when the dilatation is in excess ; and ultimately tumultuous action is brought on by some sudden strain, when the imperfect contrac tions of the ventricle, and the distended condition of the auricle, are such that no bruit is produced at all. In these cases the mitral disease may be entirely overlooked; and if the heart should happen to be much overlapped by the lung, so that its increase in size is not observed, the irregular action and feeble pulse may be set down as the result of degeneration, and the imminent dan ger of the patient unforeseen.