SYMPTOMS AND SECONDARY PATHOLOGICAL EFFECTS OF LESIONS AFFECTING THE VALVES AND ORIFICES OF THE HEART.

The primary effects of valvular lesions, which are of immediate pathological importance, have been already considered. They are, obstruction to the passage of blood by contraction of the orifices, regurgitation or the flow of blood in a retrograde direction owing to insufficiency of the valves, these effects being produced either separately or conjointly. Hence, the lesions affecting the valves or orifices may be distinguished as obstructive or regurgitant lesions; and as all the valves or orifices of the heart may be affected either separately or in various combinations, valvular lesions may be divided after their seat and primary effects into obstructive and regurgitant lesions, situated respectively, at the mitral and aortic orifices, and, much more rarely, at the pulmonic and tricuspid orifices. The secondary or remote pathological effects of these lesions, for the most part, are traceable to the primary effects. The disturbance of the circulation, due to cardiac obstruction and regurgitation, singly or combined, gives rise to a great number and variety of morbid conditions and manifestations intrinsically more or less serious, and important, also, as symptoms of the heart affection. It will be most convenient to arrange these ulterior effects according to the different anatomical systems in which they occur. Pathological effects of much importance are produced in the heart itself; other effects are appropriately considered as pertaining to the vascular system, not being limited in their consequences to any particular situation; others relate respectively to the respiratory, nervous, digestive, genito-urinary systems, etc. In considering the effects after this arrangement, their relations to obstructive and regurgitant lesions. seated at the different orifices will be incidentally considered.

SYMPTOMS AND PATHOLOGICAL EFFECTS REFERABLE TO THE HEART.

Valvular lesions involving obstruction or regurgitation, sooner or later, in the great majority of cases, lead to enlargement of the heart. They lead to this result by inducing over-distension of the cavities and over-excitement of the organ, as has been con

sidered in the chapter devoted to the subject of enlargement. The enlargement may be due either to predominant hypertrophy or dilatation. The latter predominates in most instances in which the cardiac disease has existed for a long period, and proved directly fatal, i. e. when death is not attributable to an intercurrent affection. The hypertrophy or dilatation is generally marked in, and may be limited to certain portions of the heart. The enlargement commences at one of the ventricles or auricles, according to the situations of the valvular lesions, and thence extends successively over the other compartments, observing a general rule of extension, exceptions to the rule, however, occurring not unfrequently.

Obstructive or regurgitant lesions at the mitral orifice induce, as a rule, first, dilatation of the left auricle; next, dilatation or hypertrophy of the right ventricle; next, dilatation of the right auricle, and finally, in most cases, more or less enlargement either by hypertrophy or dilatation of the left ventricle. This is the regular order of effects upon the heart, the mechanism of which has been already described. Variations from this rule are frequently observed. Thus the right auricle is sometimes much more dilated than the left, when the valvular lesions are exclusively mitral; and occasionally under these circumstances, the left ventricle is found to be more enlarged than the right. In these exceptional instances, either the walls of the portions which are enlarged out of the natural order, are particularly prone to enlargement, or there exists causes superadded to the valvular lesions. Thus, emphysema, coexisting with mitral lesions, will cause the enlargement of the right ventricle and auricle to preponderate much more than if the mitral lesion existed alone. In some cases, superadded causes may exist remote from the heart, which are not readily ascertained, causing enlargement of the left ventricle to preponderate, when, as a result of mitral lesion alone, this should be the cavity last and least affected. As an exceptional occurrence the left ventricle is sometimes diminished in size when, in consequence of mitral lesions, the other portions are enlarged. This fact, first pointed out by Dr. Law, of Dublin, is explained by the diminished supply of blood received by that ventricle when there exists much obstruction of the mitral orifice. The enlargement of one ventricle may be by hypertrophy, and that of the other by dilatation. Thus the right ventricle may be hypertrophied and the left dilated, or vice versa. The amount of enlargement of the heart, as a whole, varies greatly in different cases, and what is remarkable, is not proportionate to the amount

of obstruction or regurgitation, a fact which shows the influence of causes subsidiary to the valvular lesions. Very great enlargement is found associated with lesions involving only moderate obstruction or regurgitation, and, on the other hand, the heart is sometimes found to be but little, or not at all enlarged, when there exists a marked degree of contraction or insufficiency. The mitral orifice has been reduced to the size of a crow's quill, without notable enlargement of any of the cavities. This fact also shows the importance of causes superadded to valvular lesions. As a rule, contraction of the mitral orifice, in other words, obstruction, tends to give rise to enlargement, more than insufficiency or regurgitation ; but the tendency is of course greater when, as is frequently the case, contraction and insufficiency are conjoined. The latter occurs in the instances in which the curtains of the mitral valve become adherent at their sides, leaving a funnel-shaped canal opening into the ventricle by a narrow fissure resembling a button-hole or the chink of the glottis.

Enlargement proceeding from aortic lesions invariably commences at the left ventricle. If the valvular lesions are exclusively aortic, this ventricle is always enlarged disproportionately to the other portions of the heart, and the enlargement may be limited to the left ventricle. An examination of the heart before the cavities are opened often suffices to show that the valvular lesions are probably aortic. Either hypertrophy or dilatation may predominate in the enlargement proceeding from these lesions. As a rule, if the lesions are of a nature to allow of regurgitation without producing obstruction, dilatation predominates; but if the lesions produce obstruction without regurgitation, hypertrophy is marked. This rule is not without exceptions, but it holds good in the great majority of cases. Thus, of 21 cases of either regurgitation or obstruction, the notes of which are before me, 3 only were exceptional. Of these 21 cases, in 13 there existed regurgitation without contraction, and in 2 cases hypertrophy was predominant, dilatation predominating in the others; in 8 cases there was obstruction without regurgitation, and in all save one hypertrophy was predominant. Aortic lesions, however, frequently give rise both to obstruction. and regurgitation, and in proportion as the one or the other preponderates, dilatation or hypertrophy will be likely to be marked.

The cabinet of the Boston Society for Medical Improvement contains two specimens, illustrative of this statement, vide printed catalogue, pages 73 and 86.

Usually the enlargement extends to the other portions of the heart. The right ventricle is not proportionately enlarged, unless there are concurrent causes which exert their effect especially on this ventricle. Pulmonary emphysema, coexisting with aortic lesions, may render the enlargement of the right ventricle as great, or even greater, than that of the left. Of the two auricles, the tendency of aortic lesions is to dilate, first and especially, the left, but in some instances dilatation of the right is more marked. Enlargement associated with aortic, as well as with mitral lesions, is by no means in all cases proportionate, as regards amount, to the degree of obstruction or regurgitation. Enormous enlargement is observed in cases in which the contraction or insufficiency is small, and, on the other hand, in some instances in which the obstruction must have been extremely great, the size of the heart has been found slightly or not at all increased. This fact is illustrated by a specimen contained in the cabinet of the Boston Society for Medical Improvement, the aortic orifice being so much contracted as hardly to admit of the passage of a small probe. These facts here, as in the case of mitral lesions, show the importance of concurrent causes or morbid conditions in determining the amount of enlargement of the heart.

When, as is frequently the case, mitral and aortic lesions are associated, involving, in each situation, either obstruction or regurgitation, or both, the effects of the two classes of lesions are conjoined. Other things being equal, the enlargement of the heart, as a whole, is proportionately greater under these circumstances. The aortic lesions give rise to enlargement of the left ventricle, and combine with the mitral lesions in leading to enlargement of the other portions of the heart. Among cases of this description we are likely to find examples of excessive augmentation of bulk, constituting the cor bovinum of the old writers.

The pulmonic and tricuspid valves, as already stated, are rarely the seat of those structural changes which so often affect the valves. of the left side of the heart. Valvular lesions, seated in the right side when they occur, are usually, but not invariably, associated with mitral or aortic lesions, either separately or combined. Their effects upon the heart are similar in kind to those of lesions seated in the left side, the points of departure for enlargement being the right auricle in cases of tricuspid obstruction or regurgitation, and the right ventricle in cases of pulmonic contraction or insufficiency.

Vide Catalogue.

Examples of great enlargement of the right ventricle are observed in connection with congenital contraction of the pulmonary artery. Tricuspid regurgitation occurs not unfrequently without, strictly speaking, valvular lesions at this orifice. In certain cases of dilatation of the right ventricle, the auricular orifice becomes enlarged, the tricuspid valve not undergoing a corresponding increase in size. The consequence is insufficiency of the valve, or more or less patency of the orifice. Tricuspid regurgitation, under these circumstances, plays an important part in the production of certain pathological effects and symptoms of cardiac disease, viz., jugular turgescence and pulsation, general dropsy, etc., which will be presently noticed. In post-mortem examinations, valvular insufficiency from this cause is liable to be overlooked unless attention be directed specially to the size of the orifice, which, in its normal condition, should not greatly exceed four inches in circumference. It was remarked first by John Hunter, in his treatise on the blood, that the tricuspid valve is not so well adapted to afford complete protection to the auricular orifice as the mitral valve, and hence he infers that it is less important for this orifice to be protected on the right than on the left side. Mr. Adams,' of Dublin, and more recently and elaborately, Dr. T. W. King, of London, have advocated the opinion that the tricuspid valve is disposed with special reference to regurgitation, and that an important part of its function is to permit a retrograde current through the auricular orifice when the right ventricle becomes over-distended. Dr. King bases his view of this "safety-valve function," as he terms it, upon the connection of the free extremities of the anterior and right curtains of the valve with the anterior wall of the ventricle, by means of the papillary muscles and tendinous cords. This connection he supposes to be such as to involve a separation of these two curtains from the remaining or posterior curtain when the accumulation of blood within the ventricular cavity is sufficient to over-distend the ventricle and carry far outward the anterior wall. An examination of a large number of hearts with reference to this point leads me to doubt whether over-distension of the ventricle produces the effect on the anterior and right curtains of the valve, at least in the majority of cases, which is attributed to it by Dr. King. The arrangement of the valve, however, is such that, when the ventricle

'Dublin Hospital Reports, vol. iv.

Essay on "The Safety-valve Function in the Right Ventricle of the Human Heart," by T. W. King, Guy's Hospital Reports, vol. ii.