Chapter XLIX: Part 49

Primary defects of the systemic side of the heart are, for the reasons already given, very much more rarely seen than those of the pulmonary heart. In such cases the aortic conus and its orifice are found more frequently affected than the mitral orifice; both of these orifices, however, may be congenitally altered without foetal malformations at other parts of the heart being present; such cases are on record, though only sparsely scattered through the literature of cardiac diseases. Dilg[8] has recently made an important addition to this subject. He proposes a classification on a new basis for all forms of cardiac malformation; to these classes he makes conform the malformations of the left side of the heart. In the first class he places all cases dependent on an inflammatory process occurring in the foetal heart after its normal development is completed; in the second, those cases of malformation in which the deviation from the normal consists in defects of formation; in the third, those which present a combination of endo-myocarditis with defective development.

[Footnote 8: _Virch. Arch._, Bd. xci., S. 193-259, 1883: "Ein Beitrag zur Kenntniss seltener Herzanomalien in Anschluss an einem Fall von angeborner linksseitiger Conusstenose."]

{708} Among the many cases of malformation of the heart which he presents there are reports of 15 cases of stenosis of the conus, which are to be divided into two categories, in accordance with his classification. In the first group, in 7 cases the stenosis is due to an inflammatory process, and is conditioned by the results of the endo-myocarditis localized in the aortic conus. These cases must have originated at a late period of foetal life, and they correspond closely to the conditions arising in the adult organs from similar processes. In all the specimens the mitral orifice was involved, and contributed a share in the production of the conus stenosis; in all the cases the aortic valves also had suffered inflammatory changes. Here Dilg also speaks of a band-like hypertrophy of muscular fibres, marking the outlines of the aortic conus, similar to the condition described by Peacock in the right ventricle; in this condition there was no evidence of endocarditis, and the condition may have been due to cadaveric rigidity. The left ventricle presented varying conditions according to the state of the aortic and mitral valves; in some cases there was concentric hypertrophy, or, more strictly speaking, narrowing or shrivelling of the cavity with hypertrophied walls; in others dilatation existed. The other cavities of the heart were influenced by the competency of the mitral orifice, but almost always showed considerable hypertrophy and dilatation. The valvular apparatus of the right heart was not free from evidences of old inflammation, but this condition was not very marked. The ages of the reported cases reached from thirty to seventy-five years.

In the second group there are eight cases in which the defective condition of the aortic conus caused malformation of other parts of the heart. Here the conus stenosis occurred at an early period of foetal development, before the permanent structures of the heart were fully formed. The conus stenosis is to be considered as primary, the other defects as secondary. As we have already seen, the left side of the heart is much less liable to deforming causes, and when such do occur the secondary defects are less conspicuous. Thus, in only four of these cases were there such malformations of other parts of the heart as openings in the septa of the ventricles or auricles, patency of the ductus arteriosus Botalli. The defects consist more usually in what were formerly called excesses of development, such as the formation of bands below the aortic orifice; or of deficiencies of development, such as only two aortic valves. These conditions are very doubtfully due to formative excesses or deficiencies, but rather to intense inflammatory processes or other morbid conditions which have resulted in the formation of excessive cicatrices or the removal of normal parts.

Another division of cases shows narrowing of the aortic trunk itself. This condition is probably always a true defect of development; so far as these cases, collected by Dilg, show, it is unquestionably so. In narrowing or closure of the pulmonary artery trunk it is found that in some instances this condition was dependent on an endarteritis resulting in a partial occlusion of the lumen of the vessel; here, however, the aortic trunk furnishes no evidences of such a process. It must therefore be due to an unequal division of the truncus arteriosus communis. The cause and the mechanism of this unequal division of the common trunk, resulting in a reduction of the size of the aorta, are probably similar to what Rokitansky indicated for the reduction in the size of the pulmonary artery trunk.

In the specimens of aortic narrowing (no cases of complete closure are reported) from this cause and mechanism the pulmonary artery has been found unusually wide, but this condition of the pulmonary trunk is not very conspicuous, and does not necessarily result from the narrowed state of the aorta. The compensatory or secondary defect of open septum ventriculorum, or even of the auricular septum, is, in these cases, neither invariable nor necessary to a proper maintenance of the foetal or adult circulation. In fact, {709} the open ventricular septum is rare; the condition of the auricular septum is, in the reports, often not stated. The left ventricular walls commonly show a preponderance of hypertrophy over dilatation of this cavity, but in some cases the distension of the cavity is marked.

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SYMPTOMS.--The most striking symptom which occurs in malformation of the heart is the cyanosis, but the appearance of this peculiar symptom may be postponed until some time, even a long period, after birth. In the newly-born infant presenting a blue color the diagnosis rests between the not infrequent temporary failure of respiration from many causes and a defective development of the circulatory organs. In most cases the doubt is promptly solved by the voluntary or artificial efforts of breathing, whereby the cyanosis disappears. If the dark hue persists after the respiratory movements have been developed, the cyanosis may be found to depend either on cardiac malformation or an imperfect expansion of the lungs (atelectasis). The distinction between these two conditions can usually be made by a study of the respiratory movements, by the state of the heart's action and of the pulse, aided sometimes by an inspection of the outlines of the chest. In cardiac malformation respiration seems to be well performed and full, though often hurried or labored; in atelectasis this function is often found characteristically altered by being short, high, and imperfect, with imperfect distension; the ribs, instead of moving upward and outward, fall toward the median line, and the chest fails to expand transversely. In malformation the heart's action and the pulse are rapid, and a murmur can often be heard. The thoracic outline may deviate from the usual antero-posterior flattening by the sternum being prominent in cases where the heart, instead of its usual position to the left, is placed more centrally, as comes in certain defects of development. Both of these conditions may be present, and then the symptoms are mixed in character.

Cases of atelectasis, sufficiently marked to give rise to persistent cyanosis, if not relieved too frequently show a pretty rapid increase of color, becoming deeply livid, with convulsive movement, ending shortly in death. The diagnosis in such cases between a cardiac malformation and a non-expanded lung is almost impossible unless the respiration shows characteristic features. It is probable that the treatment proper for the latter would aggravate the condition of the circulation in malformation. In a majority of cases a post-mortem examination is necessary to determine whether the cyanosis is of cardiac or of pulmonary origin. In the atelectatic condition, if death comes within a few days of birth, the ductus arteriosus Botalli and the foramen ovale may both be found open, especially the latter, their time of normal closure not having arrived; in cases dying at a later period, if the foetal openings are still found patulous, the open state must be considered as dependent on the condition of the lung-tissue, since in malformation of the heart the patulous state of these foetal openings is, as has already been shown, rare as a primary defect, and, except in connection with defects of development resulting in obstruction, which operate at other points of the foetal circulation, is almost never found. In other words, an open foramen or ductus is a secondary defect, dependent, on the one hand, on a primary obstruction of the cardiac ostia, or, on the other hand, it may be on a primary atelectasis or malformation of the lungs.

If the child passes beyond the first weeks of life without exhibiting cyanosis, the subsequent occurrence of the condition becomes almost a pathognomonic symptom of cardiac or vascular malformation, unless it can be shown that the coloration is dependent on some acute disease, especially acquired valvular disease: in this connection collapse of the lung (post-natal atelectasis), too, must be remembered.

{710} It is during the first week of life that cyanosis makes its appearance in the great majority of cases of malformation of the heart, in the proportion of more than two to one of the cases. The coloration, once developed, may remain permanent and of equal intensity until death, but as less than 8 per cent. of infants with malformation die within the first week, and only 36 per cent. within the first year, this symptom usually remits. It may wholly disappear, to return on very slight provocation, such as excitement, or on exertion, on the advent of acute disease, or without apparent cause. Probably about one-fourth of those who die in infancy perish in paroxysms of dyspnoea, another quarter of acute disease, and the remaining half of convulsions; and toward death the cyanosis generally becomes very intense.

If the malformation is not of character or degree to develop cyanosis early in life, the child grows and passes through the usual stage of development, usually, however, feeble, poorly nourished, incapable of common exertion, but often without any special phenomena to attract attention, and the vice of formation is undetected unless by a special examination. There are several other symptoms frequently present in connection with malformation, but not of a pathognomonic character. Dyspnoea, though rarely occurring without cyanosis, may attract attention, and, if frequently brought on by active exercise, increases in violence, to be later accompanied with the cyanosis originally absent. Palpitation is not uncommon, especially in cases of great hypertrophy with dilatation, in hearts struggling to overcome an obstruction; in other cases it is absent or only occurs on exertion in connection with dyspnoea and cyanosis. The degree of animal heat varies greatly, judging by the various opinions expressed by writers. The sensation of patients able to express their feeling is often that of chilliness, and in some cases the surfaces of the body feel cold, although the indications of the thermometer show no great variation from the normal temperature. It is obvious that no very great variation from this standard is compatible with the long duration of life, although a depression may exist during or immediately after paroxysms of dyspnoea or cyanosis. Cough is also frequent, but is probably always due to some acquired pulmonary disease.

The physical signs offer increased facilities for the recognition of defects of development. In the early reported cases there are of course no records of these conditions, and there is therefore a lessened number of instances from which to collate the physical signs. In the early days of life it has been shown wherein the presence of a cardiac murmur may lead to the distinction between malformation and atelectasis. In later periods of life the physical signs cannot be regarded as characteristic. There are no signs by which a malformation can be distinguished accurately from an acquired cardiac disease, so that without the clinical history and a grouping of symptoms the diagnosis cannot be made from the physical examination.

Inspection and palpation of the chest often show the heart to be in an unusual position, placed more centrally under the sternum. It must be remembered that transposition of the heart to the right side is not unfrequently unaccompanied with any malformation of its ostia giving rise to symptoms; and this organ may be even more markedly displaced without being malformed, although under both these conditions irregularities of the principal trunks are usually found.

Percussion frequently shows enlargement of the area of cardiac dulness, but, on the other hand, at the post-mortem examination the heart is often found markedly defective without externally showing variation of its size or shape, or of its position within the thorax; hence in such cases no deviation from the normal will be revealed on percussion or inspection of the chest. It is probable that cardiac murmurs are not always to be detected in cases of even marked defects of development, but when present it is recorded most {711} frequently that a single murmur is heard over the base of the heart, blowing in character and systolic in time. Such a sound is probably produced by the passage of the blood through an abnormal opening between the ventricles or through the foramen ovale. Other murmurs may also be present; if the arterial ostia are defective from narrowing, roughness, or insufficiency of their valvular apparatus, abnormal sounds of different characters, diastolic or systolic in time, may be heard. Too few observations as yet exist for a general diagnostic scheme to be formulated. Auscultation of the intra-uterine heart may in the future become sufficiently accurate to enable us to prognosticate a congenital cardiac malformation or disease; there is one case on record in which a correct diagnosis was made in this way.

The ends of the fingers and toes are frequently described as bulbous. This rounding and retraction of the nails, frequently spoken of as clubbing, does undoubtedly exist in many cases, but the condition cannot be regarded as characteristic of malformation of the heart, since it comes with even more frequency in tubercular disease of the lungs, in chronic pleurisy, and in other chronic pulmonary maladies.

Lebert has recently insisted on the connection between stenosis of the pulmonary artery and tuberculosis, not merely as a coincidence, but as the cause of the development of the tubercles in the lungs. Many others have spoken of this connection, and very many are the cases recorded--perhaps nearly one-quarter of the whole number. In some cases large or small single cheesy masses exist; in others cavities form, and in rare cases a miliary tuberculosis exists, still more rarely affecting other organs than the lungs. In view of the recent dogmas of tuberculosis it is doubtful if many of these authors would at present insist on the connection between malformation of the heart and tuberculosis being other than a coincidence, since it is not apparent why such patients are more likely to be invaded by a bacillus of tuberculosis than other persons, and this organism is known to grow so readily wherever the spores chance to fall.

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DURATION OF LIFE.--In connection with certain malformations some indications have already been given in respect to the duration of life in such defects. It is, however, apparent that the degree of the obstruction to an orifice or vessel, and still more the completeness of the secondary compensatory alterations, exert a greater influence than the seat of the malformation on the continuance of life. The occasional slight isolated malformations, such as open septa without obstruction of the orifices, in themselves often entail no symptoms, and, unless combined with acquired valvular disease, exercise no influence on the duration of life; here, however, the prognosis merges entirely into the acquired malady.

Of the other conditions of malformation, narrowing of the aorta and of the aortic conus seems to be, on the whole, compatible with a longer duration of life than any other condition, and these defects cause death in the early days or months in fewer cases than similar obstructions on the right side of the heart. This result apparently comes from the fact that the left ventricle seems to possess unlimited capacity for hypertrophy, and hence is able to overcome the obstruction; when the aortic valves allow of regurgitation the compensation fails and death comes sooner. When the main branches of the aorta are defective or when the descending aorta is derived from the pulmonary artery, the duration of life is much shortened.

In cases of pulmonary narrowing in general it may be stated that the greater the obstruction the shorter the life. This rule is subject to many exceptions; so frequent are the exceptions that the rule is almost valueless for determining the life in any given case. Complete closure of the pulmonary trunk has permitted of the continuance of life for sixteen years, {712} and then ended from an intercurrent acute disease. When the septa are maintained open--when, therefore, the communications between the pulmonic and systemic sides of the heart are free--a greater age is attained than when these openings have become closed. This condition of the pulmonary artery in order to permit of a long duration of life must be coincident with a considerable development of the collateral circulation by which the blood freely enters the lungs for aëration; otherwise the compensation fails very soon.

In transposition of the main trunk relatively to the ventricles, with closure of the septum ventriculorum (very rare), life ends not many weeks after birth; if the septa remain open, which is not common, life may be prolonged for a year or two.

Cyanosis.

There are two views to be found, set in opposition to each other, to account for the peculiar blue coloration of the skin and mucous membranes in cases of malformation of the heart. The first explanation attributes the phenomenon to a general congestion of the venous system, due to the obstruction of the pulmonary artery. This view was proposed by Morgagni in connection with his, the first described, case of malformation of the heart. The other view considers that the intermingling of venous and arterial blood through any channel, but especially by means of abnormal openings in the septa, produces the blue coloration. Numerous writers have defended each of these theories of causation; from most of their observations darkness rather than light has resulted through the attempt to defend one or the other theory exclusively.

Gintrac defended the admixture theory for cyanosis, and his views became so well known that a large majority of persons conformed their belief to his teachings. This author distinguished four varieties of blue coloration: first, that due to some malformation of the heart or great vessels, by which the blood of the right side of the heart enters the systemic arterial circulation; second, likewise due to intermixture of the blood, but produced by conditions developed after birth through the re-establishment of the passages of communication or other changes in the circulation; third, where the coloration appears without direct admixture of the blood, but from organic disease of the heart; fourth, cases without malformation, from a suppression of the menses. Before the time of Gintrac, cyanosis had a very indefinite signification, and the condition was looked upon, and was classed by very many, as one of the cachexiæ, and was often spoken of as a form of icterus. He, however, held that the organic lesions of the heart and great vessels were the necessary conditions of its production, and that the mixture of the red and black blood, and the distribution of the mixed fluid by means of the arteries to all parts of the body, determined its essential character. He showed, too, that all communications between the right and left heart were not followed by cyanosis; the explanation of the absence of the blue color was that from the simultaneous contraction of the auricles and ventricles of the two sides of the heart an equilibrium was produced, and the blood did not deviate from its normal course. This result followed only when the normal exits of the blood were unobstructed. This supposition, as is apparent, is not in accord with the facts. During the filling of the ventricles, before the muscular contraction of the walls occurs, the blood has the opportunity of freely mingling if the opening between the cavities is sufficiently large: that the blood will not thus mingle when the muscular contraction acts remains to be proved. Cases of open septum ventriculorum, as an isolated defect, without obstruction of the great vascular trunks (a rare condition), are not attended with cyanosis: the absence of this symptom, as will be shown later, is readily to {713} be explained on other grounds than those supposed by Gintrac. The normal outlets of the blood are, however, almost always obstructed to a greater or less degree; and here the explanation of the absence of the cyanosis fails. In the delayed appearance of cyanosis Gintrac considered the reason to be that the venous blood differed less from the arterial in the young subject than in those of more advanced age, because, on the one hand, the aëration was more active, and, on the other hand, the deterioration of arterial blood was less marked. In other cases he points to an increase of the obstruction, through inflammatory changes, as the probable reason for the delayed appearance of the blue color; in still other cases it was supposed to be due to a disturbance of the equilibrium of the pulmonary and systemic circulation from an increase in the blood-mass. In cases of unilocular and bilocular hearts, of which the author speaks, his explanation completely fails, for here the admixture of the blood within the heart is very marked; yet such cases have been reported without cyanosis. He further believed that openings in the ventricular septum, as well as between the auricles, were effected after birth as the results of acquired cardiac disease.

Gintrac, in speaking of the causes of cyanosis, says that the condition shows no hereditary tendency; that the pregnancy during which the defective infant is developed is without noticeable phenomena; and that the confinement is normal. It is on some of these points that we are in want of accurate information. It has been pointed out that many congenital defects of the heart result from morbid processes affecting the organ during its developmental stage. These lesions are the same in kind as those which produce cardiac and vascular disease in the adult, and are likewise of a sort capable of communication from the parent to the foetus. Such diseases are found acting oftentimes temporarily in the parent; and if they acted during pregnancy, or even if present only at the time of conception, their results would rationally be expected to be displayed in the foetus. Such diseases as rheumatism and syphilis, which may be regarded as temporarily-acting maladies, would come under this class, and doubtless many others might be added to the list. The work of collecting the histories of pregnancies or the condition of the parents at or before the time of conception would be painfully tedious: such records do not exist at present, and they could be made sufficiently full only in exceptional cases; but their value in determining the causes which operate in the production of defective development of the heart cannot be too highly estimated.

The conclusions stated by Moreton Stillé[9] seem to be the first which justly cover the ground from a comparison of large numbers of cases of malformation of the heart. The first conclusion by him is that cyanosis may exist without admixture of the blood; by this was meant that no abnormal communication between the right and left sides of the heart, and no channels between the principal vascular trunks, are present. He mentions five cases of cyanosis occurring in which no means of admixture existed. The second conclusion is that there exists no proportion between cyanosis and the degree in which the blood is mixed; for this he cites four cases, some with the aorta arising from the right ventricle, others of hearts with only two cavities and the common trunk undivided, in which the cyanosis was only partial or transient. The third conclusion, the converse of the first, and reinforcing the preceding one, is that complete admixture of the blood may take place without cyanosis. The fourth, that the variation in the extent, depth, and duration of the discoloration is inexplicable by the doctrine of the mixture of the blood.

[Footnote 9: "Inaug. Thesis." _Amer. Journ. Med. Sci._, N. S., vol. viii., 1844.]

Having shown that commingling of arterial and venous blood cannot be the cause in itself of cyanosis, Stillé proceeds to the study of the other {714} theory--viz. that it is due to congestion of the general venous system resulting from some obstruction in the right side of the heart or in the pulmonary artery, impeding the passage of the blood through the heart. These structural lesions must fulfil the three following indications: 1st, that they shall be sufficient in degree to account for the symptom; 2d, that they be present in every case of cyanosis, or in their place some other cause acting on similar principles; 3d, that they shall never exist without cyanosis or without a satisfactory explanation of the exceptional occurrence. He holds that contraction of the pulmonary artery is to be taken as the type of all the lesions that may produce cyanosis, and that this type fulfils the indications given above.

Most writers since Stillé have coincided with him, or have regarded cyanosis as partly due to venous congestion and partly to commingling of arterial and venous blood. Some writers, however, have pointed to the abnormal communications between the right and left side of the heart, and asked why, if admixture of the venous and arterial blood is not the cause of cyanosis, should the admixture through such openings be found in such a large proportion of cases. Such writers have failed to distinguish between the primary and secondary defects of development. They have failed to see that the pulmonary obstruction which prevents the blood during extra-uterine life from passing to the lungs for aëration, and consequently produced the cyanosis, prevented the closure of the ventricular septum during intra-uterine life, or of the auricular septum within a few days of birth. In reply to the above question it may be pointed out, as Peacock has done, that such communications between the two sides of the heart are all important for the continuance of life, even for the shortest period, when the pulmonary artery is occluded.

It is evident, as Peacock has shown, that if Stillé's first and third conclusions are true, as the cases undoubtedly show, the theory of intermixture of the blood does not account for the condition of cyanosis. It is probable in many of these cases with abnormal openings in the septa that the intermixture of the blood is but slight, since if the pressure on the two sides of the heart is equal--and it may become equal through the establishment of a collateral circulation, although primarily it was unequal--no intermixture takes place through the defective septa. Neither does the admixture theory account for cases of intermittent or delayed cyanosis. Such cases can only be supposed to be due to a varying propulsive power or to a subsequent increase of the pulmonary obstruction. Neither does admixture account for localized cyanosis; for example, in the face or in one extremity: this condition, rare as it is, must be due to other causes. Peacock, while combating the admixture theory, considers that Stillé's conclusions in favor of the congestion theory as dependent on obstruction of the pulmonary artery are too exclusive. He discusses also the relationship of congenital cyanosis due to malformation, to cyanosis acquired through pulmonary and cardiac disease as seen in the adult, and shows why the latter condition is rarely ever as intense as the former, and also why acquired obstruction of the pulmonary artery is not necessarily productive of cyanosis. The reason of the difference he believes consists in the compensatory hypertrophy of the right ventricle, with perhaps a gradual diminution of the blood-mass, as seen in some cases.

On the whole, Peacock subscribes to the congestive theory, but thinks that the intensity of the cyanosis is modified by the capacity of the capillaries, by the period of development or duration of the obstruction, by the natural coloration of the skin, and by the color of the blood itself.

Under these two theories, and the arguments offered in support of them, there seems to be no other explanation possible of the condition of blueness, and yet the whole story of the mechanism of cyanosis does not seem clear. Partly, this is due to the incomplete knowledge of the physiology of the aëration of the blood which obtained during the most active period of the {715} discussion of cyanosis and its causation. Let us consider briefly the simplest case of cyanosis. Every child born has in one sense a temporary malformation of the heart--an open foramen ovale which does not close for several days after birth. Every child is born partially cyanotic, owing to compression of the uterine sinuses or pressure on the umbilical cord; it is completely cyanotic if there occurs premature separation of the placenta. The cyanosis continues until the child breathes. The cause of this cyanosis must be looked for, not in the temporary malformation, but in the imperfect expansion of the lungs. As soon as the respiratory function is assumed--as soon as, in other words, the pulmonary-artery branches carry a full amount of blood which becomes aërated in the lungs--the cyanosis ceases, although the foramen ovale is not yet closed.

The closure of the foramen by a trapdoor valve is, as has already been pointed out, not in accordance with the anatomical facts: turning the newly-born infant on its right side does not favor, as it is commonly supposed, the closure by gravity of a preformed swinging lid, which when it has dropped down for ever partitions the right from the left auricle. The right-sided position may favor the expansion of lungs or in other ways promote the pulmonary circulation, but in itself it does not tend to close the foramen. In fact, cyanosis does not here depend on the defective development, but on want of aëration of the blood.

Again, looking to the skin or mucous membrane, what is the condition of the blood and of the circulation which renders the parts of a blue color, and in what do they differ from the normal? In the normal state of the blood and circulation the capillaries of a given area are filled, one half with arterial blood, and the other half with venous blood; that is to say, the capillaries at the point of their origin from the arterioles contain pure arterial blood: as the blood-current proceeds outward the blood becomes progressively less and less red and more and more blue or black; when the venous radicle is reached the blood-current is of as dark a hue as it ever becomes. In general terms, therefore, it may be said, taking the average, that in a given area half the blood is venous, half arterial. Here, then, we see, with an equal mixture of the red and blue blood, nothing resembling cyanosis. It is evident, therefore, that to produce a cyanotic hue the blood must be wholly venous; the intensity of the blueness will vary with the amount of non-aërated blood present in the capillaries. But let us suppose an equal admixture of right- and left-sided blood to take place--for example, when the aorta arises from both ventricles, the pulmonary artery obstructed. It cannot be supposed that the venous blood would retain its dark hue. The contact of the two bloods within the aorta on their way to the capillaries would result in arterializing the venous blood at least one-half, so that when it arrives at the capillary network the intensely blue color of a marked case of cyanosis would have disappeared.

Besides this, there are other considerations to be taken into account to show that neither of the two exclusive theories accounts for the state of the blood and of the circulation in cyanosis. If the condition of the cyanotic parts, due to acquired valvular heart disease or various morbid states of the pulmonary tissue of an acute character be compared with the same parts in cyanosis from malformation of the heart, striking differences are discernible. If the simple condition of cyanosis of the part due to localized pressure on the veins be examined, the differences are even more perceptible. In the malformation there is an admixture of blood; in the other condition there is no opportunity for the intermingling of the currents. In the latter the cyanotic area becomes swollen, and the intensity of the color may become lessened through the oedematous condition; in the former the skin of the cyanotic infant rarely if ever presents any swelling; the veins of the part show little, {716} if any distension, as is so frequent in the latter; cases of malformation in which subsequent endocarditis with additional obstruction occurs may show oedema and swelling similar to cases of acquired valvular disease. In these cases of cyanosis the condition must be due to a want of aëration of the blood, since it never appears until such alterations of the pulmonary tissue and circulation are reached as to render it certain that the blue coloration is due to a want of aëration of the blood. Fulness of the veins and oedema may be present, but never general cyanosis.

Another important consideration in the production of cyanosis does not seem to have been fully appreciated. It is the fact that in all cases of obstruction of the pulmonary artery the collateral circulation, carried on by very varying channels, the bronchial arteries, the oesophageals, the coronaries in some cases, the internal mammaries and intercostal arteries in rare cases, or by the ductus arteriosus Botalli, which alone must be always inadequate in marked narrowing of the pulmonary trunk,--the collateral circulation must always remain insufficient for carrying sufficient blood to the lungs for aëration. Kussmaul was the first to call particular attention to this fact; and it is to this condition of insufficient channels for the blood reaching the lungs that certain cases of cyanosis must owe their causation.

Hence it must be that, in all the complex conditions found in cases of cyanosis from defective development of the heart, a want of due arterialization or aëration of the blood is at the foundation of the state as seen in the cyanotic area. Whether it results in a given case from excessive admixture of venous blood with the arterial when the current reaches the capillaries, or from venous stasis due to central obstruction, of which pulmonary-artery narrowing or closure is the type, or whether from a failure of sufficient blood to reach the lung, as where the collateral circulation remains imperfect, or as seen in certain cases of defective development of the lungs, is most difficult to ascertain. That sufficient consideration has not been given to the third possible factor in the causation of cyanosis--viz. failure of the blood to reach the lung, as distinguished from general venous congestion alone--is evident. That intermingling of the blood from the two sides of the heart must inevitably reduce the red color is certain--that in very many cases the reduction in color does not cause cyanosis can be readily understood from the consideration already offered. The cases of free admixture in which cyanosis does occur may coincide with a condition of very imperfect collateral circulation to the lungs, and hence with a low aëration of blood of the left ventricle, insufficient, therefore, to bring up the color of the blood from the right side of the heart above the cyanotic point.

Whether non-aëration of the blood from failure to reach the lungs, apart from general venous congestion, is a sufficient explanation of the cyanosis in a large majority of cases or in the whole number, is not apparent from the records of reported cases. Much more accurate post-mortem accounts, made with a view to determine the question, than at present exist will be required. In a number of well-reported cases of defective pulmonary artery with a free admixture of blood the pulmonary collateral circulation is found to be well developed, and no cyanosis had appeared, or had been but trifling and inconstant. In other cases of quite as marked pulmonary obstruction with but slight commingling of the blood through abnormal apertures and but slightly-developed collateral circulation, cyanosis has been found intense and constant. In the two conditions the possibilities for general venous congestion are about the same, though perhaps not equal, while the striking difference, apart from the admixture of the blood-current, consists in the conveniences for the aëration of the blood.

The only variety of malformation of the heart in which intense and constant cyanosis must inevitably be present is that very rare form of {717} transposition of the great trunks, the aorta springing from the right ventricle, the pulmonary artery from the left, with closure of the septum ventriculorum; the pulmonary veins enter the left auricle bearing red blood, and the venæ cavæ the right auricle with blue blood; if the ventricular septum is closed, the aorta necessarily carries blue blood to the systemic circulation, and the pulmonary artery is filled with red, carrying it back to the lungs, whence the fluid has just come. In such relation of the principal trunks, even if the ductus arteriosus Botalli and the foramen ovale remain open, cyanosis is necessarily present. The bulk of the blood in the aorta is blue: the only points in which it comes in contact with red blood are, first, at the foramen ovale: here the intermingling is not sufficient to bring it above the cyanotic color; and, secondly, at the ductus arteriosus, and here the tube is not favorably directed for a copious intermingling of the two bloods, neither can it probably ever be sufficient in itself for this purpose. Hence the aortic blood is almost wholly venous. If these two foetal openings did not persist life could not continue beyond a few hours, or even a few minutes, after birth. In such a case the cyanosis does not depend on general venous congestion, and specimens are reported of this sort in which the great vascular trunks were without obstruction, life having been maintained for a few months; adult existence is probably impossible. If, however, with such transposition of the vessels to the improper ventricle, the septum ventriculorum remains widely open, cyanosis may be absent or inconstant, because, apparently, admixture of the blood and also aëration are sufficiently free. But in cases of transposition of the vessels, or even in the much more frequent specimens without transposition, when the track to the lungs is defective either from want of a collateral pulmonary circulation or directly from impervious pulmonary artery, cyanosis becomes more intense and more constant or comes in more frequent paroxysms, irrespective of the presence or absence of evidences of general venous congestion.

It would seem to result from this grouping of facts, and looking at them from a reverse bearing to Moreton Stillé's point of view, that distal rather than proximal obstruction of the pulmonary artery, taken as a type, was the cause of cyanosis. Admixture of arterial and venous blood must reduce the redness of the arterial stream, just as certainly as red paint mixed with black varnish will render the black less intense: whether admixture alone ever produces a deep cyanotic hue of the surfaces is probably more than doubtful; that admixture will prevent constant cyanosis seems certain, when cases of complete transposition of the vessels with open septum ventriculorum are compared with those with closed septum, the other conditions remaining the same. General venous congestion from pulmonary obstruction or other causes outside the pulmonary tissue produces cyanosis, but of a sort quite unlike the typical cyanotic condition of malformation of the heart. It may therefore be doubted if the cyanosis seen in obstruction of the pulmonary artery is due to general venous congestion; it may be wholly produced by conditions on the other side of the obstruction--viz. want of aëration of the blood, which must ever remain the essential feature of cyanosis. This supposition allows of an easy explanation of the difference between cases of apparently equal obstruction of the artery, in some of which cyanosis is present and in others absent; it also allows of the explanation of inconstant or paroxysmal cyanosis where the obstruction, and consequently the venous congestion, is uniform and permanent.

{718}

CARDIAC THROMBOSIS.

BY BEVERLEY ROBINSON, M.D.

DEFINITION.--In general, this name is given to every deposit of coagulated blood or fibrin in one or more of the cardiac cavities. By its derivation ([Greek: thrombôsis], coagulation, from [Greek: thrombys], clot) it further implies the manner in which the coagulum is formed and all the morbid alterations connected with it.

SYNONYMS.--Heart-clot. _Fr._ Thrombose cardiaque; _Ger._ Blutgerinnungen im herzen; _Lat._ Thrombosis cordis; _It._ Trombo; _Sp._ Trumbo.

The definition offered is not wholly satisfactory, because, although it is accurate as far as it goes, it is not complete. It does not distinguish between concretions of different origin, etiology, mode of formation, and age. No separation is made between fibrinous deposits which increase from the beginning and layer by layer in the cavities of the heart, and those transported there from a distance and forming a nucleus for fresh deposits. To make the definition anything like exhaustive would require many references to the general history of THROMBOSIS AND EMBOLISM; we therefore direct our readers to that article for what relates to the common facts of these morbid processes, retaining for the present only those matters which relate specially to the heart.

Heart-clots may be formed--1, during life, when the patient enjoys, apparently, good health and strength; 2, toward the termination of life, when the general forces are evidently depressed, or at the final stage, when life ebbs low and the agony has appeared; 3, after death. These clots have therefore been divided into cadaveric clots, those of the agony, and ancient clots. To the clots of the agony exception is properly taken, for the reason that agony is a term employed with a somewhat badly-defined signification. At what period does it begin? Is it not frequently of different length? Does it always exist? The answers to these different questions render our objection proper, and show that we had better employ the word terminal for coagula of the second division.

Manifestly, the separate varieties of coagula have not an equal importance. The clots which are post-mortem productions are only interesting for their physical characters, which, fortunately, are well marked, and enable us at once to distinguish them from the two other varieties. The coagula in the first two divisions have an interest both clinical and pathological.

The ancient clots are invariably accompanied with signs and symptoms which should reveal their presence. As much might be affirmed for the terminal clots in the majority of instances and when the patient is not already in extremis. The pathological study of these varieties has great value, and especially in so far as it will the better enable us to distinguish the clots formed some time previous to death--be it of shorter or longer duration--from those which are but the result of the gradual stagnation of the blood-current in a weakened and wellnigh powerless organ. Amongst the clots which are formed in the venous system, some are transported, and pass {719} immediately through the heart, to be arrested finally in some of the larger or smaller arterial trunks, whilst others remain in situ in the heart, and are constantly increased by successive additions or layers of new fibrin or cruor.

The nomenclature to be desired is one which would assign different distinguishing names to each variety of coagulum, so that at once its origin, mode of formation, and perhaps too its age, should be exactly determined. The ancients employed the term polyp for deposits of every description in the heart, but such use of the word was, generally speaking, erroneous, since the true polyp is a very rare disease of the cardiac cavities. Bartholetti and Pissini first made use of it, and considered without doubt that the false polyps or fibrinous deposits in the heart were of analogous nature with the true polypi which are found so frequently in the uterus and nasal cavities. No doubt (as has been inferred) the term polyp in regard to these formations came into habitual use owing to lack of familiarity on the part of the older writers with the varied aspects of clots, as well as their ignorance of the distinct appearance offered by sections from them under lenses of great power. This mistake, therefore, is to-day not to be wondered at, if we duly consider how imperfect and unusual in olden times were pathological researches. Heart-clot was, as will be seen in the historical sketch which follows, the subject of numerous prolonged and animated discussions. As a result of these latter, it was ultimately believed that the great differences of appearance and formation which exist between coagula depend in great measure upon their relative age, and it is for this reason that the basis of distinction between their varieties rests mainly upon the period of time previous to a death at which they are formed. When we speak, however, of polypiform concretion or deposit, we approximate nearer the truth and indicate in a measure the local origin of a coagulum. Many others have employed the terms post-mortem and ante-mortem as being the only suitable terms with which to make a distinction between the coagula formed during active existence and those which are revealed only with the scalpel in the dead-house. In the consideration of this subject the symptoms shall be fully described which indicate the presence of heart-clot found during life, whilst in regard to clots formed in extremis or after death it is desirable particularly to show the pathological characters which shall definitely place them. For all that pertains to embolism of the heart we shall refer the reader, except when it is essential to mention certain details, to other articles in this work. Certain authors have erroneously, it is believed, regarded this subject of heart-clot as one of mere pathological interest, stating that the dead-house is the only place to study its origin and many of its organic effects. This opinion should be combated with vigor. Such a view is far too restricted, and it is here believed that the clinical aspects of cardiac thrombosis are worthy of attentive study, and that something better and further should be attained than merely to watch the downward course of a patient thus affected, and to bear in mind the pathological sequelæ of this disease.

HISTORICAL SKETCH.--The questions which have a present interest in regard to heart-clot are very different from those which formerly engaged medical attention. No longer are we uncertain as to the formation of these coagula during life, nor doubtful as to the various and important effects produced by their transport in different organs through the arterial and venous vessels. Thanks especially to the inaugural thesis of Legroux (1827), to those of Le Marchand and Ball (1862), to that of Bucquoy (1863), but particularly to the experimental researches of Virchow (1846-56) and to the observations of Senhouse Kirkes[1] in regard to the formation and transport of emboli into the cerebral vessels, these facts are all matters of ordinary information. There is little doubt that Galen had noted the formation of {720} intra-cardiac thrombi during life, and attributed to them interference with circulation and respiration, and, at times, sudden death. With the exception of Salius, mentioned by Morgagni as having remarked oedema due to this cause, we reach the sixteenth century before again meeting with any detailed mention of a similar pathological condition. Helidé of Padua, according to some,[2] Benivenius, according to others,[3] were the first authors to give full descriptions of cardiac polyps. This, indeed, was the term affixed for a long period to fibrinous concretions in the heart, beginning with Sebastian Pissini (Milan, 1654), who first employed it. The name took origin, without doubt, on account of their resemblance to polyps of the nasal fossæ, and perhaps to the animal thus named. It was particularly at this period that they acquired their significance, and became the subject of animated discussions between distinguished physicians of the last two centuries. Some, exaggerating their importance, attributed to them the gravest and most important symptoms, although a chronic affection of the heart or lungs present at the time was frequently sufficient to explain them; others, like Kerkring (1670) and Jos. Pasta[4] (1737), who contested the possibility of the blood coagulating during life, and believed they were invariably cadaveric formations, took from them even a pathological interest. This latter extreme opposition to reality originated very soon a mixed conviction, which was that held by Senac and Morgagni. These distinguished observers recognized that intra-cardiac thrombi formed both during life and after death, the former being rarely encountered. The later, or anatomical school, confirmed these views, but also added testimony to show that ancient and terminal concretions were not phenomena of such unusual occurrence as had been previously held. Testa (1810) and Kreyssig (1824) connected fibrinous deposits with inflammation of the heart, and the last-named writer described a disease which he named carditis polyposa. This view and that of Laennec, which attributed globular vegetations to an inflammatory cause, are in our day disproved. Amongst those authors who rendered certain the formation of cardiac clots during life, we should mention a few others whose names have a special importance in this connection as having made a special study of diseases of the central organ of circulation. These are Corvisart, Burns, Andral, and Bouillaud. Since this period the field of research has become far less limited, and investigations have been made in regard to similar coagulations in the large vessels of the body.

[Footnote 1: _Med.-Chir. Trans._, 1844, pp. 281-325.]

[Footnote 2: _Dict. de Méd. pratique_, vol. viii. p. 558.]

[Footnote 3: _Ziemssen's Cyclopædia_, vol. vi. p. 292.]

[Footnote 4: Quoted by Grisolle, _Pathologie interne_, Paris, 1865, p. 464.]

In 1856 a new era was established in regard to these formations, and especially with reference to their transport. Virchow at this period showed conclusively, after long-continued and accurate clinical observations and experimental researches, that a clot formed on the one hand in one of the large veins might be carried to the pulmonary artery and block up more or less completely the supply of blood to the lungs; on the other, that a portion of a thrombus formed in the left heart-cavity might become detached and plug completely one of the arteries of some far-removed organ, as the spleen or kidney, and thus give rise to those ultimate effects which we now understand under the name of infarction. Thus was first established the new pathological ideas which have become familiar with the words embolus and embolism. True it is that Virchow was not the first writer who had described the facts relating to the translation of portions of coagulum from one region to another of the circulatory system, and its fixation in a particular arterial branch. Already this subject had been clearly and succinctly narrated by Van Swieten. A passage in which the causes and mechanism of apoplexy are referred to gives lucid explanation of this doctrine: "Whatever causes change the blood, lymph, and the matter which supplies the spirits, so as they cannot pass freely through the arteries of the brain, but are there impacted. Such are {721} frequently--polypous concretions in the carotid and vertebral arteries, whether first formed about the heart or within the cranium itself."[5] These ideas of Van Swieten had not, however, produced any very permanent impression, and were almost forgotten, when Legroux (1827) promulgated his view in regard to the possibility of portions of coagulum being carried from the heart into different portions of the arterial system. He published, in fact, two most interesting cases of gangrene of the hand and forearm in which the efficient cause of the disease was found in an obliterating embolus of the brachial artery, which was evidently similar in its nature to the thrombus found in the heart of his patient. It is interesting to remark that Legroux's inaugural thesis, in which these facts were brought to light, was only the forerunner of some very complete articles on the subject of cardiac and vascular concretions, in which he goes over much of the ground which was covered in Germany by the work of Virchow. Legroux published his ulterior researches in the _Gazette hébdomadaire_, Paris, 1856, pp. 716 _et seq._ In fact, under the head of correspondence we find in No. 20 of the journal of this year (pp. 349 and 350) an interesting letter from Legroux to the editor, in which he claims for himself the priority of publication (Van Swieten excepted) of the facts pertaining to intra-cardiac thrombi and their effects due to transport of detached fragments into a region more or less removed from their place of development (p. 34). As this claim, according to my researches, appears justified, a part at least of the credit awarded to Kirkes, Virchow, and Schützenberger as discoverers and disseminators properly belongs to Legroux.

[Footnote 5: G. Van Swieten, _Commentaries upon the Aphorisms of Boerhaave_, Aph. mx., vol. iii. p. 159, ed. London, 1774.]