The evidence respecting the occurrence of an increase in the number of the parts of the heart is very unsatisfactory. The often quoted case of Kerkring,* with a double right ven tricle; one by Vetter,t with four auricles and four ventricles, quoted by Otto; a third by Che mineau4 with three ventricles, are, if genuine, the most remarkable instances on record, be sides various instances in the lower animals, especially birds. Andral states that he has seen a heart with three auricles, and another with four ventricles : it is much to be regretted that he has given no description of these sin gular malformations.§ Supernumerary cavities, or septa dividing the primitive cavities of the heart, are the most common instances of excessive developement. Adopting the arrangement of Andra1,11 we find-1, a supernumerary cavity forming a sort of accidental appendage to one of the auricles or ventricles, and communicating with the cavity of the part to which it is attached : 2, a supernumerary septum, forming an im perfect division of one of the natural cavities ; 3, a second cavity, completely partitioned off by one of these septa, and giving off super numerary vessels, which communicate with the regular vessels of the heart. It appears to me, however, to be very questionable that all cases of supernumerary cavities are the result of ex cessive development, hut that, on the contrary, they are sometimes mechanically consequent upon defective formation in other parts. At least it is in this way that I account for the con dition of the heart of a boy, aged ten years, which I examined several years ago, and which has been described by my respected friend, Dr. John Crampton, in the Transactions of the Dublin College of Physicians for 1830. In this heart there were three instances of defective developement—absence of the valves of the pulmonary artery, an open foramen, and an imperfect septum ventriculorum. Attached to the right ventricle there was a supernumerary cavity with which the pulmonary artery com municated. This cavity communicated also with the right ventricle, by an opening large enough to admit the little finger, and formed under the columns: carnew of the ventricle. The pulmonary artery was not only destitute of valves, but at the usual situation of the valves its lining membrane was puckered, by which its orifice was manifestly contracted. The su pernumerary cavity, in this instance, was in all probability occasioned by a partial dilatation of the infundibular portion of the right ventri cle, in consequence of the obstruction at the pulmonary orifice.
Increase in the number of the valves of the large arteries may be counted among the ab normal formations by excess. Thus, four or even five valves are occasionally found in the pulmonary artery more frequently than in the aorta. The supernumerary valves are always small, and sometimes appear to have been formed at the expense of the next normal one.
Anomalous connexion V the vessels of the heart. — Our space will only permit us to enumerate the principal observed varieties. I. The aorta or pulmonary artery, or both, appear to arise equally from both ventricles, the septum of the ventricles being more or less deficient. 2. The aorta may arise from the right ventricle, and the pulmonary artery from the left, the veins preserving their natural posi tion. 3. The vena azygos opens into the right auricle. 4. The hepatic veins open into the right auricle. 5. The ductus arteriosus opens into the right ventricle. 6. Two superior vane cure open into the right auricle. 7: Vcry rarely the right auricle gives insertion to one or morepulmonary veins, and on the other hand the left auricle receives sometimes the superior vena cava, and at other times the inferior. 8. Mead states that he has seen the great coronary vein of the heart to open into the left ventricle.* Professor Jeffray, of Glas gow, relates a case in which the inferior cava opened into the upper part of the right auricle, taking the course as well as the place of the vena azygos.
On displacement or ectopia (f the heart as a consequence of disease.—The most common cause of morbid displacement of the heart is an effusion of air or liquid into one of the pleural cavities. The displacement is most manifest when it follows effusion into the left side, by which the heart is pushed over to the right, the degree of displacement depending on the amount of effusion, and thus alteration of the heart's position becomes one of the diagnostics of empyema, hydrothorax, pneumo thorax. In general, the more rapid the effusion
the more certainly will the displacement be effected, and the greater will be its extent. In nine cases out of ten, as my friend Dr. Towns end remarks,1- when the heart is removed out of its natural situation, the displacement will be found to have arisen from empyema or pneumo thorax ; and of twenty-seven cases observed by him, the heart was perceptibly displaced in every instance. On the other hand, when the effusion is slow and gradual, the extensibility of the neighbouring textures is more completely brought into play, and the displacement of the heart is thus counteracted, whence it happens that in cases of chronic dropsical effusions into the chest, displacement of the heart is not of frequent occurrence, nor is it extensive when it does take place. When the effusion occurs on the right side, the heart may be pushed more to the left, and upwards, than is natural, but to effect this a considerable effusion is necessary. The first notice of this fact is due to my able friend, Dr. Townsend, to whose article I have already referred. In a case of pneumothorax to which he refers, and which I also witnessed, the effusion was on the right side, and the heart was distinctly seen and felt pulsating between the fourth and fifth ribs, near the left axilla. After paracentesis, which was performed by the late Dr. 1\I'Dowel, the heart gradually returned to its normal position, as the displacing force was removed by drawing off the air and fluid contained in the opposite pleura. More over, as has recently been ascertained by Dr. Stokes, the absorption of an effusion of the right side will cause the heart to be displaced to that side, the pleural cavity being obliterated by lymph, while the lung of the left side is en larged so as to aid in occupying the vacant space and pushing the heart over.
It is scarcely necessary to observe that tu mours forming in the right or left sac of the pleura may occasion displacement ; thus aneu rismal tumours may push the heart to the right, to the left and upwards, or even forwards and outwards against the wall of the thorax, or downwards, so that its apex will pulsate in the epigastrium. Of this last displacement, Dr. Townsend* relates an example. I have my self observed, some years ago, a case where the heart was pushed forwards and outwards, and. as it were compressed against the ribs by an enormous aneurism of the thoracic aorta; the sounds of the heart were so modified by this compression as to lead to the erroneous diagnosis of concentric hypertrophy. In the case recorded by Drs. Graves and Stokes,-t the heart was pushed upwards and to the right side by an abdominal aneurism, so as to pulsate in the in tercostal space of the third and fourth ribs. Dr. hope mentions the displacement to the left by an aneurism of the ascending aorta. Any cause which pushes the diaphragm upwards and prevents its descent, such as distension of the abdomen by an enlarged viscus, a tumour, or an effusion, will change the position of the heart, so that its axis will be directed horizon tally ; and Dr. hope has remarked that the same position may be produced by an adhesion of the pericardium to the heart, by which its enlargement downwards is prevented. A diaphragmatic hernia will displace the heart to an extent proportionate to that of the visceral protrusion. In a case recorded by Drs. Graves and Stokes, the stomach and a large portion of the transverse arch of the colon were lodged in the left cavity of the thorax, and pushed the heart and mediastinum towards the right side. When the lung is enlarged from dilated air-cells, the heart may be displaced : it may be drawn considerably downwards by the dia phragm, which yields before the enlarged lung, thus increasing the vertical diameter of the chest ; or it may suffer a slight degree of lateral displacement, the mediastinum being pushed to the right side by the lung./ Dr. Stokes has related the remarkable, and so far as I know unique case of displacement, or as he terms it " dislocation." of the heart from external violence. The patient was crushed between a water-wheel and the em bankment on NI hich the axle was supported. Several ribs were broken, as well as the right clavicle and humerus. The heart, which, ac cording to the statement of the patient, had always occupied its natural situation, was now found beating at the right side.*