ABNORMAL CONDITIONS OF THE HEART. 



641 



recorded by others, whence he has been able 

 distinctly to prove the analogies above-men- 

 tionl, anil by which much li>:lit has been 

 tin-own upon those forms of disease. 



The partial dilatation of one of the cavities, 

 or true aneurism, is by far the most com- 

 mon of the varieties above-mentioned. In 

 its early stage this disease consists in little 

 more than a bulging of the wall of the ventricle 

 or auricle in a certain direction ; as this in- 

 creases a pouch or sac is formed, which com- 

 municates with tlie heart's cavity by a more or 

 lr>s narrow opening. In some cases this sac 

 does not extend beyond the external surface of 

 the heart, nor would it be detected, were ihe 

 anatomist to content liimself with merely ex- 

 amining the exterior, it is as it were lodged in 

 the fleshy substance of the ventricular paries; 

 but in other instances a tumour is formed pro- 

 jecting considerably beyond the exterior. As in 

 arterial aneurisms, the sacs frequently contain 

 laminated coau'iila, and, as miiiht be expected 

 ii jtritiri, the larger the cavity and the narrower 

 its orifice of communication, the more abun- 

 dant is this lamellar deposit. One or more 

 aneurismal sacs may belong to the same cavity: 

 thus, in lifty-two out of fifty-eight cases col- 

 lected by Mr. Thurnam, only one aneurism 

 existed in each ; but in four cases two were 

 met with in each ; in one there were three, 

 and in another four incipient aneurisms. In 

 two instances, Mr. Thurnam states, it is not 

 improbable that two sacs which were originally 

 distinct had coalesced, so as to form a single 

 aneurism, and in another case three sacs ap- 

 pear to have united in this way. We find the 

 aneurismal pouches of all sizes: in nine of the 

 cases referred to in Mr. Thurnam's memoir, 

 the size might be compared to that of nuts ; 

 in twenty, to that of walnuts ; in seven, to 

 fowl's eggs; in fourteen, to oranges; and in 

 nine cases, it almost or quite equalled that of 

 the healthy heart itself. We cannot always 

 satisfactorily ascertain what textures enter into 

 the formation of these sacs; however, in the 

 majority of cases, the three structures of which 

 the heart's parieles are composed are found in 

 the walls of these sacs; in others the muscular 

 tissue has disappeared, atrophied probably by 

 the pressure, and the wall is composed only 

 of the endocardium and pericardium, and in 

 others again the endocardium is wanting, and 

 the muscular fibres and the pericardium are 

 the only component elements.* In some cases 

 the wall nf the sac is strengthened by an ad- 

 hesion formed with the loose layer of the peri- 

 cardium. 



These aneurisms are always in connection 

 with the left ventricle or left auricle; very rarely 

 however with the latter, and never with the 

 right cavities. In the paper already quoted 

 from, Mr. Thuniam has collected references to 

 fifty-eight cases of aneurism of the left ven- 

 tricle, and eleven of the left auricle. All parts 

 of the ventricle are liable to aneurismal dila- 

 tation, but it occurs most frequently at the 

 apex: next in frequency it is found at dif- 



ferent points of the base; less frequently still 

 it occurs in the lateral walls at situations in- 

 termediate to the two last-named, and very 

 rarely it is met with in the intcrventricular 

 septum. 



I will give the description of auricular aneu- 

 rism in Mr. Thurnam's words : " The dis- 

 ease would appear,from the preparations I have 

 inspected, and the cases which have been re- 

 corded, to have been nearly uniformly of the 

 diffused kind, and to have generally involved 

 the entire sinus of the auricle The dilated 

 walls of the cavity are often thickened and the 

 seat of fibre-cellular degeneration. The lining 

 membrane is opaque, rough, and otherwise 

 disused, and in some cases even ossified, and is 

 lined with tibrinous layers, very similar to those 

 met with in arterial aneurisms. In all these 

 cases, the lining membrane appears to have 

 been continued into the interior of the ddated 

 portion, which consequently merits the name 

 true aneurism. Occasionally the dilatation is 

 confined to the auricular appendage, which 

 becomes extensively distended with lamellated 

 concretions."* 



The false aneurism, or that resulting from 

 rupture, must be spoken of merely as a pos- 

 sible and probable occurrence. I know of no 

 unequivocal example of it; but inasmuch as 

 we must admit that partial rupture of the 

 heart's wall may take place, we cannot deny 

 the possibility of the production of cardiac 

 aneurism in a manner similar to that in which 

 arterial false aneurism is produced. 



Dr. Hope describes cases, which Mr. Thur- 

 nam very aptly compares to " the dissecting 

 aneurism." In those cases, Dr. Hope says, 

 " steatomatous degeneration had caused tl.e 

 formation of a canal from the aorta underneath 

 one of the sigmoid valves and the internal 

 membrane of the left ventricle." But Mr. 

 Thurnam's explanation seems to me much 

 more likely to be the true one. He supposes 

 that the aneurisms had been originally formed 

 in the ventricle, and had subsequently commu- 

 nicated with the aorta, as a consequence of the 

 co-existent disease of the valves of that vessel. 



The possibility of the formation of an aneu- 

 rism resembling the varicose aneurism, has been 

 likewise suggested by Mr, Thurnam, from the 

 occurrence of aneurismal pouches in the sep- 

 tum ventriculorum. If such an aneurism were 

 to burst, it would establish a communication 

 with the right ventricle, a portion of the ve- 

 nous system thus producing " a lesion alto- 

 gether analogous to that which results from the 

 wound of an artery and its accompanying vein, 

 and to which the name of tpiintunriHis varicose 

 aneurism tif the heart is peifectly applicable." 



Mr. Thurnam mentions a fourth form of 

 aneurism which is not without its ana'oL'iic in 

 the arterial system, namely, that in which the 

 aneurismal sac is formed by the endocardium 

 and pericardium. This may be compared with 

 a variety of external aneurism in which the 

 lining membrane of the vessel protrudes through 

 a rupture in the middle tunic, constituting a 



* Vide Thurnam, lot. cil. p. 219. 

 VOL. II. 



Loc. cit. p. 245. 



2 t 



