DISEASES OF THE IIEAIIT. — ENDOCARDITIS. 283 



the cuspid valves, from the A-entriciihir cmity. Besides these, 

 we occasionally meet with diverticula in the walls of the heart, 

 near its orifices, precisely analogous to the aneurisms in (piestion, 

 though a strict nse of lano-ua^e must of course forbid ns to call 

 them " valvular." These are found at the origin of the coronary 

 arteries and on the floor of the innermost sinus of Valsalva. 

 The latter, by far the most common of these pouches, project 

 into the right heart, sometimes above, sometimes below, some- 

 times between the lamellae of that curtain of the tricuspid valve 

 which is attached just opposite to them. The same three paths 

 'are open to aneurism of the membranous part of the septum 

 ventriculorum^ which comes under the present category. It may 

 force its way from the left ventricle, over, under or between the 

 folds of the left curtain of the tricuspid valve, and so into the 

 right ventricle. I have seen a case, in which an aneurism of 

 the sinus of Valsalva, as large as a cherry, projected on the 

 upper surface of that curtain, while on its under surface was one 

 as large as a pea formed by the septum pellucidum. 



After this digression, let us retmni to valvular aneurism con- 

 sequent upon endocarditis. This form is necessarily preceded 

 by the complete destruction of one of the lamellge of the valve. 

 The blood makes its way into the opening thus produced, forces 

 the lamella3 asunder, and causes a more or less extensive pouching 

 of that which is still intacti The endocarditic or acute valvular 

 aneurism is thus essentially distinguished from the first variety 

 by the fact that the pouch is formed, not by the entire valve^ but 

 by one only of its lamellae. 



c. Perforation of Valves. 



§ 252. Here too we must distinguish between destruction of 

 the valve proper by inflammatory change, and a harmless variety 

 of perforation, which is very often met with at the free borders 

 of the semilunar valves. The latter depends upon a thinning of 

 that portion of the valve which lies ahoce the actual "line of 

 contact" (the line along which the valves touch one another 

 during closure), and is in my opinion nothing more than an 

 approximation of the sigmoid to the cuspid type of valve. 



For if we glance at the anatomical arrangements intended to 

 prevent regurgitation of the blood, we see at once that they 



