Etiology, Analoiiucal Clianges. 1087 



3. Injuries to the valves are also capable of injuring their 

 function. This occurs when a valve is perforated or when, 

 during severe exertion, a semilunar valve is torn from its 

 base or one of the bicuspid or tricuspid valves has been torn 

 from the chordae tendineae by the force of the pressure which 

 is periodically exerted upon the valves. (In a case of Lustig's 

 the valve was torn off during severe work, in a case of Cantini's 

 while the horse was jumping; similar cases were observed by 

 Liithens, Gerlach and Schiitz). In exceptional cases the simple 

 over-distension of the aortic valves causes an inabilitv to close 

 (Zschokke). 



4. Tumors and Echinococci may cause both insufficiency 

 and stenosis if they grow from the annuli fibrosi or from the 

 wall of a heart cavity toward an ostium. 



5. Diseases of the heart muscle may produce a valvular 

 insufficiency even if the valves are not injured (Insufficientia 

 relativa s. muscularis). Especially in the proper functioning 

 of the auriculo-ventricular valves both the relaxation of the 

 chordae tendineae and the contractions of the muscles around 

 the ostium cooperate to a considerable degree. If the con- 

 tractions are not sufficiently energetic, the closure of the valves 

 becomes insufficient. A similar disturbance results if one of 

 the ostia has been dilated excessively in case of cardiac dilata- 

 tion of high degree. Insufficiencies from this cause are by 

 no means infrequent and are usually due to chronic myocarditis, 

 sometimes they follow upon a cardiac weakness from other 

 causes and usually affect the right heart. Finally dilatation 

 of the arterial trunks close to the heart may result in an 

 insufficiency of the semilunar valves. 



6. Cong-enital heart lesions must also be included here. 

 According to Preisz they are usually due to impeded, less often 

 to faulty development or to intrauterine heart diseases. A 

 comparatively frequent anomaly is the persistence of an open- 

 ing in the upper anterior portion of the interventricular septum 

 (Foramen interventriculare persistens) and according to Preisz 

 the cases described by Csokor and Jolme under the name of 

 Septum membranaceum persistens belong to this lesion. The 

 Foramen ovale between the auricles remains open fairly often 

 and also the Ductus Botalli. It occurs only very rarely that 

 only one auriculo-ventricular opening or a simple arterial trunk 

 proceeding from the ventricle is found in addition to the above 

 mentioned anomalies. 



Anatomical Changes. Chronic endocarditis leads to new- 

 formation followed by atrophy of the connective tissue; owing 

 to these changes the endocardium is thickened in varying 

 degrees, verrucous, polypoid or cauliflower-like excrescences are 

 formed on the borders of the valve which is in contact with the 

 blood stream, and the chordae tendinae are thickened. The 

 thickened valves become rigid and the semilunar valves are 



