3i6 Heart and Blood Vessels in Edema [Dec. 



IV. THE RELATION OF THE HEART AND BLOOD VESSELS 



TO EDEMA 



William Weinberger 



The first experiment made witli the view of explaining the 

 nature and cause of cardiac edema was carried out by Richard 

 Lower. It consisted in tying the vena cava inferior and was 

 followed by edema of both legs. These results have since been re- 

 peatedly confirmed. 



About thirty years ago Ranvier stated that ligation of the 

 femoral vein does not cause edema unless the sciatic nerve is cut, 

 the latter carrying the vasoconstrictors for the blood vessels of the 

 lower extremity. If this nerve is cut, the blood vessels become 

 dilated and the leg receives more blood. Neither venous Stagna- 

 tion per se, nor vasodilation alone, will cause edema. Both factors 

 have to work together to produce it. 



Cohnheim made the following experiment: Utilizing the fact 

 that the vasoconstrictors for the vessels of a rabbit's ear are carried 

 by the cervical sympathetic, he cut this nerve on one side, where- 

 upon the corresponding ear became fiery red. He then cut the 

 other sympathetic and ligated the large vein at the root of the cor- 

 responding ear. This double Operation was followed by edema. 

 The tying of the vein caused an increase of the venous pressure and 

 the cutting of the sympathetic caused an increase of the arterial 

 pressure. The enormously increased intracapillary pressure thus 

 resulting then induced the transudation of such a considerable quan- 

 tity of lymph that it cannot be carried away by the blood vessels and 

 the lymphatics. Cohnheim's experiments have laid the foundation 

 for many views we entertain to-day upon the pathology of edema. 

 This author, in collaboration with Lichtheim, investigated the ques- 

 tion of whether plethora can lead to anasarca, the form of edema 

 which is most characteristic of renal diseases. These investigators 

 found that infusions of large quantities of normal salt Solutions 

 into the veins of rabbits and dogs were followed indeed by ascites, 

 edema of the gastrointestinal tissues, and enormous secretions 

 within the gastrointestinal canal. But there was no edema of the 

 skin. In these experiments, then, an enormous hydremic plethora 



