444 



DISEASES OF THE CIRCULATORY SYSTEM. 



ate them. They not only frequently coexist (in valvular lesions,, 

 for instance), especially when cardiopathy is old, but their differen- 

 tial diagnosis is almost impossible, on account of the similarity of 

 the symptoms which they present. 



The usual medical terminology indicates the close relationship 

 existing between hypertrophy and dilatation ; the first, in fact, is 

 also designated under the name of active dilatation^ the second under 

 that of passive dilatation. 



Patholog-ical anatomy. Hypertrophy and dilatation are both 

 characterized anatomically by an increase of the size of the heart ; 

 but whilst in hypertrophy this alteration is due to the thickening 

 of the walls of the organ, in dilatation it is produced by the 

 enlargement of its cavities and the distention of its walls. 



1. We designate under the name of simple cardiac hypertrophy 

 • — a form of augmentation of the volume of the heart which i& 

 quite rare — the thickening of the walls of the organ ; in the great 

 majority of cases we find at the same time a dilatation of the cavi- 

 ties ; this is excentric hypertrophy y or active dilatation of the heart, 

 a form to which we generally make allusion when speaking of 

 cardiac hypertrophy. The existence of a hypertrophy which has 

 been called concentric, and in which the thickening of the walls 

 would correspond with the contraction of the cavities, is problematic. 

 Under the name of false cardiac hypertrophy we designate the in- 

 crease of the heart's size produced by the development of foreign 

 tissues in the thickness of the myocardium. 



True hypertrophies may be entire, partial (involving a single 

 ventricle) or circumscribed (affecting one or several muscular pil- 

 lars). In hypertrophy of the left heart, the much more frequent 

 form, the organ is elongated, cylindrical ; in right hypertrophy 

 of the left heart it is more or less flattened, and its length is in- 

 creased ; in entire hypertrophy it is round in shape and has often 

 acquired extraordinary dimensions. Stephenson has observed the 

 heart of a horse weighing 16 kilos; Gerlach has found one of 

 9 J kilos ; Herran ^ has seen the heart of an ox which measured 

 35 centimetres in length, weighed 18 kilos, and the walls of 

 which were affected by a calcareous incrustation. The left wall of 

 the heart is frequently thickened to twice or three times its nor- 

 mal size ; its structure may be perfectly normal ; in most cases, 

 however, the myocardium is harder and of firmer consistence ; sec- 



1 Herran : Journ. des Vét. du Midi, 1862. 



