ATROPHY. 



Simple, eccentric, concentric. Usually eccentric. Causes, effusion in 

 pericardium, obstruction of coronary arteries, by false membranes, etc., 

 general inanition. Symptoms, beats weak, sounds loud, clear, decreased 

 area of dulness on percussion, pulse slow, weak, under excitement unequal, 

 irregular, intermittent with palpitation, dropsy of limbs, etc., murmur with 

 1st sound. Treatment only in early stages by removal of the cause. 



The loss of substance in the muscular walls of the heart is 

 either swiple when there is no change in the capacity of its 

 different cavities : — eccentric when the chambers of the heart 

 are enlarged ; or concentric when these chambers are reduced 

 in size. Like hypertrophy it may affect the walls of one chamber 

 to the exclusion of the others. 



Atrophy is much less frequent in the lower animals than hyper- 

 trophy and in nearly all cases on record it was associated with 

 dilatation. 



The causes are not always very evident. Effusion into the per- 

 cardium is one of the most frequent, the compression of the heart 

 impairing its nutrition and decreasing its size. Especially is it 

 hurtful when several layers of false membranes deposited on the 

 surface of the heart become organized, preventing its sufficient 

 dilatation and compres.sing its nutrient blood-vessels. A case of 

 this kind in a dog occurred to Eeblanc ; the right auriculo- ven- 

 tricular opening was surrounded by thick organized layers of 

 fal.se membranes which by their contraction had largely di- 

 minished the opening and even pressed on the coronary artery 

 cutting off to a great extent the supply of blood to the walls of 

 the ventricle. Another alleged cause is a prolonged insufficient 

 nourishment to the entire body. Eeblanc has also observed this 

 in dogs the subjects of long continued wasting maladies. 



Symptovis. In pure atrophy these are the opposite of those 

 seen in hypertrophy. The beats of the heart are weak or inap- 

 preciable to the hand placed on the side of the chest behind the 

 left elbow. The sounds of the heart are loud and clear, their in- 

 tensity being proportionate to the thinning of the walls and the 

 dilatation of the chambers. Percussion so far as it can be made 

 effectual, which is chiefly in dogs, shows a diminished area of dul- 

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