HYPERTROPHY OF THE HEART. 



Simple, eccentric, concentric. Ventricles chiefly affected. Causes : in- 

 creased functional activity, from obstruction to the circulation, or con- 

 tinued extra exertion. Right ventricular hypertrophy-obstruction in the 

 pulmonary circulation ; left ventricular hypertrophy obstruction in the 

 systemic. Auricular hypertrophy-insufficiency of the auriculo-ventricular 

 valves. Pericarditis as a cause. Abnormal vyeights. Symptoms : beats 

 more forcible and jiroloiiged, ist sound low, prolonged, 2nd sound clear, 

 often doubled, increased dullness on percussion, diagnostic signs of hyper- 

 trophy, dilatation and a combination of the two. Simple hypertrophy 

 rarely dangerous, with dilatation grave, threatens congestions and apoplex- 

 ies. Treatment : rest, laxatives, sedatives, in irregular heart action digitalis, 

 arsenic. 



An enlargement of the heart from increase of its muscular sub- 

 stance is by no means uncommon in the horse. It may exist 

 without any change in the capacity of the cavities of the heart 

 (simple hypertrophy) or it may be associated with dilatation of 

 one or more of these cavities (hypertrophy with dilatation ; — 

 excentric hjrper trophy). A third variety has been described in 

 which the capacity of the cavities is decreased, but Cruveilhier 

 and Budd have satisfactorily shown the non-existence of this 

 condition except as a congenital deformity. 



It is in the ventricles that the increase is chiefly observed, the 

 reason of which is to be found in the causes of the malady. 

 These usually consist in some obstruction to the circulation such 

 as chronic congestions in the lungs or elsewhere, rupture of air 

 cells in the lungs, tuberculous and other abnormal deposits in 

 the chest and elsewhere, tumors which by their position interfere 

 with the circulation through the larger vessels, and the like. 

 Where by some such cause the blood is impeded in its outward 

 course, one or both ventricles are called upon to contract more 

 vigorously to force a sufficient amount of blood onward and, in 

 accordance with the inherent adaptability of the animal economy, 

 there takes place an increase of the muscular walls of the ven- 

 tricle, proportionate to the required energy of the contractions. 

 The condition then is essentially due to a more active nutrition 

 and growth of the muscular substance and finds its exact parallels 



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