240 



HYPERTROPHY OF THE HEART — CARDIAC ENLARGEMENT. 



Ilypertroijliy of tlie lieart implies augmentation of bulk in its muscu- 

 lar substance, with or without dilatation or contraction of its cavities. 

 It may exist with or without other cardiac affections. In valvular 

 disease or valvular insufficiency hypertroi^hy frequently results as a 

 consequence of increased demand for propelling jDower. The difficul- 

 ties with which it is most frequently connected are dilatation and 

 ossification of the valves. It may also occur in connection with atro- 

 phied kidneys, weak heart, etc. It may be caused by an increased 

 determination of blood to the organ, or from a latent form of myo- 

 carditis, and it may arise from a long-continued increase of action 

 dependent upon nervous disease. All the cavities of the heart may 

 have their walls hypertrophied or the thickening may involve one or 

 more. AVhile the wall of a ventricle is thickened its cavity ma}^ retain 

 its normal size — simple liypeiiropliy — or be dilated — eccentric hyper- 

 iropliy — or it may be contracted — concentric liypertropliy. Hyper- 

 trophy of both ventricles increases the length and breadth of the 

 heart. Ilypertrophj" of the left ventricle alone increases its length; 

 of the right ventricle alone increases its breadth toward the right side. 

 Hypertrophy with dilatation may affect the chambers of the heart 

 conjointly or separately. This form is by far the most frequent 

 variety of cardiac enlargement. When the entire heart is affected it 

 assumes a globular appearance, the apex being almost obliterated, 

 and situated transversely in the chest. The bulk may become three 

 or four times greater than the average size of heart. 



Symptoms. — In hypertroiDhy of the heart, in addition to the Tisual 

 symj^toms manifested in organic diseases of the heart, there is a pow- 

 erful and heaving impulse at each beat, which may be felt on the left 

 side, often also on the right. These i)ulsations are regular, and when 

 full and strong at the jaw there is a tendencj'^ to active congestion of 

 the capillary vessels, which frequently gives rise to local inflamma- 

 tion, active hemorrhage, etc. If the i^ulse is small and feeble at the 

 jaw we may conclude that there is some obstacle to the escape of the 

 blood from the left ventricle into the aorta, which has given rise to 

 the hypertrophy. In case of hypertrophy with dilatation, the impulse 

 is not only powerful and heaving, but it is diffused over the whole 

 region of the heart, and the normal sounds of the lieart are greatly 

 increased in intensity. Percussion reveals an enlarged area of dull- 

 ness, while the impulse is usually much stronger than normal. 



Dropsy of the pericardium will give the same wide space of dull- 

 ness, but the imi5ulse and sound are lessened. An animal with a 

 moderate degree of enlargement may possibly live a number of j'ears 

 and be capable of ordinary work ; it depends largely uxDon concomi- 

 tant disease. As a rule, an animal affected with hypertrophy of the 

 heart will soon be incaj)acitated for work, and become useless and 

 incurable. 



