1066 Cardiac Dilatatiou. 



dilatation may be surmised, aside from the diameter of the 

 respective cavities, by the fact that tlie trabeculae on the inner 

 surfaces of the ventricular wall are narrow and separated 

 one from the other by wide spaces. At the same time the 

 chordae tendineae are usually thin and elongated. The muscles 

 almost always show signs of parenclninatous or fatty degenera- 

 tion and also of atrophy. A dilatation of the. auricles is as 

 a rule observable at first glance and may be recogiiized bj'- 

 the fact that tlie walls have become as thin as paper and that 

 the septum has acquired larger dimensions. 



In other organs, especially in the lungs, in the liver, spleen, 

 kidneys, etc., there are sjTiiptoms of venous stasis and dropsical 

 effusions due to the same. 



Symptoms. In severe cases, enlargement of the cardiac 

 dullness may be shown, which is sometimes very considerable, 

 while in animals in which normally an absolute heart dullness 

 is not found, above all the occurrence of such an absolute 

 heart dullness is noticeable. In carnivora the dilatation of 

 the left ventricle causes an enlargement of the cardiac dullness 

 upward beyond the mammary line (Fig. 186) ; in other animals, 

 both upward and even more backward (Fig. 188). On the 

 other hand, the dilatation of the right ventricle is characterized 

 by the occurrence of an absolute dullness on the right side, or 

 by an enlargement of the dullness which is normally very slight 

 in small-chested animals. (Fig. 187 and 189.) Consideral)le 

 dilatation of the right ventricle, however, causes an increase 

 of the dullness even on the left side. It is possible, as shown 

 by a case of the author's in a dog six weeks old, for the cardiac 

 dullness in dilatation of the right half of the heart to extend 

 forward as far as the second intercostal space. It is not certain 

 whether this is to be ol)served only in very young animals. 

 The force of the heart beat is usually increased because a 

 greater portion of the heart is in apposition to the chest wall. 

 Sometimes the trunk receives a thrill synchronously with the 

 heart beat. The beat appears weaker only when the heart 

 weakness has become considerable. The systolic heart sound 

 is increased in force like the heart beat, while the second sound 

 is usually small or not at all perceptible. The action of the 

 heart is not infrequently arhythmical, and the first, less often 

 also the second heart sounds are dicrotic. Endocardial sounds 

 are caused by the relative insufficiency of the valves which 

 develops after a while in some cases. 



In contrast to the increased heart beat, the pulse is always 

 feeble. It may also be arhj^thmical and intermittent, corres- 

 ponding to the heart beat. 



In the case of a prolonged acute, and in chronic dilatation, 

 sometimes a venous stasis is observed, especially fullness and 

 pulsation of the jugular veins. In a marked dilatation of the 



