Cardiac Hypertrophy 175 



could hardly take place, so that, had the right auriculo-ventricular valve 

 been on the pattern of the mitral, an overloaded right ventricle could 

 have found relief only by pulmonary haemorrhage. In the case of the 

 venous pulse the jugular veins can be seen rilling from below upwards. 



The reflux blood passes straight into the right innominate vein, so 

 that the venous pulse is more perceptible on the right side of the neck. 

 The venous pulse is, of course, most marked in a case of tricuspid 

 dilatation, when the external jugular may be widely distended, throb- 

 bing as high as the angle of the jaw. Occasionally the pulsations 

 extend along the subclavian tributary of the innominate vein, and pass 

 down the superficial veins of the arm. Sometimes the tidal flow 

 passes backwards in the inferior cava, and through the hepatic veins, 

 so that if the liver happen to be at the same time congested and large 

 pulsations in it may be felt. Pulsation from tricuspid insufficiency has 

 also been found as low as the femoral vein. 



Just before the systolic venous pulsation occurs, a much slighter 

 throb may be sometimes detected ; it occurs as the overloaded auricle 

 is struggling to empty itself into the ventricle, a portion of its contents 

 being forced up into the superior cava. 



A respiratory pulse in the superficial veins of the neck is often 

 observable even in health, for during expiration the intra-thoracic pres- 

 sure is increased, and the veins are unable to empty themselves. Then, 

 with inspiration, their contents hurry into the right auricle, sucked,*as 

 it were, into the expanded chest, and their track is no longer visible. 



Hypertrophy. As the biceps of the blacksmith grows by constant 

 exercise, so does the wall of the heart by the continual effort to over- 

 come obstruction in the arterial circulation. When the obstruction 

 first occurs, the ventricle, unprepared for it, is unable to empty itself 

 of blood, and its cavity becomes dilated. Afterwards its wall begins 

 to thicken. Aortic obstruction (p. 1 73) becomes of comparatively little 

 importance when it is accompanied by hypertrophy of the left ventricle. 

 Thus, hypertrophy, which is always preceded by dilatation, is com- 

 pensatory for the dilatation, and for the thinning of the muscular wall. 

 With hypertrophy the impulse is excessive and 'heaving,' and the 

 cardiac region of the chest-wall may bulge, especially in a young adult. 



The larger the heart, the more boisterous its action, and the more 

 extensive its impulse. Thus, hypertrophy may be recognised at a 

 glance, or by placing the hand over the front of the chest. 



A greatly hypertrophied ' bovine ' heart may weigh twenty, thirty, or 

 even forty ounces, and, by pressing against the oesophagus (p. 139), may 

 impede deglutition. Even in the ordinary way the heart would compress 

 the gullet when the man is lying on his back, were it not swung in, and 

 held by the pericardium. If the heart be greatly enlarged, the left carti- 

 lages and ribs from the fourth to the seventh bulge, and, the lungs being 

 pushed aside, the dull area is increased, and the spaces are widened. 



Hypertrophy of the rigrht ventricle occurs when there is diffi- 



