1094 Valvular Diseases. 



pulmonary artery and tliis will at times eventually dilate. As 

 the expulsive force gradually diminishes, the right ventricle is 

 finally dilated to such a degree that the right auriculo-ventric- 

 ular opening also enlarges so far as to produce a relative insuffi- 

 ciency of the tricuspid valve. The insufficiency of the pul- 

 monary valves remains without effect upon the lungs and the 

 left heart as long as it is compensated by the increased work 

 accomplished by the right ventricle. 



The heart l)eat and the cardiac dullness show similar con- 

 ditions as in diseases of the left venous ostium. The first heart 

 sound is clear everywhere; instead of the second sound a pro- 

 longed diastolic murmur which gradually becomes weaker in all 

 directions is heard over the origin of the pulmonary artery 

 (Fig. 193. 3), while the second aortic sound becomes constantly 

 more distinct. No particular changes are noted in the pulse. 

 The disease is always accompanied by respiratory disturbances. 



(f) Stenosis of the Opening of the Pulmonary Artery. 



The 1)lood which is forced out of the right ventricle against 

 the pulmonary artery meets, in the diminished opening of the 

 pulmonary artery, an impediment which increases the work of 

 the right ventricle and leads to hypertrophy of its muscle. The 

 blood pressure in the lungs is lowered permanently, and the 

 amount of blood in the pulmonary arteries becomes less as soon 

 as the energy of the right ventricle diminishes. 



The heart beat and the cardiac dullness show the same 

 deviations as in the preceding form. Over the origin of the 

 pulmonary artery (Fig. 193.3) a loud, prolonged systolic mur- 

 mur is heard, and more posteriorly also the first heart sound 

 which originates in the left ventricle; the second sound is clear 

 but weakened over the pulmonary artery. The pulse is small 

 and feeble. Respiratory disturbances and cyanosis are noted 

 from the first. 



(g) Insufficiency of the Tricuspid Valve. 



If the unfolded tricuspid valve does not close completely, 

 a part of the blood in the right ventricle flows, during systole, 

 back into the right auricle through a more or less narrow open- 

 ing, the auricle is dilated and eventually slightly hypertrophied. 



Since the auricular wall is capable of exerting only a 

 slight force, and since the openings of the venae cavae are not 

 closed by valves, the stasis of the blood is continued into venae 

 cavae and into the other veins of the body. 



The heart beat differs from the normal at most in so far 

 as a systolic thrill is often felt simultaneously in the 3d-4th inter- 

 costal spaces. The cardiac dullness is not altered. The first 

 heart sound is heard in the left 5th-6th intercostal spaces, either 



