ETIOLOGY.—Pulmonary stenosis is rarely the result of endocarditis or of degenerative changes in the pulmonary artery. Bertin states that when abnormal communication between the two sides of the heart has existed, the arterial blood has excited endocarditis in the right heart.
Syphilis has been advanced as a possible cause of degenerations at the pulmonic orifice.
SYMPTOMS.—The only rational symptoms that have been noted in the few recorded cases of pulmonic disease admit of manifold explanations, and no one is either constant or diagnostic. In some cases anæmia existed, in others there were cardiac palpitation, dyspnoea, cyanosis, and dropsy; but none of these belong exclusively to a pulmonic lesion nor do they necessarily depend upon it.
Physical Signs.—Inspection, palpation, and percussion give negative rather than positive results. In a few instances palpation may give a systolic thrill confined to the second left intercostal articulation. Such a frémissement results both from roughness and contraction of the pulmonic orifice.
Auscultation.—A systolic murmur is heard with its maximum intensity directly over the pulmonic valves; it is very superficial, and consequently very distinct, and it is limited in its diffusion. It is never heard at the xiphoid cartilage nor along the course of the aorta. If it has an area of diffusion, it is toward the left shoulder. The murmur is loud and soft in character, sometimes bellows. It is not audible in the vessels of the neck nor is it attended by arterial pulsation.
When phthisical consolidation partially occludes the pulmonary artery, a loud but soft systolic murmur is heard, which is sometimes high-pitched and musical, and often entirely suspended during a full inspiration. In some few instances there is a bruit de diable in the jugular veins.
DIFFERENTIAL DIAGNOSIS.—It is possible to confound a pulmonic obstructive murmur with a mitral regurgitation which is propagated upward into the left auricular appendix. But the area of a mitral regurgitant is also backward, and by this it could be distinguished from a pulmonic obstruction. Besides, in mitral disease the pulse is very different from the pulse of pulmonary stenosis.
Aortic stenosis can hardly be mistaken for pulmonary obstruction, for the arterial pulsation, the peculiar pulse, and the transmission of the murmur into the arteries of the neck will suffice to discriminate between them.
An aneurism at the sinus of Valsalva may produce a systolic pulmonary murmur by the pressure which it produces upon the pulmonary artery. It would be impossible to distinguish it from a pulmonic stenosis.
The diagnosis of pulmonary obstruction is usually reached only by exclusion.