MORBID ANATOMY.—Bertin records an instance of pulmonary obstruction where the valves, distorted and adherent, formed a horizontal septum across the orifice, it being barely one-fourth of an inch.
A rigid tricuspid valve has been found to be the cause of obstruction at the pulmonary orifice, the pulmonary valves themselves being normal. A few autopsies have revealed obstructions at the pulmonary artery, caused not so much by valvular defect as by aneurisms, tumors of the pericardium or of the anterior mediastinum, enlarged bronchial glands, or pressure of a solidified lung.
The pulmonary artery may be occluded just beyond the valves by a cancerous tumor, and there are examples where a phthisical process in the left lung has induced it.
A murmur indicative of pulmonary obstruction may be produced by a cardiac thrombosis.
I have placed these statements under the head of its morbid anatomy for the reason that they cannot be appreciated and their pathological significance realized during life.
Reasoning from analogy, obstruction at the pulmonary orifice ought to be followed by compensatory hypertrophy of the right ventricle and accompanied by tricuspid regurgitation and dilatation of the right auricle.
Ormerod records 3 cases21 where pulmonary obstruction was diagnosticated during life, and where the post-mortem proved the accuracy of the diagnosis: 2 of these cases occurred in men under twenty-eight, and the other in a woman of twenty-one. In 2 of these cases all the other cardiac valves were healthy. The pulmonic orifice would barely admit the introduction of a goosequill. Warburton Bigbie mentions a case (man æt. eighteen) where reflux and stenosis at the pulmonary orifice coexisted. There were four valves, and these were incompetent. All the other valves were normal.
21 Edin. Med. and Surg. Journ.
Congenital stenosis of the infundibulum of the right ventricle is the probable result of foetal myocarditis or of syphilis.
I have never met but two pulmonic obstructive murmurs where subsequent autopsies were obtained. In both cases it was found that the murmur had been produced by mediastinal tumors pressing on the pulmonic artery so as to diminish the calibre.