Dissecting aneurysm of the aorta complicating hypertension

After a short period of slight limitation of physical activity, as shown by dyspnea on movement, an elderly man with persistent hypertension, dilatation of the aorta, and cardiac enlargement, and an aortic diastolic murmur, had a brief attack of substernal oppression, followed three weeks later by agonizing substernal pain, which continued for four days without remission and was accompanied by equally severe lumbar pain.The character and duration of this pain served to rule out the usual forms of angina pectoris; the continued myocardial sufficiency, and the absence of physical, including electrocardiographic, signs discouraged a diagnosis of coronary thrombosis.At necropsy, the finding of a dissecting aneurysm of the aorta, apparently of several weeks development, judging from the formation of an endothelial lining in the upper part of the new tract, provided an admirable explanation of the clinical course and symptoms. The initial rupture of the intima may be associated with the first attack of substernal distress; the splitting of the media produced the extreme pain of the second attack. Throughout the descending thoracic and abdominal aorta the advancing extravasation of blood brought about, it may be supposed, a rapid dissection with little or transient pain; but the obstruction to the progress of the aneurysm in the region of the bifurcation was productive of the pain in the lumbar region. Finally, the terminal rupture occurred through the adventitia into the left mediastinum, within which the blood was confined until the perforation into the pleural cavity.From the pathological standpoint, the comment may be added that in the aorta, as elsewhere, sclerotic changes were not marked, and there was no evidence whatever of syphilis. Both of these facts are worthy of emphasis. The later and more marked changes in the development of atherosclerosis, namely, the fatty and calcareous deposits, tend to separate the intima from the media, and an injury to the former is less likely to involve the latter; while in the earlier stage, with what Adami⁴ called the “hyaline fibroid” lesions, the connection between the two coats is intact, and an intimal tear is carried through into the media. In regard to the second point, the lamellar arrangement of the elastic fibers of the media is the basis of the formation of the dissecting aneurysm, for the blood finds it easier to separate the weak connective tissue binding these layers together and make its way along the vessel, than to rupture the tough elastic fibers which lie directly in its course. Syphilitic mesaortitis destroys this orderly arrangement of the medial lamellae, thus preventing dissection, and the syphilitic aneurysm remains localized.