Pure cases of this, the so-called Moenckeberg type, are seen but seldom. Most commonly there are nodules and plaques in the aorta and large branches together with thinning and sacculation of other portions of the vessels' walls. While the two processes appear at a glance to be so different from each other, it is possible for them to have a common origin. The initial lesion is in the media but the resulting sclerotic changes depend upon the kind of vessel, the strength of the coats, the pressure in the vessel, and other causes.
Thus the sclerosis of the radials of such an extent that these arteries are easily palpable, appears to be a different process from that of the sclerosis in the aorta, yet fundamentally it is the same. The difference lies in the anatomic structure of the two vessels, and possibly also in the degree of stretching and strain to which the vessels are subjected at every heart beat. In the radial artery the media as usual is affected first. The muscle cells undergo degeneration and either marked thickening takes place or sacculation results, depending upon the severity of the exciting cause. Calcification of the media is common. This occasionally takes the form of rings encircling the vessel, and gives to the examining finger the sensation of feeling a string of fine beads. There may be calcification of the subintimal tissue without deposits of lime salts in the media, but this is more commonly found in the larger arteries. When the calcification occurs in plates through the media, the well known pipe stem vessel is produced. (Fig. 6.)
[Illustration: Fig. 6.--Radiogram of a man aged seventy-five, showing calcification of both radial and ulnar arteries.]
The senile sclerosis found in old people is usually a combination of the Moenckeberg type in the large and medium-sized arteries, and the nodular type in the aorta, leading eventually to calcareous intimal deposits, and widened, elongated, inelastic aorta.
[Illustration: Fig. 7.--Syphilitic aortitis of long standing. The aortic valves are curled and thickened, the heart is enlarged and the cavity of the left ventricle is dilated. (Milwaukee County Hospital.)]
The seat of election of the syphilitic poison is in the aorta just above the aortic valves, Fig. 7, and in the ascending portion of the arch. There are semitranslucent, hyaline-like plaques which have a tendency to form into groups and, instead of undergoing an atheromatous change as in the ordinary nodular form of arteriosclerosis, they are prone to scar formation with puckering, so that macroscopically the nature of the process may, as a rule, be readily diagnosed. Microscopically the process is found to be a subacute inflammation of the media, which has been called a mesaortitis. There is marked small celled infiltration around some of the branches of the vasa vasorum and there appears to be actual absorption of the tissue elements of the middle coat. This is accompanied by hypertrophy of the intimal tissue. There follows degeneration in the deeper portions of this new tissue and new capillaries are formed which have their origin in the inflammatory area in the media. As is everywhere the case throughout the body, granulation tissue in the process of healing contracts and forms scars. This explains the scar formation in the aorta. When the process is more acute, instead of there being a reparative attempt on the part of the intima, there is actual stretching of the wall at the weakened spot and there results an aneurysmal dilatation. =Spirochetæ pallidæ= have been found in the degenerated media and in small gummata which were situated beneath the intima. Within the past years it has been found that a large percentage of patients with cardiovascular disease give the Wassermann reaction. In cases of aortic insufficiency, the reaction is present in almost every case. This is in marked contrast to the cases of diffuse endocarditis where the reaction is rarely present.