Histometrical Investigations of Arteries in Reference to Arterial Hypertension

1) A histometrical method was described, with which arterial cross sections of autopsy cases were reduced to the state, in which internal elastic membrane was perfectly stretched. The distance from the center of the arterial lumen to the middle point of the media in this condition was defined as anatomical arterial radius, R, and the thickness of the media in this condition as anatomical medial thickness, D. The values of R and D were determined byR=S/√L2+4πS-L and D=√L2+4πS-L/2π, respectively, in which L was the length of internal elastic membrane and S was the surface area of the muscular coat in arterial cross section. 2) A regular relation was confirmed between R and D, which was represented by a general equation D=aRb, a and b being constants. On a logarithmic scale, the relation gave a linear regression and was represented by a linear regression equation _? ? _=bX+A, in which X=log R, Y=log D and A=log a. Statistical treatments of the histometrical results were discussed. 3) The histometrical method was applied to renal and superior mesenteric arteries. Non-hypertensive cases were divided into 3 age groups, and in each age group common regression equations were determined of each artery to demonstrate the characteristics of arterial pattern. Each artery was composed of two parts divided at R=100μ. In the part R>100μ, b was smaller than, but very close to, 1. Superior mesenteric artery had stronger muscular coat than renal artery at R=1000μ. In the other part, R100μ, but less pronounced in the region R<100μ, and practically ceased to be noticed at R=10μ in the majority of cases with essential hypertension. Blood pressure was regarded to be abruptly lowered in the vicinity of R=100μ and arterioles were in all probability not exposed to abnormally high blood pressure in an average. The unequal medial hypertrophy induced a transformation of general arterial pattern in hypertension.