An X-ray Microscopic Study of the Blood Supply to the Valves of the Human Heart.

Descriptions of the presence of blood vessels in the valves of human hearts vary. Using routine histological, injection, and clearing techniques, the majority of authors have described vessels in the attached portion of the cusp, but differ on the incidence of this observation and its relation to completely normal histological valve structure. Thus Gross (1921) demonstrated blood vessels in 6 per cent of normal mitral valves from birth until the ninth decade of life, and reported that this finding possibly had some relation to the incidence of endocarditis in the vascularized valves. This view was supported by several authors (Kugel and Gross, 1926; Kugel, 1928; Ritter, Gross, and Kugel, 1928; Gross and Kugel, 1931). Gross and Friedberg (1936a, b) thought that any vascularized heart valve was probably abnormal. In a critical review of the observations of previous authors and from an examination of human and animal heart valves, Gross (1937) thought that the majority of human heart valves were avascular, and emphasized the need for careful interpretation of any vascularity and the presence ofprevious histological damage. Winternitz, Thomas, and LeCompte (1938) examined normal and diseased valves by injection and clearing techniques, and reported vessels in the normal cusps of atrioventricular valves, which had an endocardial origin. Harper (1945) investigated human and rabbit heart valves by injection and vital staining techniques; he showed that human heart valves were "largely avascular", that vessels in diseased valves were of inflammatory origin, and that new blood vessel formation could be induced in rabbits after the injection of aleuronate. The present work gives an account of the blood supply to the valves of the human heart, using the Coslett Nixon X-ray projection microscope. This technique gives an opportunity for examining small arterioles and capillary beds without histological preparation in contrast to the routine histological, injection, and clearing techniques of previous investigations.