Physical chemical evidence of structural weakness in coronary arterial calcification

Physical-chemical properties of calcified human coronary arteries were obtained through 857 electron probe microanalyses of samples of endarterectomy tissue from 12 patients and by X-ray and electron diffraction from separate samples. The calcific phase exhibited a weight percentage calcium to phosphorus ratio of 2.5 (SEM 0.15), a density of 2.95 (0.02) g.cm-3, and a crystalline unit cell volume of 530 (0.5) A3, or 53 (0.05) nm3. The phase has been characterised as a phosphorus deficient dahllite variant of apatite in which the crystal structure has been weakened by the incorporation of water molecules and tetrahedral hydroxyl groups in isomorphic substitution conforming with the McConnell-type defect. Isomorphic substitution within the apatitic cell appears sufficient to suggest that the crystal structure of the mineral deposit is weakened to the extent that means might be sought to attack the early formation of the pathological deposition.