Determination of elements in native and bypass human coronary artery plaque deposits from the same heart using inductively coupled plasma-mass spectrometry.

As part of an ongoing study on atherosclerotic arteries, the concentrations of 12 elements in a native and by-pass human coronary artery plaque deposits from five human hearts were determined using inductively coupled plasma-mass spectrometry (ICP-MS). These elements were Ca, P, Na, K, Mg, Zn, Cu, Pb, Fe, Al, Si, and S. For Zn, Ca, Pb, Fe, Al, and Si, the levels were at the fractional micromol/g levels and they probably played an unimportant role in plaque development. Sulfur levels varied from 23 to 140 micromols indicative of the possible presence of homocysteine, but there appeared to be no consistent relationship between by-pass and native concentrations. The calcium and phosphorus concentrations were relatively high in all cases, but the ratio of their molecular concentrations did not correspond to hydroxyapatite, which is conventionally considered to be the chemical form of calcium in heart plaque. In the mature native plaque, high calcium/phosphorus ratios indicated calcium in chemical forms other than hydroxyapatite. In undeveloped by-pass plaque, the phosphorus concentration was too high to be as hydroxyapatite but may be phospholipids. Because it is difficult to get suitable samples, only five heart samples were available. Therefore, these results should be treated as preliminary.