Electron beam tomography for cusp calcification in homograft versus freestyle xenografts

Abstract

Background. We have previously shown, by means of electron beam tomography, the pattern of calcification of the aortic root wall of homografts and porcine xenografts after aortic root replacement. However, application of similar methods for cusp calcification raises specific problems that have not been addressed before.Methods. A new method for localizing and quantifying calcification of the aortic valve cusps has been evolved. Intravenous contrast-enhanced electron beam tomography was introduced to visualize the aortic cusps. This technique was applied to quantify cusp calcification in 37 patients after aortic root replacement with a homograft (group H) or a Medtronic Freestyle valve (group F) at set intervals between 6 months and 2 years. A calcification score in Hounsfield units (HU) and a calcified volume score in cubic millimeters were calculated.Results. The aortic leaflets were clearly visualized in all patients. The mean calcium score in the cusps was 28.8 ± 64.4 HU in group F and 62.4 ± 66.9 HU in group H (p = not significant). The mean calcified volume score was 327.0 ± 425.9 mm3 in group F and 642.0 ± 443.0 mm3 in group H (p = not significant).Conclusions. Contrast enhancement electron beam tomography is a useful tool for quantification of calcium in the aortic valve leaflets. Our preliminary results show a tendency toward more calcification in the homografts. This needs to be studied further in a bigger cohort of patients followed up for longer periods.