Electron beam tomography for cusp calcification in homograft versus freestyle xenografts

Background. We have previously shown, by means of electron beam tomography, the pattern of calcification of the aortic root wall of homografts and por cine xenografts after aortic root replacement. However, application of simi lar methods for cusp calcification raises specific problems that have not b een addressed before. Methods. A new method for localizing and quantifying calcification of the a ortic valve cusps has been evolved. intravenous contrast-enhanced electron beam tomography was introduced to visualize the aortic cusps. This techniqu e was applied to quantify cusp calcification in 37 patients after aortic ro ot replacement with a homograft (group H) or a Medtronic Freestyle valve (g roup F) at set intervals between 6 months and 2 years. A calcification scor e in Hounsfield units (HU) and a calcified volume score in cubic millimeter s were calculated. Results. The aortic leaflets were clearly visualized in all patients. The m ean 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 mm(3) in group F and 642.0 +/- 443.0 mm(3) 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 preliminar y 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. (C) 2001 by The Society of Thoracic Surgeons.