Decalcification of the aortic valve does not prevent early recalcification

Background and aim of the study: The excellent results with atrioventricula r valve reconstruction have stimulated surgeons to attempt reconstruction o f calcified aortic valves using decalcifying techniques, but long-term resu lts have been disappointing. The aim of this in vitro study was to evaluate the surface structure of decalcified aortic valve tissue and its potential for recalcification. Methods: Aortic leaflets were removed from 26 patients with aortic stenosis during elective valve replacement and decalcified by meticulous dissection . Representative specimens were prepared for scanning electron microscopy ( SEM) and calcium content in the heavily calcified part of the leaflet in bo th macroscopically non-calcified and decalcified tissue was determined by a tomic absorption spectroscopy (AAS). Additional probes of 'non-calcified' a nd decalcified tissue were incubated for two and four weeks with medium con taining a physiological concentration of calcium to determine their potenti al for recalcification. As a control, 13 specimens from non-calcified valve s were incubated according to the same protocol. Results: All calcified specimens contained high calcium levels (142.70 +/- 53.76 mg/g). Surgical dissection reduced tissue calcium content significant ly (10.04 +/- 13.43 mg/g). Following two weeks' incubation with calcium, th ese specimens retained significantly higher levels of calcium (2.88 +/- 5.1 7 mg/g) than the 'non-calcified' specimens (19.17 +/- 7.61 versus 13.49 +/- 6.27 mg/g: p <0.05); after four weeks similar calcium levels were reached (32.00 +/- 10.27 versus 28.35 +/- 9.84 mg/g; p = NS). Non-calcified tissue showed the lowest calcium uptake (4.75 +/- 4.55 mg/g and 12.29 +/- 9,43 mg/ g at two and four weeks; p <0.05). SEM revealed a loss of endothelial cover age in the calcified areas; decalcification led to an irregular fibrillar s urface. Only parts of the macroscopically normal tissue contained endotheli al cells, whereas the control tissue showed intact cellular coverage, Conclusion: Aortic valve decalcification can effectively remove calcificati ons, but leaves a fibrillar structure that tends rapidly to accumulate calc ium. Even normal-appearing tissue from diseased valves has a higher potenti al for calcification than normal valvular tissue. These data support the ob servation of only limited clinical benefits being derived after aortic valv e decalcification for aortic stenosis.