In vitro effects of anticalcification treatment on the calcium uptake of bioprosthetic materials.
OBJECTIVE
The frequent need for re-replacement of tissue valves due to calcification remains their major disadvantage compared with mechanical implants. A variety of anticalcification treatments has been proposed but none has proved to prevent calcific degeneration. The study aim was to evaluate, in vitro, the time course of calcium uptake of procine and bovine biomaterials and the efficacy of anticalcification treatments.


METHODS
Samples of glutaraldehyde-tanned biomaterials with (Carpentier-Edwards, Medtronic Intact, Hancock II, MZGTB) or without anticalcification treatment (Mitroflow) were incubated with culture medium containing physiological calcium levels. Specimens were then analyzed at two, four or eight weeks for their calcium content (mg/g wet weight).


RESULTS
All specimens calcified over time, though the time courses for each were significantly different. Mitroflow and Intact valves accumulated high calcium levels rapidly during the first two weeks, with small further increases thereafter. Anticalcification treatment reduced calcium uptake of Carpentier-Edwards material during the first two weeks of incubation, but the material gradually attained comparable calcium levels at eight weeks. Hancock valves and the self-customized MZGTB valve showed the lowest calcium levels over the test period.


CONCLUSIONS
This in vitro study documented major differences in calcium uptake of different biomaterials. Some anticalcification treatments render the material temporarily less susceptible to calcium binding but none can prevent calcification. In vitro testing has proved to be a valuable instrument for evaluating anticalcification treatments, but should be combined with evaluation of bioprosthesis surface interaction with circulating blood.
Dahm
M
M
Department of Cardiothoracic and Vascular Surgery, University Hospital Mainz, Germany.
Prüfer
D
D
Krummenauer
F
F
Mayer
E
E
Hafner
G
G
Groh
E
E
Oelert
H
H
D000818:Animals; D001705:Bioprosthesis; D002114:Calcinosis / Q000517:prevention & control; D002118:Calcium / Q000493:pharmacokinetics*; D002417:Cattle; D006350:Heart Valve Prosthesis; D066298:In Vitro Techniques; D011474:Prosthesis Design; D013552:Swine
D002118:Calcium