Biocorrosion of magnesium alloys: a new principle in cardiovascular implant technology?
OBJECTIVE
To develop and test a new concept of the degradation kinetics of newly developed coronary stents consisting of magnesium alloys.


METHODS
Design of a coronary stent prototype consisting of the non-commercial magnesium based alloy AE21 (containing 2% aluminium and 1% rare earths) with an expected 50% loss of mass within six months. Eleven domestic pigs underwent coronary implantation of 20 stents (overstretch injury).


RESULTS
No stent caused major problems during implantation or showed signs of initial breakage in the histological evaluation. There were no thromboembolic events. Quantitative angiography at follow up showed a significant (p < 0.01) 40% loss of perfused lumen diameter between days 10 and 35, corresponding to neointima formation seen on histological analysis, and a 25% re-enlargement (p < 0.05) between days 35 and 56 caused by vascular remodelling (based on intravascular ultrasound) resulting from the loss of mechanical integrity of the stent. Inflammation (p < 0.001) and neointimal plaque area (p < 0.05) depended significantly on injury score. Planimetric degradation correlated with time (r = 0.67, p < 0.01).


CONCLUSIONS
Vascular implants consisting of magnesium alloy degradable by biocorrosion seem to be a realistic alternative to permanent implants.
Hannover Medical School, Leibniz Laboratory for Biotechnology and Artificial Organs, Hannover, Germany. heublein.bernd@mh-hannover.de
B
B
Heublein
R
R
Rohde
V
V
Kaese
M
M
Niemeyer
W
W
Hartung
A
A
Haverich
D020341:Absorbable Implants; D000497:Alloys / Q000378:metabolism*; D000792:Angiography; D000818:Animals; D003331:Coronary Vessels / Q000166:cytology / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism*; D015607:Stents; D013552:Swine
D000497:Alloys; D008274:Magnesium