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. 2003 Jun;89(6):651-6.
doi: 10.1136/heart.89.6.651.

Biocorrosion of magnesium alloys: a new principle in cardiovascular implant technology?

B Heublein  1 , R Rohde, V Kaese, M Niemeyer, W Hartung, A Haverich
Affiliations

Biocorrosion of magnesium alloys: a new principle in cardiovascular implant technology?

B Heublein et al. Heart. 2003 Jun.

Abstract

Objectives: 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).

Conclusion: Vascular implants consisting of magnesium alloy degradable by biocorrosion seem to be a realistic alternative to permanent implants.

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Figures

Figure 1
Figure 1
Planimetric analysis showing a linear increase in the neointimal plaque area.
Figure 2
Figure 2
Four polymer fixated and cut tissue blocks of stents (A) 10, (B) 35, and (C, D) 56 days after implantation. Unequal extension of the stents, and minimal corrosion and neointimal proliferation after 10 days, and advanced and irregular corrosion and proliferation after 35 and 56 days, are seen. The bright areas indicate strut parts that remained metallic.
Figure 3
Figure 3
Intravascular degradation of magnesium alloy stents in pig coronary arteries. The extrapolated lifetime was calculated under the assumption of a linear disappearance of metallic strut parts.
Figure 4
Figure 4
Histological section of a vessel 35 days after stenting. Deep penetration of the vessel wall results in more neointimal proliferation.
See this image and copyright information in PMC

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