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Experimental research

Histopathologic evaluation of nitinol self-expanding stents in an animal model of advanced atherosclerotic lesions

1. CVPath Institute, Inc., Gaithersburg, MD, USA; 2. Deutsches Herzzentrum Muenchen und 1. Medizinische Klinik, Klinikum rechts der Isar, Technische Universitaet Muenchen, Germany; 3. Nitinol and Device Components, Fremont, CA, USA

Aims: The histologic response to self-expanding stent implantation into advanced atherosclerotic lesions has not been systematically investigated. We tested the hypothesis of whether gradual expansion of advanced atherosclerotic plaques by self-expanding stents would be an appropriate method to seal atherosclerotic lesions without causing plaque disruption as is usually observed with balloon-expandable stents.

Methods and results: Twelve New Zealand white rabbits were fed an atherogenic diet (1% cholesterol) followed by arterial denudation and injection of washed autologous erythrocytes. Nitinol self-expanding stents of two different stent designs and strengths (n=12 for SX and n=12 for Micro-SX) were implanted into the previously formed lesions within the abdominal aorta six weeks following injection of erythrocytes. Four weeks following stent implantation, animals were sacrificed, specimens harvested and processed for histology. Histomorphometry was performed on stented and adjacent non-stented regions. Atherosclerotic lesions were composed of foam cells, cholesterol clefts and necrotic plaque. While SX stents showed an unfavourable outcome with respect to vessel remodelling and the percentage of uncovered stent struts, Micro-SX stents had fewer uncovered stent struts, less positive remodelling and less plaque injury.

Conclusions: Nitinol Micro-SX self-expanding stents might be a valuable approach to seal high risk atherosclerotic lesions.

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