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Invited Talk

Characterization of coronary arteries by electrical impedance measurements

Prof. Dr. Patrick Schwaller, Professor of Surface Physics
Michael Held, MSc Biomedical Engineering

Institute for Applied Laser, Photonics and Surface Technologies
Bern University of Applied Sciences, Burgdorf

Abstract

Coronary artery disease is the leading cause for mortality in industrialized countries. Stent implantation is the treatment of choice for symptomatic coronary artery disease. The major limitation of coronary stenting is its association with myocardial infarction or sudden cardiac death caused by stent thrombosis. Absent neointimal coverage of stents seems to be an important predictor of stent thrombosis. Regrettably, the ability to detect the thin protective biologic layer on stents by current techniques is limited. The long-term objective of our research – which is a common project together with the ARTORG Center of the University of Bern - is a novel intravascular sensor dedicated to assess neointimal coverage of coronary stents to guide therapy in appropriate situations.

In the first part of our talk we will present results of in-vitro electrical impedance measurements of different porcine and human tissue samples. The results of these experiments show that the impedance response allows distinguishing between human tissue, uncovered stents, and stents covered by a neointimal layer. Furthermore it turned out that the phase response is more stable than the gain response in terms of slight changes of the measurement conditions. In addition we will discuss interpretations of the complex electrical impedance behavior of the tested samples regarding a possible modeling.

The second part of our talk deals with the design and fabrication aspects for a future in-vivo sensor based on commercially available balloon catheters made of polyamide or PET. Key issues to be mastered are the adhesion of thin structured metallic layers on the balloons under heavy strain, the electrode geometry as well as a stable mechanical and electrical contact between the electrodes and the electrical feedthrough.

Biographies

Patrick Schwaller is professor for surface physics at the Bern University of Applied Science BFH. He received his PhD in experimental physics at the University of Zurich in the field of photoelectron spectroscopy in 1997. After a post-doc in the solid state physics group at the University of Fribourg he joined Empa in Thun as senior scientist. At Empa he was responsible for the activities in the field of nanomechanics. His current research activities at BFH include thin film technologies and laser surface microstructuring.

Michael Held is scientific collaborator at the Bern University of Applied Science BFH. He received his Bachelor of Science in Electrical and Electronics Engineering (BSEE) at the Bern University of Applied Sciences BFH. After three years of experience as an electrical engineer in a R&D position in the field of special purpose machinery manufacturing he complemented his education with a Master of Science in Biomedical Engineering at the University of Bern in collaboration with the Bern University of Applied Science BFH in 2009.

Volker Koch, 09/2010