Electrical Conductance Device for Stent Sizing

Abstract

The minimum stent area (MSA) has been clinically established as a significant predictor of restenosis, thrombosis, and ischemia using intra-vascular ultrasound (IVUS). Unfortunately, IVUS measurements are far from routine because of significant cost of IVUS, the training required, the subjectivity of image interpretation and the time added to the procedure. The objective of this study is to verify the accuracy of a conductance catheter for stent sizing. Here, we introduce an easy and entirely objective device and method for real time determination of MSA. A 10 kHz, 35 μA rms current is passed through the external electrodes of an intravascular catheter while the conductance is measured across a separate set of electrodes. Both phantom and ex vivo validations of metal stent sizing in five porcine carotid arteries were confirmed. The accuracy of the measurements were found to be excellent in phantoms (root mean square, rms, of 3.4% of actual value) and in ex-vivo vessels (rms = 3.2% of measured value). An offset of conductance occurs when a conductive metal stent (e.g., bare metal stent) is deployed in the vessel, while the slope remains the same. This offset is absent in the case of drug eluting stent where the metal is coated (i.e., insulated) or non-metal bioresorbable stent. The present device makes easy, accurate and reproducible measurements of the size of stented blood vessels within 3.2% rms error. This device provides an alternative method to sizing of stent (i.e., MSA) in real-time without subjective interpretation and with less cost than IVUS.

In vitro hemocompatibility studies on small-caliber stents for cardiovascular applications

“…The small-caliber stents were evaluated for their non-hemolytic nature in contact with human blood cells, and all the samples were found to be hemocompatible according to the ASTM 756-00 and ISO 10993-5 1992 (American Society for Testing and Materials Designation) standards. 35,36 The in vitro hemocompatibility of pure BCP and biphasic calcium phosphate samples doped with various percentages of metal ions (Mg 2+ ) were measured, and the hemolysis percentages are presented in Fig. 7.…”

“…As shown in Table 1, the obtained electrical parameters match the electrical characteristics of the biological components. 34,35 The 3%Mg-BCP bioceramic stent performed well in terms of its electrical characteristics, which is essential for cardiovascular applications.…”