Sources of Error in Monitoring High Speed Testing of Vascular Grafts
Biomedical Science Instrumentation, 34, pp. 240-245, (1998)

J. C. CONTI,1,2 Ph.D., E. Strope,2 Ph.D., and K. Price2

1 Southwest Missouri State University, Springfield, Missouri
2 Dynatek Dalta Scientific Instruments, Galena, Missouri

Compliance issues are becoming ever more important in the design, testing, and manufacture of vascular grafts. A critically important realization is the fact that three-dimensional compliance is a function of testing frequency. ¨ This becomes an issue not only with vascular graft testing but also when characterizing mock arteries to be used in intravascular stent testing.

There is a natural tendency to adopt procedures that monitor outside dimensions of the graft or artery. The theoretical problem with this approach is the fact that compliance matching is a phenomenon associated with the inner lumen of the tubes, whether it is hydrodynamic considerations in vascular grafting or loading considerations in stent testing.

Optical techniques such as lasers or ultrasound are also encumbered by two physical motion phenomena unique to this approach. The first is simple jumping of the tube due to vibrations. This problem can be overcome by sampling at high enough rates. The second is more problematic and results from the lengthening of a tube that has longitudinal as well as radial compliance. Both quantitative and qualitative examples will be examined.

A comprehensive understanding of the sources of error encountered with various monitoring techniques will be reviewed. These techniques will include lasers, dynamic internal compliance via volume displacement, and cantilevered beams.

Conti, J.C., Strope, E.R., Rohde D. J., and Spence, L. D., Frequency Dependent Radial Compliance of Latex Tubing. Biomedical Sciences Instrumentation, 33, 524-529 (1997).