In vitro performance of venous valve prostheses. An experimental model study.

The performance of fresh and glutaraldehyde fixed bovine jugular vein valves (10 mm diameter) was investigated in an experimental flow loop that provides adjustable flow rates and a downstream oscillatory pressure. Three different venous valve (VV) conduit geometries (curved [C], straight [S], and tapered [T]), were tested. The flow loop consisted of two independently adjustable components, with the mean flow generated by adjusting the elevation difference between the head tank and outflow chamber. An adjustable sinusoidal pressure pulse was superimposed on the downstream of a VV to mimic the respiratory effects. Flow visualizations were made using 100 microns mica chip tracers in the laser illuminated flow fields. To assess VV performance under various flow conditions, the closure opening (CO), partial opening (PO), and leaflet fluttering (LF) were evaluated. At a given pulse pressure, the three conduits required different flow rates to reach CO mode. At 12 cm H2O pulse pressure, the fresh valve in C-conduit exhibited stable CO operation at a flow rate of 1.01 ml/sec. That in S and T conduits required 1.67 ml/sec and 2.25 ml/sec, respectively. At higher flow rates, PO and LF performances were observed in all three conduits. Different threshold values of pulse pressure were needed to reestablish the CO operation mode for the C, S, and T conduits, individually. These observations provide some insight into the role of conduit geometry and sinus configuration in the function of VV.