Polyacrylamide-silastic shunts

Figure 4. Graft level as a function of length along the shunt for polyacrylamide-Silastic shunts prepared using the flow-grafting apparatus described in Ref 14.

Table II shows the effect on platelet consumption of increasing lengths of the polyacrylamide-Silastic tubing. The acrylamide surface is much more destructive to platelets than is the Silastic surface. Table II also shows that platelet consumption increases linearly with shunt area for both the polyacrylamide-Silastic shunts.

Figure 11. Platelet consumption vs. graft level of polyacrylamide-Silastic shunts (9). (Numbers in parentheses refer to the number of shunts tested for each value reported.)...

Because fibrinogen remains at the gel top in the electrophoresis system used here, we cannot assess its importance because staining artifacts frequently occur at the gel top. However, adsorption of 125I-fibrinogen to polyacrylamide-Silastic shunt surfaces from baboon blood in vivo is much greater than adsorption to Silastic shunt surfaces (46). 

Laser Light Scattering Detection of Microemboli. To elucidate the mechanism of platelet destruction by grafted polyacrylamide-Silastic surfaces, an optical scattering technique was developed (20) to observe and quantitate the sizes and size distributions of microaggregates in blood produced within the AV baboon shunt. Presumably, any such flowing microaggregates represent platelet microemboli. 

Laser Light Scattering Detection of Microemboli. The optical scattering technique was used to assess in vivo the thromboembolic propensity of polyacrylamide-Silastic and Silastic shunts of varying lengths. In four baboons, control measurements of the number and size distribution of throm-boemboli produced by the 35-cm proximal section of the chronically... 

A series of shunts with radiation and ceric ion-initiated grafts of polyacrylamide on the luminal Silastic surface, and having water contents varying between 51-83% were also studied. Table III shows these data. The platelet consumption increases linearly with the gel water, such that the ratio of platelet consumption to graft water content remains relatively constant. 

---