053. Proximal Ventricular Shunt Catheter Occlusion Model

Authors: David Qi

Proximal ventricular shunt catheter occlusion remains a problematic cause of shunt malfunction, and there is no consistent in vivo or in vitro model to help clinicians and researchers study this phenomenon.Methods: An in vitro model utilizing standard proximal ventricular catheter and biological occluding agents mimicking choroid plexus was designed, constructed, and calibrated. Hydrostatic pressure differential of greater than 50 cmH2O was used as a driving force to generate flow through the catheter. Chalaza and vitelline membranes were harvested from avian eggs and used as occluding agents. Occlusion was demarcated by the complete stoppage of flow through the system. Histological sections of occluded catheters were performed and interpreted by a neuropathologist. Preliminary testing of various proximal catheter designs, valves, and reservoirs with respect to occlusion rate was performed. Various de-obstruction techniques were also tested.
Standard proximal catheters were successfully, consistently occluded using both chalaza and vitelline membrane occluding agents. Histopathology demonstrated the vitelline membrane to consist of a thin, superficial layer of extraembryonic ectoderm; the chalaza was observed to consist of strands of mucin. Chalaza demonstrated faster occlusion rates, usually within minutes to an hour. Occlusion rate could be adjusted. High resistance catheter prototypes occluded faster than standard proximal catheters. Occluding agents were unsuccessfully dislodged by “micro-pump” over a Rickham reservoir and flushing. Occluding agents were successfully dislodged, and flow was reestablished via intralumenal coagulation by means of a stylet electrode. Continuous backflow at a high rate of greater than 200 ml/hr was also successful in reestablishing flow.
An in vitro model of proximal ventricular shunt catheter occlusion was developed and calibrated. Future studies may utilize this model to test both occlusion-resistant shunt designs and novel de-obstruction techniques.