The effects of ventricle geometries and boundary conditions on computational modeling of ventriculoperitoneal catheters.

Hydrocephalus is a condition where an excess amount of cerebrospinal fluid (CSF) accumulates within the ventricles of the brain, leading to elevated intracranial pressure. The most common treatment is the surgical placement of a brain shunt to drain CSF from the ventricles. However, brain shunts have extremely high failure rates and improved devices are needed to minimize device obstruction and failure. To help establish modeling standards for this complex scenario, this work computationally investigates geometric and fluid dynamic variables to determine their effects on shunt performance, in addition to evaluating physiological modeling requirements. Catheter performance metrics included total catheter flow, drainage hole flows, and wall shear stresses (WSSs), which are all known to influence catheter obstruction. It was determined that ventricle and choroid plexus parameters (size, shape, and location) did not play a significant role in catheter performance (<2 % drainage hole flow differences, <12 % WSS differences). Further, patient-specific ventricle models were found to not affect catheter performance compared to a simplified cylinder model (<1 % drainage hole flow differences, <10 % WSS differences). Intracranial pressure boundary conditions, both static and pulsatile, were also applied. It was found that drainage hole flows and WSSs averaged over time were not significantly different between the waveforms and from comparable static pressure simulations. These results show that simplified geometric models and pressure boundary conditions can be used to computationally study ventriculoperitoneal (VP) catheter performance. The results of this research will enhance overall knowledge of CSF dynamics, provide modeling guidance, and contribute to the development of improved CSF shunts.