Catheter architecture as a determinant of cerebrospinal fluid flow in pediatric hydrocephalus.

Abstract

Cerebral ventricular catheters (VCs) remain the critical but failure-prone component of cerebrospinal fluid (CSF) shunt systems for pediatric hydrocephalus, with proximal obstruction accounting for most malfunctions. Several catheter geometries have been introduced to the market in the US alone, yet none demonstrate long-term reliability. This study investigates how catheter design interacts with patient-specific ventricular anatomy and surgical placement to influence CSF drainage patterns. Three patient-specific hydrocephalic ventricles were modeled from MRI scans, with FOHR values of 0.45, 0.30, and 0.29 and corresponding ventricular volumes of 167.5 (enlarged), 12.5 (moderate), and 20.6 mL (small). Four ventricular catheters with varying architectures from our institutional biobank were reverse engineered using confocal microscopy. Catheters were virtually implanted into the lateral ventricles under frontal, parietal, and occipital placements. Computational fluid dynamic simulations were performed, and mass flow rates were quantified across drainage holes grouped into longitudinal segments. Boundary conditions consisted of a constant CSF efflux rate of 0.35 mL/min applied uniformly across all configurations and a continuous pressure outlet at the proximal catheter outlet, representing valveless drainage. Occipital placement consistently produced valve adjacent dominant inflow across catheter designs, whereas frontal and parietal placements exhibited design-specific flow behaviors when segmental inflow through the catheter drainage holes was measured. In most configurations, segments nearest the catheter valve captured the majority of inflow, accounting for 65-82% of total CSF entry. In frontal placements, smaller ventricular geometries caused valve-adjacent segments in several catheter designs to extend outside the ventricular cavity. As a result, inflow was redistributed toward the remaining tip-adjacent segments, with up to 99.5% of total flow entering through these segments when valve-adjacent holes were excluded. Catheter designs with shorter perforated lengths and more closely spaced drainage holes maintained a greater number of functionally active segments across ventricular geometries, whereas longer perforated spans were more susceptible to anatomical exclusion. These findings demonstrate that ventricular catheter drainage is governed not by catheter geometry alone, but by the interaction between catheter architecture, ventricular morphology, and surgical placement.