Mechanisms of Ventricular Catheter Obstruction

Background: Hydrocephalus is treated primarily with ventriculoperitoneal shunts, which fail over time mainly due to proximal ventricular catheter (VC) obstruction of the drainage holes. Prior computational fluid dynamics (CFD) studies based on idealized geometries have suggested that cerebrospinal fluid (CSF) preferentially enters distal holes due to lower resistance, thereby increasing the risk of obstruction at those locations. However, these models do not incorporate explanted VC data, patient-specific anatomy, or differences in catheter architecture. Methods: To evaluate whether flow distribution matches failure sites, we compared obstruction patterns from 30 explanted catheters with CFD simulations of four commercial VC designs. For every drainage hole, mass flow, velocity, pressure drop (suction), and hydraulic resistance were quantified and compared with obstruction frequencies. Results: Evidence of tissue interaction was observed in 47–60% of the catheter, rather than only at distal locations. The most obstructed segment was 4 (59.8%), contradicting the prior distal location (8) hypothesis. Hydrodynamic variables showed weak correlations with obstruction mapping (mass flow rate: R² = 0.18; velocity: R² = 0.07; resistance: R² = 0.01; suction: R² = 0.003). CFD models run without wall contact captured only the intrinsic hydraulic behavior of each catheter. These suction distributions, therefore, identify where tissue would be pulled inward if tissue were in proximity. Conclusion: These findings support a two-factor mechanism: catheter geometry creates localized suction zones, and obstruction can occur when nearby tissue lies within reach of these forces. Thus, obstruction depends on the interaction between suction and anatomical position

Comparing anatomical imaging with functional imaging for coronary artery disease: the limitations of vessel stenosis and the benefits of non-invasive measurement of fractional flow reserve

A clinical decision report appraising Neglia D, Rovai D, Caselli C, Pietila M, Teresinska A, Aguadé-Bruix S, et al. Detection of Significant Coronary Artery Disease by Noninvasive Anatomical and Functional Imaging. Circ: Cardiovascular Imaging. 2015;8(3):e002179. https://doi.org/10.1161/CIRCIMAGING.114.002179 for a stable hospitalized patient admitted for acute coronary syndrome (ACS) rule out

A Ubiquitin Code Written in Circadian Time: Evaluating Protein Linkages in a Drosophila Model

Background: Ubiquitin is a small polypeptide that serves many functions within a cell, including modifying proteins, marking them for degradation through the ubiquitin-proteasome system (UPS). Circadian rhythms regulate many cellular processes, but its role on the individual linkages of ubiquitin is poorly understood. This project aims to determine whether there is a circadian pattern for the conjugation of ubiquitin. Methods: Wild-type (Oregon R) Drosophila were entrained to a circadian cycle with standard light and dark environments. The whole heads were then frozen and removed at different times and used to quantify protein linkages using western blotting and antibodies to each linkage. Analysis of the samples will allow quantification of the amount of bound protein across the circadian rhythm. Results: This project is currently ongoing, but results are expected before the date of the symposium. We hypothesize that there will be differences in ubiquitin conjugation along a circadian rhythm. This information will identify the role of a circadian rhythm in the ubiquitination pathway and could be used to further evaluate the function of the UPS