Does Valve Design Affect the Tensile Strength of Ventriculoperitoneal Shunts?

Background and objectives: The most common treatment for hydrocephalus is ventriculoperitoneal (VP) shunting, which is problematic as shunts are prone to failure. Shunt disconnections account for a minority (8%-15%) of VP shunt failures but could be reduced through better shunt design. A better understanding of the mechanical properties of VP shunts would help explain why shunt disconnections occur. The objective of this study was to determine if the tensile properties of VP shunts differ by design.

Methods: Linear tensile testing was conducted on 5 different valve designs (Codman Certas Plus Programmable Valve, Medtronic Delta, Integra Orbis Sigma Valve II, Medtronic PS Medical, Medtronic Strata Adjustable Valve) at both the proximal and distal ends to determine the maximum load which could be applied to different shunt designs. Each valve was progressively subjected to increasing force until the catheter disconnected from the valve, the catheter fractured, or our maximum testing limits were reached.

Results: Catheters disconnected or fractured during testing with all valves. The maximum load resisted during tensile testing for similar locations in all valve designs were found to be statistically similar to one another. Only the PS Medical and Orbis Sigma II valves showed an increased maximum load at the distal end compared with the proximal end within the same device.

Conclusion: No single valve design was superior at preventing disconnections in VP shunts. Shunt disconnections remain a concerning problem as VP shunts are the gold standard for combating hydrocephalus.