Shunt obstruction: a preventable complication?

Mechanical shunt complications account for more than half of all shunt failures. This study compares the incidence and etiology of mechanical shunt failure in a recent series of 343 pediatric patients with a flow-regulating shunt, Cordis Orbis-Sigma valve (OSV; Cordis, Miami, Fla., USA) to a previous series of 1,719 pediatric patients with standard differential pressure (DP) valves. The 1- and 5-year shunt failure probabilities were 20.1 and 23.6%, respectively, for the OSV valve and 31.1 and 49%, respectively, for the standard DP valves. The incidence of slit ventricles was 8.2% for the OSV and 33.2% for the conventional DP valve. Proximal obstruction remained the commonest cause of failure in both groups. Valve obstruction was higher (18.3 vs. 9.7%) with the OSV, although the obstructions tended to occur mostly in the early postoperative period possibly for debris introduced at the time of insertion. This review of the mechanical complications reported in this and other series suggests that despite the complexity of the interactions between variables associated with the patient, the surgeon and the shunt, mechanical complications are to a significant degree preventable. Verification will require prospective randomized clinical trials.