Updating technology of shunt valves

Abstract

Cerebrospinal fluid shunts are one of the greatest advances of modern neurosurgery and represent a shift in the treatment of hydrocephalus. The underlying physical principle is quite simple and consists of diverting the flow of cerebrospinal fluid to either intracranial structures, jugular system, right heart atrium, pleura, peritoneum or to other natural cavities, such as the omental bursa and even the bladder. All systems operate by means of a differential pressure between the proximal catheter and distal catheter and are composed of ventricular and distal catheters, and a valve, which is the device that allows unidirectional cerebrospinal fluid flow. Current valve technology allows control of the shunt through regulation of drainage pressure, flow regulation or anti-siphon devices. There are valves with low, medium and high pressure designed to open and allow the flow out of CSF when the intraventricular pressure rises above the opening pressure. In contrast to fixed pressure and programmable pressure, valves with flow regulation attempt to maintain constant flow despite changes in the fluid pressure and patient position. Anti-siphon devices are used to avoid the siphon effect and prevent under-or over-drainage of fluid. We discuss briefly the current aspects of hydrodynamics and update valve technology.

Current state of the art and future directions for implantable sensors in medical technology: Clinical needs and engineering challenges

“…157 The most common type used in current clinical practice is the ventriculoperitoneal (VP) shunt, which is designed to drain excessive fluid to the abdominal cavity, 158 thus reducing the ICP when it becomes too high. While standard shunts are based on mechanical resistance to pressure, such that when the pressure increases, a valve opens and reduces the ICP, 159 in recent years, a new class of shunts have emerged in different stages of development, which integrate implantable sensors. These utilize electronic components 60,160 such as flow and pressure sensors to maintain ICP at physiological levels 160 and detect shunt failure.…”

Shunt Technology in Pediatric Neurosurgery: Current options and Scientific Evidence

“…Initial valves belonged to the group of first-generation differential pressure shunts and consisted of following working mechanisms: ball and cone, diaphragm, proximal slit and distal slit. Interestingly, the four technical principles for the construction of the first-generation valves were already established even before 1960 (2,11,12). The second generation of shunts aimed to decrease the incidence of overdrainage.…”

Malformação de Chiari: relato de experiência

“…Portanto, a hidrocefalia relacionada com Chiari Tipo I é chamada de "Hidrocefalia Obstrutiva", a qual está relacionada então com a obstrução dos forames de Magendie e Luscka, impedindo o fluxo liquórico para o espaço subaracnóideo e elevando a quantidade de LCR nas cavidades intracranianas, gerando então uma hipertensão intracraniana e dilatação dos ventrículos cerebrais. A prevalência conhecida da anomalia é 1 a cada 1.000 a 5.000 pessoas 4,[9][10][11][12] .…”