Low-profile ventriculoamniotic shunt for fetal aqueductal stenosis
The invention relates to an in-utero ventriculoamniotic shunting device that includes a shunt tube ( 26 ) composed of polymer composite and having metallic wire embedded therein, one or more anchors ( 30 ) composed of superelastic wire, e.g., thermal shape-set nitinol structures, that are mechanically attached to an exterior surface of the shunt tube ( 26 ), and a one-way passive valve ( 32 ) composed of a thin polymer membrane. The anchors ( 30 ) are effective to prevent migration and dislodgement of the shunting device following its deployment, and the valve ( 32 ) is effective to prevent the backflow of amniotic fluid ( 23 ).
1. An in-utero ventriculoamniotic shunting device, comprising:
a shunt tube ( 26 ), comprising:
an exterior surface;
a first end;
an opposite second end;
a length;
an inner diameter;
an outer diameter;
a composite that forms the inner diameter and the outer diameter, the composite comprising:
one or more polymer layers; and
metallic wire embedded in the one or more polymer layers;
one or more anchors ( 28 ) mechanically attached to the exterior surface of the shunt tube ( 26 ), the one or more anchors ( 28 ) comprising:
nitinol wire configured in a shape that extends outwardly from the exterior surface of the shunt tube ( 26 ) to prevent migration of the shunting device; and
a mechanism ( 30 ) to connect the nitinol wire to the exterior surface of the shunt tube ( 26 ); and
a one-way passive valve ( 32 ), comprising:
a membrane cover mechanically connected to a portion of a perimeter of the opposite second end of the shunt tube ( 26 ) in a hinge-like configuration.
2. The device of claim 1 , wherein the length of the shunt tube ( 26 ) is from about 2 to about 10 cm.
3. The device of claim 1 , wherein the inner diameter of the shunt tube ( 26 ) is from about 0.5 to about 1.5 mm.
4. The device of claim 1 , wherein the outer diameter of the shunt tube ( 26 ) is from about 1.0 to about 3.0 mm.
5. The device of claim 1 , wherein the nitinol wire is configured in the shape of a coil ( 5 ) having a plurality of spirals formed on the exterior surface and wrapped around the outer diameter of the shunt tube ( 26 ).
6. The device of claim 1 , wherein the nitinol wire is configured in the shape of two curves ( 10 ) extending outwardly from the exterior surface of the shunt tube ( 26 ).
7. The device of claim 1 , wherein the one or more anchors ( 30 ) is mechanically attached to the outside surface of the shunt tube at a position approximately mid-point on the length of the tube.
8. The device of claim 1 , wherein the one or more anchors ( 30 ) has a length of about 1 to about 4 cm.
9. The device of claim 1 , wherein the valve ( 32 ) comprises a thin polymeric membrane.
10. The device of claim 9 , wherein the valve ( 32 ) comprises poly(ester urethane) urea.
11. The device of claim 10 , wherein the poly(ester urethane) urea is fabricated by electrospinning.
12. A method of ventriculoamniotic shunting for fetal isolated aqueductal stenosis, comprising:
prenatally detecting and diagnosing aqueductal stenosis in a fetus;
forming a shunting device, comprising:
obtaining a shunt tube ( 26 ), comprising:
an exterior surface;
a first end having an opening;
an opposite second end having an opening;
a length;
an inner diameter;
an outer diameter;
a composite that forms the inner diameter and the outer diameter, the composite comprising:
one or more polymer layers; and
metallic wire embedded in the one or more polymer layers;
mechanically attaching one or more anchors ( 28 ) to the exterior surface of the shunt tube ( 26 ), comprising:
fabricating nitinol wire;
thermally configuring the nitinol wire in a shape that extends outwardly from the exterior surface of the shunt tube ( 26 ) for preventing migration of the shunting device; and
employing a mechanism ( 30 ) for connecting the nitinol wire to the exterior surface of the shunt tube ( 26 ); and
mechanically attaching a membrane cover ( 32 ) to a portion of a perimeter of the opposite second end of the shunt tube ( 26 ) in a hinge-like configuration;
introducing the shunting device in-utero through a skull ( 22 ) and into a brain ( 24 ) of the fetus, such that the first end of the shunt tube ( 26 ) is positioned in the skull ( 22 ) and the opposite second end of the shunt tube ( 26 ) is positioned in an amniotic sac ( 23 ) outside of the skull ( 22 );
allowing cerebrospinal fluid in the brain ( 24 ) to flow into the first end and through the shunt tube ( 26 );
pushing outward the membrane cover ( 32 ) by the flow of cerebrospinal fluid through the shunt tube ( 26 ); and
discharging the cerebrospinal fluid through the opposite second end of the tube ( 26 ) into the amniotic sac ( 23 ).