METHODS AND SYSTEMS FOR DRAINING CEREBROSPINAL FLUID INTO THE VENOUS SYSTEM
A shunt and methods for treating hydrocephalus using the shunt, the shunt having one or more CSF intake openings and an expandable anchoring mechanism in a distal portion, one or more CSF outflow openings disposed in a proximal portion, and a lumen extending between the one or more CSF intake openings and the one or more CSF outflow openings, the method including intravascularly deploying the shunt in a patient so that the distal portion is at least partially disposed within a subarachnoid space of the patient, and the proximal portion is at least partially disposed within a venous system of the patient, wherein, after deployment of the shunt, CSF flows from the subarachnoid space into the venous system via the shunt lumen.
1 . A shunt configured for endovascular deployment in a patient, the shunt comprising:
a distal portion configured for being introduced from a venous system of the patient into, and disposed within, a subarachnoid space of the patient, the subarachnoid space containing cerebrospinal fluid (CSF);
a proximal portion configured for being disposed within the venous system when the distal portion is disposed with the subarachnoid space; and
a shunt body comprising a lumen, the lumen extending from the distal portion to the proximal portion, wherein the lumen is in fluid communication with one or more CSF intake openings in the distal portion, and with one or more CSF outflow openings in the proximal portion, wherein the distal portion comprises an expandable distal anchoring mechanism configured to retain the distal portion within the subarachnoid space and to maintain the one or more CSF intake openings separated, apart, and/or directed away from an arachnoid layer of the subarachnoid space,
such that, when the distal portion of the shunt is disposed within the subarachnoid space, and the proximal portion of the shunt disposed within the venous system, CSF flows from the subarachnoid space, through the one or more CSF intake openings, shunt lumen, and the one or more CSF outflow openings, respectively, into the venous system.
2 . The shunt of claim 1 , wherein the distal anchoring mechanism is configured to prevent passage of the distal portion shunt from the subarachnoid space through an anastomosis in a dura layer proximate the subarachnoid space through which the distal portion of the shunt was introduced into the subarachnoid space.
3 . The shunt of claim 1 , wherein the distal anchoring mechanism is configured to compress or pin down the arachnoid layer within the subarachnoid space in order to prevent blockage of the one or more CSF intake openings and/or occlusion of the shunt lumen by the arachnoid layer.
4 . The shunt of claim 1 , wherein the distal anchoring mechanism is configured to self-expand from a collapsed delivery configuration to an expanded deployed configuration as the distal portion of the shunt is introduced into the subarachnoid space.
5 . The shunt of claim 1 , the distal anchoring mechanism comprising expandable members for securing the shunt distal portion against a side of a dura layer adjacent the subarachnoid space.
6 . The shunt of claim 1 , wherein the distal anchoring mechanism comprises one or more expandable arms, petals, coils, malecots, ellipticots, or t-bar features for securing the shunt distal portion within the subarachnoid space.
7 . The shunt of claim 1 , wherein the subarachnoid space comprises an intracranial subarachnoid space.
8 . The shunt of claim 1 , wherein the one or more CSF outflow openings comprise one or more slit valves in the shunt body.
9 . The shunt of claim 8 , wherein the one or more slit valves and shunt lumen are configured and dimensioned to achieve a target flow rate of 5 ml of CSF per hour to 20 ml of CSF per hour through the shunt lumen under normal differential pressure conditions between the subarachnoid space and venous system of the patient.
10 . The shunt of claim 8 , wherein the one or more slit valves are configured to open at a pressure differential between the subarachnoid space and the venous system.
11 . The shunt of claim 8 , wherein the valve is configured to prevent or resist backflow of venous blood through the shunt lumen and into the subarachnoid space.
12 . The shunt of claim 1 , wherein the proximal portion of the shunt comprises a proximal anchoring mechanism configured to anchor the proximal portion of the shunt within the venous system.
13 . The shunt of claim 2 , wherein the distal anchoring mechanism is configured to form a seal at the anastomosis.
14 . The shunt of claim 13 , wherein the seal is configured to prevent venous blood from entering the subarachnoid space through the anastomosis.
15 . The shunt of claim 1 , further comprising a second lumen configured to receive or slide over a delivery guidewire.
16 . The shunt of claim 1 , wherein the proximal portion of the shunt comprises a first interlocking element configured to engage and disengage with a second interlocking element coupled to a distal portion of a shunt delivery assembly.
17 . The shunt of claim 4 , wherein the distal anchoring mechanism comprises a plurality of members, tines or wires aligned along an axis of the shunt when distal the anchoring mechanism is in the collapsed delivery configuration.
18 . A method for treating a patient with communicating hydrocephalus, the method comprising:
percutaneously introducing the shunt of claim 1 into a venous system of the patient;
navigating the shunt through the venous system to a target location proximate the subarachnoid space;
advancing a penetrating element through a dura layer and arachnoid layer at the target location and into the subarachnoid space, to thereby create an anastomosis in the dura layer and arachnoid layer; and
introducing the distal portion of the shunt through the anastomosis and into the subarachnoid space.
19 . The method of claim 18 , wherein the distal portion of the shunt accompanies the penetrating element into the subarachnoid space.
20 . The method of claim 18 , wherein the penetrating element is attached to the shunt when the penetrating element is advanced into the subarachnoid space.
21 . The method of claim 20 , further comprising detaching the penetrating element from the shunt and withdrawing the penetrating element from the patient after the penetrating element has been advanced into the subarachnoid space.
22 . The method of claim 18 , wherein the penetrating element is configured to limit a distance that the penetrating element advances into the subarachnoid space.
23 . The method of claim 18 , further comprising compressing or pinning down the arachnoid layer within the subarachnoid space to prevent occlusion of the shunt lumen.
24 . The method of claim 18 , further comprising anchoring the shunt proximal portion in the venous system.
25 . The method of claim 18 , wherein the dura layer comprises a wall of a dural venous sinus.
26 . The method of claim 18 , wherein the subarachnoid space comprises an intracranial subarachnoid space.
27 . The method of claim 26 , wherein the intracranial subarachnoid space comprises a cerebellopontine angle cistern.
28 . The method of claim 18 , wherein advancing the tissue penetrating element through the dura layer dilates the dura layer.