Atrial appendage blood filtration systems

Abstract

Instrumentation for percutaneous delivery of blood filtration devices to atrial appendages includes a curved access sheath and a delivery tube. The curved access sheath is coursed through the patient's vasculature to gain transseptal access to a left atrial appendage. A compressed filter device attached to a tether wire is loaded in the delivery tube. The loaded delivery tube is advanced through the pre-positioned access sheath to place the device in a deployment position. The access sheath and the delivery tube can be mechanically locked and moved together to place the device in a suitable deployment position. The device is deployed by expelling it from the delivery tube either by retracting the delivery tube over the tether wire, or by moving the tether wire forward through the delivery tube. The expelled device, which is not constrained by the delivery tube walls, self expands to its useful size in the subject atrial appendage. A filter membrane in the deployed extends across the appendage ostium to filter blood flow through the ostium. The filter membrane is configured to present a flat surface to atrial blood flow past the ostium.

1 . A blood filtration system for filtering blood flow from an atrial appendage, comprising: 
 a filter device that is configured for deployment in the atrial appendage to intercept blood flow, wherein the filter device has an elastic structure that expands to its natural size from a compressed state when the device is unconstrained;    a tubular access sheath for establishing a percutaneous pathway to the atrial appendage; and    a delivery instrument for delivering the device through a lumen of the access sheath and for deploying the delivered device in the atrial appendage, wherein the delivery instrument includes: 
 a delivery tube; and  
 a movable tether that passes through the delivery tube, and that is releasably attached to the device,  
 wherein the tether provides mechanical control over the delivery and deployment of the device, and wherein the access sheath and the delivery tube comprise releasable locks for controlling the relative movement of the two.  
   
     
     
         2 . The system of  claim 1  wherein the access sheath comprises a tube having a straight portion that curves into a distal portion at a bend angle of about 90 degrees.  
     
     
         3 . The system of  claim 1  wherein the access sheath comprises a tube having a substantially straight portion that curves into a first distal portion at a first bend angle, and a second distal portion that curves away from the first distal portion at an second bend angle relative to the plane of the straight portion and the first distal portion.  
     
     
         4 . The system of  claim 3  wherein the first bend angle is about 90 degrees.  
     
     
         5 . The system of  claim 1  wherein the access sheath has a length for placing a distal sheath tip in the atrial appendage through the body's vascular system.  
     
     
         6 . The system of  claim 1  wherein the tether wire comprises a threaded fixture for rotatably attaching the filter device.  
     
     
         7 . The system of  claim 6  wherein a length of the tether wire near the threaded fixture has a diameter that is substantially smaller than the diameter of a proximal length of the tether wire to reduce its coupling stiffness to the attached device.  
     
     
         8 . The system of  claim 1  wherein the delivery tube comprises a tubular implant sheath that constrains the filter device to a compressed state during the delivery of the device through the lumen of the access sheath.  
     
     
         9 . The system of  claim 8  wherein the tether wire has a diameter that is substantially smaller than the inner diameter of the tubular implant sheath, wherein a length of the tether wire proximate to the attached filter device is encased in a larger diameter flexible coil to avoid buckling of the tether wire as it is moved through the delivery tube.  
     
     
         10 . The system of  claim 9  wherein the flexible coil has a diameter about the inner diameter of the tubular implant sheath, wherein the flexible coil comprises a lumen that is in fluid communication with the lumen of the delivery tube at its proximal end and wherein the flexible coil lumen opens to flush ports about its distal end.  
     
     
         11 . The system of  claim 1  wherein the access sheath comprises a valve assembly at its proximal end for sealably receiving the delivery tube into the lumen of the access sheath.  
     
     
         12 . The system of  claim 11  wherein the valve assembly comprises seals that are adjustably compressible against a surface of the received delivery tube to control back bleeding.  
     
     
         13 . The system of  claim 11  wherein a releasable lock for coupling the movement of the delivery tube and the access sheath is disposed on the valve assembly.  
     
     
         14 . The system of  claim 13  wherein the releasable lock disposed on the valve assembly is a luer fitting.  
     
     
         15 . The system of  claim 11  wherein the valve assembly comprises a hemostasis valve.  
     
     
         16 . The system of  claim 11  wherein the valve assembly comprises a radial compression valve.  
     
     
         17 . The system of  claim 11  wherein the valve assembly comprises a port for passage of fluids through a lumen of the access sheath.  
     
     
         18 . The system of  claim 1  wherein the delivery tube further comprises a manifold at its proximal end, and wherein the tether wire movably passes through the manifold.  
     
     
         19 . The system of  claim 18  wherein a proximal end of the tether wire terminates in a knob, and wherein turning the knob turns the tether wire to detach the device attached to the distal end of the tether wire.  
     
     
         20 . The system of  claim 19  wherein the knob is a rotatable knob mounted on the manifold.  
     
     
         21 . The system of  claim 18  wherein a casing is disposed on a length of tether wire extending into the manifold to provide rigidity for rotation and translation of the tether wire.  
     
     
         22 . The system of  claim 18  wherein a detachable stop is disposed on the tether wire at a distance from its proximal terminal end, and wherein the detachable stop acts against the manifold to limit the translation of the tether wire into the manifold.  
     
     
         23 . The system of  claim 18  wherein a length of the casing has a non-circular shape cross-section, and wherein the manifold comprises a keyway that has a similar shape cross-section, wherein the keyway allows the non-circular shape lengths of the casing to slide through and restrains rotation of the non-circular shape length of the casing.  
     
     
         24 . The system of  claim 22  wherein a length of tether wire abutting the knob has a substantially round cross section that is free to rotate in the keyway.  
     
     
         25 . The system of  claim 23  wherein the noncircular shape cross-section includes a D-shape.  
     
     
         26 . The system of  claim 18  further comprising an actuator slidably mounted on the manifold to reciprocally retract the delivery tube into the manifold over the tether wire.  
     
     
         27 . The system of  claim 18  wherein the manifold comprises a port for passage of fluids through a lumen of the delivery tube.  
     
     
         28 . The system of  claim 18  wherein a releasable lock for coupling the movement of the delivery instrument and the access sheath is disposed on the manifold, and wherein when lock is activated the distal tips of the access sheath and the implant sheath are approximately flush.  
     
     
         29 . The system of  claim 28  wherein the releasable lock disposed on the manifold is a luer fitting.  
     
     
         30 . The system of  claim 28  wherein the second part of the releasable lock disposed on the manifold is C-shape clip that releasably catches on a cylindrical valve body on the access sheath to prevent translation of the manifold relative to the access sheath.  
     
     
         31 . The system of  claim 30  wherein the C-shape clip rotatably catches on the cylindrical valve body on the access sheath to allow rotation of the delivery tube in the access sheath.  
     
     
         32 . The system of  claim 1  wherein the filter device comprises: 
 an elastic wire frame, wherein the wire frame has a closed end, wherein a threaded socket is disposed on about the wire frame's longitudinal axis at about the closed end, wherein wire sections extend radially from about the threaded socket to sides of the wire frame, and wherein the wire sections act as springs to bias the filter device to its natural size; and  
 a blood-permeable filter membrane disposed on at least the closed end of the wire frame,  
 wherein the closed end exterior surface of the filter device is substantially flat.  
 
     
     
         33 . The system of  claim 32  wherein the wire sections that act as springs have S-shapes.  
     
     
         34 . The system of  claim 32  wherein the wire frame has a cylindrical shape with a diameter for interference fit in an atrial appendage.  
     
     
         35 . The system of  claim 34  wherein the cylindrical shape is tapered away from the closed end.  
     
     
         36 . The system of  claim 1  further comprising a dilator and needle to make an opening in an atrial septum for transseptal access to the atrial appendage.  
     
     
         37 . A device for filtering blood flow from an atrial appendage, comprising: 
 an elastic wire frame, wherein the wire frame the has a diameter for an interference fit in the atrial appendage, and wherein the wire frame comprises wire sections radially extending to the sides of the wire frame from its longitudinal axis that serve as springs to bias the wire frame to its natural size when compressed;    a fixture disposed on the longitudinal axis of the wire frame at about the plane of a proximal end of the wire frame, and wherein the fixture has a structure for attachment of the device to a tether wire; and    a filter membrane that covers a proximal end of the wire frame, wherein the filter membrane stretches across the ostium of the atrial appendage to intercept blood flow therethrough, and wherein the device presents a substantially flat exterior surface along the plane of the proximal end of the wire frame.    
     
     
         38 . The device of  claim 37  wherein the wire sections are S-shaped wire sections that start from about the fixture at substantially shallow angles to the longitudinal axis and lie in radial planes of the wire frame.  
     
     
         39 . The device of  claim 38  wherein said fixture comprises a tubular collar and an insert having a socket for attachment of the device to a tether wire, and wherein the S-shape wire sections emanate from the collar.  
     
     
         40 . The device of  claim 39  wherein a portion of the filter membrane is held between the collar and the insert while other portions of the filter membrane are attached to other portions of the wire frame.  
     
     
         41 . The device of  claim 37  wherein the wire frame comprises a chicken wire-like mesh.  
     
     
         42 . The device of  claim 41  wherein distal wire ends of the wire frame are turned radially inward toward the longitudinal axis of the wire frame to provide a traumatic tissue contact.  
     
     
         43 . The device of  claim 37  wherein the wire frame has conical shape.  
     
     
         44 . A device delivery system for implanting an self-expanding device in an atrial appendage comprising: 
 a delivery tube extending into an implant sheath, wherein the delivery tube has an inner diameter of about 30 to about 100 mils and the implant sheath has an inner diameter larger than the diameter of a device in a compact state that is contained in the implant sheath;    a manifold disposed on a proximal end of the delivery tube;    a tether wire movably passing through the manifold, wherein the tether wire has a fixture attached to the device contained in the implant sheath, wherein the attached device expands to its natural size on expulsion from the implant sheath by translation of a length of the tether wire through the delivery tube, and wherein the tether wire has a coupling stiffness that allows the expelled device to attain its natural unbiased state when deployed in an appendage while it is still attached to the tether wire.    
     
     
         45 . The device delivery system of  claim 44  wherein a length of tether wire near the fixture has a reduced diameter relative to the diameter of a proximal length of the tether wire to reduce the stiffness of the coupling to the attached device.  
     
     
         46 . The device delivery system of  claim 44  wherein a length of tether wire extending into the implant sheath is encased in a flexible coil to reduce buckling of the tether wire as it is translated through the implant sheath.  
     
     
         47 . The device delivery system of  claim 46  wherein the flexible coil has a lumen that is in fluid communication with the lumen of the delivery tube and that has openings near the distal end of the flexible coil.  
     
     
         48 . The device delivery system of  claim 44  wherein the delivery tube has an inner diameter of about 45 mils, a proximal length of the tether wire has a diameter of about 35 mils and a length of tether wire near the threaded fixture has a reduced diameter of about 10 mils.  
     
     
         49 . The device delivery system of  claim 44 , wherein a casing is disposed on a proximal length of tether wire extending from near its distal end into the manifold to provide rigidity for operator-controlled rotation and translation of the tether wire.  
     
     
         50 . The device delivery system of  claim 49  further comprising a releasable stop that acts against the manifold to limit translation of the tether wire.  
     
     
         51 . The device delivery system of  claim 49  wherein a length of the casing has non-circular cross-section, wherein the manifold has keyway with a similar shape cross-section for allowing translation of the tether wire and for restricting the rotation of the tether wire.  
     
     
         52 . The device delivery system of  claim 21  wherein the keyway has a D-shape.  
     
     
         53 . The device delivery system of  claim 44  wherein the manifold comprises a Tuohy-Borst valve assembly.  
     
     
         54 . The device delivery system of  claim 44  further comprising an access sheath for transseptal delivery of the device to an atrial appendage, the access sheath comprising: 
 a tube having compound curvatures and a length to percutaneously place the distal tip of the tube about the atrial appendage; and a valve assembly disposed on the proximal end of the tube for sealably receiving the delivery tube into the tube lumen.  
 
     
     
         55 . The device delivery system of  claim 54  wherein the compound curvatures comprise a first curve of about 90 degrees and a second curve of about 75 degrees away from the plane of the first curve.  
     
     
         56 . The delivery system of  claim 54  further comprising releasable locking structures for coupling together the translational movement the delivery tube and the access sheath.  
     
     
         57 . The delivery system of  claim 56  wherein the releasable locking structures are configured to allow rotational movement of the delivery tube relative to the access sheath.  
     
     
         58 . A method for implanting an self-expanding device in an left atrial appendage using the device delivery system of  claim 44 , comprising: 
 inserting an access sheath percutaneously through the body's vasculature into the left atrium, wherein the access sheath has a valve assembly at its proximal end for sealably receiving the delivery tube;    directing the distal tip of the access sheath toward the ostium of the left atrial appendage;    attaching the device to the tether wire;    compacting the device and loading the device in the implant sheath extending from the delivery tube;    inserting the delivery tube through the access sheath lumen so that the implant sheath tip is at a deployment position;    translating the tether wire through the manifold to expel the compacted device from the implant sheath so that the device self expands and deploys in its natural unbiased state in the left atrial appendage;    turning the tether wire to detach the deployed device.    
     
     
         59 . The method of  claim 58  further comprising, assessing the unbiased state of the deployed device prior to turning the tether wire to detach the deployed device.  
     
     
         60 . The method of  claim 59 , wherein assessing the unbiased state of the deployed device comprises injecting radio opaque fluids through the delivery lumen into the region of the left atrial appendage for imaging.  
     
     
         61 . The method of  claim 58  wherein inserting an access sheath comprises inserting an access sheath tube having compound curvatures.  
     
     
         62 . The method of  claim 58  wherein inserting the delivery tube through the access sheath lumen so that the implant sheath tip is at a deployment position comprises advancing the implant sheath so that its tip is about flush with the distal tip of the access sheath.  
     
     
         63 . The method of  claim 62  further comprising using locking structures to mechanically couple the delivery tube and the access sheath, and moving the two together so that the implant sheath tip is at the deployment position.  
     
     
         64 . The method of  claim 62  wherein the deployment position is inside the atrial appendage.