Variable speed stent delivery system

• US 20070060999A1
• Filed: 08/16/2006
• Published: 03/15/2007
• Est. Priority Date: 08/17/2005
• Status: Active Grant

• Current Assignee: C.R. Bard, Inc. (Becton, Dickinson & Co)
• Original Assignee: C.R. Bard, Inc. (Becton, Dickinson & Co)
• Inventors: Fulkerson, John, Randall, Michael
• Granted Patent: US 7,935,141 B2
• Time in Patent Office: Days
• US Class Current: 623/1.110
• CPC Class Codes: A61F 2/95 Instruments specially adapted for placement or removal of stents or stent-grafts
• CPC Class Codes: A61F 2/9517 handle assemblies therefor
• CPC Class Codes: A61F 2/966 with relative longitudinal movement between outer sleeve and prosthesis, e.g. using a push rod

Abstract

A delivery system for deploying a medical device, such as a stent, at increasing deployment speed is described. The system comprises a catheter comprising a catheter shaft, a retractable sheath slidably mounted on the catheter shaft, and the device in a compressed state sandwiched between the shaft and sheath. A control handle is included with a housing and knobs for a user to apply a rotary or other force to retract the sheath. The sheath is attached to a slider that is mounted on a slide rod and attached to a drive belt. A take up pulley is provided in the housing and connected to the belt input knob, so that the pulley turns when the knob is turned. The belt is attached to the pulley so that the drive is wound onto the rotating pulley. As the belt winds upon the pulley, the overall outside diameter of the pulley increases, thereby increasing the deployment speed.

Claims

1. A delivery system for deploying a medical device at variable speeds, comprising:

a catheter assembly comprising an elongate shaft and an elongate sheath including a lumen in which the shaft is positioned, wherein the sheath is movable relative to the shaft from an initial position in which the medical device is sandwiched between the sheath and the shaft to a final position in which the medical device is exposed; and

a control handle comprising a connector element attaching an end of the sheath to the control handle and a variable speed mechanism attached to the connector element, wherein the variable speed mechanism operates to move the connector element from a first position to a second position at a retraction speed that varies from an initial speed to a final speed that is higher than the initial speed, whereby the attached sheath is moved from the initial position to the final position.

2. The system of claim 1, wherein the retraction speed increases substantially continuously from the initial speed to the final speed.

3. The system of claim 2, wherein the connector element is moved along a linear path and the retraction speed is measured as a linear velocity.

4. The system of claim 1, further comprising a user input element connected to the variable speed mechanism for receiving a substantially constant user input force, the variable speed mechanism operating to translate the user input force into the varying retraction speed.

5. The system of claim 1, wherein the variable speed mechanism comprises:

a slide rod mating with a passageway in the connector element, whereby the connector element is able to slide along the length of the slide rod;

a take up pulley; and

a drive belt attached at a first end to the connector element and at a second end to the take up pulley, wherein the drive belt is wrapped onto a contact surface of the take up pulley when the take up pulley is rotated and moves the attached connector element at the varying retraction speed.

6. The system of claim 5, further comprising a user input element adapted for rotation in response to an input force applied by a user, a translation member rigidly attached to the user input element to rotate with the user input element, wherein the translation member is linked to the take up pulley to rotate at an angular velocity based on the input force.

7. The system of claim 6, wherein an overall outer diameter of the idler pulley, comprising an outer diameter of the idler pulley and wrapped portions of the drive belt, increases with rotation of the take up pulley, whereby the angular velocity increases based on the input force with a resultant increase in the retraction speed.

8. The system of claim 5, wherein the variable speed mechanism further comprises an idler pulley mounted within the system to freely rotate and to support the drive belt to pull the connector element toward the idler pulley on the slide rod as the drive belt is wrapped onto the take up pulley.

9. A hand-operated apparatus for deploying a self-expandable stent by retracting an outer sheath covering the stent, from an initial position to a final position, comprising:

a handle;

a slide block positioned within the handle and connected on a first side to the outer sheath;

a slide rod attached rigidly at a first end to the handle and engaging a passageway of the slide block at a second end, whereby the slide block is capable of sliding along the slide rod;

a knob mounted on an external surface of the handle;

a translation element rigidly attached to the knob to rotate with the knob, the translation element extending into the handle;

a take up pulley within the handle connected to the translation element to rotate with the translation element; and

a flexible drive element attached at a first end to a second side of the slide block opposite the first side and attached at a second end to the take up pulley, wherein the drive element is wrapped onto an external surface of the take up pulley as the take up pulley rotates and the flexible drive element pulls the slide block along the slide block causing the attached outer sheath to move from the initial position to the final position.

10. The apparatus of claim 9, wherein during the wrapping of the drive element onto the take up pulley layers of the drive element at least partially overlap, whereby an overall outer radius of the take up pulley, comprising an outer diameter of take up pulley and layers of the drive element, increases with the rotation of the take up pulley.

11. The apparatus of claim 10, wherein for a fixed rotation rate of the knob the slide block moves along the slide rod in a direction opposite the first side at a retraction speed that increases from an initial speed to a higher final speed.

12. The apparatus of claim 11, wherein the increase in retraction speed is substantially continuous.

13. The apparatus of claim 10, wherein the flexible drive element comprises a belt segment and further comprising an idler pulley mounted within the handle to freely rotate and supporting the belt segment between the slide block and the take up pulley.

14. A stent deployment apparatus, comprising:

a shaft having proximal and distal ends;

an expandable stent mounted over the distal end of the shaft;

a retractable sheath slidably mounted on the shaft, the sheath being retractable from a fully extended position in which the stent is covered by the retractable sheath and a fully retracted position in which the stent is exposed; and

a flexible drive member linked to an end of the sheath distal to the distal end of the shaft and a take up pulley driven at a fixed user input rotation rate, the flexible drive member being attached to a contact surface of the take up pulley such that when the take up pulley rotates the flexible drive member is wound upon the contact surface and upon previously wound portions of the flexible drive member.

15. The apparatus of claim 14, further comprising:

a handle;

a slide block positioned within the handle and connected on a first side to the sheath;

a slide rod attached rigidly at a first end to the handle and engaging a passageway of the slide block at a second end, whereby the slide block is capable of sliding along the slide rod;

a knob mounted on an external surface of the handle and rotating at the user input rotation rate; and

a translation element rigidly attached to the knob to rotate with the knob and to the take up pulley, the translation element extending into the handle;

wherein the flexible drive member is attached at a first end to a second side of the slide block opposite the first side and attached at a second end to the take up pulley, wherein the flexible drive member pulls the slide block at the retraction speed along the slide block causing the attached outer sheath to move from the fully extended position to the fully retracted position.

16. The apparatus of claim 15, wherein during the winding of the flexible drive member onto the take up pulley, layers of the drive member at least partially overlap to increase an overall outer radius of the take up pulley comprising an outer diameter of take up pulley and the layers of the drive element with the rotation of the take up pulley.

17. The apparatus of claim 16, wherein for the fixed user input rotation rate of the knob the slide block moves along the slide rod in a direction opposite the first side at the retraction speed which increases from an initial speed to a higher final speed.

18. The apparatus of claim 15, wherein the flexible drive member comprises a belt segment and further comprises an idler pulley mounted within the handle to freely rotate and to support the belt segment between the slide block and the take up pulley.

19. A stent deployment apparatus, comprising:

a shaft having proximal and distal ends;

an expandable stent mounted over the distal end of the shaft;

a retractable sheath slidably mounted on the shaft, the sheath being retractable from a fully extended position in which the stent is covered by the retractable sheath and a fully retracted position in which the stent is exposed;

a take up pulley with a conical contact surface rotating at a fixed user input rotation rate;

and a drive belt linked to the outer sheath and to the take up pulley such that the drive belt wraps onto the contact surface from a smaller cross sectional portion to a larger cross sectional portion.