Delivery system for medical devices

Abstract

The invention is directed to a delivery system for implantation a self-expanding medical device in a body which includes a control handle and a catheter portion. The catheter portion includes an outer restraining member which covers the collapsed, medical device, an inner catheter member having a distal end including a region upon which the medical device is mounted, and an outer sheath which is removably attached to the control handle. The outer sheath creates a conduit for the catheter portion to prevent the inner catheter member from moving axially when the outer restraining member is retracted. The control handle has a rotatable thumbwheel to actuate a retraction mechanism attached to the proximal end of the outer restraining member which moves the restraining member in a proximal direction to deploy the medical device.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application is a continuation-in-part of Ser. No. 10 / 661,406 filed Sep. 12, 2003, which is assigned to the same Assignee as the present application, the contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION [0002] The present invention relates generally to delivery systems for delivering and deploying medical devices, such as stents, which are adapted to be implanted into a patient's body, such as a blood vessel and, more particularly, to a delivery system for more accurately deploying a self-expanding medical device into an area of treatment. [0003] Stents are generally cylindrically shaped devices which function to hold open and sometimes expand a segment of a blood vessel or other arterial lumen, such as coronary artery. Stents are usually delivered in a compressed condition to the target site and then deployed at that location into an expanded condition to support the vessel and help maintain it in a...

AI Technical Summary

Benefits of technology

"The present invention is a delivery system for delivering and deploying medical devices, such as stents, in a body lumen. The system includes a control handle and a catheter portion that can be advanced to a target area in the body lumen over a guide wire using the Seldinger technique. The catheter portion includes an inner catheter member and an outer restraining member that holds the medical device in a collapsed position until it is ready to be deployed. The system is designed to minimize movement during deployment, allowing for accurate placement of the medical device. The control handle is easy to use with one hand and includes a strain relief member to reduce friction during deployment. The system can be manufactured in an Rx design to improve speed and efficiency in delivering the catheter portion to the patient's body."

Problems solved by technology

One of the difficulties encountered in using prior art stents involve maintaining the radial rigidity needed to hold open a body lumen while at the same time maintaining the longitudinal flexibility of the stent to facilitate its delivery and accommodate the often tortuous path of the body lumen.

However, problems have been associated with such prior art delivery systems.

For example, systems which rely on a “push-pull design” or “pull-back design” can experience unwanted movement of the collapsed stent within the body vessel when the inner member is pushed forward which can lead to inaccurate stent positioning.

This change of the geometry of the system within the anatomy can lead to inaccurate stent positioning.

Failure to do so may result in deploying the stent beyond the target area and can cause the stent to bunch up.

When the outer sheath is retracted proximally into the deployment handle during deployment, the length of the exposed outer sheath tends to shorten.

However, the outer sheath tends to shorten during deployment, thus changing the shape of the exposed portion of the catheter.

As a result, the movement of the inner catheter member caused by the retraction of the outer sheath can cause the stent to deploy prematurely and at a location beyond the targeted site.

As a result, less than accurate deployment of the stent can occur.

However, if the delivery system is not kept straight during deployment, then the inner catheter member has this tendency to move distally during deployment.

The above-described stent delivery systems also can be somewhat difficult to operate with just one hand, unless a mechanical advantage system (such as a gear mechanism) is utilized.

Even a slight axial movement of the catheter assembly during deployment can cause some inaccurate placement of the stent in the body lumen.

In doing so, the physician usually creates a backwards force on the delivery system which also can cause the catheter portion of the delivery system to move within the patient's vasculature, resulting in less than accurate placement of the stent within the patient.

Also, some of these stent delivery systems have a limited range of retraction of the outer sheath which can limit the use of the delivery system to smaller medical devices which require only a small amount of retraction in order to expand the device.

Larger medical devices, such as vasculature grafts, may not be deployed because the control handle of the system may not retract the outer sheath a sufficient length in order to expose the entire graft.

Other problems associated with stent delivery systems include the buildup of frictional forces between the contacting surfaces of the tubing utilized to form the catheter portion of the delivery system.

Unfortunately, frictional buildup can possibly effect the performance of the control handle.

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