1. Field of the Invention
The present invention relates to surgical snares and more particularly to devices for retrieving broken, dislodged, or separated medical devices from within the vascular system.
2. Background Information
Certain snare devices have become available over recent years for retrieving malfunctioning or misplaced devices within the cardiovascular and non-vascular regions of the body. These typically consist of fairly large diameter sheaths, which house a movable central wire or wires whose distal ends are formed into a loop or loops. The loop is used to ensnare and capture the desired object for withdrawal and removal from the body. In use, the snare is typically passed through a guiding catheter or other introducing catheter that is placed within the vasculature and is directed to the vessel or area where the misplaced or malfunctioning device is located. The snare can then capture the intended device and retrieve it out of the body through the introducing catheter or by withdrawing both the snare and the introducing catheter in tandem.
Currently available snares are designed using large diameter outer sheaths that require larger entry sites. This may result in complications such as excessive bleeding and/or hematomas. Additionally, because of the large diameter of the snare, it may be necessary to remove the existing catheters and exchange to larger introducing devices, which increases the overall time and cost of the procedure. A third disadvantage of the prior snares is that the outer sheath is typically made of a plastic material that exhibits little or no torque control, which makes ensnaring the misplaced or malfunctioned device difficult. Lastly, the prior snares are stiff and typically have sharp distal leading edges, which may damage vessel walls when the device is advanced into small diameter vessels such as those in the coronary and cerebral vasculature.
Accordingly, it is an object of the present invention to provide a snare that uses a relatively small diameter outer sheath that requires only a small entry site. Another object of the present invention is to provide a small diameter snare that does not require the removal of an existing catheter or exchange to other larger devices. A third object of the present invention is to provide a small diameter snare that exhibits superior torque control, to simplify ensnaring a misplaced or malfunctioned device.
To achieve the foregoing and other objects an improved snare is provided, having a diameter of 0.39xe2x80x3 or less, that is capable of fitting through existing balloon or guiding catheters. The body of the snare includes metal tubing, which allows for a very thin wall thickness while providing stiffness for torque control and pushability. Additionally, a radiopaque coil may be attached to a distal end of the snare, to provide both visibility and a soft atraumatic leading edge.
Alternatively, or in addition, the snare employs a xe2x80x9cDxe2x80x9d shaped snare wire or wires to form the snare loop. This allows the wires to have a maximum cross sectional area within the confines of the inner diameter of the tubing, and thus, provides greater strength to the snare loop.
The snare may be further constructed with proximal end that is shaped to allow an extension to be added to the snare and thus enable catheters to be exchanged directly over the snare.