Surgery – Means for introducing or removing material from body for... – With means for cutting – scarifying – or vibrating tissue
Reexamination Certificate
2001-08-16
2004-10-19
Nguyen, Anhtuan T. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
With means for cutting, scarifying, or vibrating tissue
C604S035000, C604S043000, C606S159000
Reexamination Certificate
active
06805684
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to apparatus for use in treatment of the human body. More particularly, the present invention relates to an elongated device which may be a single catheter assembly or a multiple component catheter assembly and which is suitable for use through percutaneous or other access, for endoscopic procedures, or for intraoperative use in either open or limited access surgical procedures. Still more particularly, the present invention relates to an elongated device in the form of a waterjet thrombectomy catheter, hereinafter termed crossflow thrombectomy catheter, for fragmentation and removal of thrombus or other unwanted material from blood vessels or body cavities that uses high velocity saline (or other suitable fluid) jets to macerate the thrombus or other unwanted material. The elongated device bears certain similarities to known waterjet thrombectomy catheter constructions but differs therefrom in several material respects, a major distinction being in the provision of means which produce crossflow jets to create a recirculation flow pattern optimized for clearing a large cross section of mural thrombus or other similar material, the name crossflow thrombectomy catheter deriving from this major distinction. Further, the present invention also relates to a system constituted either by the combination of the elongated device with both pressurized fluid source means and exhaust regulation means or by the combination of the elongated device with only pressurized fluid source means.
2. Description of the Prior Art
Waterjet thrombectomy catheters have been described in which a distal-to-proximal-directed waterjet(s) flow(s) past a window, orifice or gap at the distal end of the catheter, reentering the catheter and pushing flow through an evacuation lumen. When placed in a vessel containing thrombus and activated, the high velocity jet(s) will entrain surrounding fluid and thrombus into the window, orifice or gap region, where the high shear forces of the jet(s) will macerate the thrombus. The macerated particles will be removed from the body by the pressure generated on the distal end of the evacuation lumen by the impingement of the high velocity waterjet(s).
A limitation of these waterjet thrombectomy catheters has been the inability to remove organized, wall-adherent thrombus from large vessels. In accordance with the present invention, a crossflow thrombectomy catheter is described which overcomes this limitation by optimizing the recirculation pattern at the tip of the catheter to increase the drag force exerted on the mural thrombus to break it free from the vessel wall and allow it to be removed by the catheter.
SUMMARY OF THE INVENTION
The thrombectomy effect of waterjet thrombectomy catheters has been described as using the Venturi effect to create suction at the tip of the catheter to draw thrombus into the waterjets where it is then macerated and evacuated through an exhaust lumen. However, when operating in a relatively large blood vessel, the fluid velocities in the vessel decrease rapidly as the distance from the jet increases, so that at the wall of the vessel there is a minimal amount of pressure gradient to push the thrombus towards the low pressure area of the catheter. Thus, a different force is needed to remove mural thrombus, and that source is fluid drag. Drag on a surface is proportionate to the velocity gradient at that surface. Thus, in order to maximize the drag force, the velocity gradient at the surface must be maximized.
The catheter described herein is provided with outflow means and inflow means and is designed to optimize the drag force on the surface of the vessel by synergistically utilizing inflows and outflows at the catheter tip to create a recirculation pattern. Since the blood vessel can be considered as an open system, the geometric arrangement of the outflow means and inflow means is critical to the maximization of the drag force at the wall of the vessel. Since the catheter is designed to be easily advanced axially through a blood vessel, and axial flows are more likely to dissipate before contributing greatly to recirculation, the flow vectors in the recirculation most important for creating efficient thrombectomy are in the circumferential and radial direction. Radial high velocity flow vectors are created by maximizing the flow through one or more outflow orifices where the one or more outflow orifices are designed to aim the flow perpendicular to the axis of the catheter. Circumferential high velocity flow vectors are created by the demand for entrained fluid by one or more inflow orifices and are supplied substantially from the one or more outflow orifices, with change in fluid flow direction near the vessel wall to return to the catheter.
In the preferred embodiment of the catheter, there is provided inflow means in the form of one or more inflow orifices located in an exhaust tubular means adjacent and proximal to a jet emanator means in the form of a toroidal loop jet emanator located distally on a jet body. One or more high velocity saline (or other suitable fluid) jets emanate from the toroidal loop jet emanator; these high velocity jet(s) entrain fluid, drawing flow into the inflow orifices, and can macerate thrombus drawn near the jet(s). One or more of the high velocity jets can be oriented to aid in the exhaust of macerated thrombotic material through the exhaust tubular means. Multiple inflow orifices may be formed around the circumference of the exhaust tubular means in a single axial plane. An oval-shaped inflow orifice in which the major axis lies parallel to the axis of the catheter is preferred to offer an inflow orifice as large as possible without compromising the area for inflow and the structure of the exhaust tubular means. There is also provided outflow means in the form of one or more outflow orifices located in the exhaust tubular means near the one or more inflow orifices. Multiple outflow orifices may be formed around the circumference of the exhaust tubular means in a single axial plane. Preferably, the outflow orifice(s) are located proximal to the inflow orifice(s). The outflow orifice(s) are usually located but not are limited to being located in close proximity to the inflow orifice(s). The size and quantity of the outflow orifices are determined to maximize the momentum leaving the outflow orifices while not compromising the structural integrity of the exhaust tubular means. The high velocity jets and entrained fluid create an internal pressure near the tip of the catheter. This internal pressure is partially “vented” by the outflow orifice(s). Too small of an area of the outflow orifice(s) will minimize the outflow flow rate and risk plugging of the orifice(s) by macerated thrombotic material, whereas too large of an outflow area will weaken the radial flow vector of the outflow and may reduce the ability of the catheter to exhaust the macerated thrombotic material by allowing the internal pressure at the tip to be reduced to the point that there is no driving force for the exhaust. An alternative embodiment can be made in which outflow and inflow orifices are located in the same axial plane, where the direction of flow through the orifices is determined by fluid mechanical factors, e.g., non-symmetric distributions of jets near the orifices. While single inflow and outflow orifices (or a combination inflow/outflow orifice) can be used, having multiple inflow and outflow orifices helps to create effective recirculation on all sides of the catheter, avoiding the problem of having a single orifice blocked by the vessel wall or being oriented away from the deposit.
Though not required for most applications, isolation means can be utilized, either incorporated into the catheter, or as a separate device, to isolate the portion of the blood vessel near the catheter tip during use. Isolation means can include balloons, filters, baskets, membranes, blood pressure modification, fluid flow control, or other occlusion devices such as
Beaupre Rosemary C.
Bonnette Michael J.
Bridgeman John B.
Dutcher Robert C.
Jenson Mark L.
Jaeger Hugh D.
Nguyen Anhtuan T.
Possis Medical, Inc.
Rodriguez Cris L.
LandOfFree
Thrombectomy catheter and system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thrombectomy catheter and system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thrombectomy catheter and system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3309400