Patent Application
20050131446
This invention relates generally to catheter systems used in treatment of stenoses within blood vessels. More specifically, the invention relates to a catheter having a distal occlusion balloon that is protected against damage by a treatment instrument proximal to the occlusion balloon.
Human blood vessels often become narrowed or blocked by atherosclerotic plaque, thrombi or other deposits. Such stenoses reduce the blood-carrying capacity of the vessel and can cause serious and permanent injury, even death. When significant stenosis is detected, medical interventions are performed to prevent major adverse events such as myocardial infarction, stroke or death. Besides surgical modalities, there are less-invasive transluminal catheterization techniques, such as balloon angioplasty, atherectomy, deployment of stents and introduction of medication by infusion. These catheter-based treatments carry a risk of dislodging particles of the stenotic material, which can move downstream to cause an embolism. Thus, there is a need to contain and remove such embolic debris.
Systems of catheters and/or guidewires are used in the treatment of stenoses and emboli containment within blood vessels. Before moving an interventional catheter into a stenosis, a distal protection catheter can be advanced through the stenosis into a position such that an occlusion balloon can be inflated distal to the stenosis. The distal protection catheter typically also serves as a guidewire for a treatment catheter that slides there over. As described in U.S. Pat. No. 6,569,148, for example, an inflated distal occlusion balloon can block distal blood flow to prevent distal embolization by particulate debris entrained in the blood. Such occlusion balloons are thin-walled and fragile, and are subject to damage from treatment catheters approaching from the proximal side of the balloon. It is challenging to avoid such contact with occlusion balloons because catheterization procedures take place under the visual limitations of fluoroscopy, sometimes in the coronary arteries of a beating heart. The consequence of damage to an occlusion balloon may be that it leaks and deflates, releasing any captured embolic particles, thus defeating the purpose of the distal protection catheter. It is desirable to protect a distal occlusion balloon from being damaged by a treatment catheter approaching from the proximal side of the occlusion balloon.
The present invention addresses the need to prevent treatment instruments from sliding forward into contact with the occlusion balloon of a distal protection catheter. It will be appreciated that, as used herein, the term “catheter” is broadly used to refer to a number of medical instruments, including without limitation, occlusion catheters or guidewires, therapy catheters and the like.
One aspect of the present invention provides a catheter for treating a vascular condition. The catheter includes an elongate catheter shaft, an occlusion balloon disposed on a distal region of the catheter and a stop member disposed on the catheter shaft proximal the occlusion balloon.
A second aspect of this invention provides a system for treating a vascular condition including an occlusion balloon catheter having a stop member disposed on the catheter proximal the occlusion balloon, and a treatment instrument.
The present invention is illustrated by the accompanying drawings of various embodiments and the detailed description given below. The drawings should not be taken to limit the invention to the specific embodiments, but are for explanation and understanding. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof. The foregoing aspects and other attendant advantages of the present invention will become more readily appreciated by the detailed description taken in conjunction with the accompanying drawings. The drawings are not to scale. In all the figures, like elements share like reference numbers.
System 10 for treating a vascular condition also includes conical stop member 40 mounted about distal region 16 at a location proximal to occlusion balloon 20. Conical stop member 40 comprises a frustum of a cone with its base facing in the proximal direction (to the left in all figures). Conical stop member 40 may be a hollow rigid funnel, a hollow collapsible funnel or, a solid frustum of a cone. Conical stop member 40 may be spaced a relatively short distance from balloon proximal end 23, as shown in
Conical stop member 40 may be formed of material selected from the group consisting of polyolefins, ethylene vinyl acetate (EVA), polyamides, polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET), ionomer (SURLYN), polyethylene block amide copolymer (PEBA), and urethanes.
The shaft of catheter 15 may be formed of various polymeric materials commonly used for catheter construction. For catheter 15 to also be used as a guidewire for treatment catheters, it may preferably be formed of a hypotube comprising metal such as stainless steel or TiNi (nitinol), and it may also have a flexible distal tip such as a coil spring (not shown). Catheter 15 may also be provided with a coating on its outer surface. Slippery coatings may be hydrophilic or hydrophobic, such as TEFLON or a silicone composition. Antithrombogenic coatings such as heparin compounds may also be used. Suitable coatings and their application methods are well known in the art. Additional details relative to the catheter systems described herein may be found in U.S. Pat. No. 6,569,148.
During treatment of a patient, catheter 15 may be advanced through the patient's vasculature, such as vessel 30, until occlusion balloon 20 and stop member 40 are positioned distal to stenosis 100. As illustrated in
The annular space between catheter 15 and treatment instrument 60 may, optionally, be large enough to provide an intermediate pathway for irrigation, infusion of drugs or aspiration of the treatment area. Stop member 40 has an outer diameter large enough to prevent treatment instrument 60 from sliding forward into contact with occlusion balloon 20. If treatment instrument 60 slides along catheter 15 distally of stenosis 100, then conical stop member 40 stops the distal movement of treatment instrument 60 before it can contact, and possibly damage, occlusion balloon 20. If occlusion balloon 20 were to be damaged during treatment of stenosis 100, then occlusion balloon 20 could deflate unexpectedly, thus permitting the unplanned resumption of blood flow, which may carry any captured embolic particles downstream to embolize. During a normal treatment, static blood containing any dislodged particles is aspirated after use of treatment catheter 60. Then, occlusion balloon 20 is deflated to allow uncontaminated blood to begin flowing again, and system 10 is removed from the patient.
Stop balloon 50 is conveniently inflatable and deflatable, like occlusion balloon 20. However, by using thicker and/or stronger material, stop balloon 50 is relatively more resistant to damage from abutting treatment instruments 60. Stop balloon 50 may be formed from the same group of materials described above with respect to making occlusion balloon 20; Namely, thermoplastic elastomers, including styrenic TPEs such as styrene-ethylene-butylene-styrene (C-FLEX), natural rubbers (latex), synthetic rubbers (silicone), polyesters, polyolefins, polyamides, polyvinyl chloride, and combinations of the above, such as block copolymers.
During treatment of a patient, catheter 15 may be advanced through the patient's vasculature, such as vessel 30, until occlusion balloon 20 and stop balloon 50 are positioned distal to stenosis 100. As illustrated in
Balloon stop 50 has an inflated diameter large enough to prevent treatment instrument 60 from sliding forward into contact with occlusion balloon 20. To perform its stop function, inflated balloon stop 50 does not need to contact the inner wall of vessel 30, although such contact may occur, especially in tortuous vessels. Thus, the inflated diameter of balloon stop 50 is typically smaller than the inflated diameter of occlusion balloon 20. The inflated shape of stop balloon 50 may be spherical or elongate. In one embodiment, stop balloon 50 may have an inflated diameter of about 0.020 inches (0.51 mm) and a length of about 2 mm with proximal and distal ends of stop balloon 50 each being affixed to the shaft of catheter 15 along a length of approximately 1 mm. Stop balloon 50 can be mounted to catheter 15 with adhesive, and with or without clamp rings, as will be understood to those of skill in the field of balloon catheters. Comparable to the embodiments described above, balloon stop 50 may be spaced a relatively short distance from balloon proximal end 23, as shown in
Mesh stop 70 may be formed from braided metal wires such as TiNi (nitinol) or stainless steel, or from braided polymeric filaments. Ends 73, 75 of mesh stop 70 may be attached to catheter 15 and to actuator sheath 80, respectively, by solder, adhesive or by mechanical attachments such as crimp bands. In response to relative sliding movement between actuator sheath 80 and the shaft of catheter 15, mesh stop 70 is transformable between the collapsed configuration shown in
During treatment of a patient, catheter 15 and actuator sheath 80 may be advanced through the patient's vasculature, such as vessel 30, until occlusion balloon 20 and mesh stop 70 are positioned distal to stenosis 100. As illustrated in
Additionally, prior to advancing treatment catheter 60 into and through stenosis 100, mesh stop 70 is expanded by pushing actuator sheath 80 distally while pulling catheter 15 proximally, causing the diameter of mesh stop 70 to increase as the length of mesh stop 70 decreases. To protect occlusion balloon 20, the expanded diameter of mesh stop 70 needs to be only large enough to block advancement of treatment instrument 60. Thus, the expanded diameter of mesh stop 70 does not need to contact the inner wall of vessel 30, although such contact may occur, especially in tortuous vessels. Once mesh stop 70 is expanded, sheath 80 may be temporarily held in position with respect to catheter 15 by a friction mechanism (not shown). The friction mechanism may include slight distortions or wave-like bends along a section of catheter 15. Sheath 80 fits closely around catheter 15 so the slight bends can provide sufficient normal force to hold the two parts in a fixed relative position until the clinician collapses mesh stop 70 by pulling actuator sheath 80 proximally while pushing catheter 15 distally. Actuator sheath 80 may also be held in place by an external mechanical locking mechanism (not shown) provided at the proximal end of catheter 15. Both mesh stop 70 and occluder balloon 20 are collapsed to remove system 14 from the patient.
As in the other embodiments of the current invention described above, mesh stop 70 prevents treatment instrument 60 from sliding distally over catheter 15 and actuator sheath 80 into contact with occlusion balloon 20. Thus, the fragile occlusion balloon 20 is not damaged. Mesh stop 70 may be spaced a relatively short distance from balloon proximal end 23, as shown in
Although the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.
