Patent Application
20070265564
The present invention generally relates to intravascular catheters, and more particularly to a catheter that is equipped in the vicinity of the catheter distal end with at least one exit marker for viewing the catheter's location using imaging technology.
In a typical percutaneous transluminal coronary angioplasty (PTCA) procedure, a guiding catheter is percutaneously introduced into the cardiovascular system of a patient. The guide catheter is advanced through a vessel until the distal end thereof is at a desired location in the vasculature. A guide wire and a dilatation catheter having a flexible and expandable balloon on the distal end thereof are introduced into the guiding catheter with the guidewire sliding through the dilatation catheter. The guide wire is first advanced out of the guiding catheter into the patient's coronary vasculature, and the dilatation catheter is then advanced over the previously advanced guide wire until the dilatation balloon is properly positioned across the lesion. Once in position, the preformed balloon is inflated to a predetermined size with a liquid or gas at relatively high pressure (e.g. up to twelve atmospheres) to radially compress the arthrosclerotic plaque in the lesion against the inside of the artery wall and thereby dilate the lumen of the artery. The balloon is then deflated to a small profile so that the dilatation catheter may be withdrawn from the patient's vasculature and blood flow resumed through the dilated artery.
Restenosis may occur in an artery following PTCA or other angioplasty procedure. Restenosis is a re-narrowing of the treated coronary artery that is related to the development of neo-intimal hyperplasia within the artery in response to mechanical intervention within a vascular structure. To prevent restenosis and strengthen the treated vascular area, an intravascular prosthesis generally referred to as a stent may be implanted for maintaining vascular patency inside the artery at the lesion. The stent is mounted in a pre-deployment or compressed state around a deflated balloon, and the balloon/stent assembly is maneuvered through a patient's vasculature to the site of a target lesion. The stent is then expanded to a larger diameter for implantation in the vasculature. The stent effectively overcomes the natural tendency of the vessel walls of some patients to close back down, thereby maintaining a normal flow of blood through the vessel that would not be possible if the stent was not in place.
Typically, the proximal section of a balloon catheter includes a plurality of exit markers that are printed or otherwise located on the outer shaft. The exit markers are located at exact distances from the catheter distal end. While the catheter is advanced through a patient's vasculature toward a lesion, a physician can see the exit markers before they enter the patient and know how much catheter length has been inserted into the patient. For example, the markers allow the physician to know exactly how far it is from the catheter's point of entry to the lesion.
Locating the exit markers on the outer shaft has some advantages and disadvantages. Since the exit markers are in plain view, the physician can readily see the markers before they are advanced into the catheter point of entry. The markers are blood-contacting, however, and consequently must be made from a material that is approved by a regulatory agency as biocompatible. Some approved materials are costly or inefficient to incorporate as an exit marker. Further, obtaining regulatory approval for newly introduced materials for use as exit markers requires a great deal of time and cost.
Accordingly, it is desirable to provide a catheter that includes exit markers in a manner that prevents blood contact with the markers. It is also desirable to provide a manufacturing process in which exit markers are easily located on catheter regions that are non-blood contacting. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.
According to one aspect of the invention, a catheter having non-blood-contacting exit markers is provided. The catheter includes elongate flexible inner and outer tubular lumens having proximal and distal regions, and a plurality of exit markers formed in the proximal region. The inner tubular lumen includes an outer surface, and an inner surface, the inner surface defining a guidewire passageway. The outer tubular lumen includes an elongate, flexible, and substantially transparent outer tubular lumen having an outer surface, and an inner surface surrounding the inner tubular lumen.
According to one embodiment, the exit markers are formed on the inner tubular lumen outer surface, the exit markers being visible to the naked eye through the substantially transparent outer tubular lumen. According to another embodiment, the exit markers are formed on the outer tubular lumen inner surface, the exit markers being visible to the naked eye through the substantially transparent outer tubular lumen outer surface. According to yet another embodiment, the exit markers are integrally formed from a polymer that forms a portion of the outer tubular lumen or the inner tubular lumen.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
Returning to
In addition to the balloon 12, the catheter distal region 13 includes a distal tip 20 and marker bands 22. The balloon 24 is depicted in an expanded form in order to clearly show these components. However, before and during advancement of a catheter to a blood vessel lesion, the balloon is folded around the catheter distal end 13 and has a relatively low profile. The tip 20 is affixed as a seal at the catheter distal end 13. The tip 20 is a flexible member with a rounded nose, and is thereby adapted to guide the catheter through the tortuous pathway of a patient's vasculature while preventing damage to blood vessel walls. The marker bands 22 are located on the inner lumen 16 in the vicinity of the balloon 24. The markers 22 include a radiopaque material that can be seen using imaging techniques such as x-ray or fluoroscopy to enable their visualization during their use in the body of a patient.
Exit markers 26 are located in the catheter proximal region 12 at exact distances from the catheter distal end 23. The exit markers are used as a catheter positioning tool. The exit markers 26 are in plain view, meaning that they are formed from a material that reflects light in the visible range and can be readily seen by the naked eye of the physician before they are advanced into the catheter point of entry during catheter advancement and/or retraction through a patient's vasculature. The markers indicate how much of the catheter length has been inserted into the patient. For example, the markers allow the physician to see exactly how far it is from the catheter's point of entry to the lesion. This is particularly useful, for example, if a catheter exchange becomes necessary.
As previously discussed, conventional exit markers are printed or otherwise located on the outer shaft and consequently must be made from a material that is approved by a regulatory agency as suitable for blood contact. According to various embodiments of the invention, the exit markers 26 are located at positions along the catheter proximal region 12 that do not come into contact with blood.
As illustrated in
Turning now to
According to another exemplary embodiment, the catheter inner tubular lumen 16 and/or the catheter outer tubular lumen 14 have dual-layered architectures.
Turning now to
With the exit marker-bearing lumen having a dual-layered architecture, the markers may be formed from a wide variety of methods. As with the previous embodiments, the exit markers 26 may be printed or sprayed from a spraying nozzle onto the inner layer 30 with a durable coloring dye such as a paint or ink, or may be formed from metal or polymer rings that are crimped or otherwise embedded into the inner layer 30. Another marker forming method is an alternating polymer extrusion process by which the exit markers 26 are integrally formed into a polymer forming the inner layer. One exemplary extrusion method includes using an extruder to form the inner layer 30 by alternating between extruding a first polymer that forms almost the entire inner layer 30, and extruding a second exit marker polymer having a different color than the first polymer. Another exemplary extrusion method includes using an extruder to form the inner layer 30 by extruding the same polymer to form the entire inner layer 30, but injecting a dye into the polymer during extrusion of the exit marker portion of the layer 30.
According to another exemplary embodiment, the exit markers are part of the dual-layered inner tubular lumen 16 depicted in
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.
