"SUPPLY PROBE SYSTEM" STENT "(EXTENSOR)"FIELD OF USEThis invention is in the field of probes for placing the "stents" (extensors) in a stenosis of a vessel of a human body.
BACKGROUND OF THE INVENTIONThe intravascular stents well known in the field of interventional cardiology for the treatment of arterial stenosis. When placed through the vascular system of the body, most "stents" are mounted on a balloon angioplasty probe with or without a cylindrical lining that covers the "stent" of the stent deployment by expanding the balloon into the site of a dilated stenosis. Self-expanding agents that are almost always contained within a cylindrical liner that pulls back to release the stent. If the lining is not used, the rough surface of the stent may damage or remove the endothelial cells of the arterial wall as the outer surface of the stent rubs the inner walls of the curved coronary arteries (or others). Without a liner, the stent may also be retained in the guide probe during movement in or out of the body that can cause the stent to detach from the delivery probe and embolize into the vasculature. When a liner is used, it can have a few disadvantages. A first disadvantage is that all linings of the prior art are tubes having uniform wall thicknesses and which are secured only at the proximal end of the "stent" delivery probe system. Therefore, in order to have a sufficient column strength, the lining should be relatively thick walls, throughout its length, which makes it rigid and bulky so that the passage through the sinuous coronary arteries can difficult. Another disadvantage of prior art liners is that they have blunt, distant ends that can be retained in an unfolded stent, a calcified piece of intimal dissected tissue or a restricted stenosis. Still further, when only the proximal end of a "stent" delivery probe is secured, the liner frequently either exposes the "stent" due to significant flexion of the "stent" delivery probe or the "stent". Lining advances too far beyond the distant end of the stent. Finally, due to the larger diameter, the blunt end and the stiffness of the stent delivery systems lined with the rough outer surface of the unlined stent delivery system, the pre-dilatation of another angioplasty probe The balloon is almost always required before the implantation of the stent. Another disadvantage of existing stent delivery probe systems that use either a conventional liner or have "bare" stents mounted on inflatable balloons, is that the remote steerable pushing force for these "stent" delivery probes "comes only from the internal and external arrows of the balloon angioplasty probe where an inflatable balloon is placed. Specifically, in no prior art device does the liner contribute to the thrust capability of the "stent" delivery probe system.
COMPENDIUM OF THE PRESENT INVENTIONThe present invention is a "stent" delivery probe system for placing a "stent" within a stenosis in a vessel of a human body. The stent delivery probe system uses a slidable liner with a thin-walled distal portion that is coaxially positioned above the stent and placed in a balloon placed in the distal portion of a balloon angioplasty probe. The distal end of a central portion of the liner has an inner shoulder which is capable of exerting a thrust force directed remotely on the balloon angioplasty probe, at a point just proximal to the "stent". This pushing force is then transferred through the stent not deployed to a gradually tapering distant point., highly flexible, distant tip coated in the lubricity of the balloon angioplasty probe. The structure of a continuous external surface extending backward from the distant tip and toward the distant section of the liner, plus the coating on the lubricity of the outer surfaces of the distant tip and the liner, plus the pushing ability of the system. the increased stent delivery probe provided by the liner and the stent makes it possible for the stent delivery probe system to be pushed through the stenosis still very restricted. After the stent delivery probe system is advanced through a guidewire so that the undeployed stent is placed at the site of the stenosis, the liner is then pulled back, the balloon is inflated and the "stent" is pushed radially outward resulting in dilation of the stenosis. In this way, the stent can be placed in a very restricted stenosis without requiring pre-dilatation of that stenosis.
A preferred embodiment of the liner uses a thin walled metal tube for the proximal section of the liner, which constitutes approximately 80 percent of the length of the liner. A central portion of the liner is a flexible plastic tube with comparatively thick walls, or a more plastic wire tube, the distal end of which has an inner shoulder that couples a structure in the balloon angioplasty probe at a point just proximal to the " stent "in order to exert a thrust force at that point towards the distant portion of the balloon angioplasty probe. The distant portion of the liner is a short tube(typically 2 to 5 centimeters long) which is very thin walls and highly flexible. The object of using minimum wall thickness is to increase the flexibility and decrease the outer diameter of the liner, in order to facilitate pushing the distal section of the stent delivery probe system through a restricted stenosis. One embodiment of this invention has a proximal radiopaque marker band and a remote radiopaque marker band, which are positioned just proximally and just distantly relative to the "stent". Also, the "stent" can advantageously be placed between the elastic tubes proximal and distant to pass over the inflatable balloon and are located just inside the radiopaque marker bands. The proximal elastic tube prevents the stent from being pulled back out of the balloon when the liner is pulled back before deployment of the stent. Both radiopaque marker bands and both elastic tubes allow the pushing force exerted by the liner to be transmitted to the distal tip of the probe system. Another embodiment of this invention uses only proximal and distant elastic tubes that surround the "stent" but without any radiopaque marker bands. However, for this embodiment, the elastic tubes include a highly radiopaque metal powder within the elastomer of the elastic tube to improve the radiopacity of the tube in order to help place the stent at the site of the stenosis. Thus, an object of this invention is to have a "stent" delivery probe system having a liner with an inner shoulder positioned at the distal end of a central portion of the liner, which inner shoulder can exert a thrust force. directed remotely at a point just proximal to a non-deployed stent mounted on a balloon, at a distant portion of a balloon angioplasty probe.
Another object of this invention is to have a distal portion of the liner which is a plastic tube or plastic tube plus thin-walled wire, thereby minimizing the outer diameter of the liner and increasing flexibility. Still another object of this invention is to use a non-deployed "stent" mounted on a balloon, at a distant portion of a balloon angioplasty probe to transmit a thrust force directed remotely towards the gradually tapering distant tip of a probe system of "stent" supply. Still another object of this invention is to utilize the proximal end of a radiopaque marker band positioned proximal to the stent at a point where the inner shoulder of a liner exerts a pushing force directed remotely toward the distal portion of an angioplasty probe. of the balloon. Yet another object of this invention is to utilize the proximal end of a radiopaque elastic tube positioned proximal to the stent as a point at which an inner shoulder of a liner exerts a pushing force directed remotely towards the distal portion of the probe. balloon angioplasty. Still another object of this invention is to use elastic tubes positioned just proximal and just distant from the "stent" as a means for bringing a pushing force directed remotely towards the gradually tapered distal tip of the "stent" delivery probe system. Still another object of this invention is to have a "stent" delivery probe system that utilizes a highly flexible tip, elastomeric, gradually tapering, coated with lubricity, in order to push a distal section of the stent delivery probe system through a restricted stenosis. Still another object of this invention is to locate the radiopaque marker bands and / or the radiopaque elastic tubes placed just proximal and at a distance from a "stent" instead of placing these devices inside an angioplasty balloon, under the "stent" whose placement within of the balloon results in an increased outer diameter for the undeployed stent. Still another object of this invention is to use elastic tubes positioned just proximally and remotely relative to a "stent" to prevent the stent from being dislodged from its centered position in an inflatable balloon. Still another object of this invention is to use elastic tubes positioned just proximally and distantly with respect to a "stent" to prevent the stent from dislodging from its post-deployed position in the artery because the elastic tubes push inward the "fins" that regularly form in the balloon after it deflates, whose "fins" could attach the deployed "stent" causing the inadvertent displacement of the "stent" during the removal of the balloon probe. Still another object of this invention is to have a "stent" delivery probe system that can place a "stent" in a restricted stenosis without first pre-dilating that restricted stenosis. Still another object of this invention is to utilize a slotted central section of the liner through which the guidewire that permits rapid exchange capability for the "stent" delivery probe system. These and other objects and advantages of this invention will become apparent from the detailed description of the invention and the associated drawings that are provided therein.
BRIEF DESCRIPTION OF THE DRAWINGSFigure 1 is a longitudinal cross section of a "stent" delivery probe system illustrating the structure of the proximal and distant sections of the "stent" delivery probe system. Figure 2 shows a longitudinal cross-section of the distal section of the "stent" delivery probe system as it would be placed in an arterial stenosis before the deployment of the stent. Figure 3 is a longitudinal cross-section of the distal section of the "stent" delivery probe system with the liner pulled back exposing the "stent" in this way. Figure 4 shows a longitudinal cross-section of the distal section of the stent delivery probe system with an inflated balloon and the stent deployed outward in order to dilate the stenosis. Figure 5 is a longitudinal cross section of the dilated stenosis showing the "stent" deployed radially outward and the "stent" delivery probe system removed from the patient's artery. Figure 6 is a longitudinal cross section of the distal section of the stent delivery probe system using radiopaque elastic tubes positioned just proximal and distal to the stent.
Figure 7 is a longitudinal cross-section of the "stent" delivery probe system illustrating a slotted liner that permits rapid exchange capability for the "stent" delivery probe system. Figure 8 is a highly amplified cross-section of the rapid-exchange stent delivery probe system in section 8-8 of Figure 7. Figure 9 is a highly amplified cross-sectional view of a transducer probe system. fast-exchange stent supply in section 9--9 of Figure 7. Figure 10 is a highly amplified cross-section of the rapid-exchange stent delivery probe system in section 10-10 of the Figure 7DETAILED DESCRIPTION OF THE INVENTIONFigure 1 is a longitudinal cross section of a stent delivery probe system 5 that is formed in three sections, namely; a proximal section 6, a central section 7 and a distant section 8. The "stent" delivery probe system 5 consists of a balloon angioplasty probe 10, a slidable liner 30, a "stent" 40 and a guidewire 50.
Balloon angioplasty probe 10 consists of an outer arrow 11, an internal arrow 12, a band 13P of the radiopaque marker nearby, a band 13D of the distant radiopaque marker, a proximal elastic band 14P, a distant elastic band 14D and a tip 24 elastomeric distant, having a thin-walled cylindrical end 25. At the proximal end of the balloon angioplasty probe 10 there is a Luer fitting 20 through which the guide wire 50 can be passed into the central passage 19. Also at the proximal end of the balloon angiplasty probe 10 there is a lateral arm 21 having a Luer fitting 22 and a central passage 26 remaining in fluid communication with the annular passage 17 which lies between the internal surface of the arrow 11 external and the external surface of the internal arrow 12. In section 8 remote from the stent delivery probe system 5, the balloon angioplasty probe 10 has a distal portion including an angioplasty balloon 23 whose inner chamber 29 is in fluid communication with the annular passage 17 and the central passage 26 of the lateral arm 21. In this way, a source of inflation fluid can be inserted or removed from step 26 to inflate and deflate the balloon 23. Mounted on the balloon 23, there is a stent 40 expandable by a balloon of any design that is well known in the balloon expandable stents technique. The slidable liner 30 is located coaxially around the balloon angioplasty probe 10. In the next section 6 of the system, the liner 30 has a Tuohy-Borst fitting consisting of a main body 31 having a side arm 39 with a 33 Luer fitting; the lateral arm 39 has a central passage 38 which remains in fluid communication with the annular passage 27 which lies between the inner surface of the liner 30, and the outer surface of the external arrow 11. The main body 31 of the Tuohy-Borst fitting has a threaded proximal end into which a connection and disconnect nut 35 can be screwed. The advancement of the nut 35 compresses an elastomeric stuffing box 37 which causes a fluid seal to be pressed against the external surface of the outer arrow 11. When this fluid seal exists, blood will not leak from the Tuohy-Borst fitting and the contrast fluid may be injected through the passage 38 of the lateral arm 32, in order to extract air from the annular passage 27. The liner 30 has a thin-walled metal tube 32 for most of its length, the length of which is approximately 110 centimeters. As shown in the central section 7 of the system, the distal end of the tube 32 is attached to the proximal end of a flexible tube 34 whose distal end (placed in the section 8 remote from the system) has an inner shoulder which remains in contact with the proximal end of the nearby radiopaque marker band 13P. A highly flexible thin-walled tube 36 is fixedly fixed at its proximal end to the distal end of the flexible tube 34. The distal end of the flexible tube 36 is configured to move slidably above a proximal section 24P of the tip 24. The metal tube 32 would typically be formed of stainless steel or nitinol with a wall thickness of between 0.01 millimeter and 0.1 millimeter. The external diameter for the lining 30 would typically be between 1.0 mm and 3.0 mm. The elastic tube 36 would typically have a wall thickness of between 0.01 millimeter and 0.1 millimeter and would be made of any material typically used for probes. Ideally, tube 36 would be formed of a plastic tube in which longitudinal metal wires are placed to prevent the tube from wrinkling. Ideally, these wires would be made of stainless steel or nitinol. The flexible tube 34 would typically have twice the wall thickness as the elastic tube 36. The construction of tube 34 will typically be a composite of a metal wire with a plastic material, typically used for intravascular probes.
The operation of the "stent" delivery probe system 5 is best explained with the help of Figures 2, 3, 4 and 5. Figure 2 shows a distant section 8 that has already been advanced above the wire 50 of guide until the undeployed stent 40 is centered within an arterial stenosis 2 placed within an artery 1. The radiopaque marker bands 13P and 13D are used by the doctor implanting the "stent" 23 to center the stent. 23 in the stenosis 2. It should be understood that the very tapered shape of the tip 24, and the external continuous surface of the tip 24 and the outer surface of the cylinder 36, each of which may have a lubricated outer coating, facilitates penetration through a restricted arterial stenosis. The tip 24 can be made radiopaque by forming the same as a composite of a dense metal such as tungsten, in an elastomer such as polyurethane. Figure 3 shows the liner 30 pulled back so that the "stent" 40 can easily expand. The traction backward of the liner 30 is achieved by retaining the Luer fitting 20 in the proximal portion of the fixed stent delivery probe 10 while the nut 35 of the Tuohy-Borst fitting is pulled back in the proximal portion of the liner. 30. This is achieved after the nut 35 has loosened to a certain degree so that the stuffing box 37 slides easily over the outer arrow 11. Figure 4 shows an inflated balloon 23 'which causes the stent 40' to dilate the stenosis 2 '. It should be noted that the elastomeric tube 14P 'and 14D' is distorted when the balloon 23 'is inflated. After the balloon 23 'is deflated, the tubes 14P' and 14D 'return to their original shape as shown for the tubes 14P and 14D in Figures 1, 2 and 3. Figure 5 shows the "stent" 40' in place with balloon angioplasty probe 10, liner 30 and guidewire 50 removed from the patient's arterial system. Even when the delivery probe system 5 of"Stent" is very valuable for the extension of the stenosis in the coronary arteries, it should be understood that it can be used in any spleen of the human body. It should also be noted that the system 5 can be easily used in restricted arterial stenosis without requiring pre-dilation by means of a separate, spaced, very low profile balloon angioplasty probe. This ability to insert the stent without pre-dilation saves both time and cost when stents are placed in an arterial stenosis. It should also be noted that the elastic tubes 14P and 14D exactly center the "stent" 40 in the balloon 23. Likewise, the tube 14P prevents the "stent" 40 from moving in the proximal direction, when the liner 30 is pulled back. Still further, it should be noted that this invention can be used with either balloon-expandable or self-expanding stents, and the balloon angioplasty probe can either be of the "above wire" design or a fast exchange ". The most important capability of the stent delivery probe system 5 is its ability to push through even very restricted stenosis. This capability originates from the various specific aspects of the design of the probe system 5, namely the small outer diameter of the tube 36 due to its thin wall, the extraordinarily gradual tapering of the distant tip 24 coated in lubricity, the continuous outer surface from the tip 24 to the tube 36, and the very high pushing force directed at distance achieved by means of the liner 30 acting through the stent 40 not deployed. A "gradually tapering" tip 24 is obtained when the average tip inclination relative to the longitudinal axis of the central passage 19 in the distal portion of the balloon angioplasty probe 10 is less than 3 degrees and never more than 10 degrees. Optimally, an average tilt for tip 24 is - -would determine from the maximum radius of 0.6 mm at the proximal end of the point to a radius of 0.22 mm at the far end of the points. With a tip length of 15 millimeters, it provides an average tip inclination 24 of 0.6 - 0.22 / 15 = 0.025, which is an angle of inclination of about 1.5 degrees relative to the longitudinal axis of central step 17 of the distant portion of the 10 probe of balloon angiplasty. This gradual tapering greatly improves the ability of the stent delivery probe system 5 to penetrate through a restricted stenosis. The system 5 obtains its ability to push the distant tip 24 through a stenosis restricted by a series of structures, each of which is capable of significant thrusting capacity. This series of structures that provide excellent thrust capability for the stent delivery probe system 5 are the following: (1) The Tuohy-Borst attachment at the proximal end of the liner 30, whose attachment is outside of the body of the patient. (2) The typically thin-walled stainless steel tube 32 that extends through most of the length of the stent delivery probe system 5. (3) The flexible tube 34 of comparatively thin walls which is typically a composite cylinder made of wire and an elastomeric plastic. (4) The proximal radiopaque marker band 13P, whose outer diameter is larger than the inner diameter of the inner shoulder placed at the distal end of the flexible tube 34, therefore the distal end of the tube 34 can effectively apply a force of thrust directed at a distance towards the proximal end of the rigid cylindrical radiopaque marker band 13P, thereby continuing the pushing capacity of the liner 30. It is at the intersection of the inner shoulder at the distal end of the tube 34 with the proximal end of the proximal radiopaque marker band 13P that the lining capacity of the liner is transferred from the liner to a distal portion of the balloon angioplasty probe 10. (5) The pushing force is then carried forward in the distal direction by the proximal elastic tube 14P which is adjacent to the proximal radiopaque marker band 13P and also adjacent to a proximal section of the balloon 23.(6) The "stent" 23 is the following structure that transmits the pushing force directed remotely to the distant tip 24. (7) The distant elastic tube 14D which is fixed to a distal portion of the balloon 23 transmits the pushing force to the remote radiopaque marker band 13D. (8) The remote radiopaque marker band 13D, which can be molded at the distal tip 24, is the last link in the push capacity chain that enhances the ability of the stent delivery probe system 5 to push the tip 24 distant through a restricted stenosis. In summary, the pushing ability of the liner 30 as transferred to a distal portion of the balloon angioplasty probe 10 is much greater than the thrust capability of the outer arrow 11 and the internal arrow 12 per se. It should be noted that the design of the stent delivery probe system 5 allows the tube 36 remote from the liner to be both very thin and highly flexible walls and no contribution to the pushing capacity of that structure is necessary. The flexible design of thin walls of the tube36 provides improved ability of system 5 to place the "stent" 23 into a narrowed arterial stenosis because its flexibility improves passage through the sinuous vasculature of the coronary arteries, and does not require pushability from tube 36 due to that its thin wall minimizes the outer diameter of system 5, thus improving again the ability of the system to place the "stent" 23 in the restricted stenosis. Figure 6 is another embodiment of section 8 remote from the "stent" delivery probe system. The only difference between the modality of Figure 6 compared to Figure 1 is that in Figure 6, the near and distant radiopaque marker bands 13P and 13D have been removed and the elastic bands 14P and 14D have been replaced by the proximal elastic band 60P and the distant elastic band 60D. The bands 60P and 60D would typically not be longer than the bands 14P and 14D and, in addition, the bands 60P and 60D would contain certain material to make them radiopaque. Typically, powdered tungsten or tantalum could be placed in the elastomer such as silicone rubber or polyurethane to make both bands 60P and 60D elastic and radiopaque. Figures 7, 8, 9 and 10 illustrate a "stent" delivery probe system 70 that is of a "rapid exchange" design; that is, the proximal exit of the guide wire 50 is just proximal to the proximal end of the stent 40 as opposed to a "above wire" design as shown in Figure 1, where the guide wire 50 exits at the proximal end of the system 5. Figures 7 to 10 inclusive show the elastic radiopaque marker band 60P, the balloon 23, the "stent" 40, the annular passages 17 and 27 all of which elements are of the same design as shown for the Figure 1. The new aspects of the design shown in Figures 7 to 10 inclusive, include a grooved liner 61 having a narrow elongated groove or liner 62, where the liner 67 is placed. The proximal portion of the balloon angioplasty probe rapid exchange is a double-pass tube 63 having a balloon access passage 64 through which fluid can be injected or removed to inflate or deflate balloon 23. A distal portion of step 65 of the guide wire is used for insert the guide wire 50 through an orifice 66. A short wall metal junction tube 73 is very thin and is used to seal the passage 65 of the guidewire on the internal arrow 72. The outer arrow 71 is sealed by its end near the distal end of the tube 63 of the double pass. The entire structure of the system 70 that is remote from the metal connecting tube 73 is identical in construction to the remote portion 8 of Figure 6 with the exception of the groove 62 in the liner 61.
-It should be noted that the groove 62 and the wedge 67 cooperate to prevent the distal section of the liner 61 from rotating around the tube 63 of the double pass. The length of the slot 62 is sufficient to allow the thin-walled tube 35 to be pulled back far enough to fully discover the "stent" 40. Various other modifications, adaptations, and alternative designs are certainly possible in view of the teachings previously cited. Therefore, it should be understood at this time that within the scope of the appended claims, the invention may be practiced in a manner other than that specifically described herein.