MXPA97000334A - Laser ablation of angioplas catheters and balls - Google Patents

Abstract

The present invention relates to the manufacture of a balloon dilatation (20, 98) according to a method that provides high tangential strength and uniformity in the thickness of the balloon wall. A length of flexible tube (34) is axially extended and radially extended in a shape (36) that provides the biaxial orientation and strength required. Next, an excimer laser (46,66,84) is used to remove the polymeric material by photochemical ablation, practically without thermal effects. The walls of the dilatation balloon are thinned mainly along the conical sections (26, 28) between the proximal and distal stems (30, 32) of the balloon and an average working section (24) of the balloon. The removal of material, in particular near the stems of the balloon, allows a more tight winding of the balloon to provide a reduced release profile and reduces stiffness near the stems to maneuver to improve the catheter in the tortuous passages. The conical sections of the balloon are reduced to a wall thickness substantially equal to that of the middle section. Alternatively, a set of slots (96) is formed in each coni section

Description

OBLATION BY LASER OF ANGIQPLASTIO CATHETERS AND BONONS BACKGROUND OF THE INVENTION The present invention relates to dilatation balloon catheters used in applications such as in translummal percutaneous transluminal angioplasty (PTfI) and translummal percutaneous coronary angioplasty (PTCR) procedures, and more particularly, to improvements in such catheters and their expansion balloons for provide improved processability in smaller tortuous canals of the vascular system. Dilatation balloon catheters are known to be useful in the treatment of plaque formation and other occlusions in blood vessels. A catheter is usually used to transport a balloon dilatation to a treatment site, where liquid is applied under pressure to the balloon to extend the balloon against an obstruction. The dilatation balloon is normally mounted along the region of the distal end of the catheter and surrounds the catheter. When the dilatation balloon is extended, its part of the main body or middle section has a diameter substantially greater than that of the catheter. The proxirnal or distal stems of the balloon have substantial diameters equal to the diameter of the catheter. Distal and proxirnal conical sections, or cones, connect the middle region with the proximal and distal e, respectively. Each cone diverges towards the middle section. Between the balloon and the catheter, fusion joints form a fluid tight seal that facilitates balloon dilation by introducing a pressure liquid. Along with the compatibility with the body tissue, the main attributes considered in the design and manufacture of expansion balloons are the resistance and flexibility. Greater tangential strength or breaking pressure reduces the risk of accidental balloon breakage during dilation. Flexibility refers to the ability to adopt different forms, rather than elasticity. In particular, when it is introduced by the catheter, the dilating balloon is empty, crushed and generally wound circumferentially around the distal region of the catheter. The thin and flexible expansion balloon walls facilitate a tighter winding that minimizes the combined diameter of the catheter and balloon during insertion. In addition, flexible balloon walls improve the "ability to follow a trajectory" in the distal region, that is, the ability to bend and adapt to the curvature of the vascular conduits. A process for forming a flexible and resistant polyethylene terephthalate (PET) dilation balloon is described in U.S. Patent No. 33. 561 (Levy). A flexible PET tube is heated at least to its second order transition temperature, then stretched to at least three times its original length to axially guide the flexible tube. The axially extending flexible tube of generally cylindrical shape is then radially extended to a diameter at least three times the original diameter of the flexible tube. The shape defines the main body, axes and cones previously mentioned and the resulting balloon has a breaking pressure greater than 1.38 x LO6 Pa. The aforementioned balloons have in general a variation in the wall thickness along the cones. In particular, larger expansion balloons (eg from 3.0 to 4.0 mm in diameter when extended) tend to have wall thicknesses along the main body in the range of 0.010 to 0.20 nm. . Near the main body, the cones have approximately the same wall thickness. However, the wall thickness * diverges in the opposite direction to the main body, until the wall thickness in the vicinity of each e varies in the 0.063 mm range. The smaller expansion balloons (1.5 to 2.5 mm) have the same divergence in the walls of the cones, that is, of 0, 01 to 0.02 rnm near the main body to 0.02 to 0.04 rn near the associated stem or rod. The greater wall thickness near the rods does not contribute to the tangential resistance of the balloon, which is determined by the wall thickness along the mid-balneal region. Thicker walls of the rods reduce the balloon's and catheter's nani-ability. The dilatation balloon can not be wound so tightly, indicating that its insertion profile is greater, limiting the ability of the catheter * and balloon to treat occlusions in small vessels. U.S. Patent No. 4,963,133 (Noddin) discloses an alternative technique for forming a PET expansion balloon, wherein a length of PET flexible tube is heated locally at opposite ends and subjected to axial stretching, to form two "lowered" parts that will eventually be n the opposite ends of the finished ball. The flexible tube is stretched simultaneously in the axial direction and radially expanded with a gas. The degree of recessing of the ends of the flexible tube is said to provide control over the final wall thickness along the walls (or cones) so that the wall thickness can be equal to, or less than, the thickness of wall along the main body. This technique, however, is said to produce a breaking pressure comparatively at only about 8.10 x 10 5 Pa. Therefore, it is an object of the present invention to provide an expansion balloon having a high breaking pressure. and tangential height, without there being a variation in the thickness of the wall increasing along its proxirnal and distal cones. Another object is to provide a method for manufacturing a dilatation balloon having a considerable tangential strength, still more reproducible for the treatment of occlusions in smaller and more tortuous arterial conduits. A further object is to provide a balloon with selectively thinned portions of the balloon wall to allow more tight winding of the balloon in the circumferential direction around the distal end region of the catheter, to provide a reduced profile during balloon insertion. Still another object is to provide a method for selectively removing material by ablation of a balloon catheter and its expansion balloon, to enhance the ability to follow a trajectory and amenableness without crystallization, embrittlement or other thermal degradation of the material.

BRIEF DESCRIPTION OF THE INVENTION To achieve these and other objects, a msertable device is provided on the body and extensible. The device includes a flexible, body-compatible dilation balloon having a mounting region adapted for fluid-tight connection with the catheter or other insertion system. The dilatation balloon has a working region with a diameter substantially larger than the mounting region and which is adjusted to the attachment tissue at a treatment site sensitive to the extension of the dilatation balloon. The balloon is provided in addition to a conical region between the working region and the mounting region and diverges in the direction from the mounting region to the working region. The dilatation balloon has a breaking pressure of at least about 1101 x 106 Pa and, along the comea region, it has a practically uniform wall thickness. Preferably, given an expansion balloon with a nominal wall thickness throughout its working section, the thickness of the region comma will not be more than twice the nominal wall thickness. Even more preferably, the wall thickness along the region will not be more than 1.5 times the nominal wall thickness. Typically, the mounting region includes proximal and distal mounting sections at opposite ends of the dilatation balloon, and the working region includes an average working section of the balloon. The cornea region then includes proximal and distal conical sections disposed between the mid section and the proximal and distal mounting sections, respectively. If desired, the wall thickness along the cross sections may be approximately equal to the nominal wall thickness. The expandable and msertable device in the body is manufactured according to a method including: directing an excimer laser beam on a biaxially oriented balloon at a selected position along the outer surface of the balloon, ablating polymer material and, in this way reduce a wall thickness of the balloon in the selected position. The fabrication of the extensible and insertable device may also include the following steps as steps prior to directing the excimer laser: a) axially stretching a length of flexible polymer tubing to substantially lengthen a length of flexible tubing while heating the tubing. flexible tube up to a temperature higher than its second order transition temperature, to axially orientate the flexible tube; b) radially extending the flexible tube to substantially increase the diameter along at least a part of the length of the flexible tube while keeping the flexible tube above the second-order transition temperature, to orient radially the flexible tube, thus formed a biaxially oriented balloon with a middle section having a nominal diameter and a nominal wall thickness, extreme proximal and distal mounting sections and proxirnal and distal conical sections between the mid section and the proximal and di-verse mounting sections, respectively; c) allow the biaxially oriented balloon to cool below the second order transition temperature.

Removal of material by ablation thins the dilatation balloon wall along the comedic sections, preferably to the point where the wall thickness is just as good as the nominal wall thickness along the section. work average. Alternatively, the eaten sections may have thicknesses greater than the nominal wall thickness, but with a substantially reduced variation in thickness. In each case, the thinning step increases the workability of the balloon by increasing its flexibility near the mounting sections, and allows for a tight roll of the balloon to provide a reduced insertion profile. The ablation is preferably carried out with an excimer laser beam with a wavelength of 193 nm. although other wavelengths (eg 248 nm, 308 nn) can provide satisfactory results, the wavelength of 193 nm is the one that best adapts to minimize the thermal effects of the ablation of a PET dilatation balloon. The level of creep on the surface preferably varies in the range of about 100 to 800 mj / cm and more preferably about 160 rn / cm2. The shroud laser beam is pulsed at a repetition rate in the range of about 10 to 50 pulses per second, with a duration of each pulse in the range of about 10 to 15 ns. Within the operating limits, creep, pulse repetition rate, pulse duration and, of course, total number of pulses can be selectively varied to control the nature of the ablation by excimer laser energy. The poly-eric balloon and the catheter materials have a high characteristic absorption capacity and thus limit the penetration depth of the energy and the elimination of material. For example, the PET material of the balloon can be removed in ultrafine layers in the order of a microcontroller or a microrneter fraction, mainly as a function of the selected creep. Higher creep levels eliminate greater thicknesses of material, but they also tend to increase thermal effects. The pulse duration and pulse frequency can be increased for the amount of material removed, although again the tendency is to increase the thermal effects. In any case, in the context of the thinning of the balloon wall of a catheter in approximately 0.0L min (for example), increments of an eter or fraction of rnicrornet.ro provide an exact and controlled elimination of the material. The exposure of polimeric materials to excimer laser energy is believed to have photochemical and photothermal aspects. The above * implies the breakage of bonds and the dissociation of the molecules, causing momentary increases in pressure that expel material with little or no thermal damage. The photothermal effects are the result of brane energy of the molecules. Photothermal effects can be minimized by minimizing the energy wavelength (i.e., selecting 193 n) and minimizing creep. As a result, material is virtually eliminated without any crystallization, substantial ragilization or other undesirable alteration of the remaining polyrnepic material. Furthermore, as a result of the treatment, the wetting characteristics of the polymeric material change favorably, so that the surface is more hydrophilic and the thrombogenic. There are several techniques for removing material from the conical sections of a dilatation balloon. The balloon can be held in a mandrel and inflated to provide the section with a truncated cone profile. Then, with the excimer laser beam oriented perpendicular to the angle of the ball cone, the ablation proceeds as the mandrel and the ball rotate. Alternatively, the balloon may be stationary, "rotating", the beam of the shroud being with mirrors or other optical components. Still another alternative involves positioning the balloon evacuating against a plate in inflated orientation, before its attachment to the catheter. Then the excimer laser beam is advanced through the cones and if desired, also the axes. After ablation on one side, the ball is inverted and subjected to ablation The opposite face. The catheter may also be ablated in other positions, e.g. e. at the far end! extending LL In addition to the distal cone of the dilatation balloon, selective ablation can provide a convergent distal end, to improve the ability to follow a trajectory in terms of saving the steep turns of the vascular canals. Thus, in accordance with the present invention, polymembrane material is removed from catheters and expansion balloons by selective excimer laser removal to reduce the winding profiles of the dilatation balloon and increase the flexibility of the balloon and catheter to adopt the curvature in the arterial ducts and other body cavities. The improvements are achieved without any reduction of the tangential resistance or the breaking pressure of the expansion balloon.

BRIEF DESCRIPTION OF THE DRAWINGS For a better appreciation of the above and other advantages, reference is made to the following detailed description and drawings, in which: Figure L is a side elevational view of the distal region of a balloon catheter; Figures 2 and 3 illustrate schematically the manufacture of the catheter dilatation balloon; Figure 4 is an enlarged sectional view showing a distal portion of the dilatation balloon; Figure 5 is a schematic view of an additional apparatus for manufacturing the dilatation balloon; Figure 6 is a schematic view similar to the sectional view of Figure 4, illustrating the use of the apparatus for removing material from the dilatation balloon; Figure 7 is a sectional view similar to the one in Figure 4, showing the balloon dilatation after ablation with the excimer laser; Figure 8 is a schematic view of an alternative laser ablation apparatus; Figures 9 and 10 are schematic views of another alternative laser ablation apparatus; Figures 11 and 12 illustrate grooves formed by ablation in a dilatation balloon; Figure 13 illustrates the use of the apparatus of Figure b, after adjusting the laser beam approach angle, to remove * material from a distal end of a catheter *; Figure 14 shows the distal end of the catheter after ablation; and Figure 15 shows a distal end of the alternative catheter after ablation.

DESCRIPTION DETOLLODO DE LA REOLIZOCION PREFERIDO Returning now to the drawings, in Figure 1 the far end region is shown! of a balloon ld catheter.

The balloon catheter includes an elongated and flexible length of a catheter tube 18 constructed of a polymecop material compatible with the body, preferably a poly ester such as that marketed under the name Hytrel. Other suitable materials include polyolefins, pol-lamides, thermoplastic polyurethanes and copolymers of these materials. A dilating balloon 2 ü surrounds the catheter tube 18 along the region of the distal end. The dilatation balloon is shown in its fully extended or dilated configuration, that is, when the balloon contains a fluid under pressure. The fluid is delivered to the interior of the balloon through a lumen 22 open to the inside of the balloon and to the proximal end of the catheter tube 18 *. When fully extended, the dilatation balloon 20 includes a main body or middle section 24, essentially an axially extended cylinder concentrically around the catheter tube. Along the middle section 24, the dilatation balloon has a diameter much larger than the diameter of the catheter tube 18. For example, the external diameter of the catheter flexible tube may be approximately 1 nm. The diameter of the balloon along the working section 24 usually varies in the range of 3.0 to 4.0 nm, or in the range of 1.5 to 2.5 nm to treat obstructions of the minor vascular conduits. At the opposite ends of the middle section a proximal comedose section or cone 26 and a distal section or cone 28 are disposed. The proximal cone converges in the direction opposite the middle section towards an annular proximal mounting section or rod 30. The internal diameter of the rod 30 is practically equal to the external diameter of the catheter tube, to provide an annular connecting region along which the internal surface of the rod 30 and the outer surface of the catheter tube 18 are facing each other and are contiguous. Likewise, the distal shaft 28 converges in the distal direction from the middle section 24 to the staging or stem assembly section 32. The internal diameter of the distal rod is practically equal to the outer diameter of the catheter in the region of the rod 32. Frequently, the diameter of the distal rod 32 is smaller than the internal diameter of the proximal rod at 30, because the flexible tube 18 of the catheter is usually narrower near the distal rod than near the proximal rod. The dilatation balloon 20 is constructed of a poly merne material, preferably polyethylene terephthalate (PET). Other suitable materials include polyethylene and polyarynide. The balloon 20 is sufficiently flexible to allow and facilitate the adoption of an insertion configuration in which the balloon is emptied and wound circumferentially around the catheter tube. This reduces the transverse profile of the catheter and the balloon, allowing the insertion of the dilatation balloon into the small vascular conduits. In addition, as a response to a pressurized fluid supplied thereto, the balloon 20 should rapidly adopt the extended configuration in Figure 1. Should the PET? Another ball material is relatively inextensible, as well as flexible, the balloon 20 tends to maintain * the configuration shown in Figure 1 by increasing the fluid pressure inside it, up to a bursting pressure (much higher than the pressures found during use) at which the break occurs. Figures 2 and 3 schematically illustrate the manufacture of the dilatation balloon 20. Imitationly, a length of flexible tube 34 of PET is subjected to a tensile force as indicated by the arrows, while being heated to a temperature higher than the transition temperature is second order (eg 90 ° C). Sufficient force is applied to extend the flexible tube 34 to at least three times its original length, starting to axially orientate the flexible tube. Next, the axially extended flexible tube extends radially inside a mold 36 having an internal profile defining the shape of the extended balloon. The extension is carried out by closing one end of the flexible tube, applying a gas (eg nitrogen) under pressure to the inside of the flexible tube. The PET flexible tube is oriented biaxially as a result of the radial extension. For more information regarding this technique for the manufacture of expansion balloons, take as reference US Pat. No. Re. 33,561 (Levy), said patent being added hereto as reference. The dilatation balloon 20, manufactured as described at this point, is shown partially (distal portion) in Figure 4, it being understood that the proxirnal portion of the dilatation balloon shows similar profile and wall thickness characteristics. Throughout the mid section 24, the expansion balloon has a wall thickness ti in the range of 0.01 to 0.02 nm. Along the conical section 28, there is a variation in the wall thickness. More particularly, the wall thickness is substantially equal to Ti near the middle section, then gradually increases to a thickness in the range of 0.025 to 0.062 millimeter adjacent to the distal rod 32. The tangential strength of the dilatation balloon 20 is determined by the Formula: 6 = pd / 2t; where 6 is the tangential resistance, p is the pressure, d is the diameter of the expansion balloon and t is the wall thickness. The maximum diameter d is that of section edia 24. Accordingly, the tangential strength is determined by the wall thickness ti along the middle section. The excess wall thickness along The tapered section 28 does not contribute to the tangential resistance of the balloon. On the other hand, the excess thickness, in particular near the junction of the section 28 and the rod 32, is detrimental for several reasons. First, the excess wall thickness increases the stiffness in, and near the joint. As a result, the balloon catheter 16 is less flexible and more difficult to maneuver through the curved vascular conduits. Second, the increased wall thickness increases the balloon profile. In addition, due to the greater stiffness and the greater wall thickness at the junction, the balloon 20 is more difficult to crush and wrap circumferentially around the catheter in the insertion configuration as described above. As a result, the profile of the rolled balloon is greater than necessary, limiting unduly the access to minor vascular channels. Figure 5 illustrates a device 38 for the selective removal of polymeric material from the balloon catheter 16, reducing its profile and rigidity in the region of the dilatation balloon, and enhancing its reliability and usefulness in smaller and more tortuous bodily conduits. . The device 38 includes a mandrel 40 of elongated stainless steel. The external diameter of the mandrel is approximately equal to the diameter of the rods 30 and 32 of the expansion balloon, to allow a slidable mounting of the balloon on the mandrel. The mandrel 40 is of detachable shape in a jig 42 which operates by rotating the mandrel about a longitudinal axis. The mandrel 40 at its opposite end is held in a guide 44 to increase the stability in its rotation. Near the mandrel 40, an excimer laser 46 (ArF) is attached and generates a beam 48 of the excimer laser formed by an optical assembly 50 that includes a converging lens to direct the beam onto the external surface 52 of the expansion balloon as length of the conical section 28. Between the laser and the surface 52 of the balloon a screen 54 is interposed to define more precisely the area selected for the treatment. The mandrel 40 incorporates a lumen (not shown) for extending the expansion balloon 20, so that the balloon, when mounted on the mandrel, assumes its extended shape, the conical sections 26 and 28 having truncated cone configurations. The beam 48 of the exciter laser * is perpendicular to the outer surface of the expansion balloon along the cross section 28. The expansion balloon rotates with the mandrel 40. The beam conditioning optics, the laser and the screen can be moved generally in axial and radial direction, but more particularly parallel to the profile of the section coma 28 as indicated by the arrows in the figure. At this time, the beam 48 can be made to travel over any selected part of the outer surface of the balloon along the section of the ball.

In practice, the dilatation balloon 20 can rotate in a staggered and programmed manner, according to the pulses of beam 48 of the excimer laser. As illustrated in Figure 6, the polypnepic material can be progressively removed, running from a portion of the surface of the section near the middle section 24 toward the stem 32. In the figure, a part of the section has been removed. of the PET of the coae 20 excision by laser ablation. A dashed line at 56 indicates the profile of the original comea section. The removed material is indicated as 58, with the rest of the material showing the desired profile of the comea section 22 after the treatment, ie, showing a substantial uniform wall thickness equal to the thickness th along the middle section. Although this degree of material removal is preferred, it is understood that any degree of material removal that substantially reduces the variation in wall thickness is beneficial. The excimer laser ablation of the polyene material forms a channel in the polyrnery material, of a depth approximately equal to the diameter of the bundle 48, which is preferably directed or approximately directed to the external surface. The rotation of the balloon 20 and the translation of the assembly of the beam can be continuous or stepwise. In any case, this is done to ensure a total coverage of the desired area of removed material. This area can be covered with a continuous sweep, that is, with a closed helical model, alternatively, the area can be covered in a series of adjacent rings. From Figure 6 it is evident that in order to achieve a uniform final thickness or to substantially reduce the variation in thickness, material must be removed to a depth that progressively increases in the direction towards the rod 32. Preferably, the greatest elimination is It increases the number of incremental episodes (ie, individual pulses) applied to the surface near the rod, instead of increasing the duration of the pulse or the pulse energy (ie, the creep) that can introduce thermal effects. As desired limits, the removal of material during a given annular step or a simple rotation of the balloon can be increased by increasing the pulse rate. However, due to the thermal effects of the upper frequencies around 50 Hz, increasing the number of annular steps of the balloon is the effective way to remove additional material without introducing thermal effects. Processing with excimer laser, often also called photodesk position by ablation, is believed to have photochemical and photothermal aspects. The photochromic aspect involves the breakage of chemical bonds causing dissociation of molecules of the polymer material subjected to the energy with excimer laser. There is a localized pressure and an abrupt increase in pressure, causing the material to be expelled from the exposed area. The expelled material heats up, but quickly removes the heat from the treatment site by its extrude. Accordingly, any temperature increase of the treatment site is extremely short, and thermal effects are not produced, or are negligible. Higher levels of fluence, longer pulse durations and higher pulse frequencies will be more evident Photothermal effects involving vibration of polymer molecules. Although the actual operating parameters may vary with the poly material and the nature of the material removal, it is important to minimize the thermal effects. Excessive concentrations of heat can cause crystallization or localized fusion, making the material fragile polirnepco. In any case, flexibility and more workability of the catheter are adversely affected. Conversely, by selecting a short wavelength (preferably 193 n), shorter pulse durations, less frequency of the pulses and lower level of fluence, the decomposition is mainly photochemical and the thinning of the walls of the balloon does not materially reduce the flexibility of the balloon and the catheter. Several factors control the speed of elimination of the pollenic material, within the limits that allow the elimination without undesirable thermal effects. For example, in relation to PET, a suitable interval for the fluency level ee of 100 to 800 rnj / crn2. A preferred range would be from about 160 to 750 mj / crn2, with a preference towards the lower row of this interval to minimize * the thermal effects. A suitable pulse duration is 10-15 ns, with a pulse frequency of about 10 to 50 pulses / second, and more preferably 10 to 40 pulses / second. Again, minimizing thermal effects favors the lower part of the interval. The preferred wavelength as indicated is 193 nm (ArF laser), although the absorption characteristics of a specific polymer may favor another wavelength, eg 248 n (KrF laser) or 308 nrn (XeCl laser) for a preferred range of approximately 100 nm. 190 to 31 nm. To ensure better complete removal of the eroded material and thus ensure against thermal effects, a gas stream or flow (eg nitrogen) can be directed through the dilatation balloon, in particular to, and around the ablation site. . The flow can be generated with a source of nitrogen under pressure, as indicated in 60. When the source of 60 leaves, the nitrogen suffers a rapid decrease in pressure and cooling, so it tends to cool the area of ablation mainly by convection although also taking hot eroded material. Figure 7 illustrates the part of the dilatation balloon shown in Figure 6 after ablation with excimer laser *, with all unwanted material removed. The thickness * t2 of the wall 62 of the dilatation balloon a Throughout the section is substantially uniform, preferably varying by no more than about 10% or as much as about 25%, and substantially equal to (eg. about 25% of, and more preferably about 10% of) the thickness th of the wall along the midsection 24. Although only the distal portion of the balloon 20 has been illustrated in detail, it is carried out an almost identical laser ablation * along the proxirnal cross section 26. The wall thickness * of the balloon along both sections is substantially reduced, especially near the rods. As a result, the balloon 20 is much more squashed when it is emptied and can be wound more tightly around the catheter tube 18 to have a lower insertion profile. The flexibility and flexibility of the balloon are improved, due to the substantially reduced stiffness throughout the conical sections. These improvements are achieved virtually without crystallization, embrittlement or other undesirable change in morphology. In fact, in PET and many other polyester materials, a favorable result of excimer laser treatment is a change in wetting characteristics so the balloon is more hydrophilic in the treated area. This reduces any tendency to cause or promote coagulation.

Figure 8 illustrates an alternative apparatus 64 for the excimer laser ablation of the balloon 20. A stationary excimer laser source 66 generates a beam 68 of the preferred wavelength, 193 nrn. The beam 68 is directed through a diverging lens 70 and then through a collimating lens 72. The collimating beam is deflected by a series of flat reflectors 74, 76 and 78 and then through a converging lens 80 which locates the focal point of the beam near the outer surface 52 of the dilatation balloon. The expansion balloon 20 is held on an elongated stationary axis 82 and remains stationary. The required relative movement is achieved by rotating the beam 68, in particular by rotating the flat reflectors 74-78 about an eector with the eo 82. A secondary mount including a reflector 78 and lens 80 also pivotable to axially move. and radially the beam along the cross section 28. Figures 9 and 10 illustrate another alternate excimer laser ablation apparatus 83 including a laser source 84, an optical assembly 86 for shaping and focusing a laser beam 88. and a moving plate 90 for securing a dilatation balloon 20 in an empty and collapsed configuration. The stepper motors 92 and 93 are arranged to translate the plate 90 in the perpendicular directions x and y (Figure 10) which are horizontal, ie, parallel to the main plane of the flattened ball. The combined movement of the?! ". plate 90 creates the effect of a series of adjacent sweeps of beam 88 in transverse direction to conical sections 26 and 28. To substantially reduce or eliminate variation in thickness *, the number of sweeps increases in the direction that approaches the rods. When all the excess material has been removed from the exposed upper face, the dilatation ball 20 is inverted to remove the material from the opposite side and complete the process. It can be used if a source of nitrogen under pressure is desired to cool, as indicated in 94. Alternatively, the desired relative movement can be achieved by moving the source of the object and the optics, thus displacing the beam instead of the balloon. dilatation n. The main advantage of using the apparatus 83 is that the dilatation balloon 20 does not need to be extended to remove the material. Although excimer ablation reduces the wall substantially along the conical sections to a uniform thickness, this is not necessarily the way to substantially improve the performance of the balloon catheter. As seen in Figures 11 and 12, material can be selectively eroded to form a set of channels or grooves 96 in a balloon wall 97 along each of the conical sections. The channels may be of uniform width as shown, or may diverge in a direction toward the middle section 24. In either case, the depth of each channel 96 increases in the direction toward the rod. The channels 95 reduce the profile of the balloon and the stiffness along the conical sections, especially near the rods and thus reduce the profile of the balloon, allow a tighter winding of the balloon for insertion and improve the performance level. of the catheter *. Figure 13 illustrates the device 38 with an expansion balloon 98 and a catheter 100 held on a rotating mandrel 40. The beam 48 of the laser is excimer directed toward a region 102 of the distal end of the catheter, which extends beyond the rod 104 of the dilatation balloon. The beam is not perpendicular, but is directed towards the region of the end with an acute angle with respect to the e e of rotation of the mandrel. In addition, beam 48 is not as accurate in its approach to the outer surface. The result is a variation of creep along the end region 102 with a creep level that increases in the distal direction. The result is a tendency in the pulses of the excimer laser to remove polyrneneric material at depths that increase in the distal direction. The result is a region of the convergent distal end, as shown in Figure 14. The apparatus 64 can be adjusted to achieve the same result, if desired to keep the balloon stationary during ablation, as seen in the figure. 15, the technique can be used to remove material from the dilatation balloon in a catheter in which the flexible tube 106 of the catheter * does not extend diatically beyond a rod 108 of the balloon. In both cases, there is a reduction in the end profile and lower stiffness at the distal end, with a tendency to improve the catheter inability. Thus, according to the present invention excimer laser ablation selectively shakes the walls of the dilatation balloons and catheters. The invention allows the manufacture of expansion balloons according to a method that provides favorable high breaking pressures, while substantially eliminating or substantially reducing an undesirable variation in wall thickness. The result is a dilatation balloon with the desired breaking pressure but without the excess wall thickness, in particular, along the conical sections close to the rods of the balloon. Balls extruded together or multilayer can be manufactured or treated according to this technique, although not shown. Although the above description presents dilatation balloons and catheters, it will be understood that the invention can be applied to other balloons and catheters, as well as, for example, to catheters with extensibles for the deployment of prostheses, more particularly to dilate stenosis implants (" stents ") plastically deformable. They are also improved when the catheter balloons intended for use in body conduits other than the vascular conduits are manufactured or treated according to the invention. With properly thinned walls, the balloon and the catheter facilitate a more tight winding of the balloon for a reduced insertion profile and have a greater flexibility and workability in the small and tortuous vascular conduits.

Claims (42)

NOVELTY OF THE INVENTION CLAIMS

1. A device msertable in the body and extensible that includes, a balloon (20,98) formed by a material of flexible balloon and compatible with the body, endowed with a mounting region (30, 32) adapted for a umon estanca to fluids of the balloon to the catheter (18,100, Q06) or other device for inserting the balloon, a working region (24) of diameter substantially greater than the assembly region and adapted to fit a treatment site sensitive to the extension of the balloon, and a co-region (26, 28) coupled to the work region and the mounting region; wherein the balloon has a balloon wall with a nominal wall thickness ti along the working region to provide a plank rupture pressure of at least approximately 1.013 x 106 Pa and the wall thickness of the balloon in said region comesa is at least 1, 5 x ti.

2. The device according to claim 1, wherein: the balloon wall along the conical region has a substantially uniform thickness.

3. The device according to claim 1, wherein: said mounting region comprises first and second (30, 32) assembly segments at the proximal and distal ends of the dilatation balloon, respectively, the working region comprises a section of average work (24) and region comea 3 (1) It comprises proximal and distal sections (26, 28) coupled to the mid section and to the proximal and distal mounting sections, respectively.

4. The device according to claim 3, wherein: the wall of the balloon along the conical sections next! and distal has a wall thickness t.2 substantially equal to you.

The device according to claim 1, further comprising: an elongated and flexible catheter (18, 100) attached to the mounting region in a fluid-tight manner and including a lumen (22) of the dilatation balloon for supplying a liquid under pressure to the dilatation balloon.

6. A device insertable into the body and extensible that includes: a balloon dilatation (20.98) formed by a flexible balloon material and compatible with the body, endowed with a mounting region (30, 32) adapted to a fluid-tight joint of the dilatation balloon to a catheter (18,100,106) or balloon insertion device, a working region (24) of diameter substantially greater than the mounting region and adapted to fit a sensitive treatment site the extension of the dilatation balloon, and a co-region (26, 28) coupled to the working region and to the mounting region; wherein the expansion balloon extends has a nominal diameter along the working region of at least about 3.0 nm and has a wall of halon with a nominal wall thickness, ti throughout the region. of work < That provides a rupture pressure of the balloon dilatation of at least about 11013 x 106 Pa of the balloon wall also has a thickness in the c region of at least twice ti.

The device according to claim 6, wherein: the balloon wall along the conical region has a substantially uniform thickness.

8. The device according to claim 6, wherein: The mounting region comprises first and second (30, 32) mounting segments at the proximal and distal ends; of the dilatation balloon, respectively, the working region comprises a middle work section (24) and the comea region comprises proximal and distal comel sections (26, 28) between the section and the proximal and distal mounting sections respectively .

9. The device according to claim 1, wherein: the balloon material is a biaxially oriented polymer, composed primarily of at least one of the following: polyethylene terephthalate, polyethylene, polyamide and their copolymers.

10. A msertable device in the body and extensible that includes: a flexible balloon (20,98) and compatible body tissue, equipped with a mounting region (30, 32) adapted for a fluid-tight connection to a catheter (18,100,106) or an insertion device, a working region (24) of substantial diameter greater than the mounting region and adapted to fit the tissue in a treatment site sensitive to the extension of the dilatation balloon, and a comea region (26, 28) between the working region and the mounting region and diverging in the direction of the region of the region. assembly towards the work region; further characterized in that the digestion balloon has a bursting pressure that exceeds approximately 1.013 x 10ß Pa and, throughout the comea region, has a substantially uniform wall thickness.

The device according to claim 10, wherein: the expansion balloon has a balloon wall with a nominal wall thickness along the working region, said wall thickness being at least two thirds of said thickness uniform wall of the region co ea.

12. The extensible device according to the claim 10, wherein: said mounting region comprises proximal and distal mounting sections; (30,32) at opposite ends of the dilatation balloon, the working region comprises a middle working section (24) of the balloon, and the comea region comprises proximal and distal conical sections (26,28) disposed between the middle section and the proximal and distal mounting sections, respectively.

The expandable device according to claim 12, wherein: the wall of the balloon has a nominal wall thickness along the measured section, and the uniform wall thickness along the proxirnal and distal sections. it is usually equal to the nominal wall thickness.

14. A device insertable into the body and extensible 15 comprising: a dilatation balloon (20,98) equipped with a working section (24), proxnnai and distal (30,32) smaller diameter mounting sections that the average work section, and proximal and distal sections (26,28) come between the mid work section and the proximal and distal sections, respectively, said balloon having a balloon wall which, at intervals along the One of said sections has been thinned by selective ablation with excimer laser.

The device according to claim 14, wherein: the balloon wall along the middle working section has a nominal wall thickness, and the wall thickness along said conical section, due to ablation With the excimer laser, it is at most 1.5 times the nominal wall thickness.

16. The device according to claim 14, further comprising: a balloon dilating catheter (18,100,106) supporting the dilatation balloon by fluid-tight connections at the catheter interface and proximal and distal mounting sections and a lumen ( 22) that passes through the catheter and opens to the inside of the dilatation balloon to supply a liquid under pressure to the dilatation balloon.

17. The device according to claim 16, wherein: a pair (102) of the balloon dilatation catheter extending distally beyond the distal mounting section is comatose, being convergent in the distal direction.

18. The device according to claim 14, wherein: each of the proxirnal and distal comedic sections has a truncated cone shape.

The device according to claim 14, wherein: said balloon wall incorporates a set of channels (96) along at least one reed section.

20. A method for manufacturing an expandable and extensible body treatment device, including: directing an exciter laser beam (48, 68, 88) on a balloon (20, 98) biaxially oriented at a selected position along the outer surface of the balloon, to remove polymerase material by ablation and, thereby, thinning of the balloon wall of the L > expansion point in the selected position.

The method according to claim 20, further including the following steps, carried out before directing said excimer laser beam: axially stretching a length of flexible polymer tube (34) to substantially increase a length of tube while heating the flexible tube to a temperature above its second order transition temperature, to axially orient the flexible tube; radially extending the flexible tube to substantially increase its diameter along at least a part of the length of the flexible tube, while maintaining the flexible tube above said second-order transition temperature, to radially orient the flexible tube, formed therefrom by a biaxially oriented balloon with a middle section (24) having a nominal diameter and a wall thickness nominal, proximal and distal mounting sections (30,32) and proximal and distal comel sections (26,28) between the section and the proximal and distal end mounting sections, respectively; let the biaxiairnenfe oriented tube cool below the second order transition temperature.

22. The method according to claim 21, wherein: each of the conical sections has a variation of the increasing wall thickness in the direction starting from the middle section towards the associated end assembly section, comprising said selected position. the sections comeas, reducing the variation of said thinning of the balloon wall.

23. The method according to claim 22, wherein: the variation is substantially eliminated in said thinning.

24. The method according to claim 21, wherein: the selected position includes parts of the cross sections and the removal of polymeric material forms a set of channels (96) in each of the cross sections.

25. The method according to claim 20, wherein: said excimer laser beam has a wavelength of about 193 n.

26. The method according to claim 20, wherein: said step of directing an excimer laser beam is carried out with a fluence level, on the surface of the balloon, in the range of approximately 100 to 800 rnj. / crn2.

27. The method according to claim 20, wherein: The direction of the excimer laser beam includes pulsing the beam at a repetition rate in the range of about 10 to 50 pulses per second.

28. The method according to claim 27, wherein: the repetition rate is about 10 pulses per second.

29. The method according to claim 27, wherein: said pulses have a duration comprised in the range of about 10 to 15 ns.

30. The method according to claim 20, further comprising: convection cooling the biaxially oriented balloon during said direction of the excimer laser beam on the balloon surface.

31. The method according to claim 20, wherein: said direction of the excimer laser beam includes orienting the beam substantially perpendicular to the surface in the selected position.

32. The method according to claim 20, wherein: said excimer laser beam di- rection includes orienting the beam at an acute angle with respect to the surface at the selected position, to provide a variation of the fluence through the surface in the selected position.

33. A method for selectively shaping a device insertable into the body that includes a catheter (18,100,106) for dilating the polyaromatic balloon and a balloon dilatation (20,98) fluid-tightly attached to a region of the distal end of the body. catheter, having the mid-section dilatation balloon (24) with a nominal wall thickness and a nominal diameter when the balloon is extended, extreme proximal and distal mounting sections (30,32) unit to the catheter * and proxirnal conical sections and distal (26,28) between the middle section and the proximal proximal and distal mounting sections, respectively, each of the comee sections having a variation in the increasing wall thickness in the direction from the mid section to the extreme mounting section associated: includes said method for selectively shaping the device: directing a beam (48,68,88) of excimer laser on the device to irradiate a supe external surface of the device with a fluence in the range of about 100-800 rnj / c 2, to ablate polyacryl material material in the selected positions that include at least the conical sections close to the extreme mounting sections.

34. The process according to claim 33, wherein: the polymeric material is removed by ablation in a manner that reduces the variation in wall thickness along the conical sections.

35. The method according to claim 33, wherein: each of the conical sections has a substantially uniform wall thickness after said removal of polymeric material.

36. The method according to claim 33, wherein: said removal of polyrnomeric material forms a plurality of slots in each of the conical sections.

37. The method according to claim 33, wherein said direction of the excimer laser beam includes pulsing the laser beam at a frequency in the range of about 10 to 50 pulses per second.

38. The method according to claim 33, wherein: said excimer laser beam is generated at a wavelength in the range of about 190 to 310 nrn.

39. The method according to claim 33, wherein: said excimer laser beam is pressed, each pulse having a duration in the range of about 10 to about 15 ns.

40. The method according to claim 33, further comprising: interposing a screen (54) between a source (46,66,84) of the excimer laser beam and the selected positions when directing the excimer laser beam, for determine an intercept area of the beam on the external surface at the selected positions.

41. The method according to claim 33, wherein: said direction of the exciter beam includes holding the dilatation balloon in an extended state on a mandrel (40,82) extended longitudinally, displacing the dilatation balloon and the excimer laser beam rotationally, use with respect to the other, around an ee that substantially coincides with the mandrel, and linearly displace the dilatation balloon and the beam, one with respect to the other, in longitudinal and radial direction with respect to said e e.

42. The method according to claim 33, wherein: the direction of the excimer laser beam includes emptying the dilatation balloon and keeping the balloon in a substantially collapsed state, orienting the excimer laser beam substantially perpendicular to a plane The main balloon of the dilatation balloon when in a substantially collapsed state and displacing the bundle and the dilatation balloon, one with respect to the other, in mutually perpendicular directions parallel to the main plane.