US20160144156A1 - Inflatable device with etched modifications - Google Patents

Abstract

Inflatable devices are disclosed including a surface which has a network of polymer chains and is configured to be inflatable into a therapeutically or diagnostically useful shape, and at least one ultrashort laser pulse-formed modification in the surface. The network can, for example, include a network morphology that is substantially unchanged by modification with the ultrashort pulse laser. Ultrashort laser pulses can be laser pulses equal to or less than 1000 picoseconds in duration. Advantageously, the etching process uses a relatively low-heat laser to avoid significant heating of surrounding polymers while modifying the surface (and other structures) of the device. The process is configured so that the polymer chain morphology adjacent the modification is substantially unaffected by the low-heat laser. The resulting inflatable device has customized surface features while still retaining substantially homogenous polymer network morphology. This preserves the elasticity, especially the surface elasticity, of the inflatable device.

Description

RELATED APPLICATIONS
• This application claims the benefit of priority to U.S. Provisional Application No. 62/082,241, filed Nov. 20, 2014, which is incorporated by reference in its entirety for all purposes.
FIELD
• This invention relates to the field of inflatable medical devices for diagnostic and therapeutic applications, particularly those designed to expand within an anatomical space.
BACKGROUND
• Inflatable devices are used in many surgical and minimally invasive surgical (MIS) techniques and settings. Medical balloons with thinner walls, higher strength, and smaller profiles are designed to withstand high inflation pressures and are well suited for use in a broad range of diagnostic and therapeutic procedures. They can be produced in a variety of lengths, diameters, and shapes, including complex custom shapes for specific applications, and supplied with specialty coatings for added performance. In a typical MIS procedure, uninflated devices are positioned within an anatomical space and then filled with air or fluid to expand the device and possibly the anatomical space itself. This procedure is used to deliver a prosthetic heart valve or stent to a cardiac or vascular structure. Alternatively, an inflatable device can be used to dilate an anatomical structure, as in angioplasty procedures. Other surgical procedures that incorporate the use of inflatable devices include, for example, kyphoplasty, nephrostomy, gastric balloon placement, endometrial ablation, laparoscopic hernia repair and renal denervation. Furthermore, inflatable devices can be used in the obstruction, dilation and/or stent placement within the following anatomical structures: sinuses, intestines, lacrimal ducts, Carpal tunnels, Eustachian tubes, the uterus, ureters, bile ducts, the trachea, the esophagus, the urethra, and the nasal passages. This list does not include all procedures that use inflatable devices, but is meant to demonstrate the breadth of this invention's relevance.
• By way of example, inflatable devices are used in transcatheter aortic heart valve delivery procedures. In this procedure, a guidewire is delivered through the femoral artery, through the patient's vasculature to the native aortic valve, and placed within the left ventricle. A first balloon mounted on a catheter is inserted over the guidewire into the aortic valve and inflated to widen the structure. The first balloon is removed back down the guidewire. A second, folded balloon carrying the new prosthetic heart valve is delivered to the patient's diseased aortic valve. Alternatively, a prosthetic heart valve may be moved onto the balloon once it is inside the patient's body. Once positioned, the folded balloon is inflated and the previously crimped valve is expanded to its full diameter. At its full diameter, the stent is lodged within the native heart valve. The second balloon is deflated and is routed back down the patient's vasculature and out the femoral artery via the guidewire, leaving the new valve in place.
• Given their role in treating a range of patient conditions, improvements in inflatable devices are highly desirable.
SUMMARY OF THE INVENTION
• The inventors have advantageously modified the surface (and other structures) of inflatable devices, such as balloons, using low heat lasers, such as ultrashort pulse lasers, while avoiding significant heating of the polymer surrounding the modification. The inventors have configured the process so that the polymer chain network morphology surrounding the modification is substantially unaffected by thermal effects. The resulting inflatable device has customized surface features while still retaining a substantially unchanged polymer network morphology surrounding the low heat laser-formed modification. This preserves the elasticity and other mechanical properties of the inflatable device.
• In one implementation, ultrashort laser pulses can be laser pulses equal to or less than 1000 picoseconds in duration. In another implementation, ultrashort laser pulses can be equal to or less than 1000 femtoseconds in duration.
• In one implementation, the inflatable devices have a wall which has a surface. The wall is configured to be inflatable into a therapeutically useful shape. The wall also has at least one low heat (or ultrashort) laser-formed modification on the surface. The wall is at least partially formed of a polymer, and therefore has a network of polymer chains. The network of polymer chains can have a network morphology. The network morphology surrounding the low heat laser-formed modification is substantially unaffected by thermal effects.
• The therapeutically useful shape can include a body, leg and cone regions. These regions are arranged along a longitudinal axis that extends through them.
• The laser formed modification can be on the inner surface of the wall of the device. For example, the low heat laser formed modification can be on an inner surface of the leg region.
• In other implementations, the device can have multiple layers, such as an inner layer and an outer layer. The low heat laser-formed modification can include a recession formed on the outer layer. The outer layer can be radiopaque to facilitate locating it during surgical procedures.
• The low heat laser-formed modification, for example, can be one or more recessions in the surface. The recessions can, for example, increase friction on the surface of the inflatable device. The recessions can have different configurations. For example, the recessions can extend parallel to the longitudinal axis of the device. The recessions can be in a spaced, parallel arrangement and extend circumferentially around the body region.
• The device can include a circumferential perimeter. The recession in the surface extends around at least a portion of the circumferential perimeter. The recession can even extend entirely or fully around the circumferential perimeter. The inflatable device can include a plurality of the circumferentially extending recessions. They can be spaced apart from each other and in a parallel arrangement, forming a stripe-like pattern.
• In another implementation, the recession can be etched into the cone region of the device. For example, the recession can extend from adjacent the leg region to the body region. And, the recession can continue over an axial length of the body region. In an implementation with two cone regions, the recession can extend over both cone regions as well as the body region.
• The inflatable device can include a plurality of recessions. The recessions can be on the cone region and extend only partially between the leg and body regions. The recessions themselves can change in width, such as by tapering as they extend toward the leg region.
• The plurality of recessions can have geometric shapes, such as circles. For example, the circles can be etched in pattern on the body region of the device.
• Methods include fabricating an inflatable device by applying low heat laser pulses to a surface of the inflatable device. And, the low heat laser pulses can be applied to leave a network morphology surrounding the modification substantially unaffected by thermal effects.
• The method can also include forming a body, leg and cone regions about a longitudinal axis extends through the regions. The low heat laser pulses can be applied to increase or reduce a friction of the surface.
• The low heat laser pulses could be applied to an inner or outer surface of the inflatable device. For example, the inner surface could be partially ablated to remove material.
• In a multi-layered wall, the low heat laser pulses can be used to reveal an inner layer beneath an outer layer. In this manner, excess material of the outer layer serving no functional benefit can be removed.
• The different regions can also be ablated, such as the cone, body and leg regions, selectively, for desired performance parameters. For example, the method can include ablating circumferentially around the body of the inflatable device to form strips or stripes.
• The application of low heat laser pulses can include applying ultrashort laser pulses equal to or less than 1000 picoseconds in duration. In another implementation, ultrashort laser pulses can be equal to or less than 1000 femtoseconds in duration.
• Ultrashort laser pulse-formed modifications can enable tighter folding, more predictable burst pressure, better bonding to external devices such as catheters, the ability to coordinate inflation of various parts of the device, addition of friction or physical features that prevent sliding of above-lying surfaces (such as valves or stents), removal of additional surface layers from selected areas of the device, and/or addition of markings that would assist during folding or during surgical procedures.
• These and other features and advantages of the implementations of the present disclosure will become more readily apparent to those skilled in the art upon consideration of the following detailed description and accompanying drawings, which describe both the preferred and alternative implementations of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIGS. 1A-1C are schematics of inflatable devices prior to the low heat laser pulse-formed modifications;
• FIG. 1D is an enlarged view of the multiple layers of the inflatable device ofFIG. 1C, prior to the low heat laser pulse-formed modifications;
• FIG. 2A is a schematic of an inflatable device after modification with low heat laser pulses;
• FIG. 2B is an enlarged view of a region of interest fromFIG. 2A;
• FIG. 3 is a schematic of another inflatable device after modification with low heat laser pulses;
• FIG. 4A depicts the cone region of an inflatable device prior to modification with low heat laser pulses;
• FIG. 4B depicts an inflatable device with low heat laser pulse formed modifications in the cone region;
• FIG. 5A depicts the leg region of an inflatable device prior to modification with low heat laser pulses;
• FIGS. 5B-D show inflatable devices with low heat laser pulse formed modifications to the leg region;
• FIG. 6 is a schematic of an inflatable device with low heat laser pulse formed modifications to the cone regions;
• FIGS. 7A-C are schematics of inflatable devices with low heat laser pulse formed modifications to the body regions;
• FIGS. 8A-C are schematics of inflatable devices with low heat laser pulse formed modifications along the longitudinal axis;
• FIG. 9 is a schematic of an inflatable device;
• FIG. 10 is a schematic of an inflatable device.
DETAILED DESCRIPTION OF THE EMBODIMENTS
• Disclosed herein are embodiments of inflatable devices with special surface features created or facilitated by low heat, or ultrashort, laser pulse formed modifications. Implementations of the present disclosure now will be described more fully. Indeed, these implementations can be embodied in many different forms and should not be construed as limited to the implementations set forth herein; rather, these implementations are provided so that this disclosure will satisfy applicable legal requirements. The following description of certain examples of an inflatable device should not be used to limit the scope. Other examples, features, aspects, embodiments, and advantages of the inflatable medical device will become apparent to those skilled in the art from the following description. As will be realized, the inflatable device is capable of additional aspects, all without departing from the spirit of the inflatable device. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not restrictive.
• For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The described methods, systems, and apparatus should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The disclosed methods, systems, and apparatus are not limited to any specific aspect, feature, or combination thereof, nor do the disclosed methods, systems, and apparatus require that any one or more specific advantages be present or problems be solved.
• Features, integers, characteristics, compounds, chemical moieties, or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), and/or all of the steps of any method or process so disclosed, can be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
• It should be appreciated that any patent, publication, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.
• As used in the specification, and in the appended claims, the singular forms “a”, “an”, “the”, include plural referents unless the context clearly dictates otherwise. The term “comprising” and variations thereof as used herein is used synonymously with the term “including” and variations thereof and are open, non-limiting terms.
• As used herein, inflatable devices include medical balloons. For example, inflatable devices include medical balloons such as those used in therapeutic or diagnostic procedures.
• As used herein, ablating or etching is a process by which material is removed using a laser. Modifications to an inflatable device, for example, low heat-laser pulse formed modifications, can be formed by ablating or etching.
• The inventors have noted several shortcomings in inflatable devices of the prior art. They have endeavored to address these shortcomings by implementing the principles of this invention. Inflatable device surface modifications are desirable for many reasons, which will be explained in greater detail below. However, modification with laser pulses can overheat the polymer, disorienting the network of polymer chains that surround the modification. This disorientation decreases the overall strength of the device.
• The inventors have designed a process wherein modifications by a relatively low heat laser (e.g., ultrashort pulse laser) do not heat the surrounding polymer. Additional details of such low heat lasers or ultrashort pulse lasers are disclosed in U.S. Patent Application Publication No. 2013/0110097 filed Sep. 17, 2012, which is incorporated herein by reference. The polymer chain network morphology in the area surrounding the laser pulse-formed modification is substantially unaffected by thermal effects, preserving the strength of the device. Low heat or ultrashort laser pulses as used herein are defined as laser pulses less than 1000 picoseconds in duration. In some implementations, low heat or ultrashort laser pulses can be less than 1000 femtoseconds in duration.
• The inventors have realized or determined several design considerations during their development of the implementations of the invention. Procedures using inflatable devices benefit from transfer through narrow anatomical spaces in an uninflated state. To achieve this, the inflatable devices can benefit from being tightly folded underneath an external device such as a valve or stent. The device in its folded state should generally have a narrow profile. This enables it to enter smaller anatomical spaces, reducing tissue damage. It also enables easier delivery with lower friction.
• However, certain fabrication processes create unnecessary bulk. For example, one method of producing an inflatable device is to blow mold a polymer tube into a balloon shape. This forms thinner areas that will ultimately inflate to wider dimensions, creating the body of the device. The areas outside the mold are not meant to inflate. These become the legs of the device. The transition from the thinner body area to the thicker leg region is the cone of the device. In this region, the wall changes from thin to thick. If the walls of these regions could be thinned, the overall profile of the folded inflatable device would be thinner and could fit into narrower anatomical spaces. Low heat laser pulse formed modifications can be used to even the wall thickness post-molding, improving the consistency of the bonding strength of the inflatable devices to external devices such as catheters. Furthermore, the low heat lasers could be used to newly create features that enhance bonding to external devices.
• Precisely targeted placement and orientation of a valve or stent along an inflatable device is a factor in the success of the procedure and to the safety of the patient. Proper timing of inflation is important to reduce flaring of the ends of the valve or stent. Similarly, a valve or stent increases the resistance to inflation, and areas of the inflatable device around the external device can inflate first. This creates an undesirable dog-bone shape. Improvements to valve stabilization and inflation timing would be highly beneficial, as would the improvements in the visualization of the inflatable device during delivery for assisting in orientation of the valve/stent.
• The inventors have further observed that inflatable devices could benefit from heightened predictability of bursting pressure. The ability to create inflatable devices with consistent wall thicknesses would enhance the prediction of burst pressure. Furthermore, the ability to thin a specific region of an inflatable device would enable prediction of the precise bursting location, and to locate it to the region that would cause the least tissue damage, should it ever occur. Precise manufacturing can even allow for the design of inflatable devices that leak slowly and gently instead of bursting.
• The inventors have addressed these issues by removing material from precise locations of the inflatable device using a low heat laser. Methods of laser-ablating excess material after molding have been disclosed in the prior art, such as in U.S. Pat. No. 6,719,774. However, the utility of such methods is limited because heat produced by the laser causes disorientation of the nearby polymer network, which increases chances of bursting at lower inflation pressures. In contrast, alignment of the network of polymer chains is associated with increased resistance to bursting. Thus, the maintenance of an oriented morphology is desirable for inflatable devices.
• The inventors have determined that ultrashort laser pulses have a non-thermal laser-material coupling that protects against deleterious effects to the polymer network adjacent to the laser modification. The term “low heat laser” as defined herein includes lasers that can be operated to ablate the polymeric wall compositions at temperatures less than a temperature at which the adjacent polymeric wall composition and/or organization starts to degrade. Generally, most bio-absorbable and many bio-compatible polymers have a melting point of below 100 degrees Celsius. The low heat lasers can be, for example, near-IR laser systems that have a maximum pulse energy of 40 micro-joules with a pulse duration of less than 400 femtoseconds at 200 KHz. Another example system has a maximum pulse energy of 200 micro-joules with a pulse duration of 10 picoseconds. Still another example system is a fiber-based ultrafast laser that is mode-locked and can generate ultrashort pulses centered at about 1552.2 nanometers. The power of this system can be 5, 10 or 20 watts. The pulses produced can be less than 800 femtoseconds.
• FIGS. 1A-D show examples of inflatable devices prior to modification by low heat lasers. These exemplary devices are manufactured by molding a polymer tube into a balloon shape. This fabrication process creates certain characteristics that are improved by the modifications disclosed herein. Inflatable devices can be fabricated to suit various anatomical structures without detracting from the function of the device.
• Aninflatable device101 that has not yet been modified by ultrashort laser pulses is shown inFIGS. 1A-D. As used herein, the terms “modify”, “modified”, and “modifications” refer to actions of the ultrashort laser pulses on the inflatable device surface. The term “unmodified” refers to prefabricated inflatable devices which have not been modified by ultrashort laser pulses. Theinflatable device101 ofFIG. 1A comprises abody region108, a pair ofleg regions104, and a pair ofcone regions106. These regions define alongitudinal axis103 extending generally along a direction of a guide wire (not shown) supporting the device. Each of thecone regions106 has anend109 adjacent theleg region104. The inflatable device further comprises awall121 having anouter surface105 and aninner surface107. Theregions104,106 and108 are sub-portions of thewall121.
• Implementations of theinflatable devices101 disclosed herein can be used alone or in conjunction with other devices, including but not limited to prosthetic heart valves and stents. In this manner, aprosthetic valve102 or other device can be delivered along with the inflatable device101 (both in a compressed configuration) to a relatively inaccessible location in the body, such as percutaneously to a non-functional native heart valve. Then thedevice101 is inflated to expand thevalve102 into an expanded condition. For example, inFIG. 1A, the expandedvalve102 is situated around the expandedbody region108 of theinflatable device101.
• Referring again toFIG. 1A, thebody region108 is positioned adjacent to and extends between thecone regions106. Thebody region108 has an elongate shape (as shown by the longitudinal cross-section shown inFIG. 1A) that extends in the direction of thelongitudinal axis103. Thebody region108 of theinflatable device101 also has a transverse cross section (not shown) extending perpendicular to thelongitudinal axis103. The transverse cross section can have an extruded, symmetrical shape, such as a circular or square shape, or some other geometric or irregular shape depending upon the desired application.
• Generally, the length and diameter of thebody region108 and the rest of the device can be adapted to suit various anatomical structures or to perform various functions. For example,FIG. 1B shows a variation on the dimensions of thebody region108. The length ofbody region108 of the implementation ofFIG. 1B, for example, is shorter than that of the implementation shown inFIG. 1A. The diameter of thebody region108, on the other hand, is larger inFIG. 1B than inFIG. 1A. The dimensions of the inflatable devices can also vary when they are in their crimped, folded states.
• Prior to modification with ultrashort laser pulses, thebody region108 of theinflatable device101 shown inFIG. 1A can have slight variations inwall thickness118. These slight variations are caused by the fabrication process. In some examples, the thickness of the wall may change gradually along the length of thebody region108.
• Referring again toFIGS. 1A-D, the unmodifiedinflatable device101 also includes thecone regions106. Each of thecone regions106 extends from a wide end adjacent thebody region108 to anarrow end109 adjacent theleg region104. Thecone regions106 have a frustoconical shape arranged circumferentially around thelongitudinal axis103. A diameter of thecone region106 extends perpendicular to thelongitudinal axis103.
• As described above for the body region, the dimensions of thecone regions106 vary depending upon the application. Thecone regions106 of theinflatable device101 shown inFIG. 1A have a coneregion wall thickness116 that tapers moving away from thenarrow end109. This variation occurs during the blow molding process, as the central region of the polymeric tube (which becomes the body region108) is stretched to a greater extent than the edges of the tube. For example, the coneregion wall thickness116 of the unmodifiedinflatable device101 can be thicker at thenarrow end109, adjacent to the leg region, than atend108, adjacent to the body region. Similar to the body region, the fabrication process can also cause slight, localized variability in the coneregion wall thickness116.
• As shown inFIG. 1A, theinflatable device101 includes the pair ofleg regions104 at opposite ends of the inflatable device. In this implementation, the leg regions are non-inflatable ends of thewall material121 used to construct the inflatable device. The leg regions can be compressed onto a guide wire for delivery into an anatomical space. The inflatable device is mounted onto a guide wire or catheter (not shown) viaaxial openings112.
• While the implementations discussed herein include a pair of leg regions, it is possible to fabricate inflatable devices with a single leg and cone region. Other implementations can have a range of shapes formed by thewall121, such as square, bulbous or irregular shapes that do not necessarily include theparticular regions104,106 and108 of the illustrated implementations. These alternate implementations still benefit from the formation of modifications thereon.
• Theleg regions104 extend from acone region end109 away from thebody region108 to afree end110. Theleg regions104 have a length in the direction of thelongitudinal axis103 and a transverse cross section extending perpendicular to thelongitudinal axis103. The diameter and wall thickness, generally, can be a reflection of the original polymeric tube used to form theinflatable device101. The fabrication process can cause slight variability in the legregion wall thickness114 along its length.
• Theinflatable device101 shown inFIG. 1A has awall121 with anouter surface105 and aninner surface107. Theouter surface105 is farther from thelongitudinal axis103 than theinner surface107. The outer surface generally contacts above-lying surfaces of an external device mounted thereon, including for example the inner surfaces of aprosthetic heart valve102 or stent.
• Part of the function of thebody region108 of theinflatable device101 is to allow axial positioning of the device or structure which it is expanding. To this end, the interface between the surface and the external device generates an improved frictional retaining force via the modifications of the surface. Another way to understand the effect of friction is to quantify the surface roughness of theinflatable device101.
• Generally the inflatable device'ssurfaces105,107, andwalls121 are formed of a polymer material, at least in part. The polymer material inherently includes a network of polymer chains having a network morphology. It is understood that the walls'121 elasticity and other mechanical properties are affected by the network morphology of the polymer chains making up thesurfaces105,107,walls121, or portions thereof. Without being wed to theory, it is also understood that the network morphology is affected by the polymer chain orientation.
• Although a range of materials (and combinations of materials) are capable of being inflated at the pressures needed to perform functions, polymeric materials for layers or compounds are particularly well suited for applications. They have the flexibility to shrink to small diameters and the elasticity to expand without bursting. Polymeric materials include, for example, thermoplastic and thermoset polymers. Such polymers include, for example, PET, Nylon, Pebax, polyurethane, polyetherurathane, PVP, PEO, HDPE, and LDPE.
• To fabricate aninflatable device101, a polymer can be blow molded into a hollow balloon shape. The central region of the hollow polymer has athinner body region108 that will ultimately inflate to wider dimensions. Thecone region106 and its taperedwall116 are products of this molding process. Theleg regions104 are not molded and therefore do not substantially inflate. Theleg regions104 can be bound to a catheter tube by mounting the device aroundopenings112 and bonding the leg material to the catheter tube. This bond can have a bonding strength that varies with size and application. The bonding strength can be measured by a tensile test. In these examples, the low heat laser modifications take place after the molding process. However, low heat laser modifications can also take place prior to the molding process without deviating from the inventive concept.
• As seen inFIG. 1C, in another implementation,inflatable device101 has multiple wall layers120,121 prior to modification by ultrashort laser pulses. Theouter layer120 is the farthest layer from thelongitudinal axis103, and theinner layer121 is closest to thelongitudinal axis103. An enlarged version of the multiple surface layerinflatable device101 is shown inFIG. 1D.
• Additional surface layers can have several functions. For example, an additional surface layer can be designed to increase friction, reduce friction, or add radiopacity to the device. And, as described below, the presence of multiple layers allows them to be selectively etched away and/or revealed to generate unique, customized properties for theinflatable devices101.
• The surface roughness of theinflatable device101 can impact function. Theouter layer120 can be included to alter the surface roughness—such as by using a material that is inherently rougher than theinner layer121. And, in areas where reduced roughness is desired (such as on thecone regions106 for easier insertion into body lumens) theouter layer120 can be etched away.
• Multi-layer implementations similar are not limited to the two layers shown inFIG. 1C. Instead, three, four or more layers can be used to customize the properties of theinflatable device101 to different applications and for different etching effects. The layers can be fabricated from materials such as Nylon, Pebax, PET, polyurethane, polyetherurathane, PVP, PEO, HDPE, LDPE. Radiopacity can be incorporated in an outer layer by mixing the polymer solution with a pacifier, such as Tungsten powder, prior to fabrication. Platinum, gold, palladium, iridium, magnesium, zinc, tungsten, tantalum, iron, iodine salts, bismuth salts, or barium salts can also be incorporated into an outer layer to yield a radiopaque inflatable device.
• FIG. 2A shows theinflatable device201 ofFIG. 1A with recessions formed by ultrashort laser pulses or some other low heat laser. In particular, in this implementation, theouter surface105 of thebody region208 has been partially ablated by ultrashort laser pulses. The ablations create one ormore recessions211 in the outer surface. Therecession211 has a length that extends parallel to thelongitudinal axis203. Therecession211 also extends around a perimeter of thebody208 of theinflatable device201—largely forming a tubular-shape of negative space in thewall221. The length of therecession211 in the axial direction can adapted to specific functions or applications. For example, the length can be mostly coextensive with the stent orvalve202. In this manner additional clearance is provided for crimping thevalve202 down to a smaller diameter for easier delivery.
• FIG. 2B shows an enlarged portion ofFIG. 2A with the ultrashort laser pulse-formedrecession211 in thebody region208. Thewall221 of the body region has anoriginal thickness218 and anablated wall thickness219. Theoriginal thickness218 corresponds tothickness118 of the unmodifiedinflatable device101 shown inFIG. 1A. Theablated wall thickness219 can vary by particular desired application, but in the case of an inflatable device for expansion of a stent mounted heart valve it can be about 1-40% of theoriginal wall thickness218.
• Therecession211 shown inFIGS. 2A-B inflates to a larger diameter than unmodified areas of thebody region108 because it has lower resistance to the air pressure inside the inflatable device. This reduces dog-bone effects at the ends and decreases the likelihood of damage to surrounding tissue. At the same time, the ultrashort laser pulse-formed recession leaves the adjacent surface polymer network morphology substantially unaffected by thermal effects.
• FIG. 3 shows anotherinflatable device301 withrecessions311 formed by ultrashort laser pulses. In this implementation, the outer portion of the surface of the body region308 has been ablated by ultrashort laser pulses so as to create tworecessions311 in the surface of the body region. Therecessions311 have lengths that extend parallel to thelongitudinal axis303. Therecessions311 extend fully around the perimeter forming two cylindrical strips on opposite sides of thevalve302. The wall of the body region has anoriginal thickness318 and anablated wall thickness319. Theoriginal thickness318 corresponds tothickness118 of the unmodifiedinflatable device101 shown inFIG. 1A.
• Certain areas of the body region of an unmodified inflatable device (such as the one shown inFIG. 1A) can inflate before others, which can result in slight axial movements of the valve or stent. The ultrashort laser pulse-formedrecessions311 ofFIG. 3 have lower resistance to the air pressure inside the inflatable device. They inflate to a wider diameter than the unmodified areas of the body region. They also inflate prior to the region that is under the valve orstent302. These aspects reduce axial movements of the valve orstent302 during inflation.
• FIG. 4A shows an enlarged view of thecone106 andleg regions104 of theinflatable device101 shown inFIG. 1A.FIG. 4B shows theinflatable device401 after ultrashort laser pulse formed modifications to theouter surface405 of thecone region406. In this implementation, excess material is ablated fully cylindrically around the perimeter of theouter surface405 of thecone region406. Advantageously, the reducedcone thickness416 facilitates tighter folding of the inflatable device. This enables the device to be used in narrower anatomical spaces.
• FIG. 5A shows an enlarged view of the unmodified inflatable device shown inFIG. 1a. Notably, theinner surface107 of theleg region104 has a tapered shape defining theaxial opening112.
• FIGS. 5B-D showinflatable devices501 after ultrashort laser pulse formed modifications to theleg region104. In particular,FIG. 5B shows the originalouter surface105 of theleg region104 ablated, creating the diminished legregion wall thickness514. The ablation of the excess material extends circumferentially around the perimeter of theleg region504. The reduction in leg thickness enables tighter folding of the inflatable device.
• As described above and as demonstrated inFIG. 5A, the necking process can lead to unevenness in thewall121 along the length of the leg region. In the implementation shown inFIG. 5C, low-heat laser pulses have been directed through the outer surface of the leg region to ablate the originalinner surface107 of theleg region104. This creates a thinnedinner surface507 and diminished legregion wall thickness514. This allows for a larger wire or other mating part to fit within theopening507 for better bonding. In addition to enabling tighter folding, the ablation creates a smootherinner surface507 to raise bonding strength to external devices such as catheters and guidewires. In addition, less and/or more consistent thickness leg material will generate a more consistent heating profile (and better bonding) during, for example, a heat-fusion bonding process. Laser etching of the leg material can occur before or after bonding. After etching the inner surfaces of an inflatable device, the device can undergo a cleaning process, such as ultrasonic cleaning, to remove debris prior to use in a patient.
• FIG. 5D shows anotherinflatable device501 with abonding feature511 in theleg region504. Thebonding feature511 is created by ablation of part of theinner surface507 by ultrashort laser pulses. Thebonding feature511 extends from theend510 of the leg region along thelongitudinal axis503. The shape of thebonding feature511 can be frustoconical, wedge, tapered or hook shaped, for example, or can be some increase in surface roughness. Thebonding feature511 reduces longitudinal slippage of an external device, such as a catheter or guidewire, that has been bonded toinner surface507 of the inflatable device. For example, the wedge shape ofbonding feature511 inFIG. 5D can mate with a flare at an end of a catheter or guidewire, raising the force necessary to decouple the catheter or guidewire from the inflatable device.
• FIG. 6 shows aninflatable device601 with ultrashort laser pulse-formedrecessions622 in theinflatable device101 ofFIG. 1A. In this implementation, therecessions622 are formed on thecone region606. Therecessions622 can extend from adjacent theend609 of thecone region606 in the direction of thebody region608. The width ofrecessions622 can taper gradually from larger proximate thebody region608 toward the end of thecone region609.Recessions622 promote folding in specified locations, leading to better organization of the folds and thus tighter folding.
• FIGS. 7A-C show implementations for increasing the frictional force between theinflatable device701 and an above-lying surface.Recessions724 are ablated onto thebody region708 using ultrashort laser pulses. The increased frictional force induced by these recessions decreases movement of a valve or stent along the body region of the inflatable device, improving the consistency and safety of the procedure.
• FIG. 7A shows aninflatable device701 with circular ultrashort laser pulse-formedrecessions724 for increased frictional force. A plurality ofrecessions724 can be uniformly or randomly spaced around theouter surface705 of thebody region708. While the recessions of this implementation are shown as circles,recessions724 can be other shapes such as squares, rectangles, or triangles. These recessions prevent both axial and circumferential slippage of the valve or stent. Different patterns of different types of recessions can be employed on different parts of the inflatable device, such as circles of one diameter on the body region and circles of another diameter on the cone regions.
• The implementation shown inFIG. 7B has a plurality of ultrashort laser pulse-formedrecessions724 that extend circumferentially around the perimeter of the device. The recessions have a width in the direction parallel to thelongitudinal axis703 and a depth into theouter portion705 of the surface of the body region. Therecessions724 are spaced along thelongitudinal axis703. The circumferential orientation of therecessions724 helps to prevent slippage of the stent or other device in the direction of thelongitudinal axis703.
• The implementation shown inFIG. 7C has a plurality of ultrashort laser pulse-formedrecessions724 that extend across thebody region708 in the direction of thelongitudinal axis703. The recessions are spaced around the circumference of thebody region708. The longitudinal orientation of the recessions helps to prevent slippage of the stent or other device around the circumference of thebody region708.
• FIGS. 8A-C showinflatable devices801 designed to burst at specific locations if inflated past predetermined pressures. In particular, the ultrashort laser pulse-formed modifications are tailored to weaken the wall in a particular pattern. This results in a predictable burst pattern when the inflatable device is overinflated, which can make it easier to retrieve a ruptured device. The recessions can also promote slow, gentle leaking of air (or other fluids) in the event of overinflation, as opposed to bursting.
• In the implementation ofFIG. 8A, an ultrashort laser pulse-formedrecession826 extends fromadjacent end809 of thecone region806 in the direction of thebody region808. In the implementation ofFIG. 8B, the ultrashort laser pulse-formedrecession826 extends from adjacent theend809 of thecone region806 and across thebody region808. In the implementation ofFIG. 8C, therecession826 extends from adjacent theend809 of thecone region806, across thebody region808, and toward the end of thesecond cone region807.
• InFIGS. 8A-C, the bursting pattern would occur in the longitudinal direction. This facilitates retrieval of a ruptured inflatable device. Or, the longitudinal etched recessions will result in a gentler leakage as opposed to bursting. Another advantage is that theaxial recessions826 can promote axial blood perfusion, enabling blood or drug flow around the inflatable device during and after inflation.
• FIG. 9 shows aninflatable device901 with modifications of a multi-layer inflatable device, such as thedevice101 ofFIG. 1C. Parts of theouter layer920 have been removed by ultrashort laser pulses, exposing theinner layer921. The remainingouter layer920 extends as a circumferential, tubular shaped layer around the perimeter of theinflatable device901. The length ofouter layer920, as measured parallel to the longitudinal axis903, can be formed to substantially match the length of an external device, such as a stent mountedheart valve902. Theouter layer920 ofFIG. 9 can have different properties than theinner layer921. For example, theouter layer920 can change the frictional properties between theinflatable device901 and an above-lying surface. Meanwhile, ablation of the excess outer surface material allows for tighter folding of theinflatable device901.
• FIG. 10 shows aninflatable device1001 withrecessions1028 formed by ultrashort laser pulses to serve as identifying marks.Recessions1028 can be located on thebody region1008 as seen inFIG. 10. Therecessions1028 can also (additionally or alternatively) be located on the cone region or the leg region. InFIG. 10,recessions1028 extend circumferentially around the perimeter of thebody region1008. These recessions can serve as identifying marks to assist in the assembly of the inflatable device. Markings on the inflatable device leg can help identify cutting length or welding bands, for example. They can also assist in the alignment of the stent or valve during anatomical implantation. Markings can have indicia to identify parts, product models and inflatable device sizes as another example.
• The implementation ofFIG. 10 can also have multiple layers—such as a radiopaqueouter layer1020. Therecessions1028 in the outer layer selectively remove the radiopaqueouter layer1020, for example, to reveal its orientation on radiological instruments during medical procedures.
• The ultrashort laser pulse formed modifications disclosed herein have the advantage of having low or no thermal impact on the inflatable device wall. The absence of significant thermal impact preserves the properties of the inflatable device. For example, use of the ultrashort laser preserves the homogeneity of the polymer orientation of a polymeric wall.
• Advantageously, the inflatable devices disclosed herein can be used to improve various inflatable device based medical procedures, such as to deliver a prosthetic heart valve during a transcatheter valve replacement procedure. As another example, the devices can be used to deliver a stent during percutaneous procedures. As another advantage, the laser etching procedure disclosed herein allows the thickness of the cone and body of a device to be changed independently—facilitating variations in expansion characteristics. Also, uniform wall thickness facilitates folding, retrieving and better general performance. For example, the legs of the inflatable device need to be thicker to allow stretching of the body without breaking the inflatable device. Laser etching allows the legs to be thinned for a lower profile, reducing friction on the arterial walls during deployment and retrieval.
• The various patterns of recession etching disclosed herein have a range of advantages. Reduction in body wall thickness results in resistance to formation of the dumb-bell (or dog bone) shape during expansion of a stent or valve, resulting in a more accurate final outside diameter for the device being delivered. This can be useful for aortic applications. Ablating one end selectively can result in a mushroom shape, which can be helpful for bicuspid repair. Reduction of the cone region thickness reduces inflatable device withdrawal forces. Ablating shallow rings in the body at one or both ends facilitates earlier expansion of ring portions to limit axial movement of the stent or valve. Ablating shaped patterns in the outer surface of the inflatable device wall increase the friction force between the implantable and the inflatable device. Removal of wall material in an axial direction (or other location) can create a desired point, spot or pattern for failure of the inflatable device. Reduction of leg thickness reduces bond profiles and increases efficiency of the bonding process. Also, shaping of the leg regions can increase bond strength and precision.
• Also, in multi-layered inflatable devices, the low-heat laser can be used to remove undesired layers from various locations. A dual layer can be retained in the body region for increased puncture resistance and increased (or decreased) friction between the inflatable device and stent, but removed from the cone and leg regions for profile and tackiness reduction. The inflatable device can also be modified to create “witness lines” or a mid-line to improve alignment of the inflatable device and stent or valve during crimping or other assembly steps. Or, the inflatable device can be etched with various identification marks.
• Removal of wall materials from a center or body section reduces stent or valve frame edge flaring, reducing impact on surrounding tissues during delivery. A tapered wall inflatable device could also be created to create a tapered outer or inner diameter in the vasculature, stent or valve frame, to fit tapered anatomy, such as in the peripheral vasculature, for example.
• Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing description. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (20)

We claim:

1. An inflatable medical device comprising;

a wall comprising a network of polymer chains, the wall having a surface; and

at least one low heat laser-formed modification on said surface;

wherein the wall is configured to be inflatable into a therapeutically or diagnostically useful shape.

2. The device ofclaim 1, wherein the network comprises a network morphology, and the network morphology of an area surrounding the low heat laser-formed modification is substantially unaffected by thermal effects.

3. The device ofclaim 2, wherein the therapeutically or diagnostically useful shape includes:

at least one body region;

at least one leg region;

at least one cone region extending between the body region and the leg region; and

a longitudinal axis extending through the body, leg and cone regions.

4. The device ofclaim 3, wherein the surface is an inner surface of the wall and wherein the low heat laser-formed modification is on the inner surface.

5. The device ofclaim 4, wherein the low heat laser-formed modification is on an inner surface of the leg region.

6. The device ofclaim 2, wherein the low heat laser-formed modification comprises at least one recession in the surface.

7. The device ofclaim 6, wherein the recession extends parallel to the longitudinal axis.

8. The device ofclaim 6, wherein the device further comprises a circumferential perimeter, and the recession in the surface extends around at least a portion of the circumferential perimeter.

9. The device ofclaim 6, wherein the recession is on the cone region.

10. The device ofclaim 9, wherein a width of the recession tapers as it extends toward the leg region.

11. A method of fabricating an inflatable device, the method comprising;

applying low heat laser pulses to a surface of the inflatable device;

ablating excess material from the surface of the inflatable device; and

leaving a network morphology of the surface substantially unaffected by thermal effects.

12. The method ofclaim 11, further comprising

forming at least one body region;

forming at least one leg region;

forming at least one cone region extending between the body and leg regions;

forming a longitudinal axis extending through the body region, leg region, and cone region.

13. The method ofclaim 11, further comprising partially ablating an inner surface.

14. The method ofclaim 11, further comprising exposing an inner layer beneath an outer layer.

15. The method ofclaim 11, wherein the ablating excess material includes ablating in the direction of a longitudinal axis of the inflatable device.

16. The method ofclaim 11, wherein ablating excess material includes ablating at least a portion of a cone region of the inflatable device.

17. The method ofclaim 11, wherein ablating excess material includes ablating at least a portion of a leg region of the inflatable device.

18. The method ofclaim 11, wherein ablating excess material includes ablating at least a portion of a body region of the inflatable device.

19. The method ofclaim 11, wherein ablating excess material includes ablating around a perimeter of the inflatable device.

20. The method ofclaim 11 wherein applying low heat laser pulses applies ultrashort laser pulses less than 1000 picoseconds in duration.

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