Medical balloon with enlarged transitional radii

The present invention provides a medical balloon having enlarged radii, which may be disposed on a dilation catheter. The enlarged radii balloon may reduce the trauma experienced by a patient both during the procedure and when the catheter is removed from the patient. The enlarged radii may provide the deflated balloon with smoother transitions and less mechanical rigidity at the balloon transitions.

BACKGROUND

Medical balloons may be combined with a wide variety of devices and used in a vast array of medical procedures. For example, medical balloons may be combined with a catheter to provide dilation catheters, drainage catheters, and the like.

Dilation catheters rely upon a medical balloon for applying pressure against the interior of a biological conduit, such as a blood vessel, a portion of the urinary tract, and/or a portion of the gastro-intestinal tract. Dilation catheters are useful in a variety of techniques, including gynecological procedures, cardiac procedures, general interventional radiology procedures, and the like.

One example of a cardiac procedure is percutaneous transluminal coronary angioplasty (PTCA). Using this technique, a physician can dilate a narrowed artery by inserting and advancing a catheter with a deflated medical balloon at its tip into the narrowed part of the artery. The plaque is compressed upon inflation of the medical balloon, which dilates the inner diameter of the blood vessel, allowing blood to flow more easily. Following this procedure, the medical balloon is deflated and the catheter removed from the patient's body.

Another procedure employing dilation catheters is stent delivery. A stent may be a wire mesh or a solid tube used to support an artery that has recently been cleared using angioplasty. After being collapsed to a small diameter, the stent may be placed over the medical balloon of the dilation catheter and advanced to the area of the blockage. When the medical balloon is inflated, the stent expands, locks in place, and forms a scaffold, holding the artery open.

One specific use of dilation catheters is in the treatment of obstructed blood vessels. This type of procedure normally begins with insertion of a delivery sheath using the Seldinger or other technique. Delivery sheaths are generally small-diameter plastic tubes and are another type of conduit, through which a catheter may be inserted. Generally, the delivery sheath is inserted through a patient's skin and then into a major blood vessel, for example. The delivery sheath is arranged such that the proximal portion remains on the exterior of the patient, while the distal portion is located in the major blood vessel of interest. Next, the distal portion of a wire guide may be inserted into the exterior and proximal end of the delivery sheath. Then, the wire guide may be passed through the delivery sheath, out the distal end of the delivery sheath, and into the patient. In this fashion, a delivery sheath may be used as a means for the placement of intravascular medical devices into venous or arterial systems following insertion of the delivery sheath through the skin. The delivery sheath may also protect the point of entry into the patient's body from mechanical damage and trauma.

Once inside the patient, the distal end of the wire guide may be advanced into the diseased coronary artery until it reaches the obstruction. After crossing the lesion, or other region to be dilated, the wire guide may be secured such that it remains in this location. During this entire procedure, the proximal end of the wire guide remains at the exterior of the patient.

Next, the distal tip of a dilation catheter may be slid over the proximal end of the previously placed wire guide. The dilation catheter, following the previously placed wire guide, may be advanced into the proximal end of the delivery sheath, through the body of the delivery sheath, out the distal end of the sheath, and then into the patient. The dilation catheter may be advanced over the wire guide until the medical balloon, located toward the distal end of the dilation catheter, is properly positioned adjacent to the lesion. Finally, fluid may be used to inflate the medical balloon to a predetermined size, thus compressing the lesion.

Generally, the medical balloon of a dilation catheter occupies a folded configuration prior to inflation. This configuration may reduce the force necessary to advance the dilation catheter through the conduit, which in turn may reduce the physical trauma to the patient. When the medical balloon on the dilation catheter is inflated, to compress a lesion for example, the medical balloon unfolds. Once unfolded, the medical balloon is generally not capable of again obtaining the folded configuration.

FIG. 1depicts a longitudinal cross-sectional view of a conventional dilation catheter100that includes an elongate catheter body105, having a proximal end107and a distal end108. The distal end may terminate in a distal tip110. The conventional dilation catheter body105is equipped with a conventional medical balloon115(depicted in its unfolded configuration), having a distal balloon end117and a proximal balloon end118. The medical balloon115has a distal conical region120, a proximal conical region125, and a working length130, where the working length130is defined by the distal conical region120and the proximal conical region125. The medical balloon115, including the working length130, the distal conical region120, and the proximal conical region125, is formed by a balloon wall135, enclosing a balloon cavity140. The balloon wall135may form a distal balloon lip142and a proximal balloon lip143. The conventional medical balloon115may be attached to the elongate catheter body105via the distal balloon lip142and the proximal balloon lip143. For clarity of discussion, the lips142,143are not considered part of the balloon because they do not enclose the balloon cavity140.

The distal conical region120and the proximal conical region125each include two taper transitions. There is a distal working length-to-taper transition145, a distal taper-to-neck transition150, a proximal working length-to-taper transition155, and a proximal taper-to-neck transition160. The distal working length-to-taper transition145is located between the working length130and the distal conical region120. The proximal working length-to-taper transition155is located between the working length130and the proximal conical region125. The distal taper-to-neck transition150is located between the distal conical region120and the elongate catheter body105. The proximal taper-to-neck transition160is located between the proximal conical region125and the elongate catheter body105.

The conventional medical balloon115, in its unfolded configuration, includes sharp bends at the balloon working length-to-taper transitions,145and155, and at the taper-to-neck transitions,150and160. The sharp bends at the transitions of the conventional medical balloon115do not easily collapse after the balloon has been inflated and can make it difficult to pull the balloon back through the conduit after use. The harder it is to remove the collapsed balloon after use, the more patient trauma may occur at the entry site during removal of the device. Furthermore, if the conventional medical balloon115freezes in the delivery sheath and the physician exerts excess force on the conventional dilation catheter100in attempt to remove it from the sheath, mechanical failure of the device may occur. A situation that may necessitate making a much larger incision in the patient to remove the device. A medical balloon that facilitates removal of dilation catheters from conduits may beneficially reduce patient trauma.

BRIEF SUMMARY

An inflatable medical balloon is provided having enlarged transitional radii. These medical balloons can provide many benefits, including a reduction in during and post-procedure trauma to the patient. The enlarged transitional radii may provide smoother transitions and/or less mechanical rigidity at the balloon transitions, which may decrease the force required to pull the deflated balloon back through a conduit after use.

In another aspect, the enlarged transitional radii may provide a medical balloon that more easily conforms to the shape of a conduit, thus allowing easier travel through the conduit.

The reduction in removal force may directly reduce trauma at the entry point to the patient. The reduction in removal force also may reduce mechanical damage to the distal portion of the delivery sheath, thus further reducing trauma to the patient when the delivery sheath is removed from the entry point. In another aspect, the trauma to a biological conduit also may be reduced.

In one aspect, a dilation catheter is provided that includes at least one lumen in fluid communication with a medical balloon having enlarged transitional radii at at least one of a proximal taper-to-neck transition, a proximal working length-to-taper transition, a distal taper-to-neck transition, and a distal working length-to-taper transition.

In another aspect, a medical balloon is provided having enlarged transitional radii at at least one of a proximal taper-to-neck transition, a proximal working length-to-taper transition, a distal taper-to-neck transition, and a distal working length-to-taper transition.

In another aspect, a method of making a dilation catheter is provided that includes fixing to an elongate catheter body a medical balloon having enlarged transitional radii at least one of a proximal taper-to-neck transition, a proximal working length-to-taper transition, a distal taper-to-neck transition, and a distal working length-to-taper transition.

In another aspect, the force required to remove a dilation catheter from a conduit is reduced by inserting the dilation catheter through the conduit so a medical balloon having enlarged transitional radii fixed on the catheter emerges from the conduit, inflating the balloon, deflating the balloon, and exerting a force against the catheter to remove the balloon from the conduit, where the removal force is reduced in relation to a conventional dilation catheter having a medical balloon lacking enlarged transitional radii.

Other methods, features, and advantages of the invention will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages are included within this description, are within the scope of the invention, and are protected by the following claims.

DETAILED DESCRIPTION

FIG. 2depicts a longitudinal cross-sectional view of a dilation catheter200having an elongate catheter body205and a deflated medical balloon210embodying aspects of the present invention. The catheter body205may have a longitudinal axis extending between a proximal end212and a distal end213. The distal end213may terminate in a distal tip215. The catheter body205may include one or more lumens, such as an inner lumen216and an outer lumen217, defined by a plurality of tubes, such as inner tube218and outer tube219. In one aspect, the inner tube218, and its corresponding inner lumen216, may not be present, leaving only outer lumen217. In another aspect, one or more of the lumens, such as the inner lumen216or the outer lumen217, may be in fluid communication with a balloon cavity245. Furthermore, the exterior lumen220may be in fluid communication with the balloon cavity245. The dilation catheter200also may possess an exterior lumen220, which may be located to the exterior of the elongate catheter body205on which the medical balloon210is mounted.

The deflated medical balloon210may have a distal balloon end222and a proximal balloon end223. The medical balloon210may have a distal conical region225, a proximal conical region230, and a working length235defined by the distal and proximal conical regions222and223, respectively. The distal conical region225and the proximal conical region230may be described as transitions between the elongate catheter body205and the working length235. The medical balloon210, including the working length235, the distal conical region225, and the proximal conical region230, may be formed by a balloon wall240, enclosing the balloon cavity245. The balloon wall240may form a distal balloon lip247and a proximal balloon lip248. The medical balloon210may be attached to the elongate catheter body205via the distal balloon lip247and the proximal balloon lip248. For clarity of discussion, the lips247,248are not considered part of the balloon because they do not enclose the balloon cavity245.

The distal conical region225and the proximal conical region230each include two taper transitions. There is a distal working length-to-taper transition250, a distal taper-to-neck transition251, a proximal working length-to-taper transition252, and a proximal taper-to-neck transition253. The distal working length-to-taper transition250is located between the working length235and the distal conical region225. The proximal working length-to-taper transition252is located between the working length235and the proximal conical region230. The distal taper-to-neck transition251is located between the distal conical region225and the elongate catheter body205. The proximal taper-to-neck transition253is located between the proximal conical region230and the elongate catheter body205.

The curvature of the working length-to-taper transitions,250and252, and the taper-to-neck transitions,251and253, may be expressed in terms of an enlarged radius, corresponding to a circle255scribed in each transition. For example, a distal working length-to-taper transition250has an enlarged distal working length-to-taper radius254. In this manner, the length of the enlarged radius of the scribed circle255provides a way to measure the curvature or rate at which one portion of the balloon transitions into another portion of the balloon or into the catheter body205. In addition to the enlarged distal working length-to-taper radius254, there is also an enlarged distal taper-to-neck radius260, an enlarged proximal working length-to-taper radius265, and an enlarged proximal taper-to-neck radius270. The lengths of the enlarged radii254,260,265, and270correspond to the values that may be measured when the medical balloon210is unfolded.

Because each radius has a length that may be measured in millimeters (mm), variances in transition rates may be determined by comparing the lengths of the radii. For example, to express a slower, gentler curvature from one portion of the balloon to another requires a larger circle, having a larger radius, than would be required to express a rapid curve. Similarly, a balloon having sharp bends connecting one portion of the balloon to another, such as the conventional medical balloon115depicted inFIG. 1, would have no radius or a very small radius.

Unlike conventional medical balloon designs, the balloon transitions250,251,252, and253may have curvature represented as the enlarged radii254,260,265, and270, respectively. For a medical balloon having an 8 mm diameter and a 4 cm length, the enlarged radii may be at least 1.9 mm or may each independently range from about 1.9 mm to about 13 mm. In one aspect, the enlarged radii254,260,265, and270also may be at least 4 mm or may each independently range from about 4 mm to about 12 mm. In another aspect, the enlarged radii254,260,265, and270also may be at least 7 mm or may each independently range from about 7 mm to about 12 mm.

In one aspect, at least one transition of the proximal taper-to-neck transition253, the proximal working length-to-taper transition252, the distal taper-to-neck transition251, and the distal working length-to-taper transition250comprises a radius from about 1.9 mm to about 13 mm. In one aspect, at least one transition of the proximal taper-to-neck transition253, the proximal working length-to-taper transition252, the distal taper-to-neck transition251, and the distal working length-to-taper transition250comprises a radius from about 4 mm to about 13 mm. In one aspect, at least one transition of the proximal taper-to-neck transition253, the proximal working length-to-taper transition252, the distal taper-to-neck transition251, and the distal working length-to-taper transition250comprises a radius from about 7 mm to about 13 mm. In one aspect, at least one transition of the proximal taper-to-neck transition253, the proximal working length-to-taper transition252, the distal taper-to-neck transition251, and the distal working length-to-taper transition250comprises a radius of at least 1.9 mm. In one aspect, at least one transition of the proximal taper-to-neck transition253, the proximal working length-to-taper transition252, the distal taper-to-neck transition251, and the distal working length-to-taper transition250comprises a radius of at least 4 mm. In one aspect, at least one transition of the proximal taper-to-neck transition253, the proximal working length-to-taper transition252, the distal taper-to-neck transition251, and the distal working length-to-taper transition250comprises a radius of at least 7 mm.

In one aspect, the radii265and270may be substantially the same. In another aspect, the radii254and260may be substantially the same. Furthermore, the radii254,260,265, and270may be substantially the same. In another aspect, the radii265and270may be substantially the same as each other, but different from254and260, which may be substantially the same as each other. In another aspect,254,260,265, and270may all be different.

As shown in Table 1 below, the enlarged radii254,260,265, and270of the medical balloon210may provide for a substantial reduction in the force required to pull the deflated balloon through a delivery sheath.

Table 1 compares the force required to remove a deflated conventional medical balloon from a delivery sheath (Entry 1) to the force required to remove a deflated medical balloon embodying aspects of the present invention from a delivery sheath (Entries 2-5). The data in Table 1 were collected using a series of balloons in which the radii were varied, but the balloon diameter and length were held constant. In each case, the balloon diameter was 8 mm and the balloon length was 4 cm.

Entry 1 represents a conventional medical balloon with radii of 0.1 mm. The conventional medical balloon of Entry 1 had a removal force of 2.2 N. Entries 2 through 5 represent medical balloons having enlarged radii ranging from 3.2 mm to 11.4 mm, in accordance with the present invention.

Table 1 demonstrates that medical balloons having the enlarged radii of the present invention may require less force to withdraw through a delivery sheath. For example, Entry 5 provides a 43% reduction in the amount of force required to remove the deflated enlarged radii medical balloon from the sheath when compared to the deflated conventional medical balloon. In addition to reducing the removal force, the smoothed transitions provided by the enlarged radii may increase the comfort level of the patient during the procedure and lessen the trauma to the biological conduits as the catheter is guided through the patient.

A decrease in the force required to remove the medical balloon from the delivery sheath also may protect the mechanical integrity of the catheter because if the physician doesn't have to pull as hard to remove the medical balloon, then there may be less strain on the catheter. This can reduce the chance of the medical balloon detaching in the body cavity and requiring a large incision for removal. Furthermore, if the medical balloon can be more easily removed from the delivery sheath, the risk of damaging the distal portion of the delivery sheath may be reduced. This may be beneficial, since removal of a damaged delivery sheath also may result in additional trauma to the patient, especially if the removal of the medical balloon causes a flaring in the distal end of the sheath. Finally, a reduction in the force required to remove the medical balloon may allow the physician to more easily determine if problems are occurring during the removal of the catheter. For example, the physician may be able to more readily evaluate when the dilation catheter has become ensnared by something within the delivery sheath or within a biological conduit.

The radius of enlarged radii can vary depending on the diameter of the medical balloon. Table 2 below provides a series of medical balloons and corresponding preferred enlarged radii, which may exhibit a reduction in removal force when compared to conventional medical balloons of the same diameter. As may be seen from the Table, smaller diameter medical balloons have smaller preferred enlarged radii lengths due to their smaller size. The enlarged radii medical balloons of Table 2 also may demonstrate a beneficial reduction in removal force as was previously observed for the 4×8 medical balloon in Table 1.

FIG. 3depicts a deflated conventional medical balloon having radii of 0.127 mm.FIGS. 4-12depict deflated medical balloons having enlarged radii ranging from about 1.9 mm (FIG. 4) to about 12.7 mm (FIG. 13). While the enlarged radii are initially difficult to perceive visually, by the time a radius of about 5.1 mm is reached (FIG. 6), the smoothing of the transitions is readily apparent. Even though difficult to visually perceive, the enlarged radii ofFIGS. 4 and 5can have a marked effect on the ability of the medical balloon to conform to and be removed from various conduits.

FIGS. 13A-Ddepict a comparison between a conventional medical balloon1300and a medical balloon having enlarged radii1350before and after inflation. After unfolding, it is apparent that the conventional medical balloon1300has sharp bends at its transitions1310and1315(FIG. 13A). In direct contrast,FIG. 13Cdepicts an unfolded medical balloon having smoothed transitions1360and1365resulting from enlarged radii. When the conventional medical balloon1300is inflated, as depicted inFIG. 13B, the inflation pressure smoothes the sharp bends1310and1315. Similarly, when the enlarged radii medical balloon1350is inflated, as shown inFIG. 13D, it takes on a similar appearance to the inflated conventional medical balloon1300having pressure distended sharp bends. Even though the conventional medical balloon1300may resemble a medical balloon having enlarged radii when in inflated, when deflated, the differences in the transitions are readily apparent.