BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a prior art balloon catheter and guidewire;
FIG. 2 is a side view of a prior art balloon catheter and guidewire passing through a vascular curve, illustrating the presence of a gap when the catheter passes over the guidewire in a tortuous section of the vasculature;
FIG. 3 is a side view of an embodiment of a balloon catheter according to the present disclosure when not passing over a guidewire;
FIG. 4 is a side view of an embodiment of a balloon catheter according to one embodiment of the present disclosure;
FIG. 5 is an enlarged side view of an embodiment of a balloon catheter according to the present disclosure passing through a vascular curve;
FIG. 6 is a photograph of a catheter tip portion incorporating an embodiment according to the present disclosure;
FIG. 7 is a photograph of a tip portion of a prior art catheter navigating an angled path over a guidewire;
FIG. 8 is a photograph of the catheter portion of FIG. 6 navigating an angled path over a guidewire;
FIG. 9 is a photograph of the catheter portion of FIG. 7 approaching a calcification-like protrusion;
FIG. 10 is a photograph of the catheter portion of FIG. 6 approaching the protrusion as in FIG. 9;
FIG. 11 is a photograph of the catheter portion of FIG. 7 pushed up against the calcification-like protrusion and stopped thereat and not able to pass without significant force;
FIG. 12 is a photograph of the catheter portion of FIG. 6 showing its angle tip contacting the calcification-like protrusion; and
FIG. 13 is a photograph of the catheter portion of FIG. 6 following movement beyond that shown in FIG. 12 with the angle tip easily passing over the calcification-like protrusion.
DESCRIPTION OF THE EMBODIMENTS
As required, detailed embodiments are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the embodiments disclosed here in virtually any appropriate manner.
FIG. 3 shows one embodiment of a catheter 31 according to the present disclosure. While the figures illustrate balloon catheters, other catheter systems are contemplated, including stent delivery systems. In this view of FIG. 3, the catheter 31 is shown as it would be without the presence of a guidewire. That is, the catheter is shown as it would be when the catheter tip 32 is not stressed, typically when in its as-molded configuration. The catheter tip 32 is orientated so that its axis is curved radially. The portion of the lumen 34 found in the tip follows this radially curved axis while its proximal end remains aligned with the lumen of the catheter. This can be characterized as a bent tip. The illustrated catheter tip 32 is formed on the bias. The catheter end tip edge 35 is angled in that it is not perpendicular relative to the longitudinal axis of the catheter lumen proximal to the tip 32. FIG. 6 also shows these features.
FIG. 4 is an embodiment of a catheter 41 of the present disclosure where the catheter tip 43 with a bent configuration and bias-formed edge has a wall 44 and is shown passing over a guidewire 42 as would occur in the vasculature. FIG. 8 provides a similar illustration. In FIG. 4 view the most distal portion of the tip 43 is cut away to show the lumen 45. With the guidewire within the tip, the bias-formed tip edge 46 is not strictly perpendicular to, but is angled with respect to, the longitudinal axis of the lumen 45 closely proximal of the tip. This is a typical in-use relationship between guidewire and bent tip and gives advantageous gap-minimizing effects as discussed herein.
According to this illustration or embodiment, the non-linear catheter tip 43 is orientated in the direction that the guidewire takes in the vasculature, including over tortuous paths. Due to the bent tip 43 and the bias-formed angled tip edge 46, there is a substantial reduction in the gap between the inner face of the wall of the tip 43 and the guidewire 42 when compared with the gap 26 of the catheter tip shown in FIG. 2 with its tip portion that is neither curved nor with a bias-formed edge. As shown in FIG. 4, this gap reduction or substantial elimination occurs even at a location where the curve of the guidewire and the as-molded curve of the tip portion 43 do not precisely coincide. In actual use, there often is not precise coincidence between catheter tip curve and guide-wire curve at any given guidewire length.
FIG. 5 is an enlarged view of the most distal portion of the embodiment in FIG. 4 showing the catheter tip 43 with a bias-formed angled catheter tip edge 46, the most distal portion being cut away to show the wall 44 of the catheter and the lumen 45. The tip wall 44 in this illustration engages the guidewire 42, and the tip edge 46 is closely spaced from the guidewire while substantially following its curved profile within the vasculature. This shows the substantial reduction in the “gap” 46 between the inner face of the wall 44 of the tip 43 and the guidewire 42. To the extent any gap 46 is formed, it is directed away from plaque or calcification 27, thus avoiding aggressive engagement of the plaque 27 or damage to the catheter tip as discussed herein.
It will be appreciated that the bias-formed end has the characteristic of having its inside curved wall length be less than its outside curved wall length. Also, the curvature of this distal tip portion often will be greater than that of the guidewire at a tortuous curve. As a result, the portion of the tip that is less likely to directly engage the guidewire in the typical in-use situation illustrated in FIG. 4 is substantially shorter than the portion most likely to engage the guidewire when in use. Because of this relationship, the location most susceptible to gap formation has the least area and wall length that would otherwise extend away from the guidewire and create an undesireable gap, as illustrated in broken lines in FIG. 5.
According to different embodiments, the tip may be radially bent to different degrees. The degree of bend or curve may be from about 10 to about 90 degrees from the longitudinal axis of the body lumen, or from about 25 to 75 degrees from the longitudinal axis of the body lumen, often between about 35 to 60 degrees from the longitudinal axis.
Typically, gap minimization and crossability and trackability enhancement are facilitated when this catheter tip curve angle is greater than a guidewire curve expected to be encountered during a particular medical procedure within a particular patient. This helps to ensure that the outside (or longer) wall curved length engages the guidewire during use while the portion least likely to engage the guidewire is shortest, so as to minimize the likelihood of unacceptable gap development.
According to different embodiments, the tip edge may be angled or bias-formed to different degrees. The degree of bias-formed angle of the tip edge may be from about 120 to about 240 degrees relative to the longitudinal axis of the body lumen, or from about 140 to about 220 degrees, often between about 160 to 200 degrees from the longitudinal axis of the body lumen. In a preferred embodiment, the tip edge is bias-formed to be 180 degrees relative to the longitudinal axis of the lumen.
FIG. 10 shows the angle tip of the embodiment of this catheter approaching a protrusion mock-up in the form of an intersection point shown closely distal of the angle tip. FIG. 12 illustrates subsequent distal movement and deflecting of the tip upon engagement of the protrusion, which simulates action of the inventive tip when engaging a calcification or other obstruction within a vessel. FIG. 13 shows further distal movement, with the tip easily passing over the protrusion.
The tip portion may be composed of any of a large number of materials known in the art. Ideally, the selected material should allow the tip to bend with the path of the guidewire through the vasculature but also allow the tip to return to its unstressed position when not in use. The tip may be composed, for example, of a polymer material that has adequate bendability or flexural modulus and resiliency.
Shape memory materials may also be used but are not necessary to achieve the benefits of the disclosure. These include so-called nitinol alloys. The bent or curved configuration can be heat set using interlocking dovetails to facilitate flexing. This is illustrated in U.S. Patent Application Publication No. 2004/0082881, hereby incorporated by reference hereinto.
The distal tip portion of the present disclosure may be adapted to fit catheters of different designs. The tip may be used with either over-the-wire or rapid exchange catheters. It may also be used in balloon catheters adapted for stent delivery and expansion.
To use the catheters having the distal tip portions described in the disclosure, the user passes the catheter along a guidewire. When the catheter reaches a region where the guidewire changes direction as it passes through a portion in the vasculature such as a bend, a branched region, or a constriction, the tip will rotate in order to align itself, following what may be said to be a law of least resistance. If constrained for some reason, the tip hits a blockage on the other side, it will pass easily since the tip will hit on the bevel. In essence, the tip configuration will work from both sides, and the tip angle does not need to be oriented in order to align the tip angle with the curve. As a consequence, the distal tip of the catheter more closely follows the guidewire. This brings an advantage of minimizing the gap between the guidewire and the tip.
It will be understood that the embodiments of the present disclosure which have been described are illustrative of some of the applications of the principles of the present disclosure. Numerous modifications may be made by those skilled in the art without departing from the true spirit and scope of the disclosure. Various features which are described herein can be used in any combination and are not limited to procure combinations that are specifically outlined herein.