Patent Application
20150119853
The present invention relates to the field of medical catheters. In particular, the present invention relates to catheters used to navigate vascular anatomy and cardiac structures.
There are a great number of medical conditions that necessitate physician intervention by catheter in order to provide diagnosis of or therapy for diseases of the vascular or cardiac systems. In many of the patients that require this type of treatment, the nature of their disease is such that their anatomy does not allow for easy or safe passage of catheters through the vasculature or to the target location. In these cases, a guidewire is often used to reach the target location followed by the catheter over that guidewire. However, in some cases the passage of the guidewire is also complicated by either the tortuosity of the vascular passage, the need to steer the guidewire or otherwise change the direction of advance in order to enter a selected bifurcation of the vessel or the desire to pass atraumatically through a cardiac structure such as a valve. In these cases, the guidewire is often advanced concurrently with a catheter of some type such as a coronary guide catheter or a pigtail catheter.
In the particular case of transcatheter aortic valve replacement, there is a need to place a relatively stiff guidewire across the native aortic valve in order to guide the placement of the valve delivery system. The native aortic valve is being treated because of a stenosis, or stiffening, of the native valve leaflets. This stenosis also makes it very difficult to advance a guidewire through the restricted valve. In order to pass the guidewire through the native valve, any number of catheters may be used in an attempt to orient the catheter tip in a way to allow the wire to pass through the restricted opening. In an ideal situation, a catheter called a pigtail catheter would be used to place the guidewire. The pigtail catheter is ideal because of its geometry—it is shaped in an approximately 270 degree curve such that the distal contact surface of the catheter is smooth and rounded, presenting an atraumatic surface of contact between the leading edge of the catheter and the cardiac structures that it contacts. It also provides an exit location for the guidewire that is not at the distal face of the catheter, minimizing the possibility that advancing the guidewire would perforate or otherwise damage structures upon its exit from the catheter. Unfortunately, the pigtail geometry that provides for safe advancement of the guidewire once it has passed through the aortic valve and into the left ventricle of the heart is often not the preferred geometry for orienting the tip of the guidewire for safe and effective aortic valve crossing. In many cases, a coronary guide catheter is needed for this purpose. One such curve, designated the AL1 coronary guide curve, is often used because it orients the tip of the catheter in a generally axial direction and the catheter allows for some steering of the guidewire tip to align the wire with the center of the valve. This greatly improves the likelihood of success in crossing the native valve, but following the transition across the native valve, the guidewire remains oriented in the axial direction and increases the risk of left ventricular damage or perforation. The physician has to make a tradeoff between functionality while attempting to cross the native valve and the safety of the patient while advancing the guidewire once the catheter is across the valve.
According to one aspect of the invention, a catheter is disclosed that can be converted from one preferred shape into another preferred shape by means of changing the axial alignment or radial orientation between two slidably disposed component members. In the case of a catheter that is used to cross a stenotic native aortic valve, one catheter component may be shaped in the AL1 configuration or another preferred shape in order to effect crossing of the stenotic valve with a guidewire. Once the tip of the wire has crossed the valve, the second catheter component may be advanced to configure the catheter construct into a pigtail catheter shape in order to provide a safe geometry for further advancement of the guidewire into the left ventricle and appropriate placement of the wire along the ventricular wall.
Alternately, the device can be configured in such a way that when the two catheter components are aligned longitudinally, the combination of the catheter shapes result in an AL1 or first preferred configuration. The retraction of one of the components, either the inner or outer catheter, would result in the remaining distal catheter component recovering to a pigtail or second preferred configuration.
In yet another embodiment, the two catheter components can be configured such that when the catheters are aligned longitudinally and held in a first radial orientation, the shape and stiffness of the two components result in a first preferred configuration. Rotation of either the inner or outer component to a second radial orientation changes the interactions between the two catheter component shapes with a resultant second configuration.
There are numerous means by which the two catheter components may be configured to provide a first and second preferred shape. In one embodiment the second catheter component is substantially stiffer than the first catheter component when the first catheter component is shaped in the first configuration and the second catheter is shaped in the second configuration. When the second catheter component is advanced over the first catheter component, the shape of the first catheter component is overwhelmed by the second catheter component and the combined construct substantially takes the shape of the second catheter component.
In another embodiment, the first catheter component is substantially stiffer than the second catheter component when the second catheter component is shaped in the first configuration and the first catheter component is shaped in the second configuration. When the first catheter component is advanced within the second catheter component, the shape of the second catheter component is overwhelmed by the first catheter component and the combined construct substantially takes the shape of the first catheter component.
In yet another embodiment, the lengths of the catheter components are substantially different such that advancement of one catheter component over or within the other catheter component removes the other catheter component from the effective distal end of the catheter. This allows the distal shape of the most distal catheter component to take a predetermined shape independent of the configuration of the proximal catheter shape.
In another embodiment, the catheter components are constructed with regions of variable stiffness. Relative axial alignment of the regions of greater or lesser stiffness allow the combination catheter to take on different shapes as necessary. When one catheter component with a minimally stiff regions is aligned with the second catheter component with minimally stiff regions, a configuration that provides one extreme of shape can be achieved due to the relatively flexible regions of the combined catheter. Using the same two catheter components, but with the regions of maximal stiffness on one catheter component bridging the minimally stiff regions of the second catheter, a much stiffer combined construct can be achieved and a second extreme of shape can be achieved. By modulating the engagement of the relatively stiff regions of one catheter component with those of the second catheter component, a range of combined catheter shapes can be achieved through axial manipulation of the catheter components with respect to one another.
In another embodiment, the shape of the combined catheter can be modulated by radial manipulation of one catheter component relative to the other, with or without axial adjustment of catheter component position. Two catheter components each constructed with a distal shape can provide a range of combined catheter shapes through variable rotational alignment of the two catheter components. The range of combined device shapes can vary widely depending upon the geometry and relative stiffness of the two catheter components.
In any of these embodiments, the dual catheter design has uses beyond simply crossing the native valve. With the distal catheter component in the left ventricle, the second catheter may be placed with the distal tip just proximal to the native valve and a dual-pressure measurement may be taken from the proximal hubs of each of the catheters. In this manner, a direct pressure gradient may be measured across a stenotic valve or a prosthetic valve replacement.
While these device descriptions are focused on therapy related to the aortic valve, a combination catheter as described has applications for many other diagnostic and therapeutic catheterization purposes. A combination catheter of this type may be used to provide guide and support for access to the coronary arteries, the renal arteries, crossing lesions or restrictions in the cardiac, neurovascular or peripheral vasculature, or any other application in which a first preferred catheter configuration is required for a first purpose while a second preferred catheter configuration is required for a second purpose and the exchange of catheters causes procedural delay or exposes the patient to additional risk.
a and 6b are an image series of an embodiment of a combined catheter of the invention used in an embodiment of an AL1 configuration of the invention, with retraction of an outer component resulting in an embodiment of a pigtail configuration of the invention;
a and 7b are an image series of an embodiment of a combined catheter of the invention used in an embodiment of an AL1 configuration of the invention, with retraction of an inner component resulting in an embodiment of a pigtail configuration of the invention; and,
a and 8b are an image series of an embodiment of a combined catheter of the invention, with full retraction of one catheter component providing a first preferred shape while full retraction of a second catheter component provides a second preferred shape.
Referring now to the figures, the invention generally comprises a kit of components that may include a first catheter component 1, a guidewire 2 (see e.g.
The two catheters 1 and 3 are sized such that one catheter fits within the other. In some embodiments, catheter 1 fits within catheter 3 and in other embodiments, catheter 3 fits within catheter 1. The two catheters have different shapes. In one embodiment, catheter 1 is an AL1 shaped catheter and catheter 3 is a pig-tail shaped catheter. However, because one catheter fits within the other, the shapes may override each other or combine to form new shapes. The degree to which the shapes override each other, or combine to form new shapes, is dependent on the stiffness or softness of the catheters relative to each other. Moreover, it is envisioned that unique and desired shapes could be attained by providing catheters having variable stiffnesses. Additionally, the effect that the two catheters 1 and 3 have on each other may be varied not only depending on how far one catheter is inserted into the other, but also on the radial orientation of one catheter relative to each other.
As such, methods are described herein involving attaining desired shapes by selecting two catheters 1 and 3 having different shapes, and manipulating the catheters both axially and radially relative to each other at various stages in the advancement of one or both of the catheters into a desired target location, such as the heart. In at least one embodiment, a guidewire is also used to place the catheters in the target location.
By way of non-limiting example,
Next,
In one embodiment, the guidewire 2 is left in place and, as shown in
a and 6b show the influence one catheter can have on the other.
a and 7b depict a catheter system design in which the combined shapes of the inner and the outer catheter components take on a first shape when the catheter components are axially aligned.
a and 8b depict a catheter system design in which each catheter component takes on a preferred shape independent of the other catheter component.
Although the invention has been described in terms of particular embodiments and applications, one of ordinary skill in the art, in light of this teaching, can generate additional embodiments and modifications without departing from the spirit of or exceeding the scope of the claimed invention. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.
This application claims priority to U.S. Provisional Application Ser. No. 61/897,145 filed Oct. 29, 2013 entitled Convertible Shape Catheter And Method Of Use, which is hereby incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61897145 | Oct 2013 | US |
