DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a catheter in accordance with several of the embodiments of the present invention.
FIG. 2A is a cross-sectional view of an imaging device in accordance with the present invention.
FIG. 2B is a cross-sectional view of the imaging device of FIG. 2A, showing an expandable member in its expanded state.
FIGS. 3A-C are side views of physical assessment members in accordance with the present invention.
FIG. 3D is an end view of one of the physical assessment members of FIGS. 3A-C, illustrating an alignment mechanism.
FIG. 4A is a perspective view of an electronic mapping member in accordance with the present invention.
FIGS. 4B-D are schematic representations illustrating several relative orientations of conductors carried by the electronic mapping member of FIG. 4A.
FIGS. 4E-G are alternative embodiments of electronic mapping members in accordance with the present invention.
FIGS. 5A-C are perspective views of a multi-function catheter in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is directed to methods and devices for assessing the shape, size, topography, contours, and other aspects of anatomical vessels and organs using minimally invasive surgical techniques. As summarized above, the devices are typically catheter-based devices having one or more assessment mechanisms associated with the distal portion of the catheter. Such devices are suitable for use during less invasive and minimally invasive surgical procedures. However, it should be understood that the devices and methods described herein are also suitable for use during surgical procedures that are more invasive than the preferred minimally invasive techniques described herein.
Before the present invention is described, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which these inventions belong. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited.
It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.
As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present inventions.
Turning to the drawings, FIG. 1 shows a catheter 100 suitable for use with each of the assessment mechanisms described herein. The catheter 100 includes a handle 102 attached to the proximal end of an elongated catheter shaft 104. The size and shape of the handle 102 may vary, as may the features and functionality provided by the handle 102. In the illustrated embodiment, the handle 102 includes a knob 106 rotatably attached to the proximal end of the handle 102. The knob 106 may be rotated to control the movement and/or function of one or more components associated with the catheter 100, such as for retraction of one or more catheter shafts or sheaths, or manipulation of an expandable member or other component carried at or near the distal end of the catheter shaft 104. Alternative structures may be substituted for the knob 106, such as one or more sliders, ratchet mechanisms, or other suitable control mechanisms known to those skilled in the art.
An inflation port 108 is located near the proximal end of the handle 102. The inflation port 108 is operatively connected to at least one inflation lumen that extends through the catheter shaft 104 to an expandable member 110 located near the distal end of the catheter shaft 104. The inflation port 108 is of any suitable type known to those skilled in the art for engaging an appropriate mechanism for providing an inflation medium to inflate the expandable member 110. For example, a suitable inflation mechanism is an Indeflator™ inflation device, manufactured by Guidant Corporation.
The catheter 100 is adapted to track a guidewire 112 that has been previously implanted into a patient and routed to an appropriate treatment location. A guidewire lumen extends through at least the distal portion of the catheter shaft 104, thereby providing the catheter 100 with the ability to track the guidewire 112 to the treatment location. The catheter 100 may be provided with an over-the-wire construction, in which case the guidewire lumen extends through the entire length of the device. Alternatively, the catheter 100 may be provided with a rapid-exchange feature, in which case the guidewire lumen exits the catheter shaft 104 through an exit port at a point nearer to the distal end of the catheter shaft 104 than the proximal end thereof.
Turning next to FIGS. 2A-B, a first assessment mechanism is shown and described. The assessment mechanism is located at the distal end of a catheter 100, such as that illustrated in FIG. 1 and described above. The assessment mechanism shown in FIGS. 2A-B includes an imaging device that is used to provide two-dimensional or three-dimensional images of a vessel lumen or the hollow portion of an organ within the body of a patient, as described below.
The assessment mechanism includes the outer sheath 120 of the catheter shaft 104, which surrounds the expandable member 110. In the preferred embodiment, the expandable member 110 is an inflatable balloon. The expandable member 110 is attached at its distal end to a guidewire shaft 122, which defines a guidewire lumen 124 therethrough. The guidewire 112 extends through the guidewire lumen 124.
An imaging member 130 is contained within the expandable member 110. The imaging member 130 is supported by a shaft 132 that extends proximally to the handle 102, where it is independently controlled by the user. The imaging member shaft 132 is coaxial with and surrounds the guidewire shaft 124, but is preferably movable (e.g., by sliding) independently of the guidewire shaft 124. At the distal end of the imaging member shaft 132 is the imaging head 134. The imaging head 134 may be any mechanism suitable for transmitting and receiving a suitable imaging energy, such as ultrasonic waves. A typical imaging head 134 is an ultrasonic imaging probe. The structure and function of ultrasonic imaging probes are generally known to those skilled in the art, and is beyond the scope of the present application. The reader is instead directed to the abundant and available literature sources describing such devices.
The expandable member 110 is subject to expansion when a suitable expansion medium is injected into the expandable member through the inflation lumen 126. The inflation lumen 126, in turn, is connected to the inflation port 108 associated with the handle 102. FIG. 2A illustrates the expandable member 110 in its unexpanded (contracted) state, while FIG. 2B illustrates the expandable member 110 in its expanded state, such as after a suitable inflation medium is injected through the inflation port 108 and inflation lumen 126 into the expandable member 110.
To use the assessment mechanism illustrated in FIGS. 2A-B, the distal portion of the catheter is delivered to a treatment location within the body of a patient over the previously deployed guidewire 112. In a particularly preferred embodiment, the treatment location is the aortic heart valve, and the guidewire 112 is deployed through the patient's vasculature from an entry point in the femoral artery using, for example, the Seldinger technique. Deployment of the assessment mechanism is preferably monitored using fluoroscopy or other suitable visualization mechanism. Upon encountering the treatment location, the expandable member 110 is expanded by inflating the balloon with a suitable inflation medium through the inflation port 108 and the inflation lumen 126. The expandable member 110 engages the internal surfaces of the treatment location, such as the annular root of the aortic heart valve. Once the expandable member 110 is expanded, the imaging head 134 is activated and the imaging process is initiated. The imaging head 134 is preferably advanced, retracted, and rotated within the expandable member 110 as needed to obtain images in a variety of planes to yield a 360° three-dimensional image, or any desired portion thereof. Once the imaging process is completed, the expandable member 110 is deflated, and the assessment mechanism may be retracted within the catheter shaft 104. The catheter 100 is then removed from the patient.
Optionally, the inflation medium used to expand the expandable member 110 may comprise a material that enhances the ability of the imaging head 134 to generate images. For example, the inflation medium may facilitate enhanced acoustic transmission, reception, or it may reduce the incidence of scattering of the assessment signal. Such suitable inflation media include the following: acoustic gel, dielectric fluid, saline, and the like. These effects may be enhanced further by provision of a material or coating on the surface of the expandable member 110 that optimizes the imaging process. Such suitable materials and/or coatings include relatively dense materials such as metal, ceramic, high density polymers, and the like.
Turning next to FIGS. 3A-D, a plurality of physical assessment mechanisms are shown. Each physical assessment mechanism includes an expandable member 110 attached to a guidewire lumen 122 that extends through the catheter shaft 104 (see FIG. 1) and out of the distal end of the outer sheath (not shown). The guidewire lumen 122 is adapted to receive and track a guidewire 112 that has been previously deployed through the vasculature of a patient to the treatment location. In the embodiments illustrated, the treatment location is the aortic valve annulus 600. It should be recognized, however, that other treatment locations are possible, and that assessment information may be obtained for any suitable vessel lumen or hollow portion of an organ within the body of a patient.
In FIG. 3A, the expandable member 110 includes a plurality of vertically oriented markers 140 that are located at spaced intervals extending along the tapered distal end of the expandable member 110. In FIG. 3B, the expandable member 110 includes a plurality of horizontally oriented markers 140 that are located at spaced intervals extending along the tapered distal end of the expandable member 110. In each of the embodiments, the markers 140 are preferably formed of a radiopaque material that may be embedded within the expandable member 110 or attached to the surface of the expandable member 110. The radiopaque markers 140 are thereby visible under fluoroscopy. In addition, because the markers 140 are indexed, the location of each marker indicates a particular size parameter. For example, as the tapered distal end of the expandable member 110 enters the aortic annulus 600, its forward motion is eventually stopped as the expandable member 110 engages the annulus 600. The point at which the expandable member 110 engages the annulus 600 will correspond with a particular one (or more) of the markers 140 located on the tapered distal end of the expandable member. This information may then be translated into an effective diameter, area, volume, or other physical measurement for the patient's aortic annulus 600 (or other measured lumen or hollow portion of an organ).
FIG. 3C illustrates another embodiment of the physical assessment member in which the expandable member 110 includes a plurality of graduated steps 150 formed on the distal portion of the expandable member 110. As with the previous embodiments shown in FIGS. 3A-B and described above, the graduated steps 150 are indexed. Accordingly, as the expandable member 110 engages the aortic annulus (or other lumen or hollow portion of an organ), the particular step 150 (or steps) upon which the engagement occurs will determine a size parameter (e.g., diameter, area, volume, etc.) for the annulus. The engagement step 150 is able to be visualized under fluoroscopy.
FIG. 3D shows a schematic representation of an alignment device that may be used to ensure proper alignment of the expandable member 110 relative to the target location within the body of the patient. The alignment device includes a first radiopaque marker 160 in the shape of a dot that is attached to either the distal end or proximal end of the expandable member 110 surrounding the guidewire tube 122. The alignment device also includes a second radiopaque marker 162 in the shape of a ring that is attached to the opposite end of the expandable member from the end upon which the first marker 160 is attached. The ring-shaped marker 162 is also centered around the guidewire tube 122. The alignment device is operated by visualizing each of the first marker 160 and the second marker 162 under fluoroscopy. When the first marker 160 is centered within the second marker 162 as the expandable member 110 is viewed through its longitudinal axis, as shown in FIG. 3D, the user is assured that the expandable member 110 is normal to the fluoroscope field. This position is then used to ensure proper alignment with the target location within the body of the patient.
It is contemplated that other shapes, sizes, and orientations of the first marker 160 and second marker 162 are possible while still obtaining the advantages provided by the alignment mechanism. These advantages are obtained by detecting the position of the expandable member 110 through visualization of a pair of markers 160, 162 located at known positions on the body of the expandable member 110. The relative positions of the markers 160, 162 provide the needed alignment information to determine the position of the expandable member 110.
Turning next to FIGS. 4A-G, an assessment mechanism includes an electronic mapping construction that is attached to, or embedded within, the expandable member 110. The electronic mapping construction includes a plurality of electrical conductors 170 that form a plurality of circuits that are connected to a source of electrical energy by a primary conductor 172 that extends proximally from the expandable member 110 to the handle 102 of the catheter 100. A suitable source of electrical energy may be a battery located on the handle 102 or other electrical source that is accessible by the primary conductor 172.
An electric voltage or current is applied to the electrical conductors 170 by way of the primary conductor 172. Preferably, this is done after the expandable member 110 is expanded to engage the internal surface of the target location under investigation. Upon application of the electric load, the voltage or current created in the circuits making up the electronic mapping construction create electrical signals with one another in the form of a measurable capacitance, resistance, inductance, or reactivity. Accordingly, when measurements of these properties are made between pairs of circuits, the measured values are used to determine information relating to the relative spacing between the circuits. The spacing information is then processed to determine the size, shape, and topography of the target location over the entire electronic mapping construction. In a preferred embodiment, the catheter is connected to an electronic console that is able to process the signals in the manner described above and then display a 2 or 3 dimensional image of the topography of the site, depict the compliance of the tissue, thrombus, calcification, prior implant or other structures as well as pressure gradients, flow, orifice areas, and the like. The user would thereby be provided with sufficient information to predict the performance, safety, and efficacy of a prosthetic (or other) device to be implanted in the assessed region.
A few simple examples shown schematically in FIGS. 4B-D will illustrate this method. Each of the examples illustrates an orientation that may be encountered by the expandable member 110 having, for example, eight longitudinal conductors extending axially along the length of the expandable member. Measurements are taken by measuring an electrical signal generated between each conductor relative to each of the other conductors, until a complete set of signals is collected. In the first example, shown in FIG. 4B, a relatively small diameter, generally cylindrical lumen is encountered. In this case, the conductors 1-8 are in relatively close proximity to one another, and the spacing is generally uniform between pairs of relatively spaced conductors. This orientation will generate a first measured capacitance between each pair conductors that corresponds with the relative orientations between the conductors. In the second example, shown in FIG. 4C, a larger diameter, generally cylindrical lumen is encountered. In this case, the conductors 1-8 are spaced further apart from one another than in the preceding case, although the spacing remains relatively uniform between pairs of relatively spaced conductors. This orientation will generate a second measured capacitance between each pair of conductors that corresponds with the relative orientations between the conductors. In the third example, shown in FIG. 4D, a lumen having an irregular diameter is encountered. In this example, the distance between conductors 1 and 5 is different from the distance between conductors 3 and 7, thereby creating a difference in the measured capacitance between these pairs of conductors that would indicate the irregularity.
FIG. 4E shows an alternative embodiment of the electronic mapping construction in which a second set of conductors 174 forming a second set of circuits is formed on the surface of or embedded within the expandable member 110. The second set of conductors 174 are oriented generally transversely to the first set of conductors 170 shown in the prior embodiment in FIG. 4A. FIG. 4F shows yet another alternative embodiment that includes both sets of conductors 170, 174, in which the first set of conductors 170 is generally nested within the second set of conductors 174. The electrical grid provided by the combined sets of conductors is capable of creating a three-dimensional topographical mapping of the entire treatment location to which the expandable member 110 is engaged. Finally, FIG. 4G shows another alternative embodiment in which the conductors 175 are distributed at points around the periphery of the expandable member 110, rather than linear conductors. Like the prior embodiments, the embodiment shown in FIG. 4G is also able to create a three-dimensional topographical mapping of the treatment location.
In each of the electronic mapping construction embodiments shown above, a pair of pressure sensors 176a, 176b is provided. A first pressure sensor 176a is preferably located on the guidewire tube 122 at or near the proximal end of the expandable member 110, while the second pressure sensor 176b is preferably also located on the guidewire tube 122, but at or near the distal end of the expandable member 110. The pressure sensors 176a, 176b are adapted to provide pressure measurements to indicate fluid flow (or the absence thereof) in the vessel or organ. For example, when the expandable member is fully expanded, it will preferably completely dilate a stenotic area (such as an aortic valve) and occlude fluid flow through the vessel. Occlusion may be determined through pressure measurements on the proximal and distal sides of the expandable member 110.
Turning next to FIGS. 5A-C, a multi-function catheter construction is shown. The multi-function catheter construction includes an alignment mechanism 180 for proper positioning, an exterior balloon 190 for performing a valvuloplasty procedure, and an inner expandable member 200 for determining one or more physical parameters of the target location. In alternative embodiments, the valvuloplasty balloon 190 is located on the interior of the measuring balloon 200.
FIG. 5A illustrates the distal portion of the multi-function catheter prior to deployment. The alignment mechanism 180 extends out of the distal end of the outer sheath 120 of the catheter. The alignment mechanism includes a plurality of alignment wires 182 that are attached at their proximal ends to the distal end of the outer sheath 120. The distal ends of the alignment wires 182 extend out of a plurality of holes 184 formed on an alignment cap 186. Each alignment wire 182 is preferably in the form of a wire loop. In the preferred embodiment, three alignment loops 182 are present. The valvuloplasty balloon 190 extends distally of the alignment cap 186. The guidewire 112 extends from the guidewire 122 to which the valvuloplasty balloon 190 is attached.
FIG. 5B illustrates the advancement of the alignment loops 182, which is caused by causing relative motion between the distal end of the outer sheath 120 and the alignment cap 186 toward one another, thereby causing the alignment loops 182 to advance distally relative to the alignment cap 186. As the alignment loops 182 advance, they are biased outward (i.e., radially expand). In the preferred method for treating an aortic heart valve, the catheter is then advanced such that the alignment loops 182 become lodged in the sinus located behind the native valve leaflets, thereby fixing the alignment mechanism 180 in place relative to the aortic valve annulus. This fixation also fixes the location of the remainder of the catheter 100 in place relative to the valve annulus. Tactile feedback and visual confirmation will assure that the alignment loops 182 have positioned the catheter properly, thereby placing the valvuloplasty balloon 190 and expandable member 200 directly in line with the aortic valve annulus.
In FIG. 5C, the valvuloplasty balloon is shown in its expanded state, which is achieved by injecting a suitable inflation medium through an inflation lumen provided in the catheter shaft 104. The valvuloplasty balloon 190 is preferably inflated to enlarge to a prescribed diameter larger than the estimated annulus diameter, thereby performing the function of a conventional valvuloplasty. The valvuloplasty balloon 190 is then deflated.
The inner expandable member 200 is then inflated to a measured volume and pressure. The inner expandable member 200 is preferably formed of a non-compliant material, although a compliant material is used in alternative embodiments. In the preferred embodiment shown in the Figures, a resistance strip 202 is attached to (e.g., printed onto) the outer surface of the expandable member 200. The resistance strip 202 is used to measure an increase in the size and resistance of the expandable member 200, which information is then correlated to a corresponding circumferential length or volume. This circumferential length (or volume) measurement is then used to determine the annulus size for the given pressure. Accordingly, both size and compliance of the annulus are able to be determined. In alternative embodiments, the relationship between the internal pressure of the expandable member 200 and its measured or correlated volume are used to measure the compliance of the tissue (or other environment) engaged with the external surface of the expandable member 200.
It is worth noting that although the foregoing description is based upon use of the multi-function catheter in the assessment of an aortic valve, the device may be used to obtain assessment information of other vessels and organs in the body of a patient as well. Moreover, the alignment mechanism 180 described for use with the multi-function catheter may be incorporated onto other devices, such as a delivery device used to deliver a prosthetic heart valve to a treatment location.
The preferred embodiments of the inventions that are the subject of this application are described above in detail for the purpose of setting forth a complete disclosure and for the sake of explanation and clarity. Those skilled in the art will envision other modifications within the scope and spirit of the present disclosure. Such alternatives, additions, modifications, and improvements may be made without departing from the scope of the present inventions, which is defined by the claims.
Patent Application
20080009746
