WO2014210299A1

WO2014210299A1 - Device, system, and method for implanting a prosthetic heart valve

Info

Publication number: WO2014210299A1
Application number: PCT/US2014/044322
Authority: WO
Inventors: Charles R. Bridges; Liam P. Ryan
Original assignee: Bridges Charles R
Priority date: 2013-06-27
Filing date: 2014-06-26
Publication date: 2014-12-31

Abstract

A prosthetic valve assembly, system, and method for replacing a heart valve is provided. The prosthetic valve assembly includes an elongate balloon catheter, a prosthetic valve, such as a mitral valve or an aortic valve, disposed over an expandable balloon along a distal portion of the balloon catheter, and a transducer, such as a piezoelectric crystal, disposed on the balloon catheter towards a mid-point of the prosthetic valve between the proximal and distal ends of the prosthetic valve. Positioning a transducer on the catheter towards a mid-point of the prosthetic valve helps to identify the position of the midpoint of the valve relative to the aortic annulus. As a result, the surgeon performing the valve replacement procedure may be able to accurately align the mid-point of the valve with the plane of the aortic annulus. The valve structure of the heart may be imaged using 2-D or 3-D transesophageal echocardiogram.

Description

DEVICE, SYSTEM, AND METHOD FOR IMPLANTING A

PROSTHETIC HEART VALVE

FIELD

The present invention relates generally to devices, systems, and associated methods for placement of a prosthetic heart valve in a patient. BACKGROUND

Aortic valve stenosis (AS) is a disease of the heart valves in which the opening of the aortic valve is narrowed, which can increase the potential for heart failure. The aortic valve is the valve between the left ventricle of the heart and the aorta, which is the largest artery in the body and carries the entire output of blood.

The most frequent cause of aortic valve stenosis is the result of wear and tear of the aortic valve in the elderly. This condition is also known as "senile calcific aortic stenosis." With aging, protein collagen of the valve leaflets is destroyed, and calcium is deposited on the leaflets. Once valve leaflet mobility is reduced by calcification, turbulence across the valve increases, causing scarring, thickening, and stenosis of the valve.

Symptoms and heart problems in aortic stenosis are related to the degree of narrowing of the aortic valve area. Patients with mild aortic valve narrowing may experience no symptoms. When the narrowing becomes significant (for example, greater than 50% reduction in valve area), the pressure in the left ventricle increases and a pressure difference can be measured between the left ventricle and the aorta. To compensate for the increasing resistance at the aortic valve, the muscles of the left ventricle thicken to maintain pump function and cardiac output. This muscle thickening causes a stiffer heart muscle which requires higher pressures in the left atrium and the blood vessels of the lungs to fill the left ventricle. Even though these patients may be able to maintain adequate and normal cardiac output at rest, the ability of the heart to increase output with exercise is limited by these high pressures. As the disease progresses, the increasing pressure eventually cause the left ventricle to dilate, leading to a decrease in cardiac output and heart failure. Without treatment, the average life expectancy after the onset of heart failure due to aortic stenosis is between 18 to 24 months.

When symptoms of chest pain, syncope, or shortness of breath appear, the prognosis for patients with aortic stenosis without valve replacement surgery is poor. Medical therapy, such as the use of diuretics to reduce high lung pressures and remove lung fluid, can provide only temporary relief of symptoms.

The most commonly available treatment for aortic stenosis is the surgical replacement of the stenosed aortic valve with a prosthetic valve. In conventional surgical procedures, the heart is accessed in the patient's thoracic cavity through a longitudinal incision in the chest, which requires cutting through the sternum and forcing the two opposing halves of the rib cage to be separated. Thereafter, the dysfunctional valve is cut out and replaced with a prosthetic valve. Obviously, such conventional procedures are invasive and generally require lengthy and difficult recovery periods. In addition, in some patients such conventional surgical procedures may be unavailable because the patient is deemed inoperable or the risk of surgery is too high.

More recently, new minimally invasive procedures have been developed to reduce the trauma and risk associated with conventional open heart surgery. For example, in percutaneous aortic valve replacement (e.g., Transcatheter Aortic Valve Implantation (TAVI) or Transcatheter Aortic Valve Replacement (TAVR)) a replacement valve is delivered via a catheter. In this procedure, a prosthetic valve (e.g., a transcatheter heart valve) is positioned in the dysfunctional native aortic heart valve and then expanded using a balloon catheter.

In current techniques, the valve is positioned in the aortic valve with imaging systems such as fluoroscopy, 2-D transesophageal echocardiogram (TEE), or 3-D TEE. However, in many cases these imaging systems may not adequately allow the valve to be precisely positioned in the native aortic valve. For example, fluoroscopy imaging allows for visualization of the valve, but only in two dimensions. As a result, alignment of the valve with aortic valve plane is difficult. In addition, the annulus of aortic valve cannot be visualized with fluoroscopy making it necessary for the surgeon to make an educated guess as to its position. In contrast, 2-D and 3-D TEE allow for visualization of the annulus, but the edges of the valve are indistinct making accurate position of the valve difficult.

Improper placement of the prosthetic valve in the aortic native valve may have catastrophic results. If the prosthetic valve is placed too far into the left ventricle it may become dislodged into the ventricle thereby causing a life threatening emergency. If the valve is placed too far towards the aorta, the valve can obstruct flow into the coronary arteries, which may result in myocardial infarction. If the prosthetic valve is not properly aligned with the aortic valve plane, the valve may not function properly or may become dislodged.

Consequently, improper positioning the prosthetic heart valve may result in life threatening complications, heart failure, unnecessary surgery, and in some cases, death. Accordingly, there exists a need for improved devices and method s for the positioning of prosthetic heart valves.

SUMMARY

Embodiments of the present invention are directed to a prosthetic valve assembly, system, and associated method for replacing a heart valve in a patient. In one

embodiment, the present invention comprises a prosthetic valve assembly comprising an elongate balloon catheter, sheath, or delivery catheter, a prosthetic valve, such as a mitral valve or an aortic valve, disposed over an expandable balloon along a distal portion of the balloon catheter, and a transducer, such as a piezoelectric crystal, disposed on the balloon catheter towards a mid-point of the prosthetic valve between the proximal and distal ends of the prosthetic valve.

In one embodiment, the transducer may be an active transducer or a passive transducer. For example, in some embodiments, the transducer comprises an active transducer that is configured to emit an ultrasound signal in response to being exposed to an electrical current. Examples of an active transducer may include a piezoelectric material, such as a piezoelectric crystal.

In some aspects, the transducer may comprise a passive transducer that is configured to be detectable via the reflection of a signal to which the passive transducer has been exposed. For example, the passive transducer may comprise an echogenic material that is capable of bouncing an echo to a detector (e.g., return the signal emitted by an ultrasound device). Echogenicity may be provided on the balloon catheter by providing echogenic materials, such as echogenic particles, ridges, crevices, raised surfaces, and the like that are selectively positioned on the balloon catheter to identify the position and alignment of the prosthetic valve relative to the structure of the patient's heart.

An associated detector/receiver can then be used to identify the position of the transducer, and hence, the prosthetic valve from the ultrasound signal emitted by the transducer.

By positioning a transducer on the catheter towards a mid-point of the prosthetic valve, the position of the midpoint of the valve relative to the aortic annulus may be determined. As a result, the surgeon performing the valve replacement procedure may be able to accurately align the mid-point of the valve with the plane of the aortic annulus. In one embodiment, the valve structure of the heart may be imaged using 3-D TEE or a similar imaging technique that permits the surgeon to see detailed structures of the patient's heart, such as the aortic annulus. As the prosthetic valve assembly is introduced into the aortic valve, an electric signal can be sent to the transducer in order to cause the transducer to emit a signal that is detectable by an associated detector and/or imaging system. For example, the system may be configured to detect the position of the first transducer and show its position relative to the aortic annulus. The surgeon may then adjust the position of the prosthetic valve assembly so that the mid-point of the prosthetic valve is aligned with the aortic annulus. Once a desired position is achieved, the surgeon may then collectively expand the balloon and prosthetic valve using conventional techniques.

In one aspect of the invention, the prosthetic valve assembly may include a plurality of transducers disposed on the elongate balloon catheter and arranged in an array along or adjacent to the mid-point of the prosthetic valve. A surgeon may use the signals emitted by the plurality of transducers to define a mid-point plane corresponding to the mid-point of the prosthetic valve. The surgeon may then adjust the position of the prosthetic valve so that the mid-point plane and the aortic annular plane are aligned.

In another aspect of the invention the prosthetic valve assembly may further comprise at least one proximal transducer disposed on the elongate balloon catheter towards the proximal end of the prosthetic valve. In a further aspect, the prosthetic valve assembly may include a distal transducer disposed on the elongate balloon catheter towards the distal end of the prosthetic valve. In one embodiment, the surgeon may use the position of one or more of the proximal or distal transducers to identify the positions of the proximal or distal transducers relative to the first transducer and the aortic plane. In particular, the surgeon may adjust the position of the valve such that a plane defined between the proximal or distal transducers and the transducer disposed towards a midpoint of the prosthetic valve is substantially perpendicular to the aortic annulus plane. As a result, proper positioning and alignment of the prosthetic valve may be improved.

In a further aspect, the invention also provides a system for replacing a stenotic native valve. In one embodiment, the system comprises a valve assembly having an elongate balloon catheter, a prosthetic valve disposed over an expandable balloon along a distal portion of the balloon catheter, a prosthetic valve having a proximal end and a distal end and a transducer crystal disposed on the balloon catheter towards a mid-point between the proximal and distal ends of the prosthetic valve, a current source in communication with the transducer and configured for sending an electrical signal to said transducer to cause the transducer to emit an ultrasound signal, a sensor for detecting an ultrasound signal emitted by the transducer, an imaging system configured to generate data corresponding to structures of a patient's heart, and a processor configured to display images comprising structures of the patient's heart and a position of the transducer relative to said structures.

In one embodiment, the invention is directed to a prosthetic valve assembly for replacing a stenotic native valve, wherein the assembly comprises an expandable stent such as the nitinol expandable stent. For example an expandable stent that may be used to mount the Medtronic CoreValve. The assembly may also include a prosthetic valve disposed on a catheter inside a sheath, the prosthetic valve having a proximal end and a distal end; and at least one transducer disposed on the delivery catheter or on the sheath towards a mid-point between the proximal and distal ends of the prosthetic valve, wherein the transducer is configured to image the position of the prosthetic valve relative to an annular plane of the stenotic native valve prior to and during deployment.

In one embodiment, the imaging system comprises 2-D TEE or 3-D TEE.

The system may also include one or more modules for defining structures of the heart that can be used to generate a display image. In one embodiment, the system includes a module configured to define an aortic plane in an image. The system may also a second module that is configured to identify the position of the transducer relative to the aortic annulus plane in the image. As discussed above, the surgeon may use the position of the transducer relative to the aortic plane to properly position and align the prosthetic valve with the aortic plane.

Aspects of the present invention also provide methods for replacing stenotic native valve in a patient. In one embodiment, the method may comprise the comprising the steps of: introducing a valve assembly having an elongate balloon catheter, a prosthetic valve disposed over an expandable balloon along a distal portion of the balloon catheter, a prosthetic valve having a proximal end and a distal end and a transducer crystal disposed on the balloon catheter towards a mid-point between the proximal and distal ends of the prosthetic valve at least partially into the left ventricle of a patient;

obtaining images of structures of the patient's heart; identifying an aortic annulus plane in the heart; sending an electric signal to the transducer; identifying a position of the transducer based on an ultrasound signal emitted by the transducer; aligning the position of the transducer with the aortic plane; and expanding the balloon and prosthetic valve in the aortic annulus of the patient.

In one embodiment, the method may further comprise the steps of identifying the positions of one or more of a proximal transducer or a distal transducer based on ultrasound signals emitted by the proximal and distal transducers, and aligning one or more of the proximal and distal transducers such that a plane defined between the proximal or distal transducers and the transducer defining the mid-point of the prosthetic valve is substantially perpendicular to the aortic annulus plane.

In another embodiment, the transducer may comprises a plurality of transducers arranged in an array along or adjacent to the mid-point of the prosthetic valve, and the method may also include the step of identifying a position of the transducer comprises defining a mid-point plane corresponding to the mid-point of the prosthetic valve. After the mid-point plane has been defined, the surgeon may then align the mid-point plane and the aortic plane. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

FIG. 1 illustrates a prosthetic valve assembly that is in accordance with an embodiment of the present invention;

FIG. 2 illustrates a prosthetic valve assembly in accordance with an embodiment of the present invention in which the balloon and prosthetic valve are shown in an expanded state;

FIGS. 3A-3C illustrates embodiments of the present invention in which one or more transducers can be seen;

FIGS. 4A-4D illustrate a process for implanting a prosthetic valve in accordance with at least one embodiment of the present invention;

FIG. 5 is a schematic illustration of a system in accordance with at least one embodiment of the present invention; and

FIG. 6 illustrates a schematic block diagram of circuitry in accordance with at least one embodiment of the present invention.

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal

requirements. Like numbers refer to like elements throughout.

With reference to FIG. 1 , a prosthetic valve assembly in accordance with at least one embodiment of the present invention is illustrated and designated by reference number 10. In one embodiment, the prosthetic valve assembly 10 includes an elongate balloon catheter 12 having a distal portion 14 that is configured to be introduced through an aorta of a patient. The prosthetic valve assembly includes a prosthetic valve 16 and an expandable balloon 18 that are collectively disposed towards the distal portion 14 of the prosthetic valve assembly 10. In the illustrated embodiment, the prosthetic valve is shown in a crimped or collapsed state. As discussed in greater detail below, the balloon is expandable (e.g., inflatable) to cause the prosthetic valve to expand from a collapsed state to an expanded state for positioning in a desired position within the aortic annulus of the patient. In one embodiment, the prosthetic valve may comprise a mitral valve or an aortic valve.

In some embodiments, the distal end of the catheter 12 may include a tapered nose portion or tip 20 that helps permit the expandable balloon 18 and prosthetic valve 16 to be easily introduced into the native valve. The prosthetic valve assembly may also include an outer sheath 22 through which the catheter is advance able, and an associated pusher 19.

Turning now to FIG. 2, an embodiment of the prosthetic valve assembly is shown in which the balloon and prosthetic valve are in an expanded state for implantation. As explained above, proper positioning of the prosthetic valve is difficult due to poor visualization of the position and alignment of the valve with respect to the aortic annulus. Embodiments of the present invention help to overcome this problem by using one or more transducers that are positioned on the heart valve assembly. In one embodiment, the transducer is configured to generate a computer readable signal that can be used to identify the position and alignment of the valve relevant to aortic annulus.

Turning now to FIGS. 3A-3B, the prosthetic valve assembly 10 comprises a first transducer 30 disposed on the catheter towards a mid-point M between the proximal end 32 and a distal end 34 of the prosthetic valve 16. In FIGS. 3A-3B, the structural details of the prosthetic valve 16 are not shown to aid the reader in seeing the position of the transducer. Preferably, the position of the transducer is such that the distances D1 and D2 in FIG. 3A are substantially identical to each other. It should be recognized that it is not absolutely necessary that D1 and D2 be substantially identical provided the system and surgeon are able to account for any difference in the positioning and alignment of the prosthetic valve during placement.

Preferably, the transducer 30 is in communication with a current source configured to send an electric current through the transducer, which in turn generates an ultrasound signal that can be used to identify the position of the transducer. The transducer is typically in communication with the current source via one or more electrical wires 36 that extend through the catheter and are connected to a current source external of the patient. Preferably, visualization of the position of the transducer, and hence the mid-point of the prosthetic valve is performed in combination with an imaging technique that allows for the visualization of the structure of the patient's heart, and in particular, visualization of the aortic annulus. For example, visualization of the aortic annulus may be performed using 2-D or 3-D TEE. Visualization may also be performed using transthoracic or intracardiac echocardiogram.

By positioning the first transducer on the catheter towards a mid-point M of the prosthetic valve, the position of the midpoint of the valve relative to the aortic annulus may be determined. As a result, the surgeon performing the valve replacement procedure may be able to accurately align the mid-point of the valve with the plane of the aortic annulus. As discussed below, during the valve replacement procedure the structure of the heart may be imaged using 3-D TEE or a similar imaging technique that permits the surgeon to see detailed structures of the patient's heart, such as the aortic annulus. As the prosthetic valve assembly is introduced into the aortic valve, an electric signal can be sent to the first transducer in order to cause the transducer to emit a signal that is detectable by an associated imaging system. For example, the system may be configured to detect the position of the first transducer and show its position relative to the aortic annulus. The surgeon may then adjust the position of the prosthetic valve assembly so that the mid-point of the prosthetic valve is aligned with the aortic annulus. Once a desired position is achieved, the surgeon may then collectively expand the balloon and prosthetic valve using conventional techniques.

In one aspect of the invention, the mid-point of the prosthetic valve refers to a position on the valve where the transducer is about equal distances from the proximal end 32 and the distal end 34 of the prosthetic valve 16. That is, D1 and D2 are substantially the same distance. In other aspects, the mid-point may refer to a position in which D1 and D2 are not identical. For example, in one embodiment the "mid-point" may correspond to a position where D1 or D2 is 2-15%, and preferably, 5-10% greater in length than the other. In particular, in some aspects, the position of the transducer may be arranged such that the valve is positioned 60% below the aortic annulus and 40% above the aortic annulus.

In one embodiment, transducer 30 may comprise plurality of transducers (e.g., 3 transducers) that are disposed on the elongate balloon catheter. Preferably, the plurality of transducers are arranged in an array along or adjacent to the mid-point of the prosthetic valve. As a result, the transducers may be oriented to define a plane of the prosthetic valve along a mid-point of the valve.

In some embodiments, the prosthetic valve assembly may include two or more additional transducers that are positioned proximal or distal of the first transducer. In this regard, FIG. 3B shows an embodiment of the invention in which the prosthetic valve assembly includes a second transducer 38 (e.g., a proximal transducer) positioned on the catheter proximal of the first transducer 30. In this embodiment, the position of the second transducer 38 can be used to ensure that the longitudinal alignment of the prosthetic valve relative to the aortic valve is in a desired orientation. That is, the surgeon can determine whether the alignment of prosthetic valve relative to the plane of the aortic annulus is angled. Ideally, the prosthetic valve will be aligned so that a plane defined between the first and second transducers is substantially perpendicular to the plane of the aortic annulus.

In some embodiments, the prosthetic valve assembly may include a third transducer 40 in lieu of, or in combination with, the second transducer 38. As shown in FIG. 4B, the third transducer 40 (e.g., a distal transducer) may be positioned on the catheter distal of the first transducer 30. In the illustrated embodiment, the second and third transducers 38, 40 are shown as being positioned on the catheter just slightly proximal and distal of the proximal and distal ends 32, 34, respectively, of the prosthetic valve 16. It should be recognized that the exact position of the second and third transducers 38, 40 is not critical to the practice of the invention provided that the position is selected so that the prosthetic valve may be properly aligned with the aortic annulus. For example, in one embodiment a proximal portion of the prosthetic valve may overlie, or partially overlie, the second transducer. Similarly, a distal portion of the prosthetic valve may overlie, or partially overlie, the third transducer.

In one aspect of the invention, the prosthetic valve assembly comprises three transducers that are arranged in an array along or adjacent to the mid-point of the prosthetic valve, a proximal transducer disposed on the elongate balloon catheter towards the proximal end of the prosthetic valve, and a distal transducer disposed on the elongate balloon catheter towards the distal end of the prosthetic valve.

In one embodiment, the distal (aortic) transducer may be positioned on the balloon catheter adjacent or towards the aortic margin of the prosthetic valve, and the proximal (ventricular) transducer may be positioned on the balloon catheter adjacent or towards the ventricular margin of the prosthetic valve. This arrangement may help improve the determination of whether the prosthetic valve impinges on the coronary ostia (aortic margin) or anterior leaflet of the mitral valve and/or left ventricular outflow tract (ventricular margin), respectively.

As in the second transducer, the position of the third transducer can be used to ensure that the longitudinal alignment of the prosthetic valve relative to the aortic valve is in a desired orientation. During a valve replacement procedure, an electrical signal can be sent to one or more of the transducers so that the position and alignment of the prosthetic valve relative to the aortic annulus may be determined. Once the surgeon has determined that the prosthetic valve is properly aligned and positioned, the balloon and prosthetic valve can be expanded using conventional techniques.

As noted above, the prosthetic valve may include a series of transducers arranged in array along the mid-point of the prosthetic valve. In this regard, FIG. 3C illustrates an embodiment of the invention in which transducer 30 comprises a plurality of transducers (e.g., 30a, 30b, 30c) arranged in an array to define a plane of the mid-point of the valve. As discussed in greater detail below, in some aspects of the invention, the surgeon may be able to determine the plane of the mid-point of the valve and then align this plane with the plane of the aortic annulus.

In one embodiment, the one or more transducers comprise an active transducer material that is able to generate ultrasonic sound waves in response to an applied electric field. In particular, the transducer may comprises a material that is generates an inverse piezoelectric effect in response to an applied electric field. Piezoelectric effect is manifested by the appearance of an electric potential across the faces of some materials when they are placed under pressure. When, on the other hand, a piezoelectric material (PEM) is subjected to an electric field, physical stresses are created in the material that distorts it, a phenomenon known as the inverse piezoelectric effect.

A wide variety of PEMs are currently known. Among these are crystalline substances whose unit crystal structure lacks a center of symmetry. Examples, without limitation of such substances are tourmaline, Rochelle salt and quartz. Polycrystalline substances which have been placed in a polarized state can also exhibit a piezoelectric effect and are called piezoelectric ceramics. Examples of piezoelectric ceramics include, without limitation, barium titanate (BaTi0₃) and lead zirconium titanate (PZT, PbZrTi0₃). In addition to piezoelectric crystals and ceramics, a number of polymeric materials are known to exhibit a piezoelectric effect. Most notable among these is polyvinylidene fluoride (PVDF) which was discovered by Kawai in 1969 and is still today the polymer that exhibits the strongest piezoelectric effect. Some co-polymers of PVDF, such as poly(PVDF-co-trifluoroethylene) and poly(PVDF-co-tetrafluoroethylene) are also piezoelectric. Other polymers that exhibit a piezoelectric effect include, without limitation, polyparaxylene, poly(bischloromethyloxetane) (Penton), aromatic polyamides, polysulfone, polyvinyl fluoride, synthetic polypeptides and cyanoethylcellulose.

The electrical signal sent to the piezoelectric member may constitute any number of waveforms. For example, without limitation, the signal may consist of a single DC pulse, multiple DC pulses, a continuous sinusoidal signal, or an oscillating square wave signal. Any type of signal may be employed that will initiate the converse piezoelectric effect in the piezoelectric member. Many signal types other than those exemplified herein will become apparent to those skilled in the art based on the disclosures herein and all such signal types are within the scope of this invention.

In other aspects, the transducer may comprise a passive transducer. In one such aspect, the transducer comprises a passive transducer that is an echogenic material that is configured to enhance visualization of the transducer, and hence the position and alignment of the prosthetic valve, via echocardiography. In one embodiment, the passive transducer comprises a material that is configured to be detectable via the reflection of a signal to which the passive transducer has been exposed. For example, the passive transducer may comprise an echogenic material that is capable of bouncing an echo to a detector. In one embodiment, the transducer comprises a material disposed on the balloon catheter that is configured to identify the position of the transducer relative to the plane of the aortic annulus. For example, the passive transducer may comprise an echogenic material Echogenicity may be provided on the balloon catheter by providing echogenic materials, such as sound reflective particles that are embedded in matrix material. Particles are preferably made of a hard or crystalline material, and it has been found that small glass particles are especially well suited for this application. Specifically, glass particles having a generally spherical shape forming glass microspheres are very suitable. Glass microspheres with an outer diameter of about 5 microns are one acceptable size. Other sized particles may be utilized as, for example, ranging between 1 and 50 microns and beyond. In addition, the particles do not necessarily have to be spherical, or may be partially spherical, although it is believed that spherical geometry for particulate such as particles is preferred.

In some embodiments, a partially spherical surface may be provided on the outside and/or the inside of particles, as for example a particle with a hollow spherical space therein. Particles may be made up of a different material than matrix, it is believed that the spherical shape provides for sound reflections at a variety of angles regardless of the direction from which the ultrasonic sound waves are emanating from, and accordingly, are more likely to reflect at least a portion of the transmitted signal back to the ultrasonic receiver to generate an image, and thereby identify the position of the transducer. Since many of the matrix materials available are relatively ultrasonically transparent in a patient, sound reflective particles provide adequate reflection.

The use of a composite, rather than a solution, provides adequate size for acoustic reflection off of the discrete particles embedded in the matrix. As indicated, a variety of materials may be utilized for the sound reflective particles, such as aluminum, hard plastic, sand, metal particles, and the like. Additionally, liquids, gases, gels, microencapsuiants, and/or coacervates suspended in the matrix may alternatively be used either alone or in combination, so long as they form a composite with ultrasonically reflective particles in the matrix. Of this variety, glass balls have been found to be very well suited. For example, one commercially available supply of glass microspheres used for particle blasting is offered by Potters Industry, 377 Route 17, Hasbrouck Heights, N.J., U.S.A.

In other aspects, the passive transducer may comprise a roughened surface or region on the balloon catheter. Such roughened surface may comprise ridges, raised surfaces, crevices, and the like formed on a surface of the balloon catheter, Preferably, the prosthetic valve assembly includes at least one transducer having a position that is selected so that it is aligned with the mid-point of the prosthetic valve.

Embodiments of the present invention can be used in combination with a wide variety of prosthetic valves conventionally used in replacing a stenotic native aortic valve. In particular embodiments, the prosthetic valve generally comprises an expandable stent portion that supports a valve structure. The stent portion desirably has sufficient radial strength to hold the valve at the treatment site and resist recoil of the stenotic native valve leaflets. For example, the prosthetic valve comprises valvular tissue made of a biological or synthetic biocompatible material. Examples of synthetic biocompatible materials include TEFLON® or DACRON®, polyethylene, polyamide. Examples of biological material include, without limitation, valve tissuefrom another human heart, a cow (bovine pericardium), a pig (porcine valve), a horse (equine pericardium) and the like. As is known in the art, such materials are commonly used in cardiac surgery and are quite resistant, particularly to folding movements due to the increasing systolo-diastolic movements of the valvular tissue.

Additional details regarding balloon expandable valve embodiments can be found in U.S. Pat. Nos. 6,730,1 18, 6,893,460, 7,585,321 , 7,981 ,151 , 8,349,000, which are incorporated by reference herein.

In one embodiment, the prosthetic valve is a transcatheter heart valve

manufactured by Edwards Lifesciences under the product name SAPIEN. In other embodiments, the prosthetic valve is a pulmonary transcatheter heart valve manufactured by Medtronic under the product name MELODY Or another type of transcatheter aortic valve under the product name CoreValve also manufactured by Medtronic. In the case of CoreValve, the valve is mounted to a nitinol self-expanding stent.

It will also be appreciated that the present invention may be used with self- expanding prosthetic valves such as the Medtronic CoreValve. For example, when using a self-expanding valve, a pusher may be used to assist in ejecting the self-expanding valve from a delivery sleeve that maintains the valve in its compressed state. In this case the transducer(s) may be mounted on the delivery sleeve to allow for unequivocal placement prior to initiating deployment. The prosthetic valve assembly may be configured to be positioned in the body by standard catheter procedures, for example, within a blood vessel or the heart by guiding the catheter through various blood vessels.

When the prosthetic valve 16 is used to replace the native aortic valve (or a previously implanted, failing prosthetic aortic valve), the valve 16 can be implanted in a retrograde approach where the valve, mounted on the balloon in a collapsed state, is introduced into the body via the femoral artery and advanced through the aortic arch to the heart.

With reference to FIGS. 4A-4D, a sectional view of a heart 400 having a left ventricle chamber 402 opening to an ascending aorta 404 through an aortic annulus is shown. The ascending aorta 404 continues over an aortic arch 408, and branches off into several upper body arteries 410 before descending to the abdominal aorta (not shown).

As shown in FIG. 4A, a prosthetic valve assembly 10 is shown in the cutaway portion of the ascending aorta 404, having been introduced along the direction of the arrow 414 so that a distal end thereof lies adjacent the aortic annulus. The prosthetic valve assembly 10 can be introduced percutaneously into the patient's arterial system (e.g. into a peripheral artery such as the femoral artery) and advanced to the ascending aorta 404.

In one embodiment the catheter has a length of at least about 80 cm, usually about 90-100 cm, to allow transluminal positioning of the catheter from the femoral and iliac arteries to the ascending aorta. Alternatively, the catheter may have a shorter length, e.g. 20-60 cm, for introduction through the iliac artery, through the brachial artery, through the carotid or subclavian arteries, through the apex of the left ventricle or through a penetration in the aorta itself.

In the femoral approach, the catheter is preferably long enough and flexible enough to traverse the path through the femoral artery, iliac artery, descending aorta and aortic arch. At the same time, the catheter has sufficient pushability to be advanced to the ascending aorta by pushing on the proximal end, and has sufficient axial, bending, and torsional stiffness to allow the physician to control the position of the distal end, even when the catheter is in a tortuous vascular structure. Alternatively, the catheter 12 may be passed through a port between ribs in the patient's thorax above the heart and through an incision in the aortic arch 408, in a so-called minimally-invasive procedure.

Techniques for introducing catheters into the human vasculature are well-known, and typically involve the introduction of a guidewire 416 first, that can be used to assist in advancing the delivery the prosthetic valve 16 through the patient's vasculature.

Thereafter, an obturator or dilator (not shown) can be advanced through sheath 22. The dilator facilitates introduction of the catheter sheath 22 into the vasculature, and is then removed, though the guidewire 416 typically remains in place. Dilator diameters typically range between, for example, 12 and 22 French.

In one embodiment, a heart valve assembly of the present invention is delivered over the guidewire 416 and to the distal end of the sheath 22. In accordance with one aspect of the present invention, the valve assembly includes a balloon-expandable prosthetic valve 16 and thus is mounted over an expandable balloon. In some embodiments, a pusher may be used to facilitate passage of the prosthetic valve through the sheath 22.

As shown in FIG. 4B, an imaging system, such as 3-D TEE can be used to provide images of the heart structure, which can be provided on a display device.

Typically, the imaging system will include an associated computer (e.g., a processor) that includes one or more modules configured to analyze the imaging data and provide an image of the heart structure to the surgeon. In one embodiment, the computer may also be configured to identify the aortic annular plane, which is identified by reference character 418 in FIGS. 4B. In other embodiments, the surgeon may identify the annular plane by marking three points on the image of the heart structure, which may then allow the computer to define the aortic plane on the images. In one embodiment, the surgeon may use an input device, such as a mouse, pointer, etc., in communication with the computer to input the plane of the aortic annulus. In one embodiment, the display device may include a touch screen that can be used to define the plane of the aortic annulus. In other embodiments, the surgeon may simply dray a line on the display that defines the plane of the aortic annulus.

In addition to analyzing the data communicated by the imaging system, the computer will also be configured to analyze ultrasound data generated by the one or more transducers 30. In particular, an electrical current will be sent to the transducer in order to generate ultrasound signal data that can be detected by the system. The computer will then analyze this data and determine the position of the transducer relative to the aortic plane 418. As discussed previously, prosthetic valve assembly 10 includes at least one transducer 30 that is disposed on the catheter towards a mid-point M between the proximal end and a distal end of the prosthetic valve. Identifying the position of transducer 30 will therefore also identify the position of the prosthetic valve relative to the aortic plane.

In one embodiment, the imaging data and the ultrasound signal data will be analyzed by the computer and then displayed together in a single image in real-time. The surgeon can use the resulting images to adjust the position of the prosthetic valve relative to the aortic plane. In the illustrated embodiment, a single transducer 30 is shown. However, it should be recognized that the prosthetic valve assembly may include multiple transducers, and that these multiple transducers can be used to provide images to the surgeon to help position and align the prosthetic valve in a desired orientation prior to implantation.

In FIG. 4B, the sheath 22 is shown in the process of being retracted in a proximal direction as indicated by arrow 426. Retraction of the sheath 22 exposes the prosthetic valve 16, which is the positioned within the aortic annulus using the imaging and ultrasound signal data provided by the imaging system and the one or more transducers.

In FIG. 4C, the position of the prosthetic valve 16 has been adjusted so that the transducer 30 is substantially aligned with the aortic plane 418. In one aspect of the invention, the position of the prosthetic valve can be further adjusted by using one or more additional transducers that are located proximal and/or distal of transducer 30. For example, a second transducer located proximal (towards the aortic end of the catheter) of transducer 30 and a third transducer disposed distal (towards the ventricular end of the catheter) of transducer 30. The position of the second and third transducers can then be used to ensure that the prosthetic valve is aligned properly with respect to the aortic plane. That is, the prosthetic valve is not angled or tipped relative to the aortic plane. In one embodiment, this may be performed by adjusting the prosthetic valve so that the perpendicular distance of the second and third transducers to the aortic plane is substantially the same.

Finally, in FIG. 4D, the balloon 18 is inflated to cause the prosthetic valve 16 to radially expand into contact with the aortic annulus, as indicated by the arrows 430. FIG. 4D shows the balloon inflation catheter 12 projecting from the sheath 22 and through the balloon and prosthetic valve. Once the valve 16 is fully expanded and securely attached to the annulus, the balloon is deflated and removed. Such an operation may include elongating the balloon in the distal direction and reducing its radial dimension by, for example, twisting. After the balloon has been retracted within the sheath, the entire catheter is removed from the patient.

Referring to FIG. 5, a schematic containing the principle system components in accordance with at least one embodiment of the invention is shown. The system includes the prosthetic valve assembly 10 having an elongate catheter 12 and an expandable balloon 18 and a prosthetic valve 16 disposed towards a distal portion of the catheter. In the illustrated embodiment, various other components that may be used for introducing and implanting the prosthetic valve are also shown and designated by reference character 50. As discussed above, the prosthetic valve assembly includes one or more transducers 30 that are disposed on the catheter adjacent to the prosthetic valve. The transducers are in communication with a current source 52 via one or more electrical wires 36. Ultrasound signals emitted by the transducers are detected by an ultrasound sensor/receiver 54, which is in communication with a computer (e.g., a processor) 56. The system also includes an imaging system 58 for providing images of the heart structure, such as 2-D or 3-D TEE system. The ultrasound signal data obtained by the ultra sound sensor/receiver 54 and the imaging system 58 are communicated to a computer 56 that is configured to analyze the data and determine the position of the transducer, and hence, the prosthetic valve relative to the structure of the heart, such as the aortic annulus.

Although FIG. 5 shows the imaging system 58 and the computer 56 as separated modules/devices, it should be recognized that each of these modules/devices may be incorporated into a single device, or alternatively, comprise separate devices that are in communication with each other. For example, in some embodiments the imaging system software may also be configured to analyze data communicated from the ultrasound sensor 54.

In one aspect of the invention, imaging and ultrasound data received is communicated to the computer/processor for further analysis. The computer includes one or more modules that are configured to analyze the data and determine the position of the prosthetic valve in the patient relative to the structure of the patient's heart. In one embodiment, the imaging data and ultrasound signal data will be displayed as one or more images on an associated display 60. Preferably, the images will show the position of the one or more transducers relative to the aortic annulus. With this information, the surgeon may then be able to manipulate the position and alignment of the properly align the prosthetic valve with respect to the aortic annulus. Once the prosthetic valve is in a desired position, the surgeon can then expand the balloon and the prosthetic valve for implantation.

FIG. 6 illustrates a schematic block diagram of circuitry 600, some or all of which may be included in, for example, as part of the imaging system or the computer (see FIG. 5, reference character 56). As illustrated in FIG. 6, in accordance with some example embodiments, circuitry 600 may include various means, such as a processor 602, memory 604, communication module 606, input/output module 608 and/or imaging data and ultrasound signal data analysis module 610.

As referred to herein, "module" includes hardware, software and/or firmware configured to perform one or more particular functions. In this regard, the means of circuitry 600 as described herein may be embodied as, for example, circuitry, hardware elements (e.g., a suitably programmed processor, combinational logic circuit, and/or the like), a computer program product comprising computer-readable program instructions stored on a non-transitory computer-readable medium (e.g., memory 604) that is executable by a suitably configured processing device (e.g., processor 602), or some combination thereof.

Processor 602 may, for example, be embodied as various means including one or more microprocessors with accompanying digital signal processor(s), one or more processor(s) without an accompanying digital signal processor, one or more

coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits such as, for example, an ASIC (application specific integrated circuit) or FPGA (field programmable gate array), or some combination thereof. Accordingly, although illustrated in FIG. 6 as a single processor, in some embodiments, processor 602

comprises a plurality of processors. The plurality of processors may be embodied on a single computing device or may be distributed across a plurality of computing devices collectively configured to function as circuitry 600. The plurality of processors may be in operative communication with each other and may be collectively configured to perform one or more functionalities of circuitry 600 as described herein. In an example

embodiment, processor 602 is configured to execute instructions stored in memory 604 or otherwise accessible to processor 602. These instructions, when executed by processor 602, may cause circuitry 600 to perform one or more of the functionalities of circuitry 600 as described herein.

Whether configured by hardware, firmware/software methods, or by a combination thereof, processor 602 may comprise an entity capable of performing operations according to embodiments of the present invention while configured accordingly. Thus, for example, when processor 602 is embodied as an ASIC, FPGA or the like, processor 602 may comprise specifically configured hardware for conducting one or more operations described herein. As another example, when processor 602 is embodied as an executor of instructions, such as may be stored in memory 604, the instructions may specifically configure processor 602 to perform one or more algorithms and operations described herein.

Memory 604 may comprise, for example, volatile memory, non-volatile memory, or some combination thereof. Although illustrated in FIG. 6 as a single memory, memory 604 may comprise a plurality of memory components. The plurality of memory components may be embodied on a single computing device or distributed across a plurality of computing devices. In various embodiments, memory 604 may comprise, for example, a hard disk, random access memory, cache memory, flash memory, a compact disc read only memory (CD-ROM), digital versatile disc read only memory (DVD-ROM), an optical disc, circuitry configured to store information, or some combination thereof. Memory 604 may be configured to store information, data, applications, instructions, or the like for enabling circuitry 600 to carry out various functions in accordance with example embodiments discussed herein. For example, in at least some embodiments, memory 604 is configured to buffer input data for processing by processor 602.

Additionally or alternatively, in at least some embodiments, memory 604 may be configured to store program instructions for execution by processor 602. Memory 604 may store information in the form of static and/or dynamic information. This stored information may be stored and/or used by circuitry 600 during the course of performing its functionalities.

Communications module 606 may be embodied as any device or means embodied in circuitry, hardware, a computer program product comprising computer readable program instructions stored on a computer readable medium (e.g., memory 604) and executed by a processing device (e.g., processor 602), or a combination thereof that is configured to receive and/or transmit data from/to another device, such as, for example, a second circuitry 900 and/or the like. In some embodiments, communications module 606 (like other components discussed herein) can be at least partially embodied as or otherwise controlled by processor 602. In this regard, communications module 606 may be in communication with processor 602, such as via a bus. Communications module 606 may include, for example, an antenna, a transmitter, a receiver, a

transceiver, network interface card and/or supporting hardware and/or firmware/software for enabling communications with another computing device. Communications module 606 may be configured to receive and/or transmit any data that may be stored by memory 604 using any protocol that may be used for communications between computing devices. Communications module 606 may additionally or alternatively be in

communication with the memory 604, input/output module 608 and/or any other component of circuitry 600, such as via a bus.

Input/output module 608 may be in communication with processor 602 to receive an indication of a user input and/or to provide an audible, visual, mechanical, or other output to a user. Some example visual outputs that may be provided to a user by circuitry 600 are discussed in connection with the displays described above. As such, input/output module 608 may include support, for example, for a keyboard, a mouse, a joystick, a display, an image capturing device, a touch screen display, a microphone, a speaker, a RFID reader, barcode reader, biometric scanner, and/or other input/output mechanisms. In embodiments wherein circuitry 600 is embodied as a server or database, aspects of input/output module 608 may be reduced as compared to embodiments where circuitry 600 is implemented as an end-user machine (e.g., consumer device and/or merchant device) or other type of device designed for complex user interactions. In some embodiments (like other components discussed herein), input/output module 608 may even be eliminated from circuitry 600. Input/output module 608 may be in communication with memory 604, communications module 606, and/or any other component(s), such as via a bus. Although more than one input/output module and/or other component can be included in circuitry 900, only one is shown in FIG. 6 to avoid overcomplicating the drawing (like the other components discussed herein).

Imaging Data Module 610 may also or instead be included and configured to perform the functionality discussed herein related to analyzing imaging data transmitted from the imaging system, such as imaging data generated by 3-D TEE. In some embodiments, some or all of the functionality facilitating analysis of the optical data may be performed by processor 602. In this regard, the example processes and algorithms discussed herein can be performed by at least one processor 602 and/or Imaging Data Module 610. For example, non-transitory computer readable storage media can be configured to store firmware, one or more application programs, and/or other software, which include instructions and other computer-readable program code portions that can be executed to control processors of the components of system 600 to implement various operations, including the examples shown above. As such, a series of computer- readable program code portions may be embodied in one or more computer program products and can be used, with a computing device, server, and/or other programmable apparatus, to produce the machine-implemented processes discussed herein.

In one aspect of the embodiment, Imaging Data Module 610 may also be configured to analyze ultrasound signal data generated by one or more of the

transducers. In one embodiment, the Imaging Data Module may be configured to show both images of the heart structure and the position of the transducer(s) on a single image.

Any such computer program instructions and/or other type of code may be loaded onto a computer, processor or other programmable apparatuses circuitry to produce a machine, such that the computer, processor other programmable circuitry that executes the code may be the means for implementing various functions, including those described herein.

The illustrations described herein are intended to provide a general understanding of the structure of various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus, processors, and systems that utilize the structures or methods described herein. Many other

embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Additionally, the illustrations are merely representational and may not be drawn to scale. Certain proportions within the illustrations may be exaggerated, while other proportions may be minimized. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.

Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are 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

THAT WHICH IS CLAIMED:

1 . A prosthetic valve assembly for replacing a stenotic native valve, the assembly comprising:

an elongate balloon catheter;

a prosthetic valve disposed over an expandable balloon along a distal portion of the balloon catheter, the prosthetic valve having a proximal end and a distal end; and at least one transducer disposed on the balloon catheter towards a mid-point between the proximal and distal ends of the prosthetic valve,

wherein the transducer is configured to image the position of the prosthetic valve relative to an annular plane of the stenotic native valve.

2. A prosthetic valve assembly for replacing a stenotic native valve, the assembly comprising:

an expandable stent;

a prosthetic valve disposed on a catheter inside a sheath, the prosthetic valve having a proximal end and a distal end; and

at least one transducer disposed on the delivery catheter or on the sheath towards a mid-point between the proximal and distal ends of the prosthetic valve,

wherein the transducer is configured to image the position of the prosthetic valve relative to an annular plane of the stenotic native valve prior to and during deployment.

3. The prosthetic valve assembly of claim 1 or 2, wherein the transducer comprises an active transducer including but not limited to a piezoelectric crystal.

4. The prosthetic valve assembly of claim 1 or 2, wherein the transducer comprises a passive transducer comprising an echogenic material.

5. The prosthetic valve assembly according to any one of the preceding claims, wherein the prosthetic valve comprises a mitral valve, pulmonary valve or an aortic valve.

6. The prosthetic valve assembly according to any one of the preceding claims, wherein the assembly includes at least three transducers disposed on the elongate balloon catheter, sheath or delivery catheter, the transducers being arranged in an array along or adjacent to the mid-point of the prosthetic valve.

7. The prosthetic valve assembly according to any one of the preceding claims, wherein the assembly further comprises at least one proximal transducer disposed on the elongate balloon catheter, sheath or delivery catheter towards the proximal end of the prosthetic valve.

8. The prosthetic valve assembly of claim 7, wherein the prosthetic valve is positioned over the elongate balloon catheter such that the prosthetic valve overlies the proximal transducer.

9. The prosthetic valve assembly of claim 7, wherein the proximal transducer is configured to be aligned with an aortic plane of the stenotic native valve.

10. The prosthetic valve assembly according to any one of the preceding claims, wherein the assembly further comprises a distal transducer disposed on the elongate balloon catheter, sheath or delivery catheter towards the distal end of the prosthetic valve.

1 1 . The prosthetic valve assembly according to any one of the preceding claims, wherein the transducer is configured to be aligned with a ventricular plane of the stenotic native valve.

12. The prosthetic valve assembly according to any one of the preceding claims, wherein the elongate balloon catheter, sheath or delivery catheter comprises a tubular shaft having an inner and outer surface, and wherein the transducer is disposed on the outer surface of the shaft.

13. The prosthetic valve assembly according to any one of the preceding claims, wherein the assembly comprises three transducers arranged in an array along or adjacent to the mid-point of the prosthetic valve, a proximal transducer disposed on the elongate balloon catheter, sheath or delivery catheter towards the proximal end of the prosthetic valve, and a distal transducer disposed on the elongate balloon catheter, sheath or delivery catheter towards the distal end of the prosthetic valve.

14. The prosthetic valve assembly of claim 13, wherein the transducers comprise piezoelectric crystals.

15. The prosthetic valve assembly of claim 13, wherein each of the transducers is independently configured to generate an ultrasound signal.

16. The prosthetic valve assembly according to any one of the preceding claims, wherein the assembly further comprises:

a current source in communication with said transducer and configured for sending an electrical signal to said transducer to cause the transducer to emit an ultrasound signal;

a sensor for detecting an ultrasound signal emitted by the transducer;

an imaging system configured to generate data corresponding to structures of a patient's heart; and

a processor configured to display images comprising structures of the patient's heart and a position of the transducer relative to said structures.

17. The system of claim 16, wherein the imaging system comprises 3-D TEE.

18. The system of claim 16, wherein the system includes a first module configured to define an aortic annulus plane in said image.

19. The system of claim 18, wherein the system includes a second module configured to identify the position of the transducer relative to the aortic annulus plane in said image.

20. The system of claim 18, wherein the prosthetic valve assembly further comprises at least one proximal transducer disposed on the elongate balloon catheter, sheath or delivery catheter towards a proximal end of the prosthetic valve, and wherein the system is configured to identify the position of the proximal transducer relative to the first transducer and the aortic annulus plane.

21 . The system of claim 18, wherein the prosthetic valve assembly further comprises at least one distal transducer disposed on the elongate balloon catheter, sheath or delivery catheter towards a distal end of the prosthetic valve, and wherein the system is configured to identify the position of the distal transducer relative to the first transducer and the aortic annulus plane.

22. The system of claim 19, wherein the transducer comprises a plurality of transducers arranged in an array along or adjacent to the mid-point of the prosthetic valve, and wherein the system includes a module configured to define a mid-point plane of the prosthetic valve based on ultrasound signals emitted by the array of transducers.

23. A method for replacing stenotic native valve in a patient comprising the steps of: introducing the prosthetic valve assembly according to any one of the preceding claims at least partially into the left ventricle of a patient;

obtaining images of structures of the patient's heart;

identifying an aortic annulus plane in the heart;

sending an electric signal to the transducer;

identifying a position of the transducer based on an ultrasound signal emitted by the transducer;

aligning the position of the transducer with the aortic annulus plane; and positioning the prosthetic valve in the aortic annulus of the patient.

24. The method of claim 23, further comprising the steps of identifying the positions of one or more of a proximal transducer or a distal transducer based on ultrasound signals emitted by said proximal and distal transducers, and aligning one or more of the proximal and distal transducers such that a plane defined between the proximal or distal transducers and said transducer is substantially perpendicular to the aortic annulus plane.

25. The method of claim 23, wherein the transducer comprises a plurality of transducers arranged in an array along or adjacent to the mid-point of the prosthetic valve, and wherein the step of identifying a position of the transducer comprises defining a mid-point plane corresponding to the mid-point of the prosthetic valve.

26. The method of claim 25, further comprising the step of aligning the mid-point plane and the aortic annulus plane.

The method of claim 23, wherein the transducer comprises a piezoelectric crystal.