WO2017016565A1

WO2017016565A1 - Apparatus for breaking artificial heart valve ring

Info

Publication number: WO2017016565A1
Application number: PCT/DK2016/050253
Authority: WO
Inventors: John Michael Hasenkam; Henning Rud Andersen; Tommy Kragh BECHSGAARD
Original assignee: Mike Air V/Michael Hasenkam
Priority date: 2015-07-20
Filing date: 2016-07-15
Publication date: 2017-02-02

Abstract

An apparatus for breaking an artificial ring, where said artificial ring is supporting a heart valve in the heart in an associated patient, the apparatus comprising a delivery system configured for percutaneous delivery, an expandable mechanism (516) being positioned at a distal end of the delivery system, where the expandable mechanism is arranged for being placed inside the artificial ring, expanding in a radial direction, and exerting a force on the artificial ring, which force is sufficient for breaking the artificial ring, wherein the expandable mechanism is arranged so that a shape and size of the expandable mechanism immediately before breaking of the artificial ring is substantially similar to a shape and size of the expandable mechanism immediately after breaking of the artificial ring. The apparatus may in embodiments allow blood flow through the expandable mechanism during maximum expansion and may furthermore enable detection of valve ring breakage.

Description

APPARATUS FOR BREAKING ARTIFICIAL HEART VALVE RING

FIELD OF THE INVENTION The present invention relates to an apparatus for breaking a ring, more

particularly the present invention relates to an apparatus and a corresponding method for breaking an artificial ring wherein said artificial ring is supporting a heart valve in the heart in an associated patient. BACKGROUND OF THE INVENTION

Thousands of patients worldwide have had a diseased heart valve replaced with a prosthetic heart valve, such as a bioprosthetic heart valve. Subsequent failure of the (bio-)prosthetic heart valve may necessitate surgical intervention in order to re-establish the function. Repeat cardiac surgery may carry significant morbidity and mortality risks. Treatment of deteriorated bioprostheses by transcatheter aortic valve replacement (TAVR) in failed surgical valves is clinically effective and has become an alternative to repeat surgery. However, this procedure may be challenged, for example by surgical prostheses of small sizes since placing a new valve inside the ring of an already small valve can lead to a too small orifice.

One way to overcome the problem of valve-in-valve therapy related to small surgical prostheses may be to crack the ring of the biological valve by high- pressure balloon predilatation for implantation of a transcatheter valve with a larger effective orifice area. An example of this is given in the reference "Cracking the ring of Edwards Perimount bioprosthesis with ultrahigh pressure balloons prior to transcatheter valve in valve implantation" , D. Tanase, et a/., International Journal of Cardiology 176 (2014) 1048-1049. The process of cracking the ring e.g. with a high pressure balloon may be associated with some disadvantages and may even entail a risk for the patient.

Hence, an improved apparatus and method for overcoming the problems related to small prosthetic rings would be advantageous, and in particular, an apparatus and method, which mitigates or eliminates those disadvantages and/or which mitigates or eliminates the risk.

SUMMARY OF THE INVENTION

It may be seen as an object of the present invention to provide an improved apparatus and method for cracking the ring, which mitigates or eliminates the disadvantages and/or which mitigates or eliminates the risk for the patient. It is a further object of the present invention to provide an alternative to the prior art.

Thus, the above described object and several other objects are intended to be obtained in a first aspect of the invention by providing an apparatus for breaking an artificial ring, where said artificial ring is supporting a heart valve, such as a prosthetic heart valve, such as a bioprosthetic heart valve, in the heart in an associated patient, the apparatus comprising :

- A delivery system, such as a catheter or a flexible rod, such as an

extended and flexible catheter, configured for percutaneous delivery, such as configured for insertion into a blood vessel, such as an artery or a vein of the associated patient, such as configured for entering through a small incision in the chest and through the apex of the heart,

- an expandable mechanism being positioned at a distal end of the

delivery system, where the expandable mechanism is arranged for

o being placed inside the artificial ring,

o expanding in a radial direction,

o exerting a force on the artificial ring, which force is sufficient for breaking the artificial ring,

wherein the expandable mechanism is arranged so that

- a shape and size of the expandable mechanism immediately before

breaking of the artificial ring

is substantially similar, such as similar, to

- a shape and size of the expandable mechanism immediately after

breaking of the artificial ring. The invention is particularly, but not exclusively, advantageous for obtaining an apparatus which can be used for breaking an artificial ring, where said artificial ring is supporting a heart valve in the heart in an associated patient, where a relatively large force is required to break the ring, and where the application of said relatively large force is associated with a risk for the patient. This risk comes from the sudden release of the relatively large force on the surrounding

structures, such as surrounding tissue, upon the typically sudden breaking of the ring. If for example a balloon is used, which balloon is inflated to a relatively large pressure(often beyond its rated burst pressure) in order to supply sufficient force, then a rupture of the ring will abruptly diminish the reactive force on the balloon which will in consequence expand rapidly which may be associated with a risk for the patient. By having an expandable mechanism which is arranged to stay in a substantially similar shape and size immediately before and after rupture, this sudden expansion upon rupture is avoided, which in turn entails a safer procedure, which may for example be of benefit for patients subject to a valve-in- valve operation. Another obvious risk entailed with balloon expansion is rupture of the balloon with risk of dislodgement of balloon material in the patient's blood circulation. The 'artificial ring' (which may be referred to interchangeably with Ving') may be a ring for supporting a heart valve, such as a previously implanted ring for supporting a heart valve, such as an artificial heart valve implanted in either the pulmonic, tricuspid, mitral or aortic valve ostium. The ring may have an inner diameter in the range 10-35 mm such as 15-30 mm, such as 10-30 mm, such as 15-25 mm, such as 17-25 mm or as 15-23 mm.

The 'artificial ring' may for example be part of a trileaflet stent-supported bioprosthetic valve with bovine pericardium, where valves are mounted on an artificial ring comprising a scaffold of steal wires, which are fixed on a band of Elgiloy Polyester, and where a Dacron cuff covers the band to facilitate surgical implantation (such as a 19 mm Edwards Perimount® bioprosthesis (Edwards Lifesciences Corporation, Irvine, US) where the effective orifice diameter of a 19 mm Perimount valve is 17 mm). The 'artificial ring' may for example be a part of a 19 mm or a 21 mm aortic bioprosthesis, which is built from a single bovine pericardial sheet sutured to the outside of an inner acetyl stent to form the leaflets, where a sewing ring, that forms a fluoroscopic part of the bioprosthesis, is made from soft silicone covered on the outside by Dacron. For example, the 'artificial ring' may be a 19 mm or a 21 mm Mitroflow® (Sorin Group) aortic bioprosthesis. A Mitroflow® 21 mm prosthesis has an internal stent diameter of 17.3 mm and a 19 mm valve has an internal diameter of 15.4 mm. The 'expandable mechanism' may be any mechanism capable of delivering the sufficient force, which furthermore can hold the shape and size even upon rupture of the ring. This may, for example, be realized by implementing a means for controlling the expansion or an expansion limiter, such as a screw or gearwheel, which can control the expansion, such as which can enable adjusting the expansion in certain step sizes so that a rupture upon an increase in size does not entail a further increase in size. The 'expandable mechanism' may allow blood to flow through the expandable mechanism, such as through the valve ostium, before, during and/or after, such as while, the expansion takes place. The expandable mechanism could be wrapped in a balloon or netting to prohibit tissue to get caught in the expandable mechanism, such as to get caught in the expandable mechanism while expanding and/or compressing (where compressing is understood to be the opposite of expanding), inserting and/or retracting the expandable (where inserting/retracting is understood of delivering/taking out the expandable mechanism to/from the body of the associated patient).

The expandable mechanism is arranged so that a shape and size of the

expandable mechanism immediately before breaking of the artificial ring is substantially similar, such as similar, such as identical, to a shape and size of the expandable mechanism immediately after breaking of the artificial ring. It is to be understood that 'size' here may refer to a width of the expandable mechanism at a position which may be enclosed by the artificial ring during use, such as a maximum size at a position which may be enclosed by the artificial ring during use measured in a direction orthogonal to a longitudinal axis of the delivery system Ά shape' may refer to a visible characteristic or outline of a particular contour or outer edge of the expandable mechanism. The shape may in particular be defined by the relative proportions between the longest length and the widest width of the expandable mechanism, such as an aspect ratio given by a ratio between

- the longest length of the expandable mechanism in a direction parallel with a longitudinal axis of the delivery system, and

- a maximum size at a position which may be enclosed by the artificial ring during use measured in a direction of the diameter of the artificial ring orthogonal to a longitudinal axis of the delivery system.

It may, in general, be understood that the shape and the size of the expandable mechanism are 'similar' before and after breaking of the artificial ring, where 'similar' may be understood to mean that each of the shape and size after breaking is within [90; 110] % with respect to respectively the shape and size before breaking (i.e. being not smaller than 90 % and not larger than 110 % of the size and shape before breaking), such as within [95; 105] % with respect to respectively the shape and size before breaking, such as within [99; 101] % with respect to respectively the shape and size before breaking, such as within [99.5; 100.5] % with respect to respectively the shape and size before breaking, such as within [99.9; 100.1] % with respect to respectively the shape and size before breaking.

In an compressed state the expandable mechanism has a first maximum size di in a direction orthogonal to a length axis being within 2-8 mm, such as 4-6 mm, and a length along the axis within 5 mm-50 mm, such as within 5-20 mm or such as within 20-50 mm. In an expanded state the scissor jack has a first maximum size d₂ in a direction orthogonal to a length axis being within 20-35 mm, such as within 20-30 mm) and a length along the axis within 5 mm-50 mm, such as within 5-20 mm (such as within 8-20 mm) or such as within 20-50 mm.

The 'delivery device' may in general be any device suitable and configured for subcutaneous delivery, such as entering through the femoral artery (large artery in the groin), called the transfemoral approach, which does not require a surgical incision in the chest, or using a minimally invasive surgical approach with a small incision in the chest and entering through a large artery in the chest or through the tip of the left ventricle (the apex), which is known as the transapical approach. The 'delivery device' may furthermore be suitable and optionally configured for delivery and deployment (expansion) of a (new) valve for implantation in the (previously) implanted ring (subject for breaking) in a so- called valve-in-valve operation.

In an embodiment there is provided an apparatus, wherein the expandable mechanism comprises a scissor jack. By a 'scissor jack' may be understood a jack operated by an extendable force element, such as a leadscrew, that lengthens or shortens a diagonal in a parallelogram consisting of the linkages of the jack. For example, a leadscrew along an axis substantially centered with respect to the artificial ring, and being substantially orthogonal to a plane defined by the artificial ring, wherein a shortening of a diagonal in a parallelogram defined by corners formed by the ends of the extendable force element and a plurality of points on the inside of the artificial ring. A shortening of the force element will then cause the elements of said parallelogram to exert a radial force at the points of contact with the artificial ring.

In an embodiment, the jack could entirely be manufactured in stainless steel, titanium alloy or a cobalt-chromium alloy or a polymer or nitinol. Fully expanded the jack could have a diameter of 30 mm and fully compressed it could be 5 mm or less in diameter. The overall length of the expandable mechanism may be 20- 50 mm. Another setup could be with the entire body in a radiolucent material, like hard plastic, with radiopaque joints to help identify correct placement of the expandable mechanism using x-ray imaging.

The transmittance of external force to the expandable mechanism could be provided by a stainless steel wire inside a guide tube, where the wire is attached to one end of the expandable mechanism, and the guide tube attached to the other end, thus allowing for expansion of the arms by applying force to the wire.

In an embodiment there is provided an apparatus, wherein the expandable mechanism comprises a ring shaped band, where two ends of the band are overlapping, and where these two ends may be displaced relative to each other in a circumferential direction, so that an outer diameter of the ring shaped band is increased. The expandable mechanism could be manufactured in stainless steel, titanium alloy or a cobalt-chromium alloy or a polymer or nitinol. Fully expandable it could have a diameter of 30 mm and fully compressed it could be 5 mm or less in diameter. The overall length of the expandable mechanism is 20-50 mm. In an embodiment there is provided an apparatus, wherein the expandable mechanism comprises a plurality of elements, which elements are positioned relative to each other in a first configuration so that they extend across a first distance, and which elements are positioned relative to each other in a second configuration so that they extend across a second distance, wherein the second distance is larger than the first distance. This may for example be carried out by arranging a plurality of wedge shaped elements along a center axis of the ring, and arranged for moving them into the center of the ring, thus forcing at least some of the wedge shape elements (within the plurality of wedge shaped elements) outwards. Alternatively, a mechanism based on a similar principle as a mechanical iris shutter (or diaphragm) wherein a series of plates can fold in on each other or expand out, e.g., for use in a camera - albeit applied inversely - may be utilized. Alternatively, a mechanism based on a similar principle as a so- called crimper (for example Edwards® THV Crimper Model 9600 CR, Edwards Lifesciences Corporation, Irvine, US), which may be used for gradually crimping, e.g., a bioprosthesis to a certain diameter - albeit applied inversely - may be utilized

It is conceivable that one or more embodiments of the invention may be combined with other embodiments, e.g., the Ving shaped band' referred to above may be combined with the 'plurality of elements' referred to above.

In an embodiment there is provided an apparatus, which is enabled for functioning in the absence of a balloon (such as a scissor jack, a ring shaped band or a plurality of elements as described above). In an embodiment there is provided an apparatus, which does not comprise a balloon. In an embodiment there is provided an apparatus, wherein the expandable mechanism comprises any one of:

a controlled balloon, such as a balloon arranged for delivering the sufficient force and controlled by an outer element which is retaining it at a maximum diameter,

a motor, such as an electrical or hydraulic or pneumatic motor,

a shape memory alloy,

a heating element and a material which expands upon application of heat, a piezoelectric actuator.

In an embodiment there is provided an apparatus, wherein the apparatus is further comprising a force and/or energy providing mechanism being positioned at a proximal end of the delivery system, the force and/or energy providing mechanism being connected with the expandable mechanism through the delivery system, so that a force and/or energy input at the force and/or energy providing mechanism can be transferred to the expandable mechanism.

For example, a force providing mechanism may be provided in form of a motor or a handle, which a person can turn and thereby provide a force. A force providing means may also be provided in the form of an automatic or manual pump which an increase a pressure, which can be transmitted to the expandable mechanism. Energy may be provided in the form of, e.g., heat or electrical energy.

In an embodiment there is provided an apparatus, wherein the apparatus is further comprising a communication channel between a proximal end of the delivery system and the expandable at the distal end. This may for example be relevant if the expandable mechanism comprises a motor and a power unit, such as a battery, which can then be controlled via the communication channel, which may be an electrical conductor, a flexible shaft or a wireless connection. In an embodiment there is provided an apparatus, further comprising any one of:

- A force measuring unit capable of measuring the force delivered to the artificial ring via the expandable mechanism,

the force measuring unit optionally capable of being positioned at the proximal end of the delivery system,

and/or - A microphone being capable of capturing an acoustical signal.

Here "force" is to be construed broadly as also being part of any one of force "as such" (F), pressure (F/A) or torque. Having a microphone may be advantageous because it is relatively simply and can be placed inside or outside the body of the associated patient. Having a force measuring unit may be advantageous, because an acoustical signal may be spoiled by interfering sounds, e.g., if the associated patient is coughing. The force measuring unit may be any unit capable of measuring a force, such as any one of a strain sensor, a piezoresistive element, a fiber optic waveguide, a capacitive force sensor. The force measuring unit may for example be mounted on the expandable mechanism and arranged for measuring the force applied at a point of contact between the expandable mechanism and the artificial ring.

In an embodiment there is provided an apparatus, wherein the apparatus is further comprising a unit for detecting a breaking of the artificial ring, optionally comprising any one of:

- A force measuring unit, such as a force measuring unit previously

described, wherein the force measuring unit is being arranged for sensing a changing of the force indicative of a ring breaking event, - A microphone, such as a microphone as previously described, and

furthermore comprising a processor, where the microphone is being operationally coupled with the processor, which processor is arranged for detecting a change in said acoustical signal being indicative of a ring breaking event.

The unit for detecting breaking may be arranged for taking some signal (e.g., force or sound) and detect an event indicative of a ring breaking, i.e., a ring breaking event.

In an embodiment there is provided an apparatus, wherein the unit for detecting a ring breaking event is furthermore arranged for subsequent to detecting a ring breaking event

initiating a corresponding alarm, such as said alarm involving one or more of

o an acoustical signal,

o a tactile signal, o a visual signal,

and/or

- automatically decreasing the force exerted on the artificial ring.

An advantage of this may be that a signal upon breaking is created or the force is decreased, which may in turn enable stopping a breaking process and save time and/or reduce the risk of cardiovascular rupture and potential fatal bleeding in the associated patient.

In an embodiment there is provided an apparatus, wherein the expandable mechanism is arranged so as to allow a flow, such as a normal or substantially normal flow, of fluid, such as blood, through the artificial ring when the

expandable mechanism is being placed inside the artificial ring and is exerting a force on the artificial ring, such as the apparatus being arranged so as to allow said flow immediately before breaking of the ring, such as the apparatus being arranged so as to allow said flow throughout a process of breaking the ring. An advantage of this may be that blood can flow during the process of breaking the ring, which greatly facilitates the overall process. This may be an advantage with respect to, e.g., balloons, which substantially fill out, such as block the cross- sectional area within the artificial ring during use, thus blocking flow of fluid, such as blood, during use. A balloon in, for example, the aorta of a patient, may block circulation for the rest of the body, entailing blocking blood supply to the brain of the patient.

In an embodiment there is provided an apparatus, wherein the apparatus is arranged so that a cross-sectional area of the expandable mechanism in the plane of the ring, such as in a plane being orthogonal to an axial direction, is smaller than a cross-sectional area inside the artificial ring, such as equal to or less than 90 % of a cross-sectional area inside the artificial ring, such as equal to or less than 75 % of a cross-sectional area inside the artificial ring, such as equal to or less than 50 % of a cross-sectional area inside the artificial ring, such as equal to or less than 25 % of a cross-sectional area inside the artificial ring, such as equal to or less than 10 % of a cross-sectional area inside the artificial ring, when the expandable mechanism is being placed inside the artificial ring and is exerting a force on the artificial ring, such as immediately before breaking of the ring, such as throughout a process of breaking the ring. An advantage of having a small cross-sectional are may be that blood can flow relatively uninterrupted during the process of breaking the ring, which greatly facilitates the overall process.

In a further embodiment there is provided an apparatus, wherein the force applied on the artificial ring by the expandable mechanism gives rise to hoop stresses exceeding a point of rupture of the artificial ring and thereby breaking the artificial ring. The hoop stress is the force exerted circumferentially (perpendicular both to the axis and to the radius of the object) in both directions on every particle in the cylinder wall. Point of rupture may be used synonymously with fracture point or failure point. Breaking may be used synonymously with rupturing, cracking, or fracturing.

In an embodiment there is provided an apparatus, wherein the force applied on the artificial ring by the expandable mechanism comprises forces working in a radial direction. In other words, the forces are applied in a direction from the inside and out, such as in a direction from the center of the ring and away from the center in a plane of the ring, i.e., in a direction being orthogonal to the axis of the ring. In a further embodiment there is provided an apparatus, wherein the net force, such as the net radial force (where 'net radial force' is understood to be the net force of any and all forces working in a radial direction), exerted by the

expandable mechanism on a segment of the artificial ring, where said segment is corresponding to one half of the artificial ring, is equal to or larger than 0.5 Newton (N), such as equal to or larger than 1 N, such as equal to or larger than 5 N, such as equal to or larger than 10 N, such as equal to or larger than 25 N, such as equal to or larger than 50 N, such as equal to or larger than 75 N, such as equal to or larger than 100 N, such as equal to or larger than 150 N, such as equal to or larger than 250 N, such as equal to or larger than 300 N, such as equal to or larger than 500 N, such as equal to or larger than 750 N, such as equal to or larger than 1000 N. Tests performed show that the expandable mechanism is capable of exerting a net force of minimum 700 N on a segment of the artificial ring (where said segment is corresponding to one half of the artificial ring), such as wherein the test comprises encircling the apparatus with a string (so that the string is at a position of an artificial ring during use of the apparatus) and measuring the tensile force (of 700 N) in the string during expansion of the expandable mechanism.

An advantage of a relatively large force may be that it enables breaking of the ring. By a 'net force' or 'net radial force' is understood the forces (such as the radial forces) being vectorically summed. For example, for a balloon dilatation, this vectorial summation could be carried out by summing by integration the forces (taking into account their directions) on all of the infinitesimally small portions of said segment. The force on each of all of the infinitesimally small portions would correspond to the pressure exerted by the balloon (which would typically need to be close to or at or even above its rated burst pressure in order to provide sufficient force) multiplied with the area of the infinitesimally small portion, and the direction would be anti-parallel with a normal direction of the surface of said portion, i.e., for a circular cylindrical ring, the direction would be directly away from the center of the circle. For example for a segment

corresponding to an upper half of the ring (cf., e.g., FIG. 1) where the net force, such as the net radial force, on the upper half segment can be identified by integrating the balloon forces (taking the direction of the balloon force at any given point on the ring into account) on the upper half of the ring (note that in principle all forces on the upper half of the ring which are not in an upwards direction cancel with each other). The 'net force' (which may in this context be referred to interchangeably with the 'net radial force') would be in a direction from the axis and through the middle of said one half. It is generally understood that the net force applied by the expandable mechanism on the entire ring is zero. By one half of the ring is understood a coherent half, such as an upper half or right half, and it is generally understood that said half corresponds to an angular section of 180 degrees (or pi) and that said half and the remaining half may be divided from each other by a plane being parallel with the axis of the ring. It is noted that this force (net force on one half of the ring) may be relevant, since it determines the circumferential stress (hoop stress) in the ring at the cross-section of the ring between said one half and the remaining other half of the ring (i.e., the cross-section in a plane being parallel with an axis of the ring and separating said two halves of the ring from each other, such as for a ring with a rectangular shape this would be twice the product of height and wall thickness). In an embodiment there is provided an apparatus, wherein the expandable mechanism is arranged so that the force exerted by the expandable mechanism on the artificial ring gives rise to a circumferential stress in the artificial ring which is equal to or larger than 0.1 MPa, such as equal to or larger than 0.5 MPa, such as equal to or larger than 1 MPa, such as equal to or larger than 1 MPa, such as equal to or larger than 5 MPa, such as equal to or larger than 7.5 MPa, such as equal to or larger than 10 MPa, such as equal to or larger than 15 MPa, such as equal to or larger than 25 MPa, such as equal to or larger than 50 MPa, such as equal to or larger than 100 MPa, such as equal to or larger than 250 MPa, , such as equal to or larger than 500 MPa, such as equal to or larger than 500 MPa, such as equal to or larger than 1000 MPa.

In a further embodiment there is provided an apparatus, wherein the expandable mechanism is arranged so that a total force applied by the expandable mechanism on the ring is equal to or larger than 1 N, such as equal to or larger than 5 N, such as equal to or larger than 10 N, such as equal to or larger than 25 N, such as equal to or larger than 50 N, such as equal to or larger than 75 N, such as equal to or larger than 100 N, such as equal to or larger than 150 N, such as equal to or larger than 250 N, such as equal to or larger than 300 N, such as equal to or larger than 500 N, such as equal to or larger than 750 N, such as equal to or larger than 1000 N, such as equal to or larger than 2000 N. By 'total force' is understood the force being summed in an absolute manner. For example, for a balloon dilatation, this would correspond to the pressure exerted by the balloon on the artificial ring multiplied with the area of the ring whereupon this pressure is exerted.

In an embodiment there is provided an apparatus, wherein net force, such as net radial force (where 'net radial force' is understood to be the net force of any and all forces working in a radial direction), exerted by the expandable mechanism on a segment of the artificial ring, where said segment is corresponding to one half of the artificial ring, at least corresponds to a net force on a corresponding segment applied by balloon dilatation, such as dilatation by inflation, such as where the diameter of the balloon at the position of the artificial ring is limited by the artificial ring (i.e., the balloon is nominally larger than the inner diameter of the ring, so it touches the ring and transmits the pressure to the ring) so that the balloon exerts a pressure on the artificial ring corresponding to an inner pressure in the balloon, wherein an inner pressure in the balloon is larger than 2

atmosphere, such as larger than 5 atmosphere, such as larger than 10

atmosphere, such as equal to or larger than 11 atmosphere, such as larger than 15 atmosphere, such as larger than 20 atmosphere, such as equal to or larger than 22 atmosphere. The artificial ring may in this context be given by a circular ring with an inner diameter of 15.4 mm and a height of 2.4 mm (corresponding to a ring as depicted in FIGs 1-2 with Di = 15.3 mm and H = 2.4 mm) or 17.3 mm and a height of 2.4 mm (corresponding to a ring as depicted in FIGs 1-2 with Di = 17.3 mm and H = 2.4 mm).

In an embodiment there is provided an apparatus, wherein the expandable mechanism comprises, such as consists of, rigid elements, such as wherein said rigid elements are arranged for being in contact with the artificial ring and for applying the force sufficient for breaking the artificial ring. By rigid may be understood at least more rigid than a high-pressure balloon for balloon dilatation (such as a 20 mm ultra-high pressure balloon (ATLAS®, Bard Peripheral

Vascular, Inc., Temple, US) or a 22 mm high-pressure balloon (ATLAS® Gold, Bard, Temple, US)) of prosthetic heart valves, such as bioprosthetic heart valves.

According to a second aspect of the invention, there is presented use of an apparatus for breaking an artificial ring according to the first aspect for breaking an artificial ring for supporting a heart valve, such as a prosthetic heart valve, such as a bioprosthetic heart valve.

According to a third aspect of the invention, there is presented a method for breaking an artificial ring for supporting a heart valve, such as a prosthetic heart valve, such as a bioprosthetic heart valve, such as an artificial ring for supporting a heart valve being implanted in the heart of an associated patient, said method comprising :

Providing an apparatus for breaking an artificial ring according to the first aspect,

using the delivery system for placing the expandable mechanism within the an artificial ring, - expanding the expandable mechanism in a radial direction, such as until a size of the expandable mechanism in the radial direction corresponds to an internal diameter of the artificial ring,

- exerting a force on the artificial ring with the expandable mechanism, which force is sufficient for breaking the artificial ring, thereby breaking the artificial ring, such as whereby

o a shape and size of the expandable mechanism immediately

before breaking of the artificial ring

is substantially similar, such as similar, to

o a shape and size of the expandable mechanism immediately after breaking of the artificial ring.

In an embodiment there is provided a method for implantation, such as valve-in- valve implantation, of a secondary artificial heart valve, such as wherein the primary artificial ring is a ring for supporting a heart valve and said primary ring being implanted in the heart of an associated patient, said method comprising :

a. Breaking the primary artificial ring for supporting a valve according to the previously described method,

the method further comprising :

b. Implanting the secondary artificial heart valve, such as implanting the secondary artificial heart valve at or close to the position of the primary artificial ring.

For example, according to this method, it may be possible to employ a 23 mm Z- MED balloon for implanting an Edwards SAPIEN® transcatheter heart valve in vitro in a 21 mm Mitroflow® bioprosthesis in which the valve ring had been fractured (or broken) using an apparatus according to the first aspect.

According to a fourth aspect of the invention, there is presented a method for expanding or dilating an artificial ring for supporting a heart valve, such as a prosthetic heart valve, such as a bioprosthetic heart valve, such as an artificial ring for supporting a heart valve being implanted in the heart of an associated patient, said method comprising :

Providing an apparatus for breaking an artificial ring according to the first aspect, using the delivery system for placing the expandable mechanism within the artificial ring,

- expanding the expandable mechanism in a radial direction, such as until a size of the expandable mechanism in the radial direction corresponds to an internal diameter of the artificial ring, and

- exerting a force on the artificial ring with the expandable mechanism,

which force is sufficient for expanding or dilating the artificial ring, thereby expanding or dilating the artificial ring

The invention according to the fourth aspect is particularly advantageous in that the method for expanding or dilating an artificial ring by using an apparatus according to the first aspect ensures the expansion of the artificial ring is performed in a controllable manner, so that, if the artificial ring during such an expansion unintentionally breaks, it will not have the additional disadvantage that the apparatus will also suddenly expand significantly because of the controlled expansion. The artificial rings that can be expanded or dilated according to the fourth aspect may be flexible rings or even rigid rings not from outset designed for expansion or dilation.

The first, second, third and fourth aspect of the present invention may each be combined with any of the other aspects. These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE FIGURES

The apparatus, use and method according to the invention will now be described in more detail with regard to the accompanying figures. The figures show one way of implementing the present invention and is not to be construed as being limiting to other possible embodiments falling within the scope of the attached claim set.

FIG. 1 shows a schematic of an artificial ring. FIG. 2 shows another schematic of an artificial ring in a perspective view.

FIG. 3 shows a schematic of a cracking of an artificial ring.

FIG. 4 shows a schematic of an embodiment of an apparatus.

FIG. 5 shows an expandable mechanism in the form of a scissor jack. FIG. 6 shows an expandable mechanism comprising a ring shaped band. FIG. 7 shows another expandable mechanism comprising a ring shaped band.

FIG. 8 shows another expandable mechanism comprising a ring shaped band.

FIG. 9 shows another expandable mechanism in the form of a scissor jack.

DETAILED DESCRIPTION OF AN EMBODIMENT

FIG. 1 shows a schematic of an artificial ring 102 as observed from a point on the axis of the ring or a cross-section of the ring in a plane being orthogonal to the axis of the ring (which axis would be orthogonal to the plane of the paper and intersect the centre of the ring). Furthermore, the figure indicates forces 104 applied on the ring, where the net forces on a right hand side of the ring result in a net force 105 in a direction from the centre and to the right hand side. The forces 104 have been drawn uniformly distributed, such as could be the case for a balloon, but the expandable mechanism may also be arranged so as to only apply forces at two or more locations. The figure also indicates an outer diameter D₂ and an inner diameter Di, where a wall thickness t of the ring would correspond to a difference between inner and outer diameter, t = D₂-Di. FIG. 2 shows another schematic of an artificial ring 102 in a perspective view, where a height H of the ring in an axial direction and wall thickness t are indicated. Furthermore, the axis 106 of the ring which protrudes though the centre of the ring and being orthogonal to a plane of the ring is shown. FIG. 3 shows a schematic of a cracking of an artificial ring, such as carried out by D. Tanase, et al., cf., International Journal of Cardiology 176 (2014) 1048-1049.

FIG. 3(a) shows an intact ring to be cracked 302a wherein a balloon 308a is inflated so as to exert a force on the ring. However, the still intact ring 302a also exerts a force on the balloon leading to a waist 310 in the balloon immediately prior to cracking.

FIG. 3(b) shows a cracked ring 302b wherein a gap 312 is formed, which reduces the force exerted by the ring on the balloon, which in turn entails that the balloon takes on a different and more spherical shape, and in particular a shape without the waist. Thus, the pressure in the balloon upon rupture causes it to expand rapidly in a radial direction at the position of the ring upon cracking of the ring, which rapid expansion may be harmful to the surrounding tissue. This tissue damage may be exhibited in form of rupture and fatal bleeding in the patient. FIG. 4 shows a schematic of an embodiment of an apparatus according to the present invention.

FIG. 4(a) shows the apparatus before expansion, such as prior to insertion into an 5 artificial ring. The apparatus comprises a delivery system 414 configured for

percutaneous delivery, an expandable mechanism 416 being positioned at a distal end of the delivery system, where the expandable mechanism is arranged for being placed inside the artificial ring, such has as a first maximum size di in a direction orthogonal to a length axis 406 being relatively small, such as less than

10 20 mm, such as less than 15 mm such as less than 10 mm, such as less than 6 mm, such as less than 5 mm. An advantage of a relatively small size di may be that it facilitates delivery through narrow passages, such as through a blood vessel and/or a stenosed heart valve. In the present embodiment, a force measuring unit 418 is placed at the expandable mechanism. A force providing

15 mechanism 420 is shown at the proximal end of the delivery system.

FIG. 4(b) is similar to FIG. 4(a) except it shows the apparatus after expansion, such as after insertion into an artificial ring, and after expansion in a radial direction of the expandable mechanism, so that a second maximum size d₂ at a 20 position on the axis corresponding to the ring and in a direction orthogonal to a length axis 406 substantially corresponds, such as corresponds to an inner diameter of the artificial ring.

FIG. 4(c) is similar to FIG. 4(b) except it shows the apparatus immediately after 25 breaking of the artificial ring, such as after insertion into an artificial ring, and after expansion in a radial direction of the expandable mechanism, and after breaking of the ring, where a third maximum size d₃ at a position on the axis corresponding to the ring and in a direction orthogonal to a length axis 406 substantially corresponds to the second maximum size d₂. It may in general be 30 understood that third maximum size d₃ is within [90; 110] % with respect to the second maximum size d₂ (i.e., d₃ being at not smaller than 90 % of d₂ and not larger than 110 % of d₂), such as d₃ being within [95; 105] % with respect to d₂, such as d₃ being within [99; 101] %. The similarity of d₂ and d₃ entails that the expandable mechanism is arranged so that a size of the expandable mechanism immediately before breaking of the artificial ring is substantially similar, such as similar, to a size of the expandable mechanism immediately after breaking of the artificial ring.

FIG. 5 shows an expandable mechanism in the form of a scissor jack 516.

FIG. 5A shows the scissor jack in a fully compressed state, such as before expansion, such as prior to insertion into an artificial ring, where the scissor jack has as a first maximum size di in a direction orthogonal to a length axis 506 being relatively small. The figure furthermore shows a delivery system 514. In the compressed state (cf., FIG. 5A) the scissor jack has a first maximum size di in a direction orthogonal to a length axis 506 being 5.8 mm (but could be within 2-8 mm) and a length along the axis 506 of 33.6 mm (but could be within 20-50 mm).

FIG. 5B shows the scissor jack after expansion, such as after insertion into an artificial ring, and after expansion in a radial direction of the expandable mechanism, so that a second maximum size d₂ at a position on the axis corresponding to the ring and in a direction orthogonal to a length axis 506 substantially corresponds, such as corresponds to an inner diameter of the artificial ring. In an expanded state (cf., FIG. 5B) the scissor jack has a first maximum size d₂ in a direction orthogonal to a length axis 506 being 25.8 mm (but could be within 20-35 mm, such as within 20-30 mm) and a length along the axis 506 of 13.6 mm (but could be within 8-20 mm).

FIG. 5C shows a perspective view of the scissor jack 516 in an expanded state.

The sscissor jack in FIG. 5 is operated by an extendable force element 518, such as a leadscrew or a telescopic arrangement, that lengthens or shortens a diagonal in a parallelogram consisting of the linkages 520a, 520b, 520c of the jack (which in the present embodiment is rather hexagonal due to the middle linkage 520b being of equal length with respect to the outer linkages 520a, 520c). The extendable force element is provided along an axis 506 substantially centered with respect to the artificial ring (where it is understood that the axes of the extendable force element and the artificial ring are typically coincident during use), and being substantially orthogonal to a plane defined by the artificial ring (during use), wherein a shortening of a diagonal (such as the diagonal being parallel with length axis 506) in a parallelogram defined by corners formed by the ends of the extendable force element (such as the end points at the proximal and distal points on the length axis 506) and a plurality of points on the inside of the artificial ring (such as the points which are shown separated with a distance di or d₂) will then cause the elements of said parallelogram to exert a radial force at the points of contact with the artificial ring. In the present embodiment, each of the outer linkages 520a, 520c are 11. 6 mm (but could be within 5-20 mm) and the middle (contact surface) linkage 520b is 10mm (but could be within 5-20 mm).

An advantage of the scissor jack depicted in FIG. 5 may be that (even in an expanded state) the scissor jack does not block flow of liquid through the artificial ring (since the cross-sectional area of the scissor jack in a plane being orthogonal to the axis 506 is smaller than an area inside the artificial ring (even in an expanded state during use)).

FIG. 6 shows an expandable mechanism comprising a ring shaped band.

FIG. 6A shows an expandable mechanism as seen from a point along the axis, which expandable mechanism comprises a ring shaped band 630, where two ends of the band are overlapping at a section 632 of the ring shaped band, and where these two ends may be displaced relative to each other in a circumferential direction, so that an outer diameter of the ring shaped band is increased. The circumferential displacement may be driven by a toothed wheel 634 at the end of a delivery system 614, which toothed wheel engages with teeth or cavities on the inside of the band, such as the toothed wheel 634 and the ring shaped band 630 forming a substantially circular rack and pinion arrangement.

FIG. 6B shows a perspective view of the expandable mechanism comprising a ring shaped band 630. This view more clearly shows the through-going cavities 636 in the band with which the toothed wheel 634 can engage and drive the expansion. The height (or axial length) of the expandable mechanism comprising a ring shaped band is 12.9mm (but could be within 5-20 mm). In FIG. 6 it is shown having a maximum size in a direction orthogonal to a length axis being 13.2 mm (but could be within 5-20 mm). A wall thickness of the band is 0.5 mm. However, another wall thickness, such as a smaller wall thickness, such as 0.25 mm, or a wall thickness within a range of 0.1-1 mm, may also be provided. The toothed wheel has a diameter of 3.6 mm, however another diameter, such as a smaller diameter of the toothed wheel, or a diameter within 1-5 mm, may also be provided.

FIG. 7 shows an expandable mechanism comprising a ring shaped band similar to the mechanism in FIG. 6, except that a casing 738 is arranged for covering the toothed wheel, which may be advantageous for avoiding that the toothed wheel can damage and/or entangle tissue during use, i.e., prohibit that tissue can get caught in the expandable mechanism.

FIG. 8 shows an expandable mechanism comprising a ring shaped band similar to the mechanism in FIG. 7, except that the ring shaped band in FIG. 8 the toothed wheel engages with non-through-going cavities 836 in the band, which may be advantageous for enabling a smooth surface of band 830 which may in turn reduce a risk that the band can damage tissue during use, i.e., prohibit that tissue can get caught in the expandable mechanism.

FIG. 9 shows another expandable mechanism in the form of a scissor jack. The scissor jack is somewhat similar to the jack shown in FIG. 5, but with some differences as it will be explained below.

FIG. 9A shows a second design of the scissor jack, similar to the scissor jack shown in FIG. 5. The scissor jack is shown in a fully compressed state, similar to FIG. 5A, such as before expansion, such as prior to insertion into an artificial ring. According to this embodiment the scissor jack may have a slidable element 540. The slidable element may be connected to one or more linkages 520a, 520b, 520c and/or 520d. The slidable element 540 may further comprise two opposing ends, one or both of said ends may be configured to move along the length axis 506, so as to move closer to the opposing end and/or away from the opposing end. Thus, the slideable element 540 can be compressible and/or extensible. In other embodiments, it can be of a fixed length. According to the shown embodiment of the scissor jack, linkages 520d of the scissor jack may be connected to the slidable element in one end, and, in a compressed state of the scissor jack, these linkages may be oriented parallel to some or all of the other linkages 520a, 520b and 520c in a direction parallel to the length axis 506.

FIG. 9B shows the scissor jack after expansion, similar to FIG. 5B, such as after insertion into an artificial ring, and after expansion in a radial direction of the expandable mechanism. According to this embodiment the middle linkages 520b may not be of equal length with respect to the outer linkages 520a, 520c. The activation of the expansion may be performed in various ways, i.e. by displacing one, or both, ends of the slidable element 540, and/or by displacing one, or both, end parts 550a and 550b of the scissor jack.

FIG. 9C shows the scissor jack as in FIG. 9A and 9B in a perspective view.

To sum up, there is presented an apparatus for breaking an artificial ring, where said artificial ring is supporting a heart valve in the heart in an associated patient, the apparatus comprising a delivery system configured for percutaneous delivery, an expandable mechanism being positioned at a distal end of the delivery system, where the expandable mechanism is arranged for being placed inside the artificial ring, expanding in a radial direction, and exerting a force on the artificial ring, which force is sufficient for breaking the artificial ring, wherein the expandable mechanism is arranged so that a shape and size of the expandable mechanism immediately before breaking of the artificial ring is substantially similar to a shape and size of the expandable mechanism immediately after breaking of the artificial ring. Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

Claims

An apparatus for breaking an artificial ring, where said artificial ring is supporting a heart valve, the apparatus comprising :

- A delivery system configured for percutaneous delivery,

- an expandable mechanism being positioned at a distal end of the

delivery system, where the expandable mechanism is arranged for o being placed inside the artificial ring,

o expanding in a radial direction,

wherein the expandable mechanism is arranged so that

- a shape and size of the expandable mechanism immediately before breaking of the artificial ring

is substantially similar to

- a shape and size of the expandable mechanism immediately after

breaking of the artificial ring.

An apparatus according to any one of the preceding claims, wherein the expandable mechanism comprises a scissor jack.

An apparatus according to any one of the preceding claims, wherein the expandable mechanism comprises a ring shaped band, where two ends of the band are overlapping, and where these two ends may be displaced relative to each other in a circumferential direction, so that an outer diameter of the ring shaped band is increased.

An apparatus according to any one of the preceding claims, wherein the expandable mechanism comprises a plurality of elements, which elements are positioned relative to each other in a first configuration so that they extend across a first distance, and which elements are positioned relative to each other in a second configuration so that they extend across a second distance, wherein the second distance is larger than the first distance.

5. An apparatus according to any one of the preceding claims, wherein the apparatus is further comprising a force and/or energy providing mechanism being positioned at a proximal end of the delivery system, the force and/or energy providing mechanism being connected with the expandable mechanism through the delivery system, so that a force and/or energy input at the force and/or energy providing mechanism can be transferred to the expandable mechanism.

An apparatus according to any one of the preceding claims, wherein the apparatus is further comprising a communication channel between a proximal end of the delivery system and the expandable element at the distal end.

An apparatus according to any one of the preceding claims, further comprising any one of:

- the force measuring unit optionally capable of being positioned at the proximal end of the delivery system,

and/or

- A microphone being capable of capturing an acoustical signal.

An apparatus according to any one of the preceding claims, wherein the apparatus is further comprising a unit for detecting a breaking of the artificial ring, optionally comprising any one of:

- A force measuring unit according to claim 7, wherein the force

measuring unit is being arranged for sensing a changing of the force indicative of a ring breaking event,

- A microphone according to claim 7, and furthermore comprising a

processor, where the microphone is being operationally coupled with the processor, which processor is arranged for detecting a change in said acoustical signal being indicative of a ring breaking event.

An apparatus according to claim 8, wherein the unit for detecting a ring breaking event is furthermore arranged for subsequent to detecting a ring breaking event

initiating a corresponding alarm, such as said alarm involving one or more of o an acoustical signal,

o a tactile signal,

o a visual signal,

and/or

- automatically decreasing the force exerted on the artificial ring.

10. An apparatus according to any one of the preceding claims, wherein the expandable mechanism is arranged so as to allow a flow of fluid through the artificial ring when the expandable mechanism is being placed inside the artificial ring and is exerting a force on the artificial ring.

11. An apparatus according to any one of the preceding claims, wherein the apparatus is arranged so that a cross-sectional area of the expandable mechanism in the plane of the ring is smaller than a cross-sectional area inside the artificial ring, such as equal to or less than 90 % of a cross- sectional area inside the artificial ring, such as equal to or less than 75 % of a cross-sectional area inside the artificial ring, such as equal to or less than 50 % of a cross-sectional area inside the artificial ring, such as equal to or less than 25 % of a cross-sectional area inside the artificial ring, such as equal to or less than 10 % of a cross-sectional area inside the artificial ring, when the expandable mechanism is being placed inside the artificial ring and is exerting a force on the artificial ring.

12. An apparatus according to any one of the preceding claims, wherein the force applied on the artificial ring by the expandable mechanism gives rise to hoop stresses exceeding a point of rupture of the artificial ring and thereby breaking the artificial ring.

13. An apparatus according to any one of the preceding claims, wherein the force applied on the artificial ring by the expandable mechanism comprises forces working in a radial direction.

14. An apparatus according to any one of the preceding claims, wherein the net force exerted by the expandable mechanism on a segment of the artificial ring, where said segment is corresponding to one half of the artificial ring, is equal to or larger than 0.5 Newton (N), such as equal to or larger than 1 N, such as equal to or larger than 5 N, such as equal to or larger than 10 N, such as equal to or larger than 25 N, such as equal to or larger than 50 N, such as equal to or larger than 75 N, such as equal to or larger than 100 N, such as equal to or larger than 150 N, such as equal to or larger than 250 N, such as equal to or larger than 300 N, such as equal to or larger than 500 N, such as equal to or larger than 750 N, such as equal to or larger than 1000 N.

15. An apparatus according to any one of the preceding claims, wherein the expandable mechanism is arranged so that the force exerted by the expandable mechanism on the artificial ring gives rise to a circumferential stress in the artificial ring which is equal to or larger than 0.1 MPa, such as equal to or larger than 0.5 MPa, such as equal to or larger than 1 MPa, such as equal to or larger than 1 MPa, such as equal to or larger than 5 MPa, such as equal to or larger than 7.5 MPa, such as equal to or larger than 10 MPa, such as equal to or larger than 15 MPa, such as equal to or larger than 25 MPa, such as equal to or larger than 50 MPa, such as equal to or larger than 100 MPa, such as equal to or larger than 250 MPa, such as equal to or larger than 500 MPa, such as equal to or larger than 500 MPa, such as equal to or larger than 1000 MPa.

16. An apparatus according to any one of the preceding claims, the wherein net force exerted by the expandable mechanism on a segment of the artificial ring, where said segment is corresponding to one half of the artificial ring, at least corresponds to a net force on a corresponding segment applied by balloon dilatation, wherein an inner pressure in the balloon is larger than 2 atmosphere, such as larger than 5 atmosphere, such as larger than 10 atmosphere, such as equal to or larger than 11 atmosphere, such as larger than 15 atmosphere, such as larger than 20 atmosphere, such as equal to or larger than 22 atmosphere.

17. An apparatus according to any one of the preceding claims, wherein the expandable mechanism comprises rigid elements, such as wherein said rigid elements are arranged for being in contact with the artificial ring and for applying the force sufficient for breaking the artificial ring.

18. Use of an apparatus according to any one of the preceding claims for

breaking an artificial ring for supporting a heart valve, such as a prosthetic heart valve, such as a bioprosthetic heart valve.

19. A method for breaking an artificial ring for supporting a heart valve, where said artificial ring is supporting a heart valve, said method comprising :

Providing an apparatus for breaking an artificial ring according to any one of the preceding claims,

using the delivery system for placing the expandable mechanism within the an artificial ring,

- expanding the expandable mechanism in a radial direction, such as until a size of the expandable mechanism in the radial direction corresponds to an internal diameter of the artificial ring,

- exerting a force on the artificial ring with the expandable mechanism, which force is sufficient for breaking the artificial ring, thereby breaking the artificial ring, whereby

o a shape and size of the expandable mechanism immediately

before breaking of the artificial ring

is substantially similar, such as similar, to

20. A method for implantation, such as valve-in-valve implantation, of a

secondary artificial heart valve, said method comprising :

a. Breaking the primary artificial ring for supporting a valve according to the method of claim 19,

the method further comprising :