Method of manufacturing a prosthetic valve assembly

ES 2 425 320 T3

DESCRIPTION

Heart valve prosthesis that has an inner covering to prevent regurgitation

The present invention relates to a valve prosthesis for the replacement of a stenotic native aortic valve to be implanted by means of a transcutaneous catheterization technique.

The valve prosthesis can also be applied to other body conduits provided with native valves, such as veins, or in organs (liver, intestine, urethra, ...).

Implantable valves, which will be referred to interchangeably in the following as IV, valve prosthesis or prosthetic valve, allow the repair of a valve deficiency using a less invasive technique, instead of the usual surgical implantation of valves which, in the case of valvular heart disease, requires thoracotomy and cardiopulmonary bypass. A particular use for IV affects patients who cannot be operated due to an associated disease or because they are very old, or also patients who could be operated but only with a very high risk.

Although the IV of the present invention and the procedure for implanting said IV can be used in various heart valve diseases, the following description will first refer to the aortic orifice in aortic stenosis, more particularly in its degenerative form in elderly patients.

Aortic stenosis is a disease of the aortic valve in the left ventricle of the heart. The aortic valve orifice is normally capable of opening up to 4 to 6 cm during systole², thus allowing the free ejection of the ventricular blood volume into the aorta. This aortic valve orifice can become firmly stenotic and thus blood can no longer be freely ejected from the left ventricle. By default, the left ventricle can only eject a small amount of blood, which has to significantly increase the intracavitary pressure to force the stenotic aortic orifice. In such aortic diseases, patients may have syncope, chest pain, and mainly breathing difficulties. The evolution of this disease is disastrous when symptoms of heart failure appear, since 50% of patients die in the year following the first symptoms of the disease.

The only commonly available treatment is surgery to replace the stenotic aortic valve with a prosthetic valve: this treatment also provides excellent results. If surgery is impossible to perform, that is, if the patient is considered inoperable or operable only with too high surgical risk, an alternative possibility is to dilate the valve with a balloon catheter to widen the aortic orifice. Unfortunately, a good result is only obtained in about half of the cases, and there is a high rate of restenosis, that is, about 80% after one year.

Aortic stenosis is a very common disease in people over seventy years of age and occurs more and more frequently as the subject ages. As has been evidenced, the current trend of the general evolution of the population is that it ages more and more. Furthermore, it can be assessed, as a rough estimate, that approximately 30 to 50% of subjects who are older than 80 years and have severe aortic stenosis, or cannot be operated on for aortic valve replacement with reasonable surgical risk or they may not even be considered for surgery at all.

It can be estimated that approximately 30 to 40 people out of a million per year could benefit from an implantable aortic valve placed using a catheterization technique. Until now, implantation of a valve prosthesis for the treatment of aortic stenosis has been considered unrealistic to perform since it is considered difficult to superimpose another valve, such as an implantable valve, on the deformed stenotic native valve without removing the latter.

Since 1985, the technique of aortic valvuloplasty with a balloon catheter has been introduced for the treatment of subjects in whom surgery cannot be performed at all, or in whom it could only be performed with prohibitive surgical risk. Despite the considerable deformation of the stenotic aortic valve, commonly with marked calcification, the aortic orifice can often be significantly dilated by balloon inflation, a procedure that is considered low-risk.

However, most clinicians have abandoned this technique due to the extremely high rate of restenosis, which occurs in approximately 80% of patients within 10 to 12 months. In fact, immediately after deflating the balloon, a strong recoil phenomenon often causes a loss of half or even two-thirds of the opening area obtained by the inflated balloon. For example, inflation of a 20 mm diameter balloon into a 0.5 cm stenotic aortic orifice² of area provides, when fully and vigorously inflated, an opening area equal to the cross-sectional area of ​​the balloon inflated to the maximum, i.e. approximately 3 cm². However, measurements made a few minutes after deflating and removing the balloon have only an area of ​​approximately 1 cm.² at 1.2 cm². This is due to the considerable receding of the fibrous tissue from the diseased valve. The drawbacks of this procedure have also been clearly demonstrated in fresh postmortem specimens.

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However, it is important to note that while the natural normal aortic valve is capable of opening with an orifice of approximately 5 to 6 cm² and to adapt to a blood flow of more than 15 l / min during intense exercise, for example, an opening area of ​​approximately 1.5 to 2 cm² can accept a blood flow of 6 to 8 L / min without a significant pressure gradient. Said flow corresponds to the cardiac output of the elderly subject with limited physical activity.

Therefore, an IV would not have to produce a large opening of the aortic orifice since an opening of approximately 2 cm² it would be sufficient in most subjects, particularly in elderly subjects, whose cardiac output probably does not reach more than 6 to 8 L / min during normal physical activity. For example, surgically implanted mechanical valves have an opening area that is far from the natural valve opening, ranging from 2 to 2.5 cm², mainly because of the space occupied by the large circular structure that supports the valve part of the device.

The prior art describes examples of heart valve prostheses that are intended to be implanted without surgical intervention by means of catheterization. For example, US Patent No. 5,411,552 describes a collapsible valve that can be inserted into the body in a compressed presentation and expanded into the correct position by inflation of a balloon.

Such valves, with a semilunar leaflet design, tend to mimic the natural valve. However, this type of design is inherently fragile, and these structures are not strong enough to be used in the case of aortic stenosis due to the strong recoil that would deform this weak structure, and because they would not be able to resist the inflation of the balloon made to place the implantable valve. Furthermore, this valve structure is attached to a metal frame of fine wires that could not be firmly fixed against the valve ring. The metal frame of this implantable valve is made of fine wires as in stents, which are implanted into the vessels after balloon dilation. Such a lightweight stent structure is too weak to allow the implantable valve to be energetically embedded in the aortic annulus. In addition, there is a high risk of massive regurgitation (during the diastolic phase) through the gaps between the frame wires, which is another prohibitive risk that would make this implantable valve impossible to use in clinical practice.

In addition, an important point of view in IV development is that the balloon within the compressed implantable valve can be fully inflated to expand and insert it into the stenotic aortic valve to approximately 20-23 mm in diameter. At the moment of maximum inflation of the balloon, the balloon is absolutely hard and cylindrical without any waist. At that time, the implantable valve narrows and collapses between the strong aortic annulus and the rigid balloon, risking irreversible damage to the valve structure of the implantable valve.

WO-A-93/01768 discloses an endovascular aortic valve replacement.

Summary of the invention

The invention aims to overcome these drawbacks and implant an IV that will continue to be reliable for years to come.

A particular objective of the present invention is to provide an IV, which is especially intended to be used in the case of aortic stenosis, whose structure is capable of resisting the powerful recoil force and withstanding the energetic inflation of the balloon carried out to deploy the IV and embed it in the aortic annulus.

Another objective of the present invention is to provide an effective prosthetic valve that can be implanted by a catheterization technique, in particular in a stenotic aortic orifice, taking advantage of the strong structure composed of the deformed stenotic valve and the large opening area produced by preliminary inflation. of the balloon performed as the initial stage of the procedure.

A further objective of the present invention is to provide an implantable valve that would not cause any risk of fluid regurgitation.

The IV, which is heavily embedded, allows the implantable valve to remain in the correct position without any risk of additional displacement, which would be a catastrophic event.

More specifically, this valve structure comprises a valve tissue compatible with the human body and blood, which is soft and resistant to allow said valve structure to pass from a closed state to an open state to allow a body fluid, more particularly blood. , which exerts pressure on said valve structure, flow. The valve tissue forms a continuous surface and can be provided with a guide means formed or incorporated therein, creating hardened areas that induce the valve structure to follow a patterned movement from its open position to its closed state and vice versa, thus providing therefore a sufficiently rigid structure to avoid a deviation, in particular in the left ventricle and, therefore, prevent any regurgitation of blood into the left ventricle in the case of an aortic implantation.

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Furthermore, the guided structure of the IV of the invention allows the tissue of this structure to open and close with the same prescribed movement and to occupy as little space as possible in the closed state of the valve. Therefore, thanks to these guide means, the valve structure withstands the incessant movements under the changes of blood pressure during the heartbeat.

As another advantageous example, the guide means of the valve structure are strips inclined from the base to the upper end of the valve structure with respect to the central axis of the valve structure. This inclination initiates and confers a general helical movement of the valve structure around said central axis at the time of closure or opening of said structure, allowing said movement to contribute to initiating and finalizing the closure of the valve structure. In particular, this movement improves the folding of the valve structure towards its base at the time of diastole and during the reversal of flow just at the beginning of diastole. During diastole, the valve structure therefore falls, bends over on itself, and folds over its base, thereby closing the aortic orifice. The strips can be pleats, reinforcing struts or thickened areas.

In other examples, said guide means are rectilinear strips from the base to the upper end of the valve structure. In this case, the guide means may comprise folds, struts or thickened areas. In a particular embodiment, the hardened areas created then can advantageously be two main parts, trapezoidal in shape, formed symmetrically to each other with respect to the central axis of the valve structure, and two less rigid parts separating said two main parts to lead to a narrow proximity in the form of a closed slot at the time of closure of the upper extremities of the main parts of the valve structure. The thickened areas can extend upward to form the hardened areas.

More particularly, each of said slightly rigid main parts occupies approximately one third of the circumference of the valve structure when the latter is in its open position. The slightly rigid parts keep the valve structure closed during diastole by pressing firmly against each other. The closure of the valve structure at the time of diastole therefore has no tendency to fold too far towards the aortic annulus.

Preferably, the guide means is a number of folds formed within the fabric by bending, or formed by gaps or slits generated in the fabric. The shape of the folds is adapted to achieve an overall shape of the type desired for said position.

Alternatively, the guide means are composed of reinforcing struts, preferably at least three, incorporated into the fabric in combination or not with said folds.

The guide means and, in particular, the reinforcing struts, help prevent the valve tissue from folding too far back and reversing into the left ventricle through the base of the frame, preventing the risk of blood regurgitation.

The prosthetic valve of the invention, said valve tissue is made of pericardium. This material is commonly used in cardiac surgery and is quite resistant, particularly to bending movements, due to the increasing systolo-diastolic movements of the valve tissue and, particularly, at the junction with the implantable valve frame.

The valve structure is held along a substantial portion of an expandable frame, by stitching it together, to show a sufficiently tight joint to prevent any regurgitation of said body fluid between the frame and the valve structure.

An inner cover is attached to the valve structure and positioned between said valve structure and the internal wall of the frame to prevent any passage of body fluid through said frame. Therefore, regurgitation of blood does not occur, as would be the case if there were any space between the valve structure attached to the framework and the site of application of the framework in the aortic annulus. The inner cover generates a kind of sleeve at least below the clamping of the valve structure that covers the inner surface of the frame and thus prevents any regurgitation of blood through the frame.

In the present invention, the frame is a substantially cylindrical structure capable of holding said open body conduit in its expanded state and of supporting said collapsible valve structure.

In accordance with the invention, the scaffold is made of metal that is distinguishable from biological tissue so that it is easily visible by non-invasive imaging techniques.

Preferably, said frame is a stainless metal structure, generated by crosslinking, preferably with rounded and smooth linear bars. This framework is strong enough to resist the recoil phenomenon of the fibrous tissue of the diseased valve. The size of the bars and their number are determined to give it both the maximum stiffness when said frame is expanded and the least volume when the frame is compressed.

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More preferably, the frame has projecting curved ends and is concave in shape. This is intended to reinforce embedding and immobilization of the implantable valve in the deformed aortic orifice.

In one example, the IV is manufactured in two parts, a first reinforced frame coupled with a second frame that is made of bars thinner than said first frame and which is embedded within the second frame. This second frame to which the valve structure is attached as described above, is preferably less bulky than the first frame to occupy as little space as possible and to be easily expanded using low pressure balloon inflation.

The present description also refers to a double balloon catheter for separately positioning the first frame in the dilated stenotic aortic valve and positioning the second frame comprising the valve structure. This catheter comprises two balloons fixed on a catheter shaft and separated by a few centimeters.

The first balloon is of the type strong enough to prevent it from exploding even at a very high inflation pressure and is intended to carry, in its deflated state, a strong frame that is intended to support the previously dilated stenotic aortic valve. The second balloon is intended to carry the second frame with the valve structure.

An advantage of this double balloon catheter is that each balloon has an outer diameter that is smaller than known balloons since each element to be expanded is smaller.

In addition, this double balloon catheter allows to expand the options of generating an effective valve structure that allows to overcome the following two contradictory conditions:

1) have a soft and mobile valve structure capable of opening and closing freely in the bloodstream, without risk of being damaged by balloon inflation; Y

2) require a very strong structure capable of resisting the recoil force of the stenotic valve and capable of withstanding, without damage, a strong inflation pressure of the expanded balloon.

Furthermore, the shaft of said double balloon catheter comprises two lumens for successive and separate inflation of each balloon. It should be noted that an additional light capable of allowing rapid inflation takes up additional space on the tree.

Description of the drawings

The invention will be explained below, and other advantages and characteristics will appear in relation to the accompanying schematic drawings, in which:

Figures 1a, 1b and 1c illustrate, in section views, respectively, the normal aortic valve in systole, in diastole and a stenotic aortic valve;

Figures 2a and 2b illustrate two examples of a metal frame that is combined with a valve structure according to the present invention;

Figures 3a and 3b illustrate a frame according to the invention in its expanded position with an opening towards the outside of the extremities, respectively, with a cylindrical and concave shape;

Figures 4a and b illustrate an IV, respectively, in its compressed position and in its expanded position in an open position as in systole;

Figures 5a and 5b respectively illustrate an IV in its closed position and a sectional view according to the central axis of such a valve structure which is closed as in diastole;

- Figures 6a to 6d illustrate a sectional view according to the central axis of an IV according to the present invention and showing the internal cover and the external cover of the valve structure, partially covering or not covering the bars of the frame ;

- Figure 7 illustrates the front zig-zag fastening line of the valve tissue in the frame;

Figures 8a and 8b illustrate, respectively, a perspective view of a valve structure and an internal cover all made in one piece, and a perspective view of the corresponding frame in which they will be inserted and fastened;

Figures 9a and 9b illustrate inclined reinforcing points, an example of a valve structure, respectively in the open position and in the closed position;

Figures 10a and 10b illustrate an example of a valve structure comprising pleats, respectively in the open and closed position;

Figures 11a and 11b illustrate a valve structure comprising two slightly rigid trapezoidal parts, respectively in the open and closed position;

Figures 11c to 11e illustrate a valve structure comprising a hardened rectangular area, respectively in the open, intermediate and closed position;

Figures 12a and 12b illustrate, respectively, perspective and cross-sectional views of an implantable valve in its constricted compressed presentation in a balloon catheter;

Figures 13a to 13l illustrate views of the successive procedural steps for IV implantation in a stenotic aortic orifice;

- Figure 14 illustrates an implantable valve made in two parts in its compressed presentation tapered in

ES 2 425 320 T3 a double balloon catheter with a reinforced frame in a first balloon and with the implantable valve in the second balloon; Y

Figures 15a to 15f illustrate the successive stages of implantation of the implantation valve in two parts with a two-balloon catheter;

Detailed description of the preferred embodiments

In the diastole and systole illustrations of the sectional views of Figures 1a and 1b, arrows A indicate the general direction of blood flow. The semilunar leaflets 1 and 2 of a native aortic valve (only two of the three are shown here) are thin, smooth, and easily move from the fully open position (systole) to the closed position (diastole). The leaflets originate from the aortic annulus 2a.

The 1 'and 2' leaflets of a stenotic valve as illustrated in Figure 1c, are thickened, deformed, calcified and more or less fused, leaving only a small hole or a narrow slit 3, which hinders and limits blood ejection from the left ventricular cavity 4 towards the aorta 5. Figures 1a to 1c also show the ostium of the coronary artery 6a and 6b and Figure 1a shows, in particular, the mitral valve 7 of the left ventricular cavity 4.

An implantable valve according to the invention essentially comprises a soft valve structure supported by a strong frame. The placement of the implantable valve is an important point since the expanded framework has to be positioned exactly at the level of the native valve leaflets 1, 2 of the native valve, whose structures are pushed aside by the inflated balloon.

Ideally, the implantable valve is positioned with the clamping line of the valve structure in the frame exactly over the remains of the crushed stenotic valve to avoid any regurgitation of blood. In practice, it is difficult to place the implantable valve in less than 2 or 3 mm. However, any risk of blood regurgitation is eliminated by the presence of an inner covering, as will be described below.

The upper limit of the framework should be positioned below the opening of the coronary arteries, that is, the coronary ostium 6, or at its level, so that the framework does not impede the free flow of blood in the coronary arteries. This point is a delicate part of placing an IV since the distance between the upper limit of the natural valve leaflets and the coronary ostium 6 is only approximately 5 to 6 mm. However, the ostia are located within the Valsalva 8, which constitutes a hole that is located a little out of the way. This helps prevent obstruction of coronary blood flow through the IV.

At the time of implantation, the surgeon evaluates the exact placement of the coronary ostium by looking at the image produced by a contrast-injection susvalvular angiogram performed prior to the implantation procedure. This image will be fixed in the same projection on a satellite TV screen and will allow evaluation of the level of the origin of the right and left coronary arteries. Possibly, in case the ostia are not clearly seen by susvalvular angiography, a fine guide wire, such as those used in coronary angioplasty, is placed in each of the coronary arteries to serve as a marker for the coronary ostia.

The lower part of the IV frame preferably extends 2 or 3 mm into the left ventricle 4, below the aortic annulus 2a. However, this part of the frame should not reach the insertion of the septal valve of the mitral valve 7, so that it does not interfere with its movements, particularly during diastole.

Figures 2a and 2b respectively show an example of a cylindrical frame 10 comprising intersecting linear bars 11, with two intersections I per bar 11, the bars 11 being welded or provided from a bent wire to constitute the frame, with, for example, a height of 20mm, 15mm or 12mm, and an example with only one intersection of bars 11. Preferably, said framework can expand from a size of approximately 4 to 5 millimeters to a size of approximately 20 to 25 mm in diameter, or even up to approximately 30-35 mm (or more) in particular cases, for example for the mitral valve. Furthermore, said frame, in its fully expanded state, has a height of approximately between 10 and 15 mm, and in its fully compressed state, a height of approximately 20 mm. The number and size of the rods is adapted to be strong and rigid enough when the framework is fully open in the aortic orifice to resist the strong recoil force exerted by the deformed stenotic aortic orifice after deflating the balloon used in the technique of catheterization, which has been previously inflated to the maximum to dilate the orifice of the stenotic valve;

The frame can have various configurations according to the number of bars 11 and intersections. This number, as well as the size and strength of the bars 11, are calculated taking into account all the described requirements, that is, a small size in its compressed form, its ability to increase in size to at least 20 mm in diameter and be strong when placed in the aortic orifice to be able to energetically embed itself in the remnants of the diseased aortic valve and resist the recoil force of the aortic annulus. The diameter of the bars is selected, for example, in the range 0.1-0.6 mm.

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A particularly advantageous frame has, when deployed in its expanded state, an outward opening 12 at both ends, as shown in Figures 3a and 3b, the frame having a linear profile (Figure 3a) or a concave shaped profile ( Figure 3b). This is intended to reinforce the embedding of the IV in the aortic orifice. However, the free ends of the openings 12 are rounded and very smooth to avoid any trauma to the aorta or myocardium.

The preferred frame structure used in the present invention both keeps the aortic orifice fully open once dilated and provides support for the valve structure. The frame can also be bent. When bent by compression, the diameter of said frame is approximately 4 to 5 millimeters, in view of its transcutaneous introduction into the femoral artery through a 14 to 16 gauge arterial sheath (F stands for French, a unit used usually in the field of cardiology) that is, approximately 4.5 to 5.1 mm. In addition, as described below, when placed in the aortic orifice, the framework is capable of expanding with the force of an inflated balloon to a size of 20 to 23 mm in diameter.

The frame is a metal frame, preferably made of steel. It constitutes a framework with a grill-like design capable of supporting the valve structure and behaving as a strong support for the open stenotic aortic orifice.

When the framework is fully expanded, its criss-cross bars press against the remnants of the native stenotic valve that has been crushed to one side against the aortic annulus by the inflated balloon. This produces a penetration and embeds the rods within the remains of the stenotic valve, in particular thanks to a concave profile of the frame provided with an outward opening, as illustrated in Figure 3b. This embedding of the framework in the aortic annulus or, more specifically, in the remains of the crushed deformed aortic valve, will be decisive for the strong fixation of the IV in the correct position, without any risk of displacement.

Furthermore, the fact that the valve leaflets in degenerative aortic stenosis are highly deformed and calcified, sometimes leaving only a small hole or a narrow slit in the middle of the hole, has to be considered an advantage for valve implantation and for its stable placement without risks of subsequent mobilization. The fibrous and calcified structure of the deformed valve provides a strong foundation for the IV frame, and the powerful recoil phenomenon that occurs as a result of tissue elasticity contributes to the fixation of the metal frame.

The height of the fully expanded frame of the illustrated frames 10 is preferably between 10 and 15 mm. In fact, since the transition from the compressed state to the expanded state results in a shortening of the metallic structure, the structure in its compressed form is slightly longer, that is, preferably about 20 mm in length. This does not constitute a disadvantage for its transcutaneous introduction and its placement in the aortic orifice.

As mentioned above, the frame is strong enough to be able to oppose the powerful recoil force of the distended valve and the aortic annulus 2a. Preferably, it does not possess any flexible properties. When the frame has reached its maximum expanded shape with the thrust of a vigorously inflated balloon, it remains substantially without any decrease in size and without any change in shape. The size of the bars, which are the basic elements of the frame, are calculated to provide substantial stiffness when the frame is fully expanded. The size of the bars and their number are calculated to give both the maximum stiffness when expanded and the least volume when the metal frame is in its compressed position.

At the time of generating the IV, the framework is expanded by dilation to its widest dimension, that is, between 20 mm and 25 mm in diameter, to be able to hold the valve structure on the inner side of its surface. This clamping is done using the techniques currently in use for the generation of products such as other prosthetic heart valves or multipolar catheters, etc. It is then compressed to its minimum size, that is, 4 or 5 mm in diameter in view of its introduction into the femoral artery. At the time of IV placement, the scaffold is again expanded by inflation of the balloon to its maximum size in the aortic orifice.

If the frame is constructed in an expanded position, it will compress, after clamping the valve structure, exerting a circular force on its periphery and / or on its total height until the smallest compressed position is obtained. If the frame is constructed in its compressed position, it will first expand, for example, by inflation of a balloon, and then it will be compressed again as described above.

To help locate the IV, with the frame being the only visible component of the valve, the shaft of the balloon catheter on which the IV will be mounted prior to insertion into the body (see below) preferably has easily referenced metal markings observable on fluoroscopy. One mark will be at the level of the upper edge of the frame and the other at the level of the lower edge. The IV, when mounted on and crimped onto the catheter shaft, is positioned exactly with these reference marks on the shaft in mind.

Consequently, the frame is visible during fluoroscopy when it is inserted into the patient's body. When the framework is positioned at the level of the aortic annulus, the upper edge of the framework is positioned below the

ES 2 425 320 T3 coronary ostium. Furthermore, the implantation procedure during which the balloon inflation completely obstructs the aortic orifice, as can be seen below, is performed in a very short time, that is, approximately 10 to 15 seconds. This also explains why the frame is clearly and easily seen, without wasting time locating it. More particularly, its upper and lower edges are clearly delineated.

Figures 4a and 4b show an example of an IV 13, respectively in its compressed position, in view of its introduction and placement in the aortic orifice, and in its expanded and open position (systole). Figures 5a and 5b show the expanded position of this example closed in diastole, respectively, in perspective and in cross-sectional view along the central axis X'X of the valve prosthesis.

Valve structure 14 is compressed within frame 10 when in its compressed position (Figure 4a), that is, it fits into a 4 to 5 mm diameter space. On the other hand, the valve structure can expand (Figure 4b) and follow the expansion of the framework produced by the inflated balloon. You will need to be able to reach the size of the inside of the fully deployed frame.

The illustrated IV 13 is made of a combination of two main parts:

1) the expandable but substantially rigid structure of frame 10, a metal frame in the example; Y

2) a soft and mobile tissue that constitutes the valve structure 14, which has a continuous truncated surface between a base 15 and an upper extremity 16; the tissue is attached to the bars 11 of the frame at its base 15 and is capable of opening in systole and closing in diastole at its extremity 16, as blood flows in a pulsatile manner from the left ventricle to the aorta.

The fabric has rectilinear struts 17 incorporated therein in a plane that includes the central axis X'X, to reinforce it, in particular, in its closed state, with minimal occupation of space, and to induce a patterned movement between its open state and closed. Other examples of reinforcement struts are described below. They are formed from thicker areas of the fabric or from strips of hardening material incorporated into the fabric; they can also be glued or welded to the valve tissue.

These reinforcement struts help prevent the valve tissue from folding too far back into the left ventricle through the base of the frame. These reinforcements of the valve tissue help to keep the tissue folded above the level of the orifice during diastole, preventing it from bending too far back and the risk of reversal of the valve structure inside the left ventricle. By also preventing it from bending too much, a decrease in the risk of thrombus formation can also be expected by reducing the number of folds.

The truncated shape that forms a continuous surface allows to obtain a strong structure and is more effective for the systolo-diastolic movements of the valve tissue during the heartbeat. The truncoid shape facilitates the closure of the valve structure at the beginning of diastole by facilitating the initiation of the reverse movement of the valve tissue towards its base at the time of diastole, that is, at the time of reversal of flow just at the beginning of diastole. During diastole, the valve structure 14 therefore falls, folding back on itself, thus folding over its base, and thus closing the aortic orifice. In fact, the valve structure preferably has, as illustrated, a hyperboloid shape, with a curvature on its concave surface towards the aortic wall that will help initiate its closure.

Furthermore, the base of the truncated hyperboloid is fixed to the bottom of a frame and the smaller end of the truncated hyperboloid is free in the bloodstream, during the respective opening and closing phases.

An important advantage of this hyperboloid shape is that the upper extremity 16 of the valve structure 14 can remain at a distance from the coronary ostium during systole, as well as during diastole, due to its smaller diameter, thus offering additional safety for make sure that blood flow from the aorta to the coronary ostium is not obstructed.

The base 15 of the truncated fabric is attached to the frame 10 along a mating line 18 arranged between the lower quarter and the third quarter of the frame in the example. The upper end 16, with the smallest diameter, passes over the top of the frame by a few millimeters; 6 to 8 mm, for example. This gives the valve structure a total height of approximately 12 to 15 mm.

The upper extremity 16 of the truncated tissue, that is, the smallest diameter of the hyperboloid structure 14, is approximately 17 to 18 mm in diameter (producing an opening of an area of ​​2.3 to 2.5 cm²) for a 20 mm diameter base of the truncated structure, or 19 to 20 mm diameter (producing an opening of an area of ​​2.8 or 3 cm²) for a 23 mm diameter base. An opening area of ​​about 2 cm², or slightly higher, provides satisfactory results, particularly in elderly patients who would not reasonably require a high cardiac output.

For example, in the present example, the fastening line of the base of the truncated tissue in the framework will have to expand from a perimeter of 12.5 mm (for a 4 mm external diameter of the compressed IV) to a perimeter of

ES 2 425 320 T3 mm (for an external diameter of 20 mm of the expanded IV), or to a perimeter of 72 mm (for an external diameter of 23 mm, in case a 23 mm balloon is used).

Another advantage of this truncated continuous shape is that it is stronger and has less risk of being destroyed or deformed by the forceful inflation of the balloon at the time of deployment of the IV. Furthermore, if the truncated hyperboloid shape is pronounced, for example, with a diameter of 16 or 17 mm for the upper extremity compared to a diameter of 20 mm for the base (or 18 to 20 mm for 23 mm), the part Smaller top conforms during balloon inflation to allow the balloon to expand cylindrically to its maximum diameter of 20mm (or 23mm). This is made possible by using a material with certain elastic or compliance properties.

The valve structure of the invention, as shown in the illustrated example, advantageously includes a third part, that is, the inner cover 19 that will be fixed to the inner wall of the frame 10. This internal covering prevents any passage of blood through the spaces between the bars 11 of the frame in case the implantable valve is placed with the clamping line of the valve structure in the frame not exactly on the remains of the dilated aortic valve. , that is, above or below. It also reinforces the attachment of the valve structure 14 to the frame 10.

In the different sectional views of the different examples of IV, as illustrated in Figures 6a to 6c, the inner cover 19 covers the entire internal side of the frame 10 (Figure 6a), according to the invention only the lower part of the framework 10 (Figure 6b), or it may also partially cover 3 to 5 mm, as shown in Figure 6c of the passage of blood from the aorta to the coronary ostium, the upper part defined above the coupling line 18 of the valve structure.

For example, said extension of the inner cover 19 above the clamping line 18 of the valve structure will provide another security to avoid any risk of regurgitation through the spaces between the bars 11 in case the IV is placed too low. relative to the border of the native aortic valve.

As an example, the inner cover can also be molded to or fused to the valve structure, thereby constituting an integral structure. The valve structure and the inner covering are therefore strongly immobilized to each other with minimal risk of detachment of the valve structure, which is incessantly in motion during systole and diastole. In that case, only the inner cover has to be clamped on the inner surface of the frame, which makes the IV easier to manufacture and makes the entire device stronger and more resistant. In particular, the union of the mobile part of the valve structure and the fixed part that is molded as one piece is stronger and capable of coping with the incessant movements during systolo-diastolic movements without any risk of detachment.

The presence of the inner cover creates an additional layer of plastic material that occupies the interior of the frame and increases the final size of the IV. Therefore, in the case where the inner cover is limited to the bottom of the frame (that is, below the clamping line of the valve structure), it does not occupy any additional space within the frame. Here also it is more convenient and safer to manufacture the valve structure and this limited inner cover in one piece.

In other aspects, to prevent any regurgitation of blood from the aorta into the left ventricle during diastole, the base of the valve structure is preferably positioned exactly at the level of the aortic annulus against the debris of the deformed stenotic valve pushed aside by the inflated balloon. Therefore, there is no possibility of blood passing through the spaces between the bars of the metal frame 11 below the junction of the valve structure.

However, to avoid any risk of leakage, the part of the frame below the valve structure support (approximately 3 to 5 mm) is covered by an internal cover that is made of the same fabric as the valve structure. Therefore, there would be no regurgitation of blood, which is a possibility when there is any gap between the valvular structure clamped in the metal framework and the line of application of the framework in the aortic annulus. The internal cover generates a kind of jacket below the fastening of the valve structure on the internal surface of the frame, covering the spaces between the bars of the frame at this level, thus preventing any regurgitation of blood through these spaces.

The inner cover can also have another function, that is, it can be used to hold the valve structure within the frame, as described below.

In Figure 6d, the inner cover 19 extends at its lower end 19 'towards an outer cover 19 which is rolled to engage the outer wall of the stent 10. The inner and outer covers are molded, glued or welded to the stent rods 10.

The procedure of coupling the valve structure to the frame is important since it has to be very strong without any risk of detachment of the valve structure from the frame during millions of heartbeats with pulsatile blood flow, alternately opening and closing the valve structure.

ES 2 425 320 T3

The valve structure of the invention bends to a very small size within the frame in the compressed position of the valve and can expand to a diameter of 20 to 23 mm. Furthermore, the valve structure can withstand the intense force exerted by the fully inflated balloon, which will forcefully press it against the frame bars or against the inner cover, the latter tapering directly against the frame bars. The joint area is also particularly subjected to a very intense pressure exerted by the inflated balloon. In addition, this joint area must not tear or split during expansion of the balloon. At this time, each part of the joint zone is narrowed against the bars but nevertheless follows the expansion of the framework.

As shown in Figure 7, the joint area is a clamping line 20 that follows the pattern of a zig-zag line drawn by the criss-cross bars 11 of the frame on the inner cover 19.

The fastening of the valve structure to the frame is done by sewing the inner cover and eventually the outer cover to the bars. To prevent any leakage of blood, the stitches are preferably numerous and closely spaced, as separate stitches or as a continuous suture line. Also, the points are made directly around the 11 bars. Furthermore, since the valve structure expands together with the metal frame, the stitches, if manufactured as a continuous suture line, are also capable of expanding at the same time.

According to one example, the fastening procedure can be carried out by molding the base of the valve structure onto the frame. At this level, the bars 11 are embedded in the coupling line of the valve structure 14. This form of mold also concerns the inner cover 19, when it goes below the coupling line 14 in the frame along a few millimeters, for example 2 to 4 mm. As mentioned above, this is intended to prevent any regurgitation of blood just below the bottom of the valve structure 14 in the event that the frame 10 is not positioned exactly on the aortic annulus but within a few millimeters of it. .

The exemplary clamping procedure can further be carried out by gluing or welding the valve structure onto the bars with sufficiently strong biocompatible adhesives. The same observation can be made in relation to the inner shell of the frame below the coupling line of the valve structure.

Furthermore, this allows the coupling line to follow the changes of the frame from the compressed to the expanded position.

The valve structure can also be attached to the internal cover previously attached to the full length of the internal surface of the metal frame. The inner cover therefore constitutes a surface onto which any type of valve structure can be more easily sewn, molded or glued. Because it is a large-surface structure and is not involved in valve tissue movements during systole and diastole, the inner covering more easily attaches to the inner surface of the frame.

In the particular embodiment shown in Figure 8, the inner cover 19 is fastened, after insertion (indicated by arrow B), to the upper and lower extremities of the frame 10 in the upper and lower zig-zag lines of the crisscross bars 11. In fact, the clamping of the inner cover 19 in the zig-zag lines generated by the criss-cross bars 11 of the frame allows easier passage of blood from the aorta above the IV to the coronary ostium. In fact, blood can find more room to flow to the coronary ostium by passing through the lowest point of each triangular space generated by two intersecting bars 11, as indicated by arrows A1 (see also Figure 1b).

The grip of the inner cover 19 at the extremities can be reinforced by various attachment points at various parts of the inner surface of the frame 10. The inner cover 27 is secured by sewing the bars 11 onto the frame.

Clamping the valve tissue (and the cover tissue underneath) within the frame requires working on the frame in its expanded position to gain access to the interior of this cylindrical frame. In a preferred embodiment, the framework is expanded a first time to hold the valve tissue in its rods, then again compressed to a smaller size so that it can be inserted through an arterial introducer and finally expanded again by inflating the valve. balloon.

Since it is intended to be placed in the heart after it has been introduced by a transcutaneous catheterization technique into a peripheral artery, primarily the femoral artery, the IV should preferably have the smallest external diameter possible. Ideally, it should be able to be introduced into the femoral artery through a 14 F (4.5 mm) size arterial introducer, which is the size of the arterial introducer commonly used to perform aortic dilation. However, a 16 F (5.1 mm) or even 18 F (5.7 mm) introducer would also be acceptable.

Above this size, the introduction of the IV into the femoral artery should probably be performed by surgical technique. Still this is quite acceptable as the surgical procedure would be a very mild procedure that could be performed by a surgeon with simple local anesthesia. It has to be remembered that this technique is used to place large metal frames, approximately 24 ° F

ES 2 425 320 T3 size (7.64 mm diameter), in the abdominal aorta for the treatment of abdominal aortic aneurysms. In this situation, surgical repair of the artery is required after removal of the sheath (MD Dake, New Engl. J Med. 1994; 331: 1729-34).

Ideally, an IV should be able to last several dozen years of life without defects, like the mechanical prosthetic valves currently implanted by surgeons. However, an implantable valve that lasted at least ten years without risk of deterioration would be effective for the treatment of elderly patients.

A valve structure according to the invention is made of a soft, reinforced fabric having a thickness that is thin enough to occupy as little space as possible in the compressed form of the valve, it is collapsible, and also strong enough to withstand the incessant movements with the changes of blood pressure during the heartbeat. The valve structure is capable of moving from its closed position to its open position under the action of the force exerted by the movements of the blood during systole and diastole, without having any significant resistance to blood displacements.

As an example, the material used for the tissue, which has the requirements mentioned above, can be Teflon® or Dacron®, which are quite resistant to bending movements, at least when they are used to repair heart defects such as interatrial or ventricular defects. , or when used to repair a valve such as the mitral valve, which is subjected to high pressure changes and movements during the heartbeat. In addition, a main point is the incessant systolo-diastolic movements of the valve tissue, particularly in its union with the rigid part of the IV, and therefore it is necessary to find the tissue of a material that is as resistant as possible.

As mentioned above, the valve structure is made of biological tissue, specifically the pericardium, which is commonly used in surgically implanted bioprosthetic valves.

Furthermore, the valve prosthesis of the present invention does not induce any significant thrombosis phenomena during its stay in the bloodstream and is biologically neutral.

To prevent the risk of thrombus formation and emboli caused by clots, a substance with antithrombotic properties, such as heparin, ticlopidine, phosphorylcholine, etc., could be used. as a lining material, or it can be incorporated into the material used for the implantable valve, in particular, for the valve structure and / or for the internal cover.

The valve structure of the invention can have various types of designs and shapes. Apart from the example illustrated in Figures 4 and 5, examples of reinforced valve structures are shown in Figures 9 to 11, respectively in the closed state (Figures 9a, 10a, 11a) and open (Figures 9b, 10b, 11b) to form a prosthetic valve. In those figures, the frame line is simplified to clarify the drawings.

To help initiate and finalize the closure of the valve structure, four reinforcement struts 14 are slightly inclined from the base to the top compared to the central axis X'X of the structure, as shown in Figures 9a and 9b. . Consequently, a patterned movement of the valve structure is initiated during the closing and opening phases. This patterned movement is, in the present case, a helical type, as suggested in Figures 9b and 10b by the circular arrow.

Figures 10a and 10b illustrate another example to aid in the closure of the valve structure, and which also involves a helical movement. Represented by lines 22, inclined folds are formed in the fabric to impart said movement. As illustrated, these lines slope from the base to the top of the fabric 14. The pleats are formed by folding the fabric or alternating thinner and thicker portions. The width and number of these folds are variable, and depend particularly on the type of material used. According to another example, these pleats 34 are combined with the inclined reinforcing struts described above.

These rectilinear or inclined reinforcing folds and / or struts have the advantage of conferring reproducible movement and, consequently, preventing the valve structure from closing into an unstructured fold on the base of the frame.

Another shape of the valve structure comprises two parts: a part that is flexible but with some rigidity, that has a rectangular shape, occupying approximately one third of the circumference of the valve structure, and the other part that is softer, more flexible and capable of bending occupying the rest of the circumference at its base, as well as at its upper free edge. According to Figure 11c, this valve opens during blood ejection, that is, during systole. In Figure 11d, a front view of the valve is closed during intermediate diastole, and in Figure 11e the same valve closed during diastole is shown from a side view. The semi-rigid part 24 'barely moves during systole and diastole. The bending part 23 'is moved away from the rigid part during systole to allow blood to flow through the hole thus generated. This hole, due to the diameter of the top, which is the same as that of the open stent, is large, generally as large as that of the open stent. At the time of diastole, due to the reversal of pressure, the part capable of bending moves back towards the semi-rigid part and presses on it, thus closing the hole and preventing any regurgitation of blood.

ES 2 425 320 T3

The advantage of such a valve design is to allow a large opening of the upper part of the valve structure, not only to allow more blood flow at the time of systole after the valve has been implanted, but also at the same time of the valve. implantation, when the balloon is fully inflated to expand the valve to embed it in the valve annulus. The diameter of the upper part of the valve structure could be the same size as that of the balloon, so that there would be no distention of the valve part of the valve at the time of implantation, and therefore no risk of deterioration of the valve. the valve structure by the inflated balloon.

The bendable part of the valve could be reinforced with bracing struts to prevent eversion of the valve into the left ventricle during diastole.

Another form of the valve structure, as illustrated in Figures 11a and 11b comprises four parts, alternatively a main part 23 and a narrower part 24. The main and narrow parts face each other. Each part has an isosceles trapezoidal shape. The main parts 23 are flexible but with some slight stiffness, and the narrower parts 24 are compliant, softer and capable of bending. In this type of design, the two slightly rigid parts 23 keep the valve structure closed during diastole by firmly engaging one another at its upper extremities, thereby forming a slot-type closure 25. This particular example requires less capable tissue of bending than in previous examples, and the closure of the valve structure at the time of early diastole has no tendency to fold towards the aortic annulus.

Another design for the valve structure is a combination of a cylindrical shape, followed by a truncated shape.

This type of valve structure is longer than the hyperboloid type, for example, 25 or 30 mm long, thus exceeding the upper part of the metal frame, by 10 to 20 mm. The cylindrical part corresponds to the metal frame and remains inside it. The truncated conical shape is the upper part of the valve structure, which completely surpasses the upper extremity of the metal frame. An advantage of such a design is that the balloon can be inflated only in the cylindrical part of the valve structure, therefore without the risk of stretching the truncated conical part of the upper diameter that is smaller than that of the inflated balloon.

When the upper end of the cylindrical part is the same size as the lower end, there is no difference during balloon inflation in the degree of force exerted by the balloon on the lower and upper end of the valve structure. Preferably, rectilinear bracing struts are used in this example to reinforce the valve structure and aid in its closure without folding and inverting within the left ventricle through the aortic annulus under the force of diastolic pressure.

Two different procedures for implanting a valve according to the present invention are respectively shown in Figures 13a to 13l with a single balloon catheter, as illustrated in Figures 12a and 12b and in Figures 15a to 15f, with a balloon catheter. two balls, as illustrated in Figure 14.

The placement of the IV in the aortic orifice and its expansion can be performed with the aid of a substantially cylindrical single balloon catheter 26 in the so-called single balloon catheterization technique.

In preparation for transcutaneous introduction into the femoral artery, IV 13 is, as illustrated in the perspective view of Figure 10a, in a compressed form crimped into balloon catheter 26. A central sectional view of the IV 13 mounted on complete balloon catheter 26 is shown in Figure 12b.

The shaft 27f of the balloon dilatation catheter 26 is as small as possible, that is, 7 F (2.2 mm) or 6 F (1.9 mm) in size. Balloon 26 is mounted on shaft 27 between two R rings. In addition, shaft 27 comprises a lumen 28 (Figure 12b) as large as possible for inflation of balloon 26 with diluted contrast to allow for simple inflation and deflation. fast. It also has another lumen 29 capable of accepting a hard guidewire 30, eg, 0.036 to 0.038 inches (0.97 mm), to aid in accurate implantable valve placement.

The balloon 26 has, for example, a length of 3 to 4 cm in its cylindrical part and the smallest possible size when completely deflated, so that it can be placed inside the folded valve that has an external diameter that varies between about 4 and 5 mm. Therefore, the folded balloon preferably has at most a section diameter of about 2.5 to 3 mm.

Therefore, the ball is made of a very fine plastic material. It is inflated with saline solution that contains a small amount of contrast dye so that it remains very fluid and visible when using X-rays.

However, balloon 26 has to be strong enough to withstand the high pressure it has to withstand in order to expand the folded valve structure 14 and the frame compressed in the stenotic aortic orifice considering that, although predilated, the aortic orifice still exerts a resistance quite strong to expansion due to the phenomenon of recoil.

This procedure is shown in Figures 13a through 13e.

Contrary to the technique used when performing the usual aortic dilation (without valve implantation), it is

ES 2 425 320 T3 that is, by inflating the balloon to the maximum, notably above the nominal pressure, if possible, to the point of bursting (which always occurs with a longitudinal tear, without harmful consequences, and with the advantage of both exerting a maximum dilation force such as to restore blood ejection instantaneously), the balloon inflated for the expansion of an implantable valve should not explode in any case. If manufactured, the bursting of the balloon would imply a risk of incomplete expansion of the valve and incorrect positioning. Therefore, the balloon should be very resistant to very high pressure inflation. Furthermore, the balloon is inflated only to the nominal pressure indicated by the marker, and the pressure is controlled during inflation using a manometer. Such relatively low pressure should be sufficient since prior to IV placement, effective dilation of the stenotic aortic valve is performed according to standard technique with a maximally inflated balloon, for example 20mm or 25mm in size, so that the deformed valve tissue is softened and facilitates the enlargement of the valve opening at the time of IV implantation.

The implantation of the aortic valve 20 can be performed in two stages, as described below.

The first stage, as shown in Figures 13a to 13f, consists of introducing the shaft 27 and the balloon catheter 26 along the guidewire previously placed in the ventricle 4 (Figures 13a-13b). Dilation of the stenotic aortic valve 1 ', 2' using a normal balloon catheter, according to the commonly performed procedure, that is, with guide wire 30 inserted into ventricle 4 (Figure 13a) and with maximum inflation of balloon 26 (Figures 13c to 13d) to the point of bursting. Dilation is done with at least a balloon that is about 20mm in diameter, but can be done with a balloon that is about 23mm in diameter to maximize the opening of the aortic orifice prior to valve implantation, though the implantable valve is approximately 20 mm in diameter. This preliminary dilation of the aortic orifice helps to limit the force required to inflate the balloon used to expand the implantable valve and place it in the aortic orifice, and also to limit the recoil of the aortic valve that occurs immediately after deflating the balloon. The balloon is deflated (Figure 13a) and is withdrawn over guidewire 30 left within the ventricle.

Due to the remarkable recoil of the stenotic valve and also the strong aortic annulus, the 20 mm diameter valve is vigorously held against valve debris at the level of the aortic annulus. Preliminary dilation has another advantage in that it allows easier expansion of the IV, having a lower pressure balloon inflation that helps prevent damage to the valve structure of the IV. This also facilitates the precise placement of the prosthetic valve.

The second stage corresponds to the implantation of valve 13 and is shown in Figures 13g to 13l. The placement of the IV must have an accuracy of almost 2 or 3 mm, since the coronary ostium 6 must remain absolutely free of any obstruction by the valve 13 (Figures 13k and 13l). As mentioned above, this is done, for example, with the aid of the sus-valvular angiogram image in the same projection fixed on an adjacent TV screen. The expansion and placement of the valve prosthesis 13 takes place in a few seconds (from 15 to 20 at most) since during maximum balloon inflation (which has to be held for only a few seconds, 3, 4, 5) the orifice the aortic is obstructed by the inflated balloon 31 and the cardiac output is zero (Figure 13h). As for the act of predilatation itself, the balloon 26 immediately deflates in less than 5 or 6 seconds (Figure 13j) and, as soon as it has clearly begun to deflate, the closing and opening states of the IV are active while the balloon is rapidly withdrawn from the aorta (Figures 13j to 13l). In case the IV does not expand to the maximum by the first inflation, it is possible to replace the balloon inside the IV and to inflate it again to reinforce the expansion of the IV.

IV 13 can also be used in aortic regurgitation. This affects younger patients more often than those with aortic stenosis. The contraindication of surgical valve replacement is often not due to the advanced age of the patients, but is mainly due to particular cases in which the general condition of the patient is too weak to allow surgery, or due to associated pathological conditions. . Apart from the fact that there is no need for preliminary dilation, the procedure for implantation of the valve remains approximately the same. Balloon inflation within the IV is selected accordingly, also taking into account the fact that it is necessary to over-dilate the aortic annulus to obtain an annulus recoil phenomenon after deflating the balloon to help maintain the IV in position without no risk of displacement.

However, the size of the expanded implantable valve is approximately 25 to 30 mm in diameter, or even larger, because the aortic annulus is usually enlarged. A preliminary measurement of the annulus will need to be performed on susvalvular angiography and echocardiography to determine the optimal size to choose.

The IV can be used in the mitral position, mainly in the case of mitral regurgitation, but also in the case of mitral stenosis. Here again, the IV 20 is described only when used only in cases of contraindication to surgical valve repair or replacement. The procedure is based on the same general principles although the route for valve placement is different, using the transseptal route, such as the mitral dilatation procedure commonly performed in mitral stenosis. The size of the IV is significantly larger than for the aortic location (approximately 30 to 35 mm in diameter when expanded or

ES 2 425 320 T3 clearly above in the case of a large mitral annulus (which is frequently the case in mitral regurgitation), to be able to occupy the mitral area. A preliminary measurement of the mitral annulus is performed to determine the optimal implantable valve size to select. Since the introduction of the IV is done through a venous line, almost always through a femoral line that is quite large and compliant, the larger size of the IV in its compressed position is not an inconvenience even if the size of the IV diameter is approximately 6 or 7 mm. Furthermore, the problem of protecting the coronary ostium found in the aortic position does not exist here, thus making the procedure easier to perform.

Finally, IV can be used to replace the tricuspid valve in patients with tricuspid regurgitation. This procedure is simple to perform since the IV is placed through the venous route, using the shortest way to place it in the correct position at the level of the tricuspid orifice, with practically no danger of clot migration during the procedure. . A large implantable valve is used, with a diameter of approximately 40 mm or even larger as the tricuspid annulus is often markedly dilated in tricuspid regurgitation. Also here, as in the mitral position, the compressed IV and the catheter used can be without inconvenience much larger than for the aortic position due to the venous line used.

Furthermore, it has to be noted that IV can also be used as a first stage in the treatment of patients who are contraindicated for surgery when they are first examined, but who might improve later after correction of the initial hemodynamic insufficiency. The IV procedure can be used as a bridge to surgery for patients in a weak general condition who are expected to improve in the weeks or months following the IV procedure so that they can be treated later by open heart surgery. In the same vein, the IV procedure can be used as a bridge to surgical valve replacement or repair in patients with profoundly impaired cardiac function that may be secondarily improved by hemodynamic improvement resulting from correction of the initial valve disease by implantation of IV.

Another technique for transcutaneous catheterization of an aortic valve uses a two-balloon catheter.

An example of this technique using the two-part IV with a two-balloon catheter 40 is shown in Figure 14.

Two balloons 26 and 26 'are attached to a single catheter shaft 27, said balloons being separated by a few millimeters. The two balloons are preferably short, that is, approximately 2 to 2.5 cm long in their cylindrical part. The first balloon 26 to be used carries a first frame 10 that is intended to support the stenotic aortic orifice after initial dilation. This first balloon 26 is placed on the side of the aorta, above the second balloon 26 'that is placed on the side of the left ventricle. The second balloon 26 'carries the expandable valve 13, which is of the type described above composed of a second frame 10' and a valve structure 14 attached to said frame 10 '. The difference is that the second frame does not have to be as strong as the first frame and is easier to expand with a low pressure balloon inflation that does not present the risk of damaging the valve structure 14.

This increases the options of fabricating a valve structure without having to face two contradictory conditions:

1) have a soft and mobile valve structure 14 capable of opening and closing freely in the bloodstream, without risk of being damaged by the inflation of a balloon; Y

2) require a reinforced frame strong enough to be able to withstand without damage a strong inflation pressure of the expanded balloon.

The shaft 27 of this two successive balloon catheter 40 comprises two lumens for the successive and separate inflation of each balloon. Out of the box, an additional light capable of allowing rapid inflation takes up space on the axle and therefore an increase in the size of the tree is necessary. However, this increase in the size of the shaft stops at the level of the first balloon 26 since, in addition to said first balloon, only one light is necessary to inflate the second balloon 26 ', at the level of the IV, which is the largest part. device size.

Another advantage of this two-part IV with a two-balloon catheter is that each implantable valve and balloon assembly has a smaller outer diameter, since each element to be expanded, considered separately, is smaller than in combination. This makes it easier to obtain an end device with an outer diameter of 14 F.

The first balloon is strong enough to avoid bursting even at very high pressure inflation. This first balloon is mounted on the frame in its deflated position prior to its introduction by the strong frame, which is intended to support the dilated stenotic aortic valve. The size and shape of said frame are comparable to those described above, but said frame is calculated (in particular the material, the number and the diameter of its bars are selected by the person skilled in the art) to ensure that resist recoil of the dilated valve and become firmly embedded in the remnants of the native aortic valve.

The second ball does not have to be as strong as the first and can therefore be finer, taking up less

ES 2 425 320 T3 space and being easier to expand with lower balloon inflation pressure. This second balloon 26 'is mounted on the valve itself which, as in the previous description, comprises a frame to support the valve structure, and said valve structure.

Furthermore, the second frame 10 'does not have to be as strong as the first. This frame can be slightly shorter, 10mm instead of 12mm, and its bars can be thinner. This frame may have an outer surface that is slightly rough to allow better fixation on the first frame when expanded. The bars may also have some hooks to attach to the first frame.

The valve structure is attached in said second frame and is expanded by relatively low pressure in the second balloon, hereinafter referred to as the IV balloon. It does not have to be as strong as in the previous case (one-part IV technique and single balloon catheter) and therefore takes up less space and has less risk of damage at the time of expansion.

This technique is shown in Figures 15a to 15f.

One of the relevant problems for the IV implantation procedure as described above, with the IV in one part, is the expansion at the same time by inflating the same balloon of both the framework and the valve structure. In fact, the frame is a solid element and the valve structure is a relatively weak one that could be damaged by being constricted by the inflated balloon.

Therefore, the implantation of the valve can be carried out in two immediately successive stages. The first stage (Figures 15a-15b) corresponds to the expansion and placement of the first frame with the first balloon 26, in which the inflation is carried out at high pressure. The second stage (Figures 15d-15e) corresponds to the expansion and placement of the valve structure 14 within the frame 10 'using the second balloon 26'. This second stage follows the first in the interval of a few seconds because, in the interval of time between the two stages, there is a total aortic regurgitation into the left ventricle, which is a hemodynamic condition that cannot be maintained for more than a few heartbeat, that is, a few seconds, without inducing massive pulmonary edema and a drop to zero in cardiac output.

In another example, the first frame to be inserted comprises the valve structure, the second frame being stronger than the first to support the previously removed stenotic aortic valve.

The advantage of this two-stage procedure would be to allow the expansion and placement of the frame part 10 'of the IV 13 using a strong inflation pressure of the balloon 26' without the risk of damaging the valve structure 14 which, for its own expansion , would require only a light pressure inflation.

The procedure is schematically detailed in Figures 15a to 15f. Pre-dilation of the stenotic aortic valve is performed as an initial step in the procedure to prepare the deformed valve to facilitate the following steps:

1 / placement of the double balloon catheter 40 with the first balloon 26 with the frame at the level of the aortic ring 2a, the second IV balloon 26 'being inside the left ventricle beyond the aortic ring 2a (Figure 15a);

2 / compression of the stenotic aortic valve 1 ', 2' with the first balloon 26 having a diameter of 20 mm, preferably a diameter of 23 mm, the balloon being inflated to the maximum until the point of bursting, to prepare the insertion of the IV (Figure 15b). Inflation lasts a few seconds (preferably 10 seconds at most) with powerful pressure being used to expand the frame and forcefully embed said frame into the remains of the dilated valve;

3 / is followed by immediate rapid deflation of said first balloon 26 (Figure 15c); As soon as balloon 26 clearly begins to deflate, with first frame 10 remaining attached to stenotic valve 1 ', 2', catheter 40 is withdrawn to place IV balloon 26 'within previously expanded frame 26 (Figure 15c wherein frame 10 'is partially drawn for clarity purposes);

4 / Immediately after positioning itself, the IV balloon 26 'is rapidly inflated to expand the IV 13 (Figure 15c); Y

5 / When IV 13 is immobilized within first frame 10, IV balloon 26 'is deflated (Figure 18f).

Finally, the entire device has to be removed to allow hemostasis of the perforation hole of the femoral artery.

The total duration of the successive stages, particularly the time during which the balloons are inflated, and the time during which the shell expands while the valve has not yet been positioned and expanded, is approximately 20 to 30 seconds. This is feasible if the balloons inflate and deflate in a very few seconds, from 6 to 8, for example. This is allowed if the axle span is large enough, taking into account the unavoidable small diameter size of the tree. This can be facilitated by a device that instantly produces a strong inflation or deflation pressure.