Patent Application
20080288060
The present invention relates to a method and apparatus for treating valvular insufficiency. In particular, the invention relates to a device and method for treating valvular insufficiency occurring in valves of the heart such as the tricuspid valve, and a delivery apparatus for the same.
The body's circulation is facilitated by the heart, the cardiac pump which ensures that fresh blood is supplied throughout the body delivering nutrients to organs and transporting waste products to the body's filtration systems. The heart, simplified and illustrated in cross section in
Valves in the heart and throughout the body ensure that blood flows constantly in one direction. These include the mitral valve and the tricuspid valve, which separate the atria and ventricles of the left and right hearts respectively. The circulation is dependent on these valves to ensure that the blood is pumped continuously and efficiently through the heart and delivered to the rest of the body.
The tricuspid valve is a complex structure comprising leaflet tissue, chordae tendinae, papillary muscles and a supporting annulus. The tricuspid valve leaflets are a continuous veil of leaflet tissue that attach to the annulus. Three major leaflets are identified, anterior, septal and posterior. The tricuspid valve annulus performs multiple functions including maintenance of valvular shape and dimensions.
In some cases, valves in the circulatory system such as the tricuspid and mitral heart valves are deficient or fail. The causes of partial or total heart valve failure include congenital/structural defects, disease and infection. However, the most common cause of valve failure is dilation of the valve annulus. This occurs as part of the generalized cardiac structural dilatation allied to cardiomyopathy and heart failure. The consequences of heart valve failure can vary depending on the seriousness of the failure, but in most cases the heart's efficiency and the efficiency of the circulatory system is seriously affected and complications often result.
Failure or insufficiency of the heart valves frequently results in mitral/tricuspid valve regurgitation. In the case of the mitral valve, regurgitation results in back pressure in the lungs, whereas tricuspid valve regurgitation can result in high back pressures in the venous circulation. Clearly, this is undesirable for the health of the heart, as well as for the lungs and other organs of the body. Mitral and tricuspid valve failure can lead to ineffective and/or inefficient cardiac pumping, ventricular and atrial enlargement, pulmonary and/or circulatory hypertension, heart failure and in some cases, death.
Methods exist for repairing and replacing cardiac valves and other valves of the body and treatments for mitral valve regurgitation in particular are available. One form of treatment involves replacement of the entire valve. In other cases, the mitral or tricuspid valve annulus may be repaired by placing a biocompatible annuloplasty ring inside the annulus and suturing the ring to the fibrous tissue of the annulus. The annuloplasty ring constricts the annulus, enabling the mitral or tricuspid valve leaflets to seal during each pumping cycle and reduce or prevent backflow.
Mitral valve replacement and implantation of the annuloplasty ring both require open heart surgery and are therefore major operations. The patient must be placed under general anesthetic and undergo cardiopulmonary bypass.
Concomitant with the seriousness of such procedures are an increase in morbidity and mortality risk, and a slow and painful period of rehabilitation which follows. Post-operative complications are also common and these include infection, thromboembolism, loss of ventricular function and a need for anticoagulation medication.
The location of the tricuspid valve in the right heart complicates treatment because it is less easily accessible than the mitral valve, and it has a more complex triple-leaved structure. The mitral valve is accessible via the coronary sinus/great cardiac vein (CS/GCV) which has a close anatomical relationship with the lateral border of the posterior annulus. The small cardiac vein has a similar relationship with the tricuspid annulus. However, unlike the CS/GCV, this vessel is small, variable in size and absent in approximately 50% of cases. Therefore, reasonable vascular access to the tricuspid annulus is limited to a right atrial approach.
In the past, implications of tricuspid valve regurgitation have not been well understood, and this has only become a topic of interest in recent times. Because of this, the treatment options available for patients experiencing tricuspid valve regurgitation are limited. Currently available forms of treatment for patients experiencing mitral and tricuspid valve insufficiency are high risk, expensive and prone to complications.
Briefly, a first aspect of the present invention provides a method of treating valvular insufficiency in a patient. A plurality of filaments is used to engage tissue at spaced apart locations of an annulus of the valve being treated. The engaged filaments are drawn inward so as to draw the engaged tissue inward. The filaments are then secured with the engaged tissue in the drawn-in configuration. Inward drawing of the engaged tissue improves valve function by reducing the valve annulus.
A second aspect of the present invention provides a valve constriction device for treating valvular insufficiency. The valve constriction device has a plurality of filaments, each having an engaging portion for engaging annular tissue of the valve. A collar is also provided, facilitating a drawn-in configuration of engaged annular tissue by relative movement between the filaments and the collar. Valve function is improved when the engaged filaments are in the drawn-in configuration.
A third aspect of the present invention provides delivery apparatus for delivering a valve annulus constriction device. The apparatus includes a catheter configured to deliver a plurality of filaments percutaneously to an annulus of the valve being constricted. The catheter is also configured to deliver a collar to be applied over a length of the filaments. Relative movement between the catheter and a filament facilitates positioning of the filament prior to engagement with the valve annulus tissue.
A fourth aspect of the present invention provides a method of treating valvular insufficiency in a patient in which a plurality of filaments is used to engage tissue at spaced apart locations of an annulus of the valve being treated. The plurality of filaments are then anchored to a region of robust tissue near the valve being treated so as to draw the engaged tissue toward the anchor region thus improving closure of the valve being treated.
A fifth aspect of the present invention provides a valve constriction device for treating valvular insufficiency which includes a plurality of filaments. Each filament has an engaging portion for engaging annular tissue of the valve. Anchor means is also provided for anchoring the engaged filaments to a region of robust tissue to facilitate drawing of the engaged tissue toward the anchor means to improve leaflet closure.
Referring firstly to
Referring now to
The embodiments illustrated in the accompanying drawings demonstrate use of the invention in its various embodiments to treat insufficiency of the tricuspid valve. It is to be understood, however, that the method is also suitable for other valves of the heart and for treating insufficiency of a range of other valves around the body. Other valves for which the invention may be suitable may include but are not limited to the valves of the esophagus, urinary tract and intestinal tract.
In order to minimize the invasiveness of the procedure, it is desirable that the method is performed percutaneously. That is, using a catheter or other such lumen which is sufficiently flexible to enter the patient's circulation through the skin and into the jugular vein or other blood vessel, and to be directed to the valve being treated. For treatment of the tricuspid valve, it is preferred that the device is transported to the tricuspid valve annulus 1 through the right atrium.
It has been found that for treatment of tricuspid valve insufficiency, the method is effective when three filaments are used. However, it is to be understood that use of other quantities of filaments may be used to achieve the desired outcome of improved or restored valve function. The number of filaments used may depend, for example on the size of the patient and/or the size and geometry of the valve being treated.
In
Whilst the engaging portions 3 are illustrated throughout the embodiments illustrated as including a helical tip, it is to be understood that the engaging portion of each of the filaments may be provided in any other suitable form whilst remaining within the scope of the claims appended hereto. Such alternative forms may include hooks, barbs, spikes or other suitable engaging means. Preferably, the tip of each engaging portion is pointed or otherwise configured for ease of engagement with the fibrous tissue of the valve annulus. In some embodiments, depending on the structure of the engaging portions, staggering the engaging portions within the guide catheter 9 may be less advantageous or even unnecessary.
The delivery apparatus may also include a percutaneously operable tool such as a torque tool for engaging the engaging portions with the annular tissue. Such a tool may be releasably connectable with each of the filaments. In one embodiment, filaments 2 each have a finite length with the engaging portion 3 at an annular end and a connecting region 5 at an opposing end. Engaging portion 3 is configured to engage tissue of the valve annulus. Meanwhile, connecting regions 5 are configured to releasably connect a torque and/or other tool used to position the filament and/or facilitate engagement of the associated engaging portion with the annular tissue. One such embodiment illustrated in
As briefly mentioned, for treatment of the tricuspid valve, it is preferred that catheter 9 enters the body through the jugular vein and snakes its way into the superior vena cava and right atrium to access the tricuspid valve annulus for repair. Surgeons or physicians performing the procedure may use any suitable imaging technique to view and assess the region of the valve annulus, to position the delivery apparatus and to deploy the constriction device in engagement the valve annulus tissue. X-ray fluoroscopy is one imaging technique which may be used to assist in accurately positioning the device. Alternatively or additionally, the physician may use haptic feedback and/or ancillary devices delivered to the region via catheter 9 or an additional lumen to position the delivery apparatus and constriction device and engage the engaging portions 3 of filaments 2 with the valve annulus tissue 1.
One or more of the filaments may also include an identifier visible from outside the body to enable the physician to correctly select a filament during deployment of the device. The identifiers may be in the form of a tag attached at the physician's end of each of the filaments, with a letter or number or other identifier on the tag to indicate which of the engaging portions located near the annulus corresponds to the filament being identified by the physician. Alternatively, the filaments may be color coded. In some embodiments, it may also be desirable for one or more of the engaging portions to include a radio-opaque marker. It is to be understood that a combination of 2 or more of these identification approaches, or other approaches as would be known to the person skilled in this area, may be adopted.
Catheter 9 is configured to deliver a plurality of filaments 2 percutaneously to the valve annulus 1 and preferably, to deliver a collar 6 over the filaments also. Preferably, each of the filaments 2 is individually covered in a sheath 11. Such sheath imparts strength to the filament 2 and provides a degree of rigidity which aids in positioning the engaging portions 3 prior to engagement with the annulus tissue.
Preferably, sheathed filaments 2 within catheter 9 are pre-formed in such a way that when catheter 9 is retracted by a small amount to reveal a length of sheathed filament 16 the sheathed filaments splay, curving away from the tip of the catheter. This may be achieved using any suitable technique, such as shape memory coding. Additionally or alternatively, filaments 2 may be formed with a taper, decreasing in cross-sectional area toward the engaging portion. This too may impart strength to the filaments without significantly affecting miniaturization of the device.
Positioning of the filaments prior to engagement with the valve annulus tissue may be controlled by relative movement between the catheter 9 and one or more of the sheathed filaments. Preferably this is achieved by slightly retracting catheter 9 relative to the filament being positioned as illustrated in
The delivery apparatus may also include a centering member such as a guide wire (not shown) with a tip locatable on a distal side of the valve being constricted to facilitate centralization of the constriction device relative to the valve annulus. When treating the tricuspid valve, the centering member would be temporarily anchored in the right ventricle during deployment of the constriction device.
During engagement of one or more engaging portions with the annular tissue, torsional forces may develop, causing unengaged filaments to twist and making it difficult for the engaging portions to be positioned accurately. This torsional effect may be reduced by using a secondary support structure to support the unengaged filaments, thereby limiting twisting thereof. One such secondary support structure generally referred to as 600 is illustrated in
In one embodiment, one or more of the filaments may also be configured to conduct an electrical signal. Accordingly, when an engaging portion associated with such a filament is engaged with tissue of the heart, it will conduct electrical impulses propagating through that region of the heart. This signal can then be used as input to an analysis device to determine if the engaging portion of the filament is correctly positioned, based on the well-defined electrical characteristics of the heart. This feature is particularly useful for accurately positioning the engaging portion of a filament in the septal region of the annulus. Other techniques for accurately positioning the engaging portion 3 of each of the filaments may also be used. One such technique is to include a radio opaque marker with the engaging portions 3.
When each of the engaging portions 3 have been positioned at spaced apart locations of the valve annulus, a collar 6 having a relatively small diameter is delivered over a length of the filaments 2. In some embodiments it may be desirable to leave sheaths 11 in situ to impart further rigidity to the filaments and reduce the bending forces which would otherwise be borne by the filaments. In other embodiments it may be desirable to remove sheaths 11 with catheter 9, and apply collar 6 over the filaments as illustrated in
Relative movement between the collar and the filaments draws the engaged tissue inward. This relative movement may involve moving the collar toward the annulus, or retracting the filaments through the collar, or by a combination of these. As the collar 6 approaches the annulus 1, the engaged tissue, is radially drawn-in to reduce the valve annulus. When the engaged tissue has been sufficiently drawn-in to restore or improve valve function, the filaments are retained in the drawn-in configuration, thereby treating the insufficiency problem. During deployment of the device, some physicians may find it useful, when the collar 6 is close to the annulus 1, to pull back on the filaments slightly. This has the combined effect of lifting annulus 1 and drawing the engaged annular tissue further inward, aiding in closure of leaflets of the valve. The collar 6 may be used to retain the filaments in the drawn-in configuration by clamping or crimping the collar to the filaments, or using other suitable means.
In one embodiment, a locking member is used to retain the filaments in the drawn-in configuration.
For percutaneous delivery and deployment of the constriction device, it is desirable that the locking member 7 fits inside catheter 9 or other delivery lumen for percutaneous delivery to the collar 6 and filaments 2. It is to be understood that in certain embodiments, the locking member may be built into the collar 6. One suitable form of locking member 7 may include a set of pie jaws or chuck jaws such as a collet chuck having push or pull back operation, or screw operation enabling the jaws to close in on and clamp, crimp or otherwise lock onto the filaments. Alternatively, the locking member 7 may adopt a ratchet, wedge or clip-type system.
An example is illustrated in
In one embodiment, an anchor may be provided to secure one or more of the engaged filaments to a region of sufficiently robust body tissue near the valve to further augment and improve valve function. This is achieved by drawing the filaments and thus the engaged tissue toward the anchor, in addition to (radial) drawing in of the engaged tissue. One example of this arrangement is illustrated in
It is to be understood that the present invention, in its various forms, may achieve an improvement in valve function by augmenting the annulus of the valve being treated by drawing engaged portions of the annulus tissue inward, or by drawing engaged portions of the annulus tissue toward an anchor secured to robust body tissue located near the valve, or using a combination of these approaches.
Whilst implantation of the constriction device will have some effect on the flow characteristics of blood flowing through the valve, patients who suffer from severe valvular insufficiency will still benefit from implantation of the device, despite the potential increase in blood flow turbulence.
Various adaptations may be made to the parts previously described. For example, the collar may be in the form of a locking disc or a locking disc may be used in conjunction with the collar already described. A disc of this kind may be passed over the wires to the valve annulus, and have a hole for each of the filaments. The wires can then be drawn through the disc, thus constricting the valve annulus and the filaments secured to the disc or bound together by a knot or other means. This may be used in addition to an anchoring means for drawing the valve annulus toward the anchor thus further improving valve compliance.
Alternatively or additionally, a tensioning disc may be threaded onto the filaments and tensioned thereon to maintain the drawn-in configuration. Preferably the tensioning disc is a one-way tensioning disc. As another alternative, a physician may deliver a band over the filaments to substantially abut the disc and crimp the band to preclude withdrawal of the filaments through the disc. Use of a band in this way may also be, for example, in conjunction with the collar 6.
To avoid rejection from the body and/or infection or failure of the device, it is preferred that the device is made from a biocompatible material. In one preferred embodiment, the filaments 2 are formed from extrusions of a nickel-titanium alloy such as nitinol. Alternatively, the filaments 2, sheaths 20, support structures 600 and/or other components of the constriction device may be manufactured from other biocompatible metal alloys or materials including stainless steels, ceramics, plastics or other synthetic materials or combinations of these.
Advantageously, patients undergoing valve treatment in accordance with the various embodiments of the present invention need not require general anesthetic. Rather, the patient may be treated by percutaneous access to the valve while sedated. Clearly, this is beneficial to the patient as the recovery time is significantly reduced when compared with existing treatments for valvular insufficiency, and the device may be implanted during an outpatient procedure, reducing costs. Use of a sedative also reduces the risk of mortality which is associated with use of general anesthetic in elderly patients.
Percutaneous treatment of valve failure according to the various embodiments of the present invention eliminates the need for open heart surgery which has previously been required for treating heart valve failure, although the invention may be utilised in an open-heart procedure should the need arise. Advantageously in percutaneous delivery, patients treated according to embodiments of the invention are able to recover more quickly with reduced risk of infection, surgical complications and mortality, and the discomfort which accompanies open heart or other major surgery.
Whilst in most cases it would be desirable to constrict the annulus in such a way that a healthy annulus geometry is restored, in many serious cases of heart valve failure it may be sufficient to achieve an annulus reduction of 25% or less. In many cases, this will restore valve function to a degree which improves the quality of life of the patient. Another advantage of implantation of the inventive device and use of the inventive method is that it minimizes further dilation of the valve annulus. Moreover, the invention in its various embodiments also presents the possibility of adjustment in situ, after initial deployment of and treatment using the device
While some embodiments of the present invention have been illustrated here in detail, it is to be understood that modifications and adaptations to these embodiments may occur to one skilled in the art without departing from the scope of the present invention as set forth in the following claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/AU2005/000992 | 7/6/2005 | WO | 00 | 3/12/2008 |
| Number | Date | Country | |
|---|---|---|---|
| 60585784 | Jul 2004 | US |
