U.S. patent application number 11/612972 was filed with the patent office on 2008-06-19 for device for in situ axial and radial positioning of cardiac valve prostheses.
This patent application is currently assigned to Sorin Biomedica Cardio S.r.l.. Invention is credited to Paolo Gaschino, Laura Ghione, Eric Manasse, Giovanni Righini, Giovanni Rolando, Dong Ik Shin.
Application Number | 20080147181 11/612972 |
Document ID | / |
Family ID | 41809234 |
Filed Date | 2008-06-19 |
United States Patent
Application |
20080147181 |
Kind Code |
A1 |
Ghione; Laura ; et
al. |
June 19, 2008 |
DEVICE FOR IN SITU AXIAL AND RADIAL POSITIONING OF CARDIAC VALVE
PROSTHESES
Abstract
An instrument for positioning a cardiac valve prosthesis in a
vessel includes a wire element to slidingly guide the valve
prosthesis towards an implantation site and an expandable element
coupled to the wire element. The expandable element is expandable
in the vessel to position the wire element in association with the
implantation site. A method for positioning a cardiac valve
prosthesis includes securing a delivery instrument at an
appropriate location at the implantation site and delivering the
valve prosthesis to the implantation site using the delivery
instrument.
Inventors: |
Ghione; Laura; (Torino,
IT) ; Righini; Giovanni; (Chivasso-Torino, IT)
; Manasse; Eric; (Milano, IT) ; Rolando;
Giovanni; (Chavasso-Torino, IT) ; Gaschino;
Paolo; (Castagneto Po-Torino, IT) ; Shin; Dong
Ik; (Poway, CA) |
Correspondence
Address: |
FAEGRE & BENSON LLP;PATENT DOCKETING
2200 WELLS FARGO CENTER, 90 SOUTH SEVENTH STREET
MINNEAPOLIS
MN
55402-3901
US
|
Assignee: |
Sorin Biomedica Cardio
S.r.l.
Saluggia (Vercelli)
IT
|
Family ID: |
41809234 |
Appl. No.: |
11/612972 |
Filed: |
December 19, 2006 |
Current U.S.
Class: |
623/2.11 |
Current CPC
Class: |
A61F 2/2412 20130101;
A61F 2/2436 20130101 |
Class at
Publication: |
623/2.11 |
International
Class: |
A61F 2/24 20060101
A61F002/24 |
Claims
1. A device for use in positioning an expandable aortic valve
prosthesis in the aorta, the device comprising a wire coupled to an
expandable support, wherein the expandable support is operable to
locate at least a portion of the wire generally in a center of the
aorta.
2. A cardiac valve prosthesis implantation device, comprising: a
axial positioning element and a radial positioning element.
3. The device of claim 2 in which said radial positioning element
is structured to permit location of said prosthesis with respect to
a valve annulus at a position substantially corresponding to a
position of natural valve leaflets without interference of a
structural component of said prosthesis with naturally occurring
blood flow.
4. The device of claim 2 in which said radially positioning element
is variably adjustable.
5. An improved device for delivering an expandable cardiac valve
prosthesis to a desired position in a vessel, the improvement
comprising: a guide wire or wire-like element having an axial and
radial positioning element.
6. The improved device of claim 5 in which said axial and radial
position element is sized and dimensioned to permit the flow of
blood therethrough.
7. The improved device of claim 5 in which said axial and radial
positioning element comprises: an axial positioning element and a
radial positioning element.
8. The improved device of claim 7 in which one or both of said
axial positioning element or said radial positioning element is
variably adjustable.
9. The improved device of claim 5 further comprising an abutment
element.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is related to co-pending U.S. application
Ser. No. XX/YYY,YYY, entitled "Instrument and Method for In Situ
Deployment of Cardiac Valve Prostheses," U.S. application Ser. No.
XX/YYY,YYY, entitled "System for In Situ Positioning of Cardiac
Valve Prostheses without Occluding Blood Flow," and U.S.
application Ser. No. XX/YYY,YYY, entitled "Device for In Situ
Positioning of Cardiac Valve Prostheses," all of which were filed
on even date herewith and are hereby incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to instruments for the in situ
positioning of implantable devices. In particular, the invention
relates to the in situ positioning of expandable prosthetic cardiac
valves.
BACKGROUND
[0003] Recently, there has been increasing consideration given to
the possibility of using, as an alternative to traditional
cardiac-valve prostheses, valves designed to be implanted using
minimally-invasive surgical techniques or endovascular delivery
(so-called "percutaneous valves"). Implantation of a percutaneous
valve (or implantation using thoracic-microsurgery techniques) is a
far less invasive act than the surgical operation required for
implanting traditional cardiac-valve prostheses.
[0004] These expandable prosthetic valves typically include an
anchoring structure or armature, which is able to support and fix
the valve prosthesis in the implantation position, and prosthetic
valve elements, generally in the form of leaflets or flaps, which
are stably connected to the anchoring structure and are able to
regulate blood flow. One exemplary expandable prosthetic valve is
disclosed in U.S. Publication 2006/0178740 A1, which is
incorporated herein by reference in its entirety.
[0005] An advantage of these expandable prosthetic valves is that
they enable implantation using various minimally invasive or
sutureless techniques. One non-limiting exemplary application for
such an expandable valve prosthesis is for aortic valve
replacement. Various techniques are generally known for implanting
such an aortic valve prosthesis and include percutaneous
implantation (e.g., transvascular delivery through a catheter),
dissection of the ascending aorta using minimally invasive thoracic
access (e.g., mini-thoracotomy), and transapical delivery wherein
the aortic valve annulus is accessed directly through an opening
near the apex of the left ventricle. Note that the percutaneous and
thoracic access approaches involve delivering the prosthesis in a
direction opposing blood flow (i.e., retrograde), whereas the
transapical approach involves delivering the prosthesis in the same
direction as blood flow (i.e., antegrade) Similar techniques may
also be applied to implant such a cardiac valve prosthesis at other
locations (e.g., a pulmonary valve annulus).
[0006] For the implantation of cardiac valve prostheses, it is
important to check in a precise way the positioning of the various
parts of the valve prosthesis. This applies to both axial
positioning, to ensure that the prosthetic valve is positioned
properly with respect to the valve annulus, and angular
positioning, to ensure that the prosthesis may optimally engage the
Valsalva sinuses, thus ensuring that the prosthetic valve leaflets
are located with respect to the valve annulus at positions
essentially corresponding to the positions of the natural valve
leaflets.
[0007] There is a need in the art for delivery and implantation
instruments capable of delivering an expandable prosthetic valve to
a precise location associated with a corresponding valve annulus.
There is a further need for instruments adapted to carefully
control expansion of the valve to prevent the valve from
misaligning during valve expansion.
SUMMARY
[0008] The present invention, according to one embodiment, is a
device for use in positioning a cardiac valve prosthesis in a
vessel. The device comprises a wire element to facilitate
advancement of the valve prosthesis, the wire element including an
abutment element configured to limit advancement of the prosthesis
and an expandable element coupled to the wire element, the
expandable element including an expanded configuration operable to
axially secure the wire element with respect to an implantation
site in the vessel, while not occluding blood flow through the
vessel. The expandable element is disposed in a symmetrical fashion
about the wire element, such that at least a portion of the wire
element is generally positioned along a central longitudinal axis
of the vessel.
[0009] The present invention, according to another embodiment, is a
method of implanting a replacement aortic valve prosthesis at an
implantation site. The method includes advancing a positioning
instrument having an expandable element and a wire element through
an aortic annulus to an anchoring position distal to the Valsalva
sinuses, deploying the expandable element to secure the positioning
instrument to the aortic wall, while not occluding blood flow
through the aortic arch, advancing the aortic valve prosthesis over
the wire element to a reference point coupled to the wire element,
such that the prosthesis is in a desired position with respect to
the aortic annulus, and expanding the aortic valve prosthesis, such
that the prosthesis anchors to the aortic annulus and the Valsalva
sinuses.
[0010] While multiple embodiments are disclosed, still other
embodiments of the present invention will become apparent to those
skilled in the art from the following detailed description, which
shows and describes illustrative embodiments of the invention. As
will be realized, the invention is capable of modifications in
various obvious aspects, all without departing from the spirit and
scope of the present invention. Accordingly, the drawings and
detailed description are to be regarded as illustrative in nature
and not restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic view showing the implantation of a
cardiac valve prosthesis using an instrument described herein,
according to one embodiment of the present invention.
[0012] FIG. 2 is a schematic view showing the basic structure and
principle of operation of a deployment instrument, according to one
embodiment of the present invention.
[0013] FIGS. 3-12 (FIGS. 5, 7 and 9 being cross-sectional views
according to the lines V-V, VII-VII and IX-IX of FIGS. 4, 6 and 8,
respectively) show deployment instruments, according to various
alternative embodiments of the present invention.
[0014] FIGS. 13-15 are schematic view showing further details of
the instrument, according to various embodiments of the present
invention.
[0015] While the invention is amenable to various modifications and
alternative forms, specific embodiments have been shown by way of
example in the drawings and are described in detail below. The
intention, however, is not to limit the invention to the particular
embodiments described. On the contrary, the invention is intended
to cover all modifications, equivalents, and alternatives falling
within the scope of the invention as defined by the appended
claims.
DETAILED DESCRIPTION
[0016] Without limiting the scope of the invention, the description
that follows makes reference to an instrument employed for the
implantation of a cardiac valve prosthesis destined to replace an
aortic valve. It will be apparent that the instrument of the
present invention may likewise be employed in connection with
implantation of valve prostheses at different locations (e.g.,
pulmonary valve or mitral valve).
[0017] FIG. 1 is a schematic view showing the implantation of a
valve prosthesis at the aortic valve location. The prosthesis V may
be any of a variety of minimally-invasive or expandable cardiac
valve prostheses known in the art. The prosthesis V, for example,
could be of the type described in U.S. Publication 2006/0178740 A1.
As shown in FIG. 1, the valve prosthesis V includes two radially
expandable annular end portions, namely an inflow portion IF and an
outflow portion OF. The terms "inflow" and "outflow" refer to the
pulsated blood flow through the prosthesis V.
[0018] The prosthesis V is configured to be positioned with the
annular inflow portion IF in correspondence with the aortic annulus
A and the annular outflow portion OF located in the ascending line
of the aorta AO, in a fluidodynamically distal position with
respect to the Valsalva sinuses VS. The prosthesis V is provided
with anchoring formations (not shown) that connect in a bridge-like
fashion the annular end portions IF, OF. The anchoring formations
are configured to extend into the Valsalva sinuses to anchor the
valve prosthesis V in the implant position, thus helping to
longitudinally secure the prosthesis V. By extending into the
sinuses of Valsalva VS, which form a three-lobed cavity downstream
the valve annulus, the anchoring formations (e.g., three formations
disposed at roughly 120.degree. angles from each other over about
the circumference of the prosthesis V) also ensure the appropriate
angular positioning of the valve prosthesis V, so that the
prosthetic valve leaflets will be at angular positions
corresponding to the angular positions of the natural valve
leaflets with respect to the valve annulus. FIGS. 2-4, 8, and 10
schematically show the natural valve leaflets in correspondence
with the valve annulus. These figures show that the instrument of
the invention can be located at the implantation site before the
possible ablation of the natural valve leaflets.
[0019] The prosthesis V shown in FIG. 1 is contained in a carrier
portion of an instrument used for positioning and deploying the
valve prosthesis V in situ. This carrier portion includes a capsule
having two deployment elements 100, 200 each in the form of a
collar, sheath, or cap that constrains the prosthesis V in a
radially contracted position. Once the implantation site is
reached, the two deployment elements 100, 200 can be displaced
longitudinally so as to uncover the prosthesis V. In an embodiment
wherein the prosthesis V is formed from a superelastic material,
the prosthesis V is then able to radially expand upon release from
the deployment elements 100, 200. One exemplary embodiment of such
a deployment instrument is disclosed in co-pending,
commonly-assigned U.S. application Ser. No. XX/YYY,YYY, entitled
"Instrument and Method for In Situ Deployment of Cardiac Valve
Prosthesis," which was filed on even date herewith. In one
embodiment, the prosthesis V and the deployment instrument include
an axial lumen configured to accept a guide wire, such that the
instrument may be advanced through a patient's vasculature over
such guide wire.
[0020] As shown in FIG. 1, the instrument of the present invention
includes a stylet or guide wire 10 and an expandable element 12
mounted on a distal portion thereof. As more clearly illustrated in
FIG. 2, the expandable element 12 is configured to be located and
expanded in the ascending portion of the aorta AO at a
fluidodynamically distal position with respect to the Valsalva
sinuses SV. Accordingly, the distal portion of the wire 10 can be
positioned precisely with respect to the implantation site of the
valve prosthesis V, in both the axial and the radial direction,
with the wire 10 extending in a precise radial position (e.g.
substantially central) with respect to the implantation lumen,
which in the exemplary case considered herein is the aorta AO. In
one embodiment, the expandable element 12 is configured to be able
to expand or to swell with respect to the guide wire 10 under
conditions of substantial rotational symmetry, so that, with the
element 12 in an expanded condition, the distal part of the wire 10
is in a substantially central position with respect to the aortic
lumen.
[0021] With respect to axial positioning, once the element 12 is
disposed at a given axial position along the ascending line of the
aorta, and thus at a given position with respect to the aortic
annulus, the expandable element 12 serves as a reference point. The
prosthesis V may thus travel along the guide wire 10 to locate it
at a desired axial position, before it is anchored at the desired
location with respect to the valve annulus. The present invention
thus allows for precise positioning of a prosthesis V, by providing
a guide for advancing the prosthesis to the implantation site.
[0022] Several variations of the expandable element 12 are
contemplated. In one embodiment, once expanded, the element 12 does
not undesirably obstruct blood flow (represented by the arrow
designated BF in FIG. 1). In this embodiment, blood flow will not
be impeded, and blood will be able to keep on flowing from the
ventricle (designated LV in FIGS. 3, 4, 8 and 10) towards the aorta
AO in the pulsating fashion determined by the alternate phases of
systole and diastole. Accordingly, the instrument of the present
invention can be used without recourse to extracorporeal
circulation, with the further effect of facilitating the sequence
of positioning, deployment and implantation of the prosthesis V
without time constraints, which would inevitably apply if the
expandable element completely obstructed the cross section of the
aorta (or, in general, of the treated lumen).
[0023] In one exemplary embodiment, the expandable element 12 is a
completely "apertured" structure, namely a structure that in its
expanded position is traversed by passageways through which blood
can readily flow. Alternatively, the non-obstructive effect can be
achieved by ensuring that the element 12 has an expansion
cross-sectional radius which is smaller than the cross-sectional
radius of the treated lumen. In this embodiment, general centering
the guide wire 10 with respect to the implantation lumen will be
accomplished by the element 12 "floating" in the blood flow and
will not require the expandable element 12 to apply any radial
pressure against the lumen wall. This embodiment may be helpful in
at least some patients suffering from degenerative diseases, as the
lumen wall may be fragile and therefore susceptible to be damaged
by pressure.
[0024] In one embodiment, the guide wire 10 has a stiffness
sufficient to cause its length extending from the expandable
element 12 towards the valve annulus to remain approximately in the
center of the body lumen throughout. A distal portion of the guide
wire 10, for example, has a stiffness sufficient to hold and retain
its shape.
[0025] The embodiments of FIGS. 3 and 4 the expandable element 12
having a general cage-like structure. In this embodiment, the
expandable element 12 includes a plurality of wire-like elements
that are operable between a first position co-extensive with the
guide wire 10 and a second position projecting outwardly from the
guide wire. FIG. 3 shows an embodiment wherein the cage-like
structure includes a portion of a tubular element (for instance of
a metal tube) having a distal end fixed to the distal end of the
guide wire 10 and a proximal end fixed to a sheath 11 slidably
arranged over the guide wire 10.
[0026] In this embodiment, the wall of the tubular element includes
a plurality of slits extending in a substantially longitudinal
direction defining therebetween wire-like or band-like portions of
the tube wall. According to one embodiment, these longitudinal
slits are formed from a microtube using a laser cutting technique.
The microtube can be of the type normally used for producing
angioplasty stents (e.g., a hypotube).
[0027] These band-like expandable elements 12 may be deployed, for
example, by manipulating a proximal control means 13, of a known
type in the catheter art, to effect a relative movement of the
guide wire 10 and the sheath 11. The sheath 11 may be advanced
distally towards the expandable elements 12 to reduce the distance
between the distal end of the sheath 11 and the distal end of the
guide wire 10, thereby deforming the tubular elements and causing
the wire-like or band-like wall elements between the slits to
protrude outwardly of the guide wire 10 to form a radially expanded
element 12 as desired. The further that the sheath 11 is advanced
towards the distal end of the guide wire, the further that the
tubular elements protrude radially.
[0028] The tubular element can be comprised of any metal material
approved for use in the biomedical field, such as for instance
steel, and in that case the expansion to form the expanded element
12 is positively determined by sliding the sheath 11 over the guide
wire 10. The tubular elements may also be formed for example of any
known polymer material approved for human implantation.
[0029] FIG. 4 shows an embodiment wherein the expandable element 12
is comprised of a cage-like structure of wires or bands 121 made
from a superelastic material (for instance, Nitinol). In a "rest"
condition, namely in the absence of constraints applied thereto,
the wires or bands 121 will naturally assume the desired cage-like
configuration of the element 12 in the expanded condition. In this
embodiment, the sheath 11 extends initially to the distal end of
the guide wire 10 in order to constrain to the Nitinol wires or
bands 121 in a radially contracted position. When retracted along
the guide wire 10 (see bottom of FIG. 4), the sheath 11 will
uncover and release the wires or bands 121, which will then be free
to return, because of their superelastic characteristics, to the
radially expanded position, which corresponds to the desired
expansion of the element 12.
[0030] The cage-like structure constituting the expandable element
12 is shown FIGS. 3 and 4 in an "onion-like" configuration, with
the wire-like or band-like elements forming the cage connected at
both the proximal and distal ends of the cage. In an alternative
embodiment, the expandable element 12 could be configured in an
"artichoke-like" shape, with the wire-like or band-like elements
forming the cage spreading from the proximal extremity of the cage
according to a general wine glass configuration without any
connection at their distal ends.
[0031] According to one embodiment, the cage-like structure
includes at least three such elements. In other embodiments, the
cage-like structure includes at least five or six such elements.
FIG. 5, for example, shows a one such configuration including six
elements. More elements may provide more precise positioning of the
guide wire 10 at the center of the treated lumen (e.g., the aorta
AO). The number of elements forming the cage-like structure, as
well as the choice of the constituent material and the manner of
expanding the structure, are influenced by the fact that, in order
to reach the desired expanded position shown in FIG. 2, the
expandable element 12 must pass through the site of the aortic
valve. In some situations, wherein the natural valve leaflets NL
were not removed, the natural valve leaflets may be extensively
calcified and thus resist penetration. Accordingly, in some
situations, it is important that the expandable element 12 have an
unexpanded cross sectional profile that is as small as possible, to
facilitate penetration through the calcified valve leaflets.
[0032] According to one exemplary embodiment, as shown in FIG. 4,
the instrument further includes a filtering element 14, which is
typically located in a fluidodynamically distal position with
respect to the expandable element 12. This filtering element 14,
which can also be integrated into the expandable element 12, may be
expanded along with the expandable element 12 to form a net that is
permeable to the blood flow BF in the aorta, but will entrap and
thus retain fragments of calcified formation (e.g., possibly
released during the intervention), air and clots, thereby
preventing these materials from flowing into the aorta.
[0033] FIG. 3 also shows an embodiment wherein the distal end
portion of the guide wire 10 includes a balloon 15. The balloon 15
is typically of the inflatable type and is intended to act as a
fluidodynamic dragging element, according to the principles of
operation of those balloons generally known in the art as Swan-Ganz
balloons. As indicated, the instrument described herein is
primarily intended to be used in transapical insertion procedures,
wherein the instrument is introduced in the ventricle cavity and
advanced towards the aortic valve site. Once the instrument is
inserted in the ventricle, the Swan-Ganz balloon 15 at the distal
end portion will be carried by the blood flow during the ventricle
systole and drawn to the aorta. In this way, the distal end of the
instrument will be automatically drawn toward the aortic valve by
the blood flow. The blood flow will then further draw the Swan-Ganz
balloon 15 and the distal end of the instrument through the aortic
annulus and on through the Valsalva sinuses to the ascending line
of the aorta where the expandable element 12 is to be positioned.
In one embodiment, the Swan-Ganz balloon 15 is configured to be
selectively deflated, for instance to allow passage through heavily
calcified natural valve leaflets before ablation. The entrapment
element 14 and/or the Swan-Ganz balloon 15 can be optionally
included with any of the embodiments disclosed herein.
[0034] FIGS. 6-9 show expandable elements 12 in the form of
inflatable balloons. Specifically, FIGS. 6 and 7 show an expandable
element 12 comprising an inflatable balloons with a multi-lobed
structure. In one exemplary embodiment, a balloon comprising three
expandable sections 123 angularly spaced at 120.degree. intervals
about the circumference. Such a multi-lobed balloon structure, and
a related manufacturing process, is described in detail in EP-A-0
512 359. In this embodiment, the various lobes 123 of the balloon,
once expanded, do not obstruct the treated lumen (e.g., the aorta
AO). In an alternative embodiment, shown in FIGS. 8 and 9, the
expandable element 12 includes a bundle of expandable bar-like
balloons 124 of the type used, for instance, for implanting
angioplasty stents. Both in the case of an expandable element
comprised of a multi-lobed balloon (FIGS. 6 and 7) and in the case
of an expandable element including a bundle of bar-like balloons
(FIGS. 8 and 9), the action of inflation (and deflation) of the
expandable element 12 can be accomplished by injecting (and
withdrawing) fluid through a lumen.
[0035] FIG. 10 shows an alternative embodiment including a single
balloon. In this embodiment, the expandable element 12 can be
expanded so as to occupy only part of the net cross section of the
implantation lumen (e.g., the aorta AO). According to one
embodiment, a substantially non-obstructive effect of the free flow
of the blood in the treated lumen, which allows the expandable
element 12 to remain in an expanded condition long enough to permit
the implantation of a valve prosthesis V without the duration of
the intervention becoming a critical parameter, is achieved if the
expandable element 12, when expanded, occupies less than about 90
to 95% of the net cross sectional area of the lumen or (for
elements 12 having an apertured structure with passageways for
blood therethrough) the area of the circle whose radius is equal to
the expansion radius of the element 12 with respect to the guide
wire 10. In another embodiment, the expandable element 12 occupies
less than about 75% of the net cross sectional area of the
lumen.
[0036] As illustrated in FIG. 10, this non-obstructive effect on
blood flow can be also achieved by an element 12 having a structure
not of an apertured type by ensuring that, when expanded, the
element 12 has an expansion radius smaller that than the radius of
the lumen (the radius of the aorta, in the exemplary case
considered herein) at the location where the element is expanded.
In this way, while being still centered in a radial sense with
respect to the lumen, due to fluidodynamic actions of blood flowing
around it, the expandable element 12 will not exert any appreciable
pressure on the lumen walls which, at least in some patients
affected by particular pathologies, may be particularly sensitive
and fragile.
[0037] FIGS. 11 and 12 schematically show still other possible
embodiments of the expandable element 12. FIG. 11, for instance,
shows an expandable element 12 wherein the elements of the
cage-like or shape similar to an onion-like structure do not extend
along the "meridians" of the expandable structure (as is the case
of FIGS. 3 and 4), but rather follow approximately helical
trajectories. This solution may be advantageously used in
conjunction with both self-expandable elements (e.g., Nitinol) and
with elements whose expansions is obtained by a positive action
(e.g., inflating a balloon or sliding a sheath 11 over the guide
wire 10). According to the embodiment of FIG. 12, the guide wire 10
includes a plurality of expandable elements 12 (e.g., onion-like
cage structures) arranged in a cascaded configuration and adapted
to be selectively expandable in a coordinated manner.
[0038] FIGS. 13-15 show how the instrument described herein may
ensure the correct axial positioning of the valve prosthesis V with
respect to a valve site (e.g., an aortic valve annulus). In the
illustrated embodiment, the instrument is employed to ensure that
the annular inflow portion IF is positioned to be deployed in
appropriate correspondence with the valve annulus A.
[0039] FIG. 13 shows a solution wherein at least one opaque marker
16 is provided on the guide wire 10 (or the expandable element 12).
The designation "opaque" (e.g., radiopaque) denotes any marker
which is visible and can be observed to identify its position in
the patient body by resorting to current imaging techniques (e.g.,
radioscopy and nuclear magnetic resonance). The marker 16 assists
the operator to advance the instrument (the guide wire 10 and
expandable element 12) through the valve annulus A so as to locate
the expandable element 12 in the aorta distally with respect to the
Valsalva sinuses. Specifically, the operator will be able to verify
that the marker 16 has reached a clearly identified position, for
instance by positioning it in the plane of the valve annulus A,
about the center of the annulus.
[0040] The expandable element 12 is then expanded so that the
marker 16, and thus the guide wire 10, substantially maintain the
desired axial position. In the embodiment shown in FIG. 14, the
axial position of the guide wire 10 can be further secured at a
desired position by blocking (by means of a blocking device 19 of a
known type) the proximal end of the guide wire 10 that is located
outside the patient's body. This further inhibits axial movement of
the guide wire 10, even in the case where the expandable element 12
is free or slightly "floating" in radial sense with respect to the
aorta wall.
[0041] Positioning and securing the expandable element 12 and the
guide wire 10 facilitates positioning the valve prosthesis V at the
desired position with respect to the implantation site (e.g.,
aortic valve annulus). The results in terms of accuracy already
achieved in positioning of the instrument will thus be exploited
for the purpose of positioning of the valve prosthesis V.
[0042] During an implantation procedure, the valve prosthesis V is
advanced longitudinally over the guide wire 10 (see FIGS. 1 and 13)
until an opaque marker 160 positioned, e.g. at the inflow end IF of
the valve prosthesis V aligns (e.g., overlaps) with the marker 16
on the guide wire 10, to thus ensure that the prosthesis V is in
the desired position for implantation, with the inflow end IF in
the plane of the valve annulus A. This technique lends itself to
further refinement, both regarding the positioning of the
instrument 10, 12 and the relative positioning of the valve
prosthesis V with respect to the instrument previously
positioned.
[0043] For instance, instead of a single marker 16, the guide wire
10 may include multiple markers 161, 162, etc. defining a graduated
scale along the guide wire 10. The operator will thus be able to
position the marker 160 on the valve prosthesis V in alignment with
one particular marker in the scale, in view of specific
requirements arising at the time of implantation.
[0044] In a complementary and dual manner, it is possible to
provide multiple markers on the prosthetic valve V. These markers
can be provided, rather than on the cardiac valve prosthesis V, on
the respective deployment instrument, for instance on either or
both the deployment elements 100, 200 mentioned above. Providing
the markers on the prosthesis V allows the operator to check over
time the positioning of the valve prosthesis V.
[0045] FIGS. 14 and 15 show exemplary embodiments including an
abutment formation 17, which may, for instance, have the form of a
collar-like member mounted on the guide wire 10 (or on the
expandable element 12). The formation 17 is arranged for mechanical
co-operation with the prosthesis V and/or with the distal part of
the relative deployment instrument (for instance with the
deployment element 200) in order to stop the sliding movement of
the prosthesis V over the guide wire 10.
[0046] FIGS. 14 and 15 specifically illustrate a situation where
the distal border of the deployment element 200 must be at a
distance d with respect to the plane of the aortic annulus A, in
order to properly locate the prosthesis V at the implant site. The
guide wire 10 or expandable element 12 is thus positioned in such
way that the stop element 17 is exactly located at a distance d
with respect to the plane of the aortic annulus A. In this
embodiment, the correct axial positioning of the prosthesis V will
be easily achieved by sliding the prosthesis V over the guide wire
10 up to the point where, as schematically illustrated in FIG. 15,
the distal border of the deployment element 200 abuts against the
element 17 provided on the guide wire 10 (or, possibly, on the
expandable element 12).
[0047] At this point, by realizing that the prosthesis V can no
longer be advanced over the guide wire 10 because of the mechanical
co-operation of deployment element 200 against the abutment element
17, the operator will know that the prosthesis V has reached the
desired position. The operator can thus proceed to deploy the
annular inflow and outflow portions IF, OF of the prosthesis V
without having to worry about the axial (and radial) positioning of
the prosthetic valve. The operator will thus be able to concentrate
on other issues related to implanting the prosthesis, such as the
appropriate angular positioning of the prosthesis V, by making sure
that the protruding parts of the prosthesis V are angularly
positioned in correspondence with the Valsalva sinuses and
correctly extend into the Valsalva sinuses the prosthesis V is
deployed.
[0048] A micrometric adjustment mechanism (of a type known by
itself) actuatable from the proximal extremity of the instrument
can be associated to the abutment element 17 for regulating in a
precise way, if necessary, the position of the element 17 with
respect to the guide wire 10 and/or the expandable element 12. This
adjustment feature may turn out to be advantageous in certain
situations where the expandable element 12 must be expanded and
thus deployed in a different position with respect to the
originally anticipated position. In this case, adjusting the
position of the abutment element 17 makes it possible to position
that element at the position where it would be disposed had the
expandable element 12 been positioned in the anticipated way.
[0049] FIG. 2 refers to an exemplary embodiment that includes a
pressure sensor 18 (e.g., piezoelectric pressure sensor). The
pressure signal generated by the sensor 18 is transmitted to the
outside of the body of the patient (for instance through wires that
extend along the guide wire 10) and makes it possible to detect if
the point where the pressure sensor 18 is located is momentarily
upstream or downstream of the valve annulus A. Having such
information available is a further aid to the operator in achieving
the correct positioning of the instrument and, accordingly, of the
valve prosthesis V. In yet another embodiment, the instrument
further includes a lumen adapted to inject contrast fluid. In this
embodiment, the contrast fluid may be used by the operator to
obtain an image of the implantation site.
[0050] Various modifications and additions can be made to the
exemplary embodiments discussed without departing from the scope of
the present invention. Accordingly, the scope of the present
invention is intended to embrace all such alternatives,
modifications, and variations as fall within the scope of the
claims, together with all equivalents thereof. This is particularly
true as regards the possible combination, within a single
implantation kit, of the instrument described herein with a
deployment instrument described in the co-pending patent
application already referred to in the foregoing.
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