FRACTURING CALCIFICATIONS IN HEART VALVES
FIELD OF THE INVENTION
The present invention generally relates to devices and methods for fracturing
calcifications in heart valves, such as aortic valve leaflets.
BACKGROUND OF THE INVENTION
Essential to normal heart function are four heart valves, which allow blood to pass
through the four chambers of the heart in the proper flow directions. The valves have
either two or three cusps, flaps, or leaflets, which comprise fibrous tissue that attaches to
the walls of the heart. The cusps open when the blood flow is flowing correctly and then
close to form a tight seal to prevent backflow.
The four chambers are known as the right and left atria (upper chambers) and right
and left ventricles (lower chambers). The four valves that control blood flow are known
as the tricuspid, mitral, pulmonary, and aortic valves. In a normally functioning heart, the
tricuspid valve allows one-way flow of deoxygenated blood from the right upper chamber
(right atrium) to the right lower chamber (right ventricle). When the right ventricle
contracts, the pulmonary valve allows blood to flow from the right ventricle to the
pulmonary artery, which carries the deoxygenated blood to the lungs. The mitral valve,
allows oxygenated blood, which has returned to the left upper chamber (left atrium), to
flow to the left lower chamber (left ventricle). When the left ventricle contracts, the
oxygenated blood is pumped through the aortic valve to the aorta.
Certain heart abnormalities result from heart valve defects, such as is stenosis or
calcification. This involves calcium buildup in the valve which impedes proper valve
leaflet movement.
SUMMARY OF THE INVENTION
The invention consists of minimally invasive devices and methods that may be
used for fracturing calcifications in aortic valve leaflets, in order to increase leaflet
pliability and mobility, thereby increasing the cross-sectional area of the open valve in
patients with aortic stenosis. In addition, the devices and methods described can be
applied as a preparation step for trans-catheter aortic valve implantation, in order to allow
valve implantation in heavily calcified or asymmetrically calcified native valves, to
increase the cross-sectional area of the implanted valve and to decrease the risk of
paravalvular leaks. The devices and methods may also be used for fracturing
calcifications in other valves, such as the mitral valve, for performing angioplasty on
calcified plaque, or for fracturing hard deposits such as kidney or bladder stones.
The present invention seeks to provide improved devices and methods that may be
used for fracturing calcifications in aortic valve leaflets, in order to increase leaflet
pliability and mobility, either as standalone treatment, bridge treatment or preparation of
the "landing zone" for trans-catheter valve implantation.
The term "fracture" refers to any kind of reduction in size or any modification in
shape or form, such as but not limited to, fracturing, pulverizing, breaking, grinding,
chopping and the like.
There is provided in accordance with an embodiment of the invention a device for
fracturing calcifications in heart valves including a catheter including an external shaft in
which are disposed an expandable stabilizer, an impactor shaft on which are mounted
expandable impactor arms, and an internal shaft, characterised in that the internal shaft is
movable to cause the impactor arms to expand outwards and be locked in an expanded
shape, and wherein an impacting element is movable to cause the impactor arms, while in
the expanded shape, to move towards the tissue with sufficient energy so as to fracture a
calcification located in tissue which is fixed by the stabilizer in a certain position vis-a-vis
the impactor arms.
In accordance with a non-limiting embodiment of the invention the impacting
element includes the internal shaft which is connected to a distal portion of the impactor
arms and which is operative to move relative to the impactor shaft to expand the impactor
arms outwards and to cause the impactor arms, while in the expanded shape, to move
towards the stabilizer with the sufficient energy. The internal shaft may be lockable
relative to the impactor shaft so that the impactor arms are fixed.
In accordance with a non-limiting embodiment of the invention the impacting
element includes a weight and a biasing device, wherein the biasing device urges the
weight towards the impactor arms with the sufficient energy. In one example, the weight
is mounted on the biasing device which is fixed to a distal tip of the catheter. In another
example, the weight is fixed to the internal shaft of the catheter. In yet another example,
the biasing device includes a pneumatic energy source connected to a pressurized air
source.
In accordance with a non-limiting embodiment of the invention the stabilizer
includes a stabilizer structure that includes one or more elements (of any form or shape,
such as rods, loops or more complex structures) optionally covered by a stabilizer cover.
The stabilizer may include a stabilizer structure covered by a covering balloon. An
inflate/deflate tube may be inserted into the covering balloon. A first pressure sensor may
be located near the stabilizer (in the portion of the catheter that lies in the aorta) and a
second pressure sensor may be located near the impactor arms (in the portion of the
catheter that lies in the LVOT or left ventricle). The device can be designed in a "reverse"
manner for trans-apical use, so that the impactor is proximal and the stabilizer may be
positioned at a distal tip of the device. Stabilizer arms may be expandable outwards from
the external shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood and appreciated more fully from the
following detailed description, taken in conjunction with the drawings in which:
Fig. 1 is a simplified illustration of the anatomy of a calcified aortic valve,
ascending aorta and aortic arch.
Fig. 2 is an enlarged view of a calcified aortic valve.
Fig. 3 is a simplified top-view illustration of typical calcification patterns on aortic
valve leaflets.
Fig. 4 is a simplified illustration of valve leaflets of Fig. 3 after fractures were
obtained, in accordance with an embodiment of the invention.
Fig. 5 is a simplified illustration of an impactor catheter delivered over a
guidewire through a peripheral artery, over the aortic arch and into the aortic valve,
described in PCT Patent Application PCT/US20 10/0588 10 (WO 2011/069025).
Fig. 6 is a simplified illustration of the valve leaflets of Fig. 3 with a footprint of
both impactor and stabilizer elements on the leaflets, in accordance with an embodiment
of the invention.
Fig. 7 is a simplified illustration of the "stent-like" impactor design with a
footprint similar to the impactor footprint shown in Fig. 6, in accordance with an
embodiment of the invention.
Figs. 8-9 are top and side views, respectively, of the "stent-like" impactor, in
accordance with an embodiment of the invention.
Fig. 10 is a simplified illustration of the "M" stabilizer design with a footprint
similar to the stabilizer footprint shown in Fig. 6, in accordance with an embodiment of
the invention.
Fig. 11-12 is a simplified illustration of the top and side view of the "M" stabilizer
design, in accordance with an embodiment of the invention.
Figs. 13-15 are simplified illustrations of the double layer stabilizer design, in
accordance with an embodiment of the invention.
Figs. 16-18 are simplified illustrations of a "basket" stabilizer, in accordance with
an embodiment of the invention.
Figs. 19-21 are simplified illustrations of a "rose" stabilizer assembly, in
accordance with another embodiment of the invention.
Fig. 22 is a simplified illustration of the steps of opening and closing the "M"
stabilizer of Fig. 10, in accordance with an embodiment of the invention.
Fig. 23 is a simplified illustration of a method of using various impactor designs
for dilating the valve, in accordance with an embodiment of the invention, and of a
method of using various impactor designs for measuring the real valve diameter, in
accordance with an embodiment of the invention.
Figs. 24A-24B are simplified illustrations of an inner lumen of an impactor and
delivery system, and its ability to take pressure measurements from the ventricular and
aortic aspects of the aortic valve, in accordance with an embodiment of the invention.
Figs. 25-27 are simplified illustrations of a stabilizer assembly with cushions or
shock absorbers on stabilizing struts, in accordance with an embodiment of the invention.
Figs. 28-30 are simplified illustrations of a stabilizer assembly with cushions or
shock absorbers on stabilizing struts, in accordance with another embodiment of the
invention.
Fig. 3 1 is a simplified illustration of a stabilizer assembly with cushions or shock
absorbers on stabilizing struts, which can also be used for embolic capturing, in
accordance with yet another embodiment of the invention.
Fig. 32 is a simplified illustration of a "parachute" embolic protection structure,
capable of deflecting debris in the blood stream away from the carotid - aortic arch
junction, in accordance with an embodiment of the invention.
Fig. 33 is a simplified illustration of transmitting impact across the delivery
system to the impactor, in accordance with an embodiment of the invention.
DETAILED DESCRIPTION OF EMBODIMENTS
Reference is now made to Fig. 1, which illustrates the anatomy of a calcified
aortic valve, ascending aorta and aortic arch. Calcifications may be embedded and/or
superimposed on the valve leaflets, which are connected to the aortic wall just below the
coronary ostia. Of course, the invention is not limited to these calcifications.
Reference is now made to Fig. 2, which illustrates a calcified aortic valve. The
leaflets create concave sinuses on their aortic aspect, just below the coronary ostia.
Calcification can be either embedded or superimposed on the leaflets, making the leaflets
thicker and less pliable. Specifically, calcification that occurs at the leaflet base, i.e.
where the leaflet connects to the annulus or aortic wall, can significantly impair the
mobility of the leaflet.
Reference is now made to Fig. 3, which illustrates typical calcification patterns on
aortic valve leaflets. A "full-bridge" pattern, "half-bridge" pattern and scattered "pebbles"
are believed to be common forms of calcification in degenerated aortic stenosis of 3-
leaflet valves, although the invention is not limited to any pattern. The dashed lines show
the optimal fracture locations that need to be generated in order to maximize the increase
in open valve cross sectional area during systole. These locations include the bases of the
full-bridge and half-bridge patterns, close to the base of each leaflet, and the centerline of
the leaflet in a full-bridge pattern. Leaflets with pebble patterns do not usually obstruct
flow that much.
Reference is now made to Fig. 4, which illustrates the valve leaflets of Fig. 3 after
fractures were obtained. Both full-bridge and half-bridge patterns are broken into smaller
segments, allowing the leaflets to open during systole, creating a significantly larger
aortic valve area.
Reference is now made to Fig. 5, which illustrates an impactor catheter delivered
over a guidewire through a peripheral artery, over the aortic arch and into the aortic valve,
described in PCT Patent Application PCT/US20 10/0588 10 (WO 2011/069025), of the
inventor (and assigned to the current assignee) of the present invention. An impactor
element is opened below the aortic valve leaflets (ventricular aspect) and a stabilizer
element is opened above the leaflets. Both elements preferably then "sandwich" the
leaflets and the impactor is then pulled rapidly upwards to deliver mechanical impact to
the valve leaflets, while the opposing stabilizer holds the leaflets and counteracts the
force.
More specifically, a catheter 10 may be delivered over a guide-wire 11 through a
vessel, such as the peripheral artery, using a retrograde approach, through the aortic arch
and into the ascending aorta, just above the aortic valve. At this stage, all catheter
components are still covered by a catheter external shaft 12. The external shaft 12 is then
retracted so that an expandable (e.g., self-expanding) stabilizer 14, connected to a
stabilizer shaft 16, opens up. Stabilizer 14 is used to guide, position and anchor the
catheter distal part in the sinuses, just above the valve leaflets. It is noted that catheter 10
is just one example of a delivery system used to deliver and manipulate a stabilizer and
impactor arms described below to impact calcifications. Optionally, the stabilizer and
impactor arms described below may be delivered and/or manipulated by other devices
other than a catheter, such as a guidewire or system of guidewires and push/pull wires.
An impactor shaft 18, including impactor arms 20, is then pushed forward
(distally) through the center of the valve into the left ventricle. When pushed forward the
impactor arms 20 are folded so that they can easily cross the valve. An internal shaft 22,
which is connected to the distal portion of the impactor arms 20, is then pulled proximally
to cause the impactor arms 20 to open (expand) outwards sideways and lock them in the
expanded shape. Impactor and internal shafts 18 and 22 are then pulled back (proximally)
a bit in order for the impactor arms 20 to make good contact with the ventricular aspect of
the leaflets, so that the leaflets are "sandwiched" between the proximally-located
stabilizer 14 (from above in the sense of the drawing) and the distally-located impactor
arms 20 (from below in the sense of the drawing). In order to fracture leaflet
calcifications, impactor arms 20 are pulled abruptly towards the leaflet tissue, while the
stabilizer 14 holds the relevant portion of the leaflets in place, by pulling impactor and
internal shafts 18 and 22 at a speed of at least 1 m/sec, such as without limitation, around
5-20 m/sec, but with an amplitude of at least 0.5 mm, such as without limitation, about
0.5-3 mm, so that calcification is fractured but soft tissue is unharmed. The delivery of the
impactor and stabilizer elements can be done in a reverse manner. In such a case, the
impactor first crosses the valve and is opened in order to position and center the device.
The stabilizer is then opened in order to sandwich the leaflets, and then impact is
delivered.
The present invention seeks to provide improved structure over that described in
PCT/US2010/058810, both for impact and stabilization.
Reference is now made to Fig. 6, which illustrates the valve leaflets of Fig. 3 with
a preferred footprint (although the invention is not limited to this footprint) of both
impactor 70 and stabilizer elements 14S on the leaflets, in accordance with embodiments
of the invention described hereinbelow. The impactor, when in an open position,
preferably makes contact with the leaflets from below (the ventricular aspect), along the
regions marked as "IF", short for "impactor-footprint". The stabilizer element (such as a
stabilizer 80) preferably, but not necessarily, makes contact with the leaflets from above
(the aortic aspect) along the regions marked as "SF", short for "stabilizer-footprint". The
impactor and stabilizer elements can be brought closer together until the leaflets are
"sandwiched" by both elements. The impactor is then pulled rapidly towards the stabilizer
to deliver impact to the valve leaflets, creating a strong and rapid bending force between
opposing elements that can generate fractures in the calcifications. Any variation in the
impactor or stabilizer footprint, including an overlap/crossing of the footprints, increase
or decrease of the diameter of the impactor or stabilizer, etc., is possible.
Reference is now made to Fig. 7, which illustrates an impactor assembly 70,
having a "stent-like" impactor design, in accordance with an embodiment of the
invention, with a footprint similar to the impactor footprint presented in Fig. 6. Impactor
assembly 70 includes one or more impaction struts 72, which extend between proximal
structural struts 74 and distal structural struts 76. The "stent-like" impactor preferably, but
not necessarily, contacts the leaflets from their ventricular aspect using impaction struts
72. Impaction struts 72 run along the connection of the leaflet to the aortic wall, creating a
footprint on an area that, if not because of calcific deposits, would be flexible enough to
allow high mobility of the leaflets. The positions of distal structural struts 76 are
illustrated at about 120° apart, but the invention is not limited to this spacing. Fractures
along or near the footprint of the "stent-like" impactor results in a significant increase in
aortic valve cross sectional area during systole. The "stent-like" impactor may be used in
various rotational positions on the valve, preferably, but not necessarily, with proximal
structural struts 74 on the ventricular aspect of the commissures, which is the "natural"
rotational position of the impactor. Alternatively, the impactor can be rotated so that the
proximal structural struts contact the centerline of the valve's leaflets.
Reference is now made additionally to Figs. 8 and 9, which illustrate more views
of impactor assembly 70. The structure of the "stent-like" impactor is designed to allow
active self-positioning of the device on the aortic valve. Proximal structural struts 74 are
located higher than the impaction struts 72 and at an angle relative to the impaction struts
72, so that the proximal structural struts 74 position themselves just below the
commissures when the impactor 70 is pulled towards the valve. The positioning of the
proximal structural struts 74 below the commissures is due to stable equilibrium of
mechanical forces and therefore cannot be mistakenly altered.
The impaction struts 72, as well as stabilizer 14S (Fig. 6), that is, the portions
where the impact takes place, are preferably shaped in accordance with a shape of the
desired fracture site, e.g., leaflet bases (close to the annulus) and central folding lines of
the native valve. Accordingly, the shapes of the impaction struts and of the stabilizer may
include portions with a bicuspid shape, a tricuspid shape, or a semilunar shape, and may
additionally have a portion with a depression corresponding to the folding lines,
depending on the valve to be treated, Due to these predetermined shapes, impactor 70, by
impacting against the stabilizer 14S, is able to generate fractures along the leaflet bases
(close to the annulus) and central folding lines of the valve. This is in contrast with the
prior art wherein fractures are not purposely made at these critical places, rather at other
places along the leaflets. This method of generating fractures along the desired fracture
site, e.g., the leaflet bases (close to the annulus) and central folding lines, can provide
significant improvement in the ability to efficiently fracture calcifications within a
relatively short procedure time. In addition, as mentioned, impactor 70 and stabilizer 14S
(Fig. 6) have predetermined shapes that self-position the device with respect to the valve.
Reference is now made to Figs. 10-12, which illustrate a stabilizer assembly 80, in
accordance with an embodiment of the invention. Stabilizer assembly 80 may include a
shaft 82, from which extend a plurality of arms 84 (three are shown, spaced 120° apart, in
the non-limiting illustrated embodiment). Distal portions of arms 84 include a full bridge
section 86 which terminates in a pair of half bridge sections 88. Stabilizer assembly 80
may be considered to have an "M" stabilizer design with a footprint similar to the
stabilizer footprint presented in Fig. 6. The "M" stabilizer preferably, but not necessarily,
contacts the leaflets from their aortic aspect using full bridge sections 86 and half bridge
sections 88. The half bridge section 88 is positioned on the bases of the leaflets so as to
counteract the impactor (such as impactor 70 of Fig. 7) in order to break calcific deposits
mainly along the base of the leaflet (its connection to the aortic wall). The full bridge
section 86 is positioned on the centerline of the leaflets in order to break calcific deposits
mainly along the central folding line of the leaflets.
The "M" stabilizer can be positioned in various rotational positions on the valve,
preferably, but not necessarily, with its full bridge section 86 along the centerline of the
leaflet or with its full bridge section 86 on the commissures so that each half bridge
section 88 is touching two leaflets at a time.
Reference is now made to Figs. 13-15, which illustrate a stabilizer assembly 90, in
accordance with another embodiment of the invention. Stabilizer assembly 90 may
include a double layer stabilizer design, including an external layer 92 which pulls an
internal layer 94 and forms a flower shaped stabilizer with two "petals" on each valve
leaflet. The double layer stabilizer may be operated in various rotational positions and
thus can achieve multiple footprints on the valve in order to generate a significant amount
of calcium fractures. The double layer stabilizer is preferably positioned on the aortic
aspect of the valve and is capable of fracturing calcific deposits located in the bases of the
leaflets and in the central folding line of the leaflet. The extent of pulling of the external
layer determines the stabilizer' s diameter.
Reference is now made to Figs. 16-18, which illustrate a stabilizer assembly 100,
in accordance with another embodiment of the invention. Stabilizer assembly 100 may
include a "basket" stabilizer design, including one stabilizer arm 102 on each valve
leaflet. Each stabilizer arm 102 includes a proximal structural strut 104 from which
extends a distal structural strut 106. A rounded stabilizing tip 108 is positioned at the
junction of proximal structural strut 104 and distal structural strut 106, and another
rounded stabilizing tip 108 is positioned at the junction of all the proximal structural
struts 104. The "basket" design can be rotated to multiple positions and can increase
and/or decrease its diameter. Hence, this stabilizer is capable of touching any point on the
valve and to counteract the impact delivered by the impactor at any selected location on
the valve. The "basket" stabilizing tips 108 are fully rounded and have excellent safety
properties in addition to high rigidity and counteracting attributes.
Reference is now made to Figs. 19-21, which illustrate a stabilizer assembly 110,
in accordance with another embodiment of the invention. Stabilizer assembly 110 may
include a "rose" or "rose-petal" stabilizer design, including a plurality of structural struts
112 (for each valve leaflet). The structural struts 112 extend into curved, twisted, half
bridge stabilizing struts 114, which in turn extend into full bridge stabilizing struts 116. A
rounded stabilizing tip 118 is positioned at the junction of extensions of the full bridge
stabilizing struts 116. The "rose" design can be rotated to multiple positions and can
increase and/or decrease its diameter. Hence, this stabilizer is capable of touching any
point on the valve and to counteract the impact delivered by the impactor at any selected
location on the valve. The half bridge stabilizing struts 114 are fully rounded and have
excellent safety properties in addition to high rigidity and counteracting attributes.
Reference is now made to Fig. 22, which illustrates use of an external tip 120 of a
tube 122 for deploying the stabilizing assemblies of the present invention. The external
tip 120 of the tube 122 initially covers a stabilizer tube T (of any of the embodiments of
the invention). The external tip 120 may have an open distal end and is capable of
gradually moving forward (distally) and backwards on the stabilizer and stabilizer tube T.
When moving forward the external tip 120 covers more of the stabilizer structure and thus
reinforces it and allows a higher counteract force. It may also be pushed forward to
decrease the stabilizer diameter or to change the angle in which the stabilizer approaches
the valve. All of the mentioned actions can be reversed by pulling the external tip
backwards.
Reference is now made to Fig. 23, which illustrates a method of using various
impactor designs for increasing the open cross-sectional area of the valve during systole.
In this method the impactor (such as impactor 70) is inserted in a fully or partially closed
configuration through the valve in between the valve's leaflets and then is gradually
dilated to increase the open cross-sectional area of the valve. This method may be used
before or after impact has been delivered to the leaflets to increase the effect of valve
fractures on leaflet pliability, or without delivering impact to the valve. Impactor dilation
of the valve may enlarge present fractures, create new fractures, stretch the valve and its
immediate surroundings, separate fused commissures and soften calcific deposits within
the valve. The impactor dilation is designed so as not to obstruct blood flow from the left
ventricle towards the aorta, thus making rapid pacing unnecessary in this procedure. The
method of impactor dilation may also be designed for dilating other valves, such as the
mitral valve, for performing angioplasty on calcified plaque or for increasing the open
lumen cross-sectional area in vessels and other lumens in the human anatomy
Fig. 23 also illustrates a method of using various impactor designs for measuring
the real valve diameter, in accordance with an embodiment of the invention. In this
method the impactor (such as impactor 70) is inserted in a fully or partially closed
configuration through the valve in between the valve's leaflets, and then is gradually
dilated to increase its size until the valve is fully open. Once the valve is open to a
sufficient extent, the impactor diameter (and thus the open cross-sectional diameter) can
be viewed on the operating catheter handle. The method of impactor sizing gives a real,
in-situ measurement of the valve and may help in determining future prosthesis sizes or in
other optional therapies. The method of impactor sizing may also be designed for sizing
other valves, such as the mitral valve, for measuring the surroundings of the valve
(annulus, aorta), for measuring open lumen cross-sectional areas in healthy or partially
obstructed vessels or for measuring the cross-sectional area of other lumens in the human
anatomy.
Reference is now made to Figs. 24A-24B, which illustrate the inner lumen of the
impactor and delivery system, and demonstrates its ability to take pressure measurements
from the ventricular and aortic aspects of the aortic valve. The impaction struts 72 of
impactor 70 may be mounted around an internal sealed shaft 73. The internal sealed shaft
73 has a lumen 75 that extends from the proximal to the distal part of the catheter. In the
proximal side, lumen 75 continues all the way to a delivery system handle 79, wherein
lumen 75 may terminate in a connection point 81, which is connected to a pressure gauge
77 that indicates the pressure present in the distal part of lumen 75.
By allowing blood to enter the lumen the pressure gauge is affected by the blood
pressure and thus can indicate the real-time blood pressure at the distal end of the internal
sealed shaft. The use of this method makes it unnecessary to use a pigtail for left ventricle
pressure measurements. The method of internal sealed shaft pressure measurement may
also be designed for measuring the pressure across other valves, such as the mitral valve,
or for measuring the pressure in other lumens in the human anatomy.
Reference is now made to Figs. 25-27, which illustrate a stabilizer assembly 150
with cushions or shock absorbers 152 on stabilizing struts 154, in accordance with an
embodiment of the invention. Shock absorbers 152 are disposed on the distal portions of
half bridge stabilizer sections. Shock absorbers 152 may be made of any suitably soft
material, such as an elastomer or soft plastic, for example.
Reference is now made to Figs. 28-30, which illustrate a stabilizer assembly 160
with cushions or shock absorbers 162 on stabilizing struts, in accordance with another
embodiment of the invention. In this embodiment, shock absorbers 162 are disposed as
full "webs" on the half bridge stabilizer sections and the bridge stabilizer sections.
Reference is now made to Fig. 31, which illustrates a stabilizer assembly 170 with
cushions or shock absorbers 172 on stabilizing struts, in accordance with yet another
embodiment of the invention. In this embodiment, shock absorbers 172 are constructed
from a stretchable material, such as a stretchable plastic, that extends outwards like an
umbrella or canopy when deployed out of the stabilizer tube 122. These absorbers can
also be used as capturing means in case embolic debris is created on the aortic aspect of
the valve during valve manipulation or impact.
Reference is now made to Fig. 32, which illustrates a "parachute" embolic
protection structure (filter) 150, capable of deflecting debris in the blood stream away
from the carotid-aortic arch junction. The "parachute" embolic filter 150 includes an
external operating tube 152, a porous sleeve (the "parachute") 154 and cords 156 that
connect the "parachute" 154 at a connection area 156 to the distal part of the external tube
152. The embolic protection filter 150 is activated once the operating tube 152 is pulled
backwards in the direction of arrow 157 (towards the proximal side); the parachute sleeve
154 then opens due to the blood flow. Once the "parachute" 154 is open the aortic arch is
covered by the porous filter 150 and the blood that flows into the carotid arteries is
filtered. The debris, if present, is thus deflected to the descending aorta, making it
impossible for the debris to obstruct blood flow to the brain.
Reference is now made to Fig. 33, which illustrates the components and methods
of transmitting impact across the delivery system to the impactor. In this figure two layers
(also called impactor and stabilizer assemblies) are presented: the internal layer 200
consisting of an internal tube 202 and impactor tube 204, and the external layer 206
consisting of a stabilizer tube 208 and an external tube 210. Each layer is designed to
effectively counteract the other.
The internal layer 200 is preferably constructed of a material with negligible
elongation, such as but not limited to, a bundle of stainless steel wires. The external layer
206 is preferably constructed of a material with negligible compression, such as but not
limited to, a braided stainless steel mesh coated with a polymer, such as polyamide 12
(e.g., VESTAMID). Friction between the layers may be minimized by coating the inner
surface of the external layer 206 with polytetrafluoroethylene.
The internal layer 200 is initially pre-tensioned against the external layer 206, with
the valve tissue pinched (preferably gently pinched) therebetween. This creates a static
pre-loaded mechanical force on both layers. Impact is delivered by a rapid and short
deflection of the internal layer 200 towards the external layer 206. The internal layer 200
is rapidly pulled, such as by mechanical impact, so that the internal layer 200 is further
squeezed against the external layer 206. This causes the impactor to impact the valve
which then encounters the external layer's counteracting force. The counteracting forces
of the external and internal layers result in fractured calcific deposits along and in
proximity the footprints of the impactor and stabilizer. The ability to transmit impact
across a full catheter is due to, inter alia, the internal layer's negligible elongation, the
external layer's negligible compression, both layers' resistance to impact and negligible
friction between layers. The internal layer's negligible elongation means the internal layer
transmits the full force of the impact with negligible losses due to strain or stress on the
internal layer's material. The external layer's negligible compression means the external
layer can act as an excellent anvil to bear the brunt of the impact with negligible losses
due strain or stress on the external layer's material. Another parameter that helps to
achieve efficacious impact is both layers' pre-tensioning towards each other.
CLAIMS
What is claimed is:
1. A device for fracturing calcifications in heart valves characterised by:
a stabilizer assembly and an impactor assembly assembled on and deployed by a
delivery system, wherein said delivery system is operable to cause relative motion
between said impactor assembly and said stabilizer assembly with sufficient energy so as
to fracture a calcification located in tissue which is sandwiched between said stabilizer
assembly and said impactor assembly,
wherein said impactor assembly and said stabilizer assembly have shaped impact
delivery portions of which the footprint on the valve leaflets is shaped in accordance with
a shape of desired fracture sites.
2. The device according to claim 1, wherein said footprint of said shaped impact
delivery portions is arranged to be located in proximity to valve leaflet bases or
radial/central folding lines of valve leaflets.
3. A device for fracturing calcifications in heart valves characterised by:
a stabilizer assembly and an impactor assembly assembled on and deployed by a
delivery system, wherein said delivery system is operable to cause relative motion
between said impactor assembly and said stabilizer assembly with sufficient energy so as
to fracture a calcification located in tissue which is sandwiched between said stabilizer
assembly and said impactor assembly,
wherein said impactor assembly comprises impaction struts and structural struts
distanced and tilted relative to each other for self-positioning with respect to a valve
structure.
4. The device according to claim 3, wherein said impaction struts and structural
struts are distanced and tilted relative to each other for self-centering with respect to the
valve structure.
5. A device for fracturing calcifications in heart valves characterised by:
a stabilizer assembly and an impactor assembly assembled on and deployed by a
delivery system, wherein said delivery system is operable to cause relative motion
between said impactor assembly and said stabilizer assembly with sufficient energy so as
to fracture a calcification located in tissue which is sandwiched between said stabilizer
assembly and said impactor assembly,
wherein said stabilizer assembly comprises shock absorbers.
6. The device according to claim 1 or 3, wherein said stabilizer assembly comprises
multiple layers, movable with respect to each other, such that moving one layer with
respect to the other changes the shape of said stabilizer.
7. The device according to claim 1 or 3, wherein said stabilizer assembly comprises
a plurality of stabilizer arms, and wherein each stabilizer arm comprises a proximal
structural strut from which extends a distal structural strut, and a rounded stabilizing tip is
positioned at a junction of each of said proximal and distal structural struts.
8. The device according to claim 1 or 3, wherein said stabilizer assembly comprises
a plurality of structural struts that extend into curved, twisted, half bridge stabilizing
struts, which in turn extend into full bridge stabilizing struts.
9. The device according to claim 1 or 3, further comprising an embolic protection
structure.
10. The device according to claim 1 or 3, wherein said impactor assembly is mounted
on a shaft constructed of a material having negligible elongation, and said stabilizer
assembly is mounted on a shaft constructed of a material having negligible compression.
11. A method comprising:
reducing calcification on a cardiac valve by generating fractures along leaflet
bases and folding lines of the valve.
12. A method of delivering mechanical impact over a catheter, comprising:
using a first shaft assembly and a second shaft assembly, said first shaft assembly
being constructed of a material with minimal elongation properties and said second shaft
assembly being constructed of a material with minimal compression properties, and
wherein both shaft assemblies are pre-loaded with static mechanical force and then said
first shaft assembly is rapidly pulled against said second shaft assembly.