U.S. patent application number 16/139385 was filed with the patent office on 2019-06-06 for functional element, in particular fluid pump, having a housing and a conveying element.
The applicant listed for this patent is ECP ENTWICKLUNGSGESELLSCHAFT MBH. Invention is credited to Mario Scheckel.
Application Number | 20190170153 16/139385 |
Document ID | / |
Family ID | 41682600 |
Filed Date | 2019-06-06 |
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United States Patent
Application |
20190170153 |
Kind Code |
A1 |
Scheckel; Mario |
June 6, 2019 |
FUNCTIONAL ELEMENT, IN PARTICULAR FLUID PUMP, HAVING A HOUSING AND
A CONVEYING ELEMENT
Abstract
The invention relates to a fluid pump (1) having a housing (5)
delimiting a fluid chamber (13) and having a conveying element (8)
for the fluid disposed in the fluid chamber, the housing (5), with
respect to the shape and/or size thereof, being able to be changed
between at least a first, expanded state and a second, compressed
state. The object, to stabilise adequately a corresponding housing,
is achieved according to the invention by the housing having at
least one stabilisation chamber (19, 20, 25, 26, 31) which can be
supplied with a fluid pressure and is different from the fluid
chamber, the first state of the housing being assigned to a first
fluid pressure in the stabilisation chamber and the second state of
the housing being assigned to a second fluid pressure.
Inventors: |
Scheckel; Mario; (Berlin,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ECP ENTWICKLUNGSGESELLSCHAFT MBH |
Berlin |
|
DE |
|
|
Family ID: |
41682600 |
Appl. No.: |
16/139385 |
Filed: |
September 24, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13261216 |
May 17, 2012 |
10107299 |
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PCT/EP2010/005865 |
Sep 22, 2010 |
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16139385 |
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61244608 |
Sep 22, 2009 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61M 1/122 20140204;
A61M 1/1098 20140204; A61M 1/101 20130101; A61M 1/1024 20140204;
Y10T 137/85978 20150401; A61M 1/1012 20140204; A61M 2205/0266
20130101; A61M 1/125 20140204; F04D 29/181 20130101; A61M 1/1034
20140204 |
International
Class: |
F04D 29/18 20060101
F04D029/18 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 22, 2009 |
EP |
09075439.1 |
Claims
1-21. (canceled)
22. A fluid pump comprising: a catheter; a rotor; an expandable
housing defining an inner chamber configured to receive the rotor,
the housing configured to transition between a compressed state and
an expanded state within a blood vessel, the housing having an
outflow opening connected to the catheter and an inflow opening
positioned distal of the outflow opening, wherein an outer diameter
of the housing is smaller than an inner diameter of the blood
vessel when the housing is in the expanded state, wherein the
housing comprises an inner wall and an outer wall, wherein the
rotor is disposed within the inner chamber and configured to be
radially compressed by the inner wall when the housing is in the
compressed state; and a one-way inflow valve positioned distal to
the rotor.
23. The fluid pump according to claim 22, wherein the fluid pump
further comprises an one-way outflow valve positioned proximal of
the inflow valve.
24. The fluid pump according to claim 23, configured such that,
during operation of the pump, fluid is suctioned in through the
inflow opening and out through the outflow opening.
25. The fluid pump according to claim 23, wherein the outflow valve
comprises outflow valve flaps configured to prevent fluid flow from
the catheter to the inner chamber.
26. The fluid pump according to claim 22, wherein the inflow valve
comprises inflow valve flaps configured to prevent fluid flow from
exiting the inner chamber in a direction distal to the inflow
valve.
27. The fluid pump according to claim 22, wherein the housing
comprises the inflow valve.
28. The fluid pump according to claim 22, further comprising an
elongate hose comprising a proximal end and a distal end, the
proximal end of the elongate hose connected to the inflow opening
of the housing and the distal end of the elongate hose configured
to extend distally into a ventricle of the patient.
29. The fluid pump according to claim 28, wherein the elongate hose
comprises the inflow valve.
30. The fluid pump according to claim 28, wherein the housing is
configured to be positioned within an aorta and a distal end of the
elongate hose is configured to extend distally across the aortic
valve.
31. The fluid pump according to claim 22, wherein at least one of
the inner and outer wall is configured to contract elastically from
the expanded state into the compressed state,
32. The fluid pump according to claim 22, the fluid pump further
comprising at least one expandable stabilization chamber, wherein a
change in inflation pressure of at least one of the inner chamber
or the at least one expandable stabilization chamber corresponds to
a transition between the compressed state and the expanded
state.
33. The fluid pump according to claim 32, wherein the at least one
expandable stabilization chamber is disposed between the inner wall
and the outer wall.
34. The fluid pump according to claim 32, wherein the at least one
expandable stabilization chamber is configured to be supplied with
a fluid pressure, wherein the compressed state of the housing
corresponds to a first fluid pressure in the expandable
stabilization chamber and the expanded state of the housing
corresponding to a second fluid pressure in the expandable
stabilization chamber, wherein the second fluid pressure is higher
than the first fluid pressure.
35. The fluid pump according to claim 32, wherein the at least one
expandable stabilization chamber comprises an expandable region,
the expandable region having a distal end and a proximal end, and
wherein a distal end of the rotor is positioned proximal to the
distal end of the expandable region when the housing is in the
compressed state.
36. The fluid pump according to claim 22, wherein the rotor
comprises at least one blade, the blade being flexible elastically
radially towards the rotor axis.
37. The fluid pump according to claim 36, wherein the rotor
consists at least partially of a volume-compressible material.
38. The fluid pump according to claim 32, wherein the rotor is
designed to be hub-free.
39. A fluid pump comprising: a catheter; a rotor; an expandable
housing defining an inner chamber configured to receive the rotor,
the housing configured to transition between a compressed state and
an expanded state within a blood vessel, the housing having an
outflow opening connected to the catheter and an inflow opening
positioned distal of the outflow opening, wherein an outer diameter
of the housing is smaller than an inner diameter of the blood
vessel when the housing is in the expanded state, wherein the
housing comprises an inner wall and an outer wall, wherein the
rotor is disposed within the inner chamber and configured to be
radially compressed by the inner wall when the housing is in the
compressed state; and a one-way outflow valve positioned proximal
to the rotor.
40. The fluid pump according to claim 39, wherein the outflow valve
comprises outflow valve flaps configured to prevent fluid flow from
the catheter to the inner chamber.
41. The fluid pump according to claim 39, wherein the housing
comprises the outflow valve.
42. The fluid pump according to claim 39, further comprising an
elongate hose comprising a proximal end and a distal end, the
proximal end of the elongate hose connected to the inflow opening
of the housing and the distal end of the elongate hose configured
to extend distally into a ventricle of the patient.
Description
[0001] The present invention resides in the field of mechanical
engineering, in particular micromechanics, and can be used with
functional elements which are used to convey or influence
fluids.
[0002] The invention can be used particularly advantageously in
medical technology, where it is made to work, in particular in
invasive medicine, on body fluids, for example blood. For this
purpose, micromechanical functional elements, for example pumps,
are known, which have such a small construction that they can be
conveyed through a blood vessel. Pumps of this type can be operated
within a blood vessel itself or in a ventricle.
[0003] In order to enable a particularly efficient and effective
operation, it is known to design such functional elements such that
they have a compressed state in which they can be moved through a
bloodstream and also an expanded or dilated state which they can
adopt for example after introduction into a ventricle or another
body cavity. In this expanded state, for example a pump can then
have a rotor and a housing which apply sufficient pump power by
means of their size and nevertheless can be introduced in the
compressed state into the body and removed again therefrom.
[0004] Various techniques are known for compressing or expanding
such pumps. For example, so-called shape memory materials in the
form of alloys are used, one of which is known by the trade name
Nitinol, the corresponding components generally adopting various
geometric shapes as a function of temperature. The type of
construction can be designed such that a first dimensional size is
adopted in a first state of a Nitinol frame, whilst a second size
is achieved in a second state at a different temperature. For
example in the case of pumps, both the housings and the rotors can
in principle be compressed and expanded in this way.
[0005] However pumps without rotors which transport a fluid by
expulsion by means of volume changes are also known. Such a pump is
known for example from DE 10 2007 012 817 A1. Use of such a
toroidal pump is known there for assisting the heart, the pump
being inserted in a blood vessel. The housing has a stable external
shape but can be folded up. The whole pump is designed as a double
chamber hollow body, a balloon which can vary within the housing
effecting the volume change of a pump volume and hence suctioning
in and expelling fluid. With respect to the type of housing and in
addition in what manner this housing is compressible, nothing is
stated in the document.
[0006] A pump is known from the public inspection document 4124299
A1, which has a housing which can be filled with a fluid and
consequently stiffened and also a conveying element which can be
pumped up therein so that alternately fluid in the housing interior
can be suctioned in and expelled.
[0007] Similar pumps are known from U.S. Pat. Nos. 5,820,542 and
5,827,171.
[0008] U.S. Pat. No. 5,928,132 discloses a pump with an expandable
housing which can be stiffened by means of fluid-filled
cavities.
[0009] Against the background of the state of the art, the object
underlying the invention, in the case of a pump having a fluid
chamber and a housing delimiting the latter and also a conveying
element disposed in the fluid chamber, is to design the housing
such that it can be compressed with respect to the radius and, on
the other hand, can be expanded and, in the expanded state, has as
high stability as possible.
[0010] The object is achieved by the features of the invention
according to patent claim 1.
[0011] In the case of a pump of the initially mentioned type, the
housing, with respect to the shape and/or size thereof, can be
changed between at least a first, expanded state and a second,
compressed state, as a result of the fact that it has at least one
stabilisation chamber which can be supplied with a fluid pressure
and is different from the fluid chamber, the first state of the
housing being assigned to a first fluid pressure in the
stabilisation chamber and the second state of the housing to a
second fluid pressure.
[0012] The different filling or pressure supply to the
stabilisation chambers effects different material stresses in the
wall/the elastic walls of the housing. For example, the
stabilisation chamber or a plurality of stabilisation chambers can
be recessed on the housing walls, and this will typically lead to
the fact that, at low pressure in the stabilisation chambers, the
housing contracts elastically and relaxes, the housing walls become
moveable and the housing diameter is reduced both with respect to
the outer diameter and with respect to the inner diameter. For this
purpose, at least the inner and/or the outer wall of the housing
which directly surrounds the conveying element and, for its part,
is possibly surrounded by stabilisation chambers or one
stabilisation chamber has an elastic configuration. In the case of
increased pressure, the stabilisation chambers become taut and
hence the walls are for the moment widened and stiffened so that
the housing expands. The states can however also be chosen such
that the walls of the housing have pre-tensions which lead to the
fact that, in the case of a high pressure application to the
stabilisation chamber(s), compression of the housing is effected,
whilst, at low pressure in the stabilisation chambers, expansion of
the housing is effected due to the inherent stress of the housing
walls.
[0013] It can thereby be advantageously provided that, in the
second state, the diameter of the housing is reduced by the
inherent elasticity to such an extent that the interaction element
in its expanded state is compressed radially.
[0014] Hence, the elastic compression effect of the housing
facilitates the compression of the interaction element, for example
a fluid conveying element. This can have for example the form of a
pump rotor.
[0015] The cavity or cavities can be provided as recesses in a
solid housing wall or as intermediate space/spaces between two
spaced layers of the housing wall--i.e. between an inner wall and
an outer wall. Inner wall and outer wall can have an equally
elastic configuration or differently elastic configuration. The
outer wall can thereby have a more flexible configuration than the
inner wall or the inner wall have a more flexible configuration
that the outer wall.
[0016] The elasticity of the housing wall in total is advantageous
such that the housing contracts elastically and without folds from
the expanded state with a first inner diameter at least to half, in
particular to a third, of the first diameter, when the inner
pressure and also the pressure in the stiffening chambers is
reduced. During compression, the housing hence makes a decisive
contribution to the compression of the conveying element, in
particular of the rotor.
[0017] The housing wall can be designed for example as an open-pore
foam, the pores on the inner and outer side of the wall being
closed, e.g. by welding or be a separate coating. If the expansion
of the cavities is intended to take place by a material transport
by diffusion or the like, then the open-pore foam can also be
covered by a semipermeable membrane.
[0018] The structure of the cavities can also be such that a first
group of cavities is open towards one of the walls of the housing,
e.g. in the form of access channels or as open-pore foam, and such
that one or more cavities of a second group are embedded in the
first group, respectively one semipermeable membrane being provided
between the first and the second chambers. For example, the
semipermeable membrane can surround respectively one or more
cavities of the first group or of the second group.
[0019] As partially permeable membrane for delimiting cavities,
there can be used, according to the used filling materials for the
cavities and the materials which are intended to be allowed through
or held back, membranes of microfiltration (0.5-0.1 .mu.m particle
size), ultrafiltration (0.1-0.01 .mu.m particle size) and
nanofiltration (1-10 nm). Independently of the particle size,
basically biological or synthetic membrane materials can be used
(as biological materials, for example Cuprophan, Hemophan or
cellulose triacetate, as synthetic membrane for example Teflon or
Goretex).
[0020] Synthetic materials in general have a higher water
permeability and are themselves often hydrophobic. There can be
used as synthetic materials, polysylphone, polyamide,
polyacrylonitrile and also copolymers thereof and also
polymethylmethacrylates, polytetrafluoroethylene and derivatives
thereof.
[0021] High-flux membranes are advantageously used, which allow
through molecules up to a molecular weight of 50,000 Dalton and
which ensure rapid material transport.
[0022] Advantageously, the material is chosen such that it retains
germs/bacteria/microorganisms preventing contamination or
infection.
[0023] Either a gas or a liquid, in particular a biocompatible
liquid such as salt solution, can thereby be chosen as fluid for
filling cavities/stiffening chambers/stabilisation chambers.
Advantageously, the housing can have the shape of a hollow
cylinder, a toroid or a hollow spheroid at least in portions. Such
a shape basically leads to good usability of the housing in a body
since these shapes can basically be moved easily through a
naturally occurring body vessel. A rotational-symmetrical shape is
possible in particular if the housing is used for a fluid pump. The
housing is normally sealed at the ends, either by flat end-sides or
by sealing surfaces which are conical or rotational-symmetrical in
another way and have corresponding inflow/outflow openings.
[0024] The stabilisation chamber can be provided particularly
efficiently in the form of a cavity which is strand-shaped in the
first housing state. In this case, the stabilisation chamber forms
a stabilisation web as it were in the housing wall in the case of
high pressure application. Hence, a relatively small quantity of
fluid is required in order to fill the stabilisation chamber(s) and
to stabilise the house. Advantageously, a plurality, in particular
three or more stabilisation chambers, can be provided in the form
of strand-shaped cavities. These can be distributed symmetrically
in the housing.
[0025] It can also be provided advantageously that at least one
strand-shaped cavity (viewed in the expanded state of the housing)
has a circumferential configuration in the circumferential
direction of the hollow cylinder, toroid or hollow spheroid. In
this case, a particularly efficient stabilisation structure for the
housing is produced, which counteracts in particular a compression
of the housing during pressure application to the stabilisation
chamber. This is particularly advantageous when the functional
element is designed as a fluid pump and a suction pressure is
produced within the housing at least at times in order to suction
in body fluid, in particular blood. At this moment, the housing is
sensitive to the tendency to collapse and must in particular be
stabilised relative to this compression. Also a toroidal or hollow
cylinder-shaped body can be provided as stabilisation chamber.
[0026] Alternatively or additionally to a strand-shaped cavity as
stabilisation chamber, which extends in circumferential direction,
one or more strand-shaped cavities can extend parallel to the
longitudinal axis of the hollow cylinder, toroid or hollow spheroid
in the wall thereof. In this way, a stabilisation grating can be
formed, which, at a low total volume of the stabilisation chambers,
allows good stabilisation and a good, i.e. a high ratio, between
the radius of the housing in the expanded state and the radius in
the compressed state.
[0027] It can also advantageously be provided that the
stabilisation chamber essentially fills the space of the housing
wall. As a result, the structure of the housing is simplified and
this can be filled or also emptied again rapidly and without
complication by pressure application. The housing can then have for
example the shape of a hollow-walled balloon.
[0028] In many case, it can be provided for stabilisation that the
corresponding cavities are penetrated by webs of the housing
material. In this way, stabilisation of the housing even relative
to a relative movement of inner and outer walls is achieved.
[0029] On its housing, the fluid pump has an inflow opening and an
outflow opening which can be provided respectively with a valve, in
particular a one-way valve. It can be ensured in this way that the
function is optimised during use as a pulsating pump with a suction
phase and an expulsion phase. Body fluid is then suctioned in
through the inflow opening, whilst this is conducted out through
the outflow opening in the expulsion phase.
[0030] Basically, such a housing can also be provided with a
conveying element which is designed as rotor with at least one
blade for the fluid. It can thereby be provided that the conveying
element is radially compressible by folding in, folding up or
collapsing the conveying blades.
[0031] The blade/blades can thereby be flexible elastically
radially towards the rotor axis.
[0032] However, the rotor can also consist at least partially of a
volume-compressible material, in particular a foam.
[0033] Additionally or alternatively to the housing, the rotor can
likewise have compressible cavities.
[0034] The rotor can thereby also be configured without a hub, the
blade being stabilised in a self-supporting manner as conveying
surface and transmitting the torque.
[0035] In connection with the present invention, the advantage of a
compressible rotor resides in the fact that the latter is at least
partially compressed already by the contraction of the housing so
that no high additional forces require to be applied when the fluid
pump must be moved through a blood vessel in a body.
[0036] A further advantage of the elastic contraction of the
housing resides in the fact that the forces act regularly radially
inwards on the rotor. If the housing collapses when it is merely
relaxed, then the effect on the rotor is not reproducible.
[0037] Advantageously, it can also be provided that the conveying
element is designed as a fluid-fillable hollow body/balloon which
can hence be changed with respect to its volume. Hence, it is
achieved that expulsion in the interior/fluid chamber of the
housing takes place with pressure application to the hollow body so
that the fluid situated there is expelled. If the pressure
application to the hollow body is reduced, then the latter is
compressed by the elasticity of its walls and frees additional
volume in the housing so that fluid from outside is suctioned into
the fluid chamber of the housing.
[0038] Hence a pulsating pump is produced for conveying the fluid.
Advantageously, the conveying element in the filled form can
essentially fill the fluid chamber of the housing. Hence, the
stroke of the pump is optimised when fluid is suctioned in and
expelled.
[0039] Advantageously, the conveying element can be filled with the
same fluid as the stabilisation chamber(s). Since both the
stabilisation chamber(s) and the conveying element must be supplied
with pressure after introduction of the functional element into the
body, great simplification is produced if the same fluid can
thereby be used. Normally, a biocompatible fluid, for example a
salt solution, is used. However, also the use of a gas, for example
a bioinert gas such as helium, is conceivable.
[0040] Handling is further simplified by the conveying element and
the stabilisation chambers of the housing being able to be
connected to the same fluid pressure source.
[0041] The object of the invention, to produce a fluid pump having
a compressible housing, is also achieved by the following
functional element. Involved hereby is a fluid pump having a
housing delimiting a fluid chamber and having a conveying element
for the fluid disposed in the fluid chamber, both the housing and
the conveying element, with respect to the shape and/or size
thereof, being able to be changed between at least a first,
expanded state and a second, compressed state, the average change
in density of the housing material between the first and the second
state being at least 10%.
[0042] There is hereby meant the average change in density of the
housing material at constant temperature, for example 36.degree. C.
The local change in density of the housing can vary greatly, what
is crucial is the average change in density of the housing
material, this housing material not requiring at all to be
homogeneous, but rather for example metallic parts can also be a
component here which would then have a correspondingly smaller
change in density.
[0043] Preferably, reversibly or even irreversibly deformable
materials should be provided here, which, because of an osmotic
mode of operation in the decompressed state, have a greater
volume/smaller density, or foams which have a smaller density in
the decompressed state. These foams can be open-pore or
closed-pore.
[0044] The housing is preferably distinguished by a material
mixture or a material which can be converted by compression from a
first, lower density or from a first, lower specific weight to a
second, higher density or a higher specific weight. The cavities
can thereby be closed and filled with a gas, such as for example
air or nitrogen, or a noble gas or another bioinert gas which can
be compressed easily in volume by pressure.
[0045] Such closed cavities tend to expand again in the absence of
an external pressure force due to the gas elasticity so that the
housing, as soon as it is brought to the place of use, can unfold
again automatically. At least the unfolding movement is assisted
however by the gas elasticity.
[0046] In addition, also gas lines to the housing can however be
provided, which gas lines end in one or more cavities and actively
allow the cavities to be pumped up. The gas for the compression can
possibly also be suctioned out via the same lines.
[0047] Likewise, the operation can take place with a liquid if this
is introduced into the cavities, if a liquid is situated in the
cavities, then this is normally very much less compressible but,
due to suitable choice of the viscosity in cooperation with the
remaining constructional parts of the housing, it can enable high
moveability and hence compressibility nevertheless support a
certain housing stability during operation due to the
incompressibility after unfolding of the housing.
[0048] The cavities can also have an open design, hence high
compressibility likewise being provided. The material which
delimits the cavities must then have a correspondingly elastic
configuration. This can be provided for example in the case of an
open-pore foam.
[0049] The invention can also be implemented advantageously by the
cavity/cavities being at least partially delimited by a partially
permeable membrane.
[0050] In this case, a cavity can be filled with a liquid which,
together with the membrane used and as a function of the liquid in
which the pump can be inserted, in particular human blood, allows
diffusion into the cavity as a result of osmosis, which leads to an
increase in pressure and to pumping-up of the housing.
[0051] Likewise, also materials can be used which, after coming in
contact with the liquid to be conveyed, lead to swelling processes
as a result of absorption of the liquid and hence assist
decompression of the housing via an increase in volume.
[0052] In the case of the osmosis process, filling the cavities
with a salt or a salt solution, the salt concentration of which is
higher than that of the liquids to be conveyed, is possible. For
this purpose, also semipermeable membranes which surround
fluid-filled stabilisation chambers at least partially and which
can be designed as biological or synthetic membranes, for example
cellulose-based, are then provided.
[0053] Advantageously, it can also be provided that at least the
predominant part of the cavities is surrounded by solid material of
the housing and connected via openings to the outside and/or to
each other. In this case, during compression, a fluid transport can
take place via the cavities and possibly also out of the housing so
that the corresponding cavities can be easily compressed
entirely.
[0054] The housing can consist for example partially of a porous
material, such as foam, in particular polyurethane. Such a foam can
be open- or closed-pore. In the case of an open-pore foam, the
elasticity is based on the supporting material which surrounds the
pores and moves after compression by itself back into its original
form, the gas or fluid being able to flow back into the pores. Due
to the limited flow cross-sections of the connections of the
cavities/pores to each other, a time constant in the
compression/decompression can be chosen within specific limits.
This can ensure, during operation of the pump, that sudden
deformations of the housing due to irregular mechanical loading are
counteracted.
[0055] It can be provided to produce such a housing by injection of
a foam into a pre-manufactured mould.
[0056] The invention is shown in a drawing and subsequently
described with reference to an embodiment in the following.
[0057] There are thereby shown
[0058] FIG. 1 an overview of the use of a fluid pump according to
the invention in a blood vessel,
[0059] FIG. 2 a longitudinal section through a fluid pump with a
compressed conveying element,
[0060] FIG. 3 a longitudinal section as in FIG. 2 with an expanded
conveying element,
[0061] FIG. 4 a longitudinal section through a housing with
stabilisation chambers,
[0062] FIG. 5 a cross-section through the construction according to
FIG. 4,
[0063] FIG. 6 a longitudinal section through a housing having a
further configuration of stabilisation chambers,
[0064] FIG. 7 a cross-section as indicated in FIG. 6,
[0065] FIG. 8 a longitudinal section through a hollow balloon-like
housing in spheroid form,
[0066] FIG. 9 a longitudinal section through the functional element
in total in compressed form,
[0067] FIG. 10 a fluid pump in longitudinal section having a pump
rotor,
[0068] FIG. 11 in a side view, a hub-free rotor and
[0069] FIG. 12 a detailed view of a pore structure.
[0070] FIG. 1 shows the functional element 1 in the form of a fluid
pump in a section, inserted in the human body. The fluid pump is
introduced by means of a hollow catheter 2 into a blood vessel 3
which leads to a ventricle 4. The housing 5 of the fluid pump is
connected to the interior of the ventricle 4 via a suction hose 6
which extends through the blood vessel 3 and the suction hose there
has one or more suction openings 7. The suction hose 6 is rounded
off at its end in the vicinity of the suction openings 7 in order
to avoid injuries to the interior of the heart.
[0071] Within the housing 5 of the fluid pump, a conveying element
8 in the form of a balloon is situated, in the present case
essentially in cylindrical form, which balloon is connected via a
pressure line 9 to a pressure source 10 outside the body. The
pressure line 9 extends through the hollow catheter 2 and both are
guided out of the blood vessel 3 to the outside of the body in a
lock, not represented.
[0072] The pressure source 10 is shown only schematically in the
form of a cylinder 11 and a piston 12 which is moveable therein,
the piston producing, during a pulsating movement, a likewise
pulsating pressure which leads to an alternating expansion and
compression of the conveying element 8.
[0073] As a result, the conveying element 8 in the interior of the
housing 5 takes up more or less space alternately so that, as a
countermove, more or less space remains available for the fluid to
be conveyed in the fluid chamber 13 of the housing 5. The fluid is
hence expelled and suctioned in by the conveying element 8 in a
pulsating manner.
[0074] By using valve flaps, the fluid flow is directed in the
desired form. In the illustrated example, valve flaps 14 are
provided in the suction line 6 and allow the fluid to flow in the
direction of the arrow 15. The valve flaps could be provided
equally well in the corresponding opening of the housing 5. Thereby
involved is a return- or one-way valve which allows the fluid to
flow in the direction of the arrow 15 but not to flow out in the
opposite direction. This leads to the fact that, during compression
of the conveying element 8, fluid, i.e. in particular blood, can be
suctioned via this path, but that this cannot flow out again there
during expansion of the conveying element.
[0075] Outflow flaps 16 which can be disposed for example directly
on the housing 5 and which likewise allow the fluid to flow out in
only one direction, namely in the direction of the arrow 17, are
provided for the outflow.
[0076] With cooperation of the valve flaps 14, 16, it is ensured
that the fluid is conveyed from the fluid pump only in the
direction of the arrows 15, 17.
[0077] The throughput of the fluid pump is determined, apart from
the residual power of the patient's heart as long as this is still
functioning, by the pulsating frequency of the conveying element 8,
on the one hand, and by the volume expelled respectively by the
conveying element or by the free volume remaining in the fluid
chamber 13. The conveyance is maximised when the conveying element
can expand to completely fill the fluid chamber 13 and thereafter
collapses so far that its interior is completely emptied. The
conveying element can consist for this purpose of a highly elastic
material which, after lowering the pressure in the pressure line 9,
ensures compression of the conveying element. This leads to a
pressure drop in the fluid chamber 13, as a result of which further
fluid is suctioned subsequently.
[0078] However, it is a prerequisite for functioning of this
mechanism that the housing 5 remains stable and does not collapse
even when producing a low pressure in its interior. This
requirement is connected, according to the invention, to the
further requirement that the housing must be compressible for
introduction and removal into and out of a body.
[0079] The invention provides for this purpose that the housing is
provided with at least one stabilisation chamber which stiffens the
housing as a result of pressure application.
[0080] In an extreme case, the entire housing can be configured
thereby as a double-walled balloon, the space between the balloon
walls being typically at a higher pressure, in the expanded state,
than the space of the blood vessel surrounding the housing. It can
also be provided that this pressure is higher than the pressure
prevailing at most in the conveying element and in the fluid
chamber.
[0081] FIG. 2 shows schematically the state of a fluid pump having
a hollow cylindrical housing 5 and a compressed conveying element 8
in the suction phase. The fluid chamber 13 is essentially filled
with the fluid flowing through the suction line 6.
[0082] The conveying element 8 has an essentially cylindrical form
and consists for example of rubber or polyurethane or an elastomer
with similar properties, the surface of the conveying element being
able to be coated with a material which, on the one hand, prevents
infections and, on the other hand, avoids accumulation of blood on
the surface. The same coating can be provided in the interior of
the housing 5 on the walls thereof.
[0083] The conveying element 8 is connected to a pressure source
via a pressure line 9 which is essentially designed not to be
expandable.
[0084] FIG. 3 shows the configuration of FIG. 2 in an expanded
state of the conveying element 8 in which the free residual space
of the fluid chamber 13 is minimised and the fluid/the blood can
flow out of openings 18 of the housing 5 through valve flaps
16.
[0085] It should be noted than the housing 5 with respect to its
outer diameter can be configured such that it does not completely
fill the clear opening of the blood vessel 3 so that, when inserted
into a body, blood can be conveyed through the vessel 3 by the
inherent function of the heart, in addition to the fluid pump.
However, it is also conceivable that the diameter of the blood
vessel is completely filled by a suitably chosen diameter also for
specific purposes.
[0086] In FIG. 4, the strengthening of the housing 5 by
stabilisation chambers is dealt with in more detail. In this
embodiment, a plurality of strand-shaped stabilisation chambers 19,
20 is aligned parallel to the longitudinal axis 21 of the housing 5
and disposed in We housing wall.
[0087] FIG. 5 shows a cross-section with seven such stabilisation
chambers. The individual stabilisation chambers are separated from
each other in this case and connected individually to a fluid
pressure source via pressure lines 22, 23, 24. The stabilisation
chambers can be supplied with pressure in order to stiffen the
housing 5. In order to introduce or remove the housing 5, they are
emptied so that the housing 5 can collapse on itself.
[0088] The stabilisation chambers can also be connected amongst
each other via a pressure line in order to ensure that the same
pressure respectively prevails in them and in order to simplify
filling and emptying.
[0089] FIG. 6 shows another arrangement of the stabilisation
chambers in the form of annular strands which are disposed
respectively coaxially to each other and to the housing 5. The
stabilisation chambers are designated with 25, 26. In the
embodiment, four of these stabilisation chambers are provided
equidistant from each other in the housing wall. They are connected
to a pressure source 29 by means of pressure lines 27, 28.
[0090] Such annular or even possible, helical stabilisation
chambers offer particularly good stiffening of the housing and,
during pressure application, a corresponding resistance to the
pulsating low pressure in the housing interior.
[0091] In the embodiment, the stabilisation chambers and the
conveying element 8 are connected to the same pressure source 29
via a multi-way control valve 30. As a result, the pressure source
29 can be used both for filling the stabilisation chambers and for
the pulsating pumping of the conveying element 8. FIG. 7 shows a
cross-section through the housing represented in FIG. 6 in
longitudinal section with a toroidal stabilisation chamber 26.
[0092] In FIG. 8, another concept of the housing within the scope
of the invention is represented, in which the housing wall is
double-walled, the two outer walls (balloon walls) have a very thin
design and the housing is hence constructed in the manner of a
balloon. The housing forms a double-walled balloon having a large
cavity 31 which can however be subdivided into a plurality of
partial chambers. Either thin intermediate walls are provided for
this purpose or, if no complete subdivision is desired, also only
individual reinforcing struts in the form of webs 32, 33 can be
provided. These ensure that inner wall and outer wall of the
balloon cannot perform shear movements relative to each other so
that the housing 5 in total is stabilised. The interior 31 is
connected to the pressure source 29 by means of a pressure line 34.
The housing 5 has in total the contour of a spheroid.
[0093] The stabilisation struts 32, 33 can typically consist of the
same material as the balloon walls of the housing 5 and be produced
in one piece with the latter. The struts can thereby surround the
housing 5 annularly or be configured as axis-parallel webs.
However, also any orientation, for example even a grating-shaped
structure, is conceivable.
[0094] Likewise, also in the above-described embodiments not only
is the concretely described orientation of the strand-shaped
stabilisations chambers conceivable but also a grating-shaped or
network-shaped structure there which penetrates a solid housing
wall.
[0095] In FIG. 9, finally the collapsed shape of the housing
represented in FIG. 8 is shown, the spheroid being collapsed. The
conveying element 8 must likewise be compressed of course for
introducing/removing the fluid pump into a blood vessel.
[0096] For removal of the fluid pump from the vessel, it can
provided that firstly the housing 5 is collapsed by reducing the
pressure in the stabilisation chambers and only thereafter is the
conveying element 8 emptied. As a result, an oblong shape is
produced when the housing 5 is folded up and the latter is
predominantly prevented from collapsing in the longitudinal
direction and hence adopting a higher cross-section. The elastic
contraction of the housing can thus also assist compression of the
conveying element.
[0097] By means of the invention, a functional element is formed
which is compressible to a high degree and nevertheless has the
necessary stability in operation to resist both low and high
pressures in a dimensionally stable manner during pulsating
pumping.
[0098] In FIG. 10, a housing 5 similar to that represented in FIG.
9 is shown, which however surrounds a pump rotor here, which
rotates about its longitudinal axis 40 and thereby conveys a fluid
axially. The blades 41 can thereby be secured individually to
branch off on a shaft 42 or also a helically circumferential blade
can be provided. The rotor is radially compressible and can be
manufactured for example from a framework comprising a memory
alloy, for example Nitinol, or from another elastic material. The
rotor can have open or closed cavities in the blades and/or the hub
which are elastically compressible. In FIG. 10, the inner wall of
the housing is designated with 46, the outer wall with 47. At least
the inner wall can be widened and contracted elastically. A
contracted state of the housing 5 is represented in broken lines
and the inner wall is designated with 43. This presses the blades
41', in the represented state, into a radially bent-in state so
that the entire rotor is already reduced in size by some distance
radially.
[0099] In FIG. 11, a hub-free rotor which can also be used is
represented and consists of a helically bent flat plate. This can
consist for example of an easily deformable or compressible
material, such as for example a sheet metal grating covered with
foil or a foam, the rotor which is represented as open-pore or
closed-pore is hub-free and self-supporting, i.e. the blade itself
transmits the torque and is only mounted outside rotatably and
connected to a driveshaft 44 (FIG. 10) which extends through a
hollow catheter 45.
[0100] FIG. 12 shows, in greatly enlarged, microscopic
representation, a housing material in the form of a foam 132 having
closed pores 128, 129, the material of the walls between the pores
being configured, in a variant (cavity 128), as a semipermeable
membrane.
[0101] Such a membrane allows the diffusion of specific liquids,
which can be used for example for an osmotic effect. If the
cavities/pores 128 are filled for example with a liquid in which a
salt in a highly concentrated form is dissolved and if the foam is
brought into a liquid which has a lower solution concentration,
then the combination tends to bring the concentrations of both
liquids to approximate to each other such that the solvent diffuses
from outside into the interior of the cavity 128 through the
membrane 130. As a result, an increased osmotic pressure is
produced and can be used to pump up the cavity 128 into the shape
represented in broken lines. As a result, an expansion and
stiffening of the foam can be achieved.
[0102] This effect can also be used specifically for larger
cavities in the housing. Alternatively, also swelling processes can
be used to expand the rotor.
[0103] In connection with the cavity 129, a hose 131 is represented
and symbolises that corresponding cavities can also be filled with
a fluid via individual or collective supply lines or that such a
fluid can be suctioned out of them in order to control
corresponding decompression/compression processes.
* * * * *