U.S. patent application number 10/239980 was filed with the patent office on 2003-05-22 for narrowing implant.
Invention is credited to Darvish, Nissim, Shalev, Ilan, Tsehori, Jonathan.
Application Number | 20030097172 10/239980 |
Document ID | / |
Family ID | 24132263 |
Filed Date | 2003-05-22 |
United States Patent
Application |
20030097172 |
Kind Code |
A1 |
Shalev, Ilan ; et
al. |
May 22, 2003 |
Narrowing implant
Abstract
A reducer implant for insertion in a blood vessel, for reducing
an inner diameter of said vessel and flow therethrough, having at
least one narrowed section having a first diameter; and at least
one flared section having a diameter substantially greater than
said first diameter. Optionally, the reducer is formed of a
material and has a geometry that does not cause coagulation of
blood in its vicinity.
Inventors: |
Shalev, Ilan; (Givatain,
IL) ; Tsehori, Jonathan; (Ramat-Gan, IL) ;
Darvish, Nissim; (Tzrufa, IL) |
Correspondence
Address: |
William H Dippert
Reed Smith
29th Floor
599 Lexington Avenue
New York
NY
10022-7650
US
|
Family ID: |
24132263 |
Appl. No.: |
10/239980 |
Filed: |
September 26, 2002 |
PCT Filed: |
March 27, 2001 |
PCT NO: |
PCT/IL01/00284 |
Current U.S.
Class: |
623/1.31 ;
623/1.15 |
Current CPC
Class: |
A61F 2230/0078 20130101;
A61F 2220/0075 20130101; A61F 2/88 20130101; A61F 2002/91525
20130101; A61F 2220/0016 20130101; A61F 2230/008 20130101; A61F
2002/018 20130101; A61F 2230/0069 20130101; A61F 2/01 20130101;
A61F 2002/91533 20130101; A61F 2/2475 20130101; A61F 2002/91558
20130101; A61F 2230/005 20130101; A61F 2250/0039 20130101; A61F
2/91 20130101; A61F 2230/0006 20130101; A61F 2/915 20130101; A61F
2002/068 20130101; A61F 2002/9155 20130101 |
Class at
Publication: |
623/1.31 ;
623/1.15 |
International
Class: |
A61F 002/06 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2000 |
US |
09/534,968 |
Claims
1. A reducer for insertion in a blood vessel, comprising: at least
one narrowed section having a first diameter; and at least one
flared section having a diameter at least 20% greater than said
first diameter, wherein said reducer is formed of a material and
has a geometry that does not cause coagulation of blood in its
vicinity.
2. A reducer according to claim 1, wherein said reducer is
operative to increase a coronary artery blood pressure when
inserted in a coronary vein.
3. A reducer according to claim 1, wherein said reducer is
operative to modify a coronary artery blood flow distribution when
inserted in a coronary vein.
4. A reducer according to claim 1, wherein said reducer is
operative to increase a coronary sinus blood pressure when inserted
in a coronary sinus.
5. A reducer according to claim 1, wherein said reducer is
operative to increase an intra-myocardial perfusion when inserted
in a coronary sinus.
6. A reducer according to any of claims 1-5, wherein said flared
section includes at least one area adapted to contact a wall of a
vein.
7. A reducer according to claim 6, wherein said area is made large
enough to prevent damage to the wall.
8. A reducer according to claim 7, wherein said area has an axial
extent of at least 2 mm.
9. A reducer according to claim 7, wherein said area has an axial
extent of at least 4 mm.
10. A reducer according to any of claims 1-9, wherein said flared
section has an outside edge.
11. A reducer according to claim 10, wherein said outside edge lies
on a single plane.
12. A reducer according to claim 10 or claim 11, wherein said
outside edge is defined by a plurality of elongate sections that
cooperate to define a maximal rim for said reducer.
13. A reducer according to any of claims 10-12, wherein said
outside edge is smooth.
14. A reducer according to any of claims 10-13, wherein said
outside edge is curved inwards towards an axis of said reducer.
15. A reducer according to any of claims 10-14, wherein said
outside edge is coated with a soft material.
16. A reducer according to any of claims 1-15, wherein said reducer
doesn't cause turbulence inside a lumen defined by said narrowed
section and said flared section.
17. A reducer according to any of claims 1-16, wherein said
narrowed section comprises a ring segment having a different
surface design from flared section.
18. A reducer according to any of claims 1-17, wherein said
narrowed section comprises a solid ring.
19. A reducer according to any of claims 1-17, wherein said
narrowed section comprises an array of cell elements.
20. A reducer according to any of claims 1-19, wherein said reducer
is expanded, after insertion, from an unexpanded configuration to
an expanded configuration.
21. A reducer according to claim 20, wherein said flared section is
plastically deformable to provide said configuration change.
22. A reducer according to claim 20, wherein said flared section is
self-expanding to provide said configuration change.
23. A reducer according to any of claims 20-22, wherein said
narrowed section self-expanding to provide said configuration
change.
24. A reducer according to any of claims 20-22, wherein said
narrowed section is plastically deformable to provide said
configuration change.
25. A reducer according to claim 20, wherein said narrowed section
does not expand.
26. A reducer according to claim 20, wherein said narrowed section
is further expandable after said reducer is in said expanded
configuration.
27. A reducer according to any of claims 1-26, comprising a ring
mounted outside of said narrowed section, said ring defining a
maximal diameter of said narrowed section.
28. A reducer according to any of claims 1-27, wherein said
narrowed section is formed of a pliable material.
29. A reducer according to any of claims 1-27, wherein said reducer
is formed of at least one of an elastic material, a shape-memory
material and a super-elastic material.
30. A reducer according to any of claims 1-29, wherein different
parts of said reducer have different degrees of resistance to
deforming.
31. A reducer according to claim 30, wherein said narrowed section
has a greater resistance to deformation than said flared
section.
32. A reducer according to claim 30, wherein a rim area of said
flared section has a greater resistance to deformation than an
adjacent part of said flared section.
33. A reducer according to any of claims 1-32, wherein said
narrowed section has an axial extent of between 1 mm and 5 mm.
34. A reducer according to any of claims 1-33, wherein said reducer
has an axial extent of between 10 nm and 30 mm.
35. A reducer according to any of claims 1-34, wherein said
narrowed section has a cross-sectional area of less than 70% of a
maximum cross-sectional area of said flared section.
36. A reducer according to any of claims 1-34, wherein said
narrowed section has a cross-sectional area of less than 50% of a
maximum cross-sectional area of said flared section.
37. A reducer according to any of claims 1-34, wherein said
narrowed section has a cross-sectional area of less than 40% of a
maximum cross-sectional area of said flared section.
38. A reducer according to any of claims 1-34, wherein said
narrowed section has a cross-sectional area of less than 30% of a
maximum cross-sectional area of said flared section.
39. A reducer according to any of claims 1-34, wherein said
narrowed section has a cross-sectional area of less than 20% of a
maximum cross-sectional area of said flared section.
40. A reducer according to any of claims 1-39, wherein said flared
section has an axial extent of between 4 mm and 10 mm.
41. A reducer according to any of claims 1-40, wherein said reducer
is adapted for insertion in a human coronary sinus.
42. A reducer according to any of claims 1-41, wherein said reducer
is adapted for insertion in a human coronary vein.
43. A reducer according to claim 41 or claim 42, wherein said
adaptation is by size.
44. A reducer according to any of claims 1-43, wherein said at
least one flared section comprises at least two flared
sections.
45. A reducer according to any of claims 1-44, wherein said reducer
describes an hourglass figure.
46. A reducer according to any of claims 1-45, wherein said flared
section is dense, to reduce blood flow therethrough.
47. A reducer according to any of claims 1-46, wherein said flared
section is coated, to reduce blood flow therethrough.
48. A reducer according to any of claims 1-47, wherein said reducer
is formed of a soft material, to reduce contact force against an
enclosing vessel wall.
49. A reducer according to any of claims 1-48, wherein said reducer
is operative to release a slow release molecule after it is
deployed.
50. A reducer according to any of claims 1-49, wherein said reducer
has an outside surface adapted to attach to a wall of a vein.
51. A reducer according to any of claims 1-50, wherein said
narrowed section comprises a valve.
52. A reducer for insertion in a blood vessel having a diameter,
comprising: at least one narrowed section having a first diameter;
and at least one flared section having a diameter at least 20%
greater than said first diameter, wherein said reducer is adapted
to be plastically deformed from a first configuration in which said
reducer is unexpanded to a second configuration in which said
reducer is expanded.
53. A reducer according to claim 52, wherein said narrowing section
has a length of at least 10% of a total axial length of said
reducer.
54. A reducer according to claim 52, wherein said narrowing section
has a length of at least 20% of a total axial length of said
reducer.
55. A reducer for insertion in a blood vessel having a diameter,
comprising: at least one narrowed section having a first diameter;
and at least one flared section having a diameter greater than said
first diameter, wherein said reducer is adapted to contact a vein
at said flared section.
56. A reducer according to claim 55, wherein said adaptation
comprises forming said flared section to reduce a probability of
damage to said vein.
57. A reducer according to claim 55, wherein said adaptation
comprises forming said reducer of a soft material to reduce a
contact force between said reducer and said vein.
58. A reducer according to claim 55, wherein said reducer is
adapted to cause coagulation in an area defined between said
reducer and a wall of said vein.
59. A reducer for insertion in a blood vessel having a diameter,
comprising: at least one narrowed section having a first diameter;
and at least one flared section having a diameter at least 20%
greater than said first diameter, wherein said flared section is
resistant to blood flow across a wall of said section, such that at
least 50% of blood flow through the reducer passes through a lumen
defined by said flared section and said narrowed section.
60. A reducer according to claim 59, wherein at least 80% of blood
flow through the reducer passes through a lumen defined by said
flared section and said narrowed section.
61. A reducer according to claim 59, wherein at least 90% of blood
flow through the reducer passes through a lumen defined by said
flared section and said narrowed section.
62. A reducer for insertion in a blood vessel having a diameter,
comprising: at least one narrowed section having a first diameter;
and at least one flared section having a diameter substantially
greater than said first diameter, wherein said flared section and
said narrowed section cooperate to substantially reduce blood flow
through a lumen defined by said sections, relative to flow through
a cylinder having a maximal diameter of the flared section
63. A blood vessel reducer delivery kit, comprising: a guide
catheter; a plastically deformable reducer having an hour-glass
figure when deformed and adapted to ride on said catheter; and a
balloon having an inflation profile matching said hour-glass
figure.
64. A method of reducer selection, comprising: determining a
desired hemodynamic effect in a coronary vascular system; and
selecting a reducer having a suitable geometry to achieve said
desired hemodynamic effect, from a set of reducers of different
geometries.
65. A method according to claim 64, wherein said desired effect is
at least one of: increase in myocardial perfusion pressure,
increase in myocardial pressure, increase in myocardial perfusion
duration, increase in coronary artery pressure, redistribution of
blood flow in coronary arteries, increase in pressure in a coronary
sinus and/or a restarting of a coronary artery autoregulation
mechanism.
66. A method of affecting hemodynamic parameters of a coronary
system, comprising: selecting a reducer for reducing a diameter of
a coronary vein; and implanting said reducer in said coronary
vein.
67. A method according to claim 66, wherein said coronary vein is a
coronary sinus.
68. A kit for reducing blood flow in a venous system, comprising: a
plurality of vascular implants, each defining a narrowed section,
said plurality of implants including at least two implants with
different geometrical properties.
69. A kit according to claim 68, wherein said two implants have
different degrees of narrowing.
70. A kit according to claim 68 or claim 69, wherein said two
implants have different outer diameters, for matching different
coronary veins.
Description
RELATED APPLICATIONS
[0001] This application is related to U.S. application Ser. No.
09/534,968, filed Mar. 27, 2000 the disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to devices for narrowing
bodily conduits, for example, blood vessels, to less than their
normal diameter.
BACKGROUND OF THE INVENTION
[0003] The heart pumps blood through the body. The heart itself is
fed by coronary arteries that end at capillaries. The capillaries
are drained by a network of coronary veins, that (typically) flow
into a vein known as the coronary sinus. The coronary sinus is a
short, large diameter vein that is substantially contiguous with a
right atrium, the atrium that collects all venous blood from the
body.
[0004] Occlusion of coronary arteries is a leading cause of death,
especially sudden death, in what is commonly called a "heart
attack". When blood flow to a portion of the heart is suddenly
stopped, the portion becomes ischemic and its electrical activity
is disrupted. As the activity of the heart is mediated by
electrical signal propagation, such disruption typically propagates
to the rest of the heart, disorganizes the heart's activation and
causes the heart output to be reduced drastically, which leads to
ischemia and death of the brain. In addition, the disorganized
activity often damages the heart beyond what was caused directly by
the blockage.
[0005] If a patient survives the direct effects of the heart
attack, the damage to the heart may predispose the patient to
future electrical disorders and/or may significantly reduce the
cardiac output, thus reducing quality of life and life
expectancy.
[0006] Angina pectoris is a chronic or semi-chronic condition
which, while not life-threatening, significantly reduces quality of
life. In general, the heart responds to increased demand by working
harder, requiring more coronary blood flow. When coronary arteries
are stenosed or occluded, the increased blood flow cannot be
provided, and pain, caused by the resulting ischemia, is
produced.
[0007] The heart has natural mechanisms to overcome stenosis in
coronary arteries. One such mechanism is angiogenesis, in which new
arteries are created, for bypassing the stenosis.
[0008] Since angiogenesis does not always occur naturally, various
procedures have been suggested to encourage it. For example
Trans-Myocardial Revascularization (TMR), is a process in which
multiple holes are drilled in the heart, with the intent of causing
new vessels to be created.
[0009] Beck, in "The Surgical Management of Coronary Artery
Disease: Background, Rationale, Clinical Experience" by C. S. Beck
and B. L. Brofinan, 1956, by the American College of Physicians in
Annals of Internal Medicine Vol. 45, No. 6, December 1956 and in
"Long Term Influence of the Beck Operation for Coronary Heart
Disease", by B. L. Brofman in the American Journal of Cardiology
August 1960, the disclosures of which are incorporated herein by
reference, performed open chest surgery in which a coronary sinus
vein was restricted, by an external suture. After a few months,
coronary blood supply apparently improved. However, this method has
fallen in disfavor, in part probably due to the need to open the
chest and lift up the heart, to reach the coronary sinus vein.
[0010] A standard treatment of stenosed arteries is inserting a
stent into the artery, at the stenosed point. The stent, for
example a metal coil or mesh, is expanded to have an inner diameter
similar to that of the original stenosed blood vessel. If many
stenoses are present, it is not common to implant multiple stents.
Instead, a bypass procedure, in which a conduit is used to bypass
the stenoses, is performed.
[0011] U.S. Pat. No. 5,618,301, the disclosure of which is
incorporated herein by reference, describes a stent-like device for
reducing the diameter of a body conduit. What is described is an
open mesh stent that can be inserted in a stented channel created
by a TIPS (Trans-Jugular Intra-Hepatic Portal-Systemic Shunt)
procedure, to reduce the blood flow rate through the channel. In
order to ensure the flow diameter is reduced and prevent flow
through the open mesh, a plurality of thromobogentic threads are
provided on the outside of the mesh. However, as can be
appreciated, intentionally forming thrombosis in most any part of
the vascular system, and especially near the heart, can lead to
propagating coagulation or floating thromboses, which are
potentially fatal.
SUMMARY OF THE INVENTION
[0012] An aspect of some embodiments of the invention relates to a
diameter reducing implant adapted for insertion into blood vessels.
In an exemplary embodiment of the invention, the implant (reducer)
includes at least one narrowed lumen portion, for limiting blood
flow. In an exemplary embodiment of the invention, the reducer is
designed to not cause blood coagulation outside of the narrowed
blood flow. The reduced diameter may, for example, reduce total
blood flow through the implant or change the temporal profile of
such flow and/or temporal profile of pressure in the vessel.
[0013] In an exemplary embodiment of the invention, the reducer is
designed not to damage vessel walls, for example, artery walls or
vein walls. In one example, the reducer edges are curled.
Alternatively or additionally, the reducer edges are coated with a
soft coating. Alternatively or additionally, the reducer edges
extend parallel to the vessel. Alternatively or additionally, the
elasticity of the reducer is low, to prevent undue pressure on the
walls.
[0014] In an exemplary embodiment of the invention, the blood
vessel is a coronary vein or a coronary sinus. Optionally, the
narrowing reduces the vessel cross-section by 30%, 50%, 80%, 90% or
any other lower, larger or intermediate amount, or even completely
occludes the vessel. It should be noted that the heart generally
has additional drainage paths besides the coronary sinus, so that
even complete occlusion of the coronary sinus will not generally
prevent blood from reaching the coronary capillaries. For example,
the narrowing may have an inner diameter of 1 mm, 2 mm, 3 mm or any
larger, smaller or intermediate size. Optionally, the unexpanding
reducer is between 10 mm and 80 mm long. Optionally, the reducer is
asymmetric, for example, adapted to fit the normal shape of the
coronary sinus.
[0015] In an exemplary embodiment of the invention, the reducer
includes one or more narrowed sections and one or more un-narrowed
sections. In an exemplary embodiment of the invention, narrowing
sections are non-expandable, expand less or require a greater force
to cause them to expand, as compared to un-narrowed sections. In an
exemplary embodiment of the invention, the un-narrowed sections
expand a considerable amount, for example a factor of 2, 3, 4 or 5,
or any greater, smaller or intermediate factor, in diameter, from
their diameter during insertion.
[0016] In an exemplary embodiment of the invention, the narrowed
sections comprises a ring. Optionally, the ring defines a mesh to
allow some expansion thereof. Optionally, after a reducer is
deployed, the ring may be further expanded, to reduce the degree of
narrowing.
[0017] In some embodiments of the invention, the vessel walls
collapse or are urged to collapsed onto the reducer. Alternatively,
in some embodiments of the invention, a coagulation-encouraging
material or threads are provided outside the narrowed portion
(i.e., between the portion and the vessel wall) to encourage the
formation of clots between the reducer body and the vessel
wall.
[0018] Optionally, the reducer is coated with a flexible coating
(inside and/or out) and/or defines a dense mesh pattern, that
prevents or reduces blood flow through the reducer surface, for
example, forcing at least 40%, 60%, 80%, 90% or any smaller,
greater or intermediate flow percentage to be through an axial
lumen defined by said reducer. In an exemplary embodiment of the
invention, the dense mesh fills at least 30%, 40%, 60%, 70%, 80% or
any greater, smaller or intermediate percentage of a surface of the
reducer.
[0019] In an exemplary embodiment of the invention, the reducer
comprises a rim, which rim is constructed to be more difficult to
expand (for plastic) or expand less (for self-expanding) than
portions of the reducer just inside the rim. Thus, when the reducer
is expanded, the rim does not flare out and an inwards curving or a
parallel profile is achieved in the reducer. Optionally, the rim
defines a maximal radius of the rim, to prevent over expansion of
the rim of the reducer.
[0020] In an exemplary embodiment of the invention, the reducer is
a plastically deformed reducer, expanded using a balloon. In an
exemplary embodiment of the invention, in order to prevent the
balloon from catching in the narrowed section of the reducer, the
balloon comprises a plurality of fingers on its outside, so that
the fingers can bend back and be pulled out through the narrowing.
Alternatively or additionally, the fingers are asymmetric, so that
when the balloon deflates, the balloon will twist closed.
[0021] An aspect of some embodiments of the invention relates to a
method of installing a narrowing device. In an exemplary embodiment
of the invention, the narrowing device is installed in a coronary
sinus vein (hereafter "coronary sinus"). Alternatively or
additionally, the narrowing device is installed in one or more
coronary veins, for example the great coronary vein. In an
exemplary embodiment of the invention, a delivery catheter is
inserted through a central vein, such as the Jugular vein and
brought to the coronary sinus. The reducer is released from the
delivery catheter and allowed to elastically expand and/or is
plastically expanded using a balloon. Optionally, a pressure sensor
is provided on the delivery catheter for assessing the effect of
the reducer on the venous pressure before the reducer and/or after
the reducer.
[0022] An aspect of some embodiments of the invention relates to a
method of selecting a reducer. In an exemplary embodiment of the
invention, functional information on the heart is used to assess
need. An image, such as an echo-cardiography image, a Doppler image
or a CT image is used to measure the coronary sinus (or any other
target vein). The size of the reducer and its degree of narrowing
are then selected to match the geometry of the coronary sinus
and/or the desired therapeutic effect.
[0023] There is thus provided in accordance with an exemplary
embodiment of the invention, a reducer for insertion in a blood
vessel, comprising:
[0024] at least one narrowed section having a first diameter;
and
[0025] at least one flared section having a diameter at least 20%
greater than said first diameter,
[0026] wherein said reducer is formed of a material and has a
geometry that does not cause coagulation of blood in its vicinity.
Optionally, said reducer is operative to increase a coronary artery
blood pressure when inserted in a coronary vein. Optionally, said
reducer is operative to modify a coronary artery blood flow
distribution when inserted in a coronary vein. Optionally, said
reducer is operative to increase a coronary sinus blood pressure
when inserted in a coronary sinus. Optionally, said reducer is
operative to increase an intra myocardial perfusion when inserted
in a coronary sinus.
[0027] In an exemplary embodiment of the invention, said flared
section includes at least one area adapted to contact a wall of a
vein. Optionally, said area is made large enough to prevent damage
to the wall. Optionally, said area has an axial extent of at least
2 mm. Optionally, said area has an axial extent of at least 4
mm.
[0028] In an exemplary embodiment of the invention, said flared
section has an outside edge. Optionally, said outside edge lies on
a single plane. Alternatively or additionally, said outside edge is
defined by a plurality of elongate sections that cooperate to
define a maximal rim for said reducer. Alternatively or
additionally, said outside edge is smooth. Alternatively or
additionally, said outside edge is curved inwards towards an axis
of said reducer. Alternatively or additionally, said outside edge
is coated with a soft material.
[0029] In an exemplary embodiment of the invention, said reducer
doesn't cause turbulence inside a lumen defined by said narrowed
section and said flared section. Alternatively or additionally,
said narrowed section comprises a ring segment having a different
surface design from flared section. Alternatively or additionally,
said narrowed section comprises a solid ring.
[0030] In an exemplary embodiment of the invention, said narrowed
section comprises an array of cell elements.
[0031] In an exemplary embodiment of the invention, said reducer is
expanded, after insertion, from an unexpanded configuration to an
expanded configuration. Optionally, said flared section is
plastically deformable to provide said configuration change.
Alternatively said flared section is self-expanding to provide said
configuration change.
[0032] In an exemplary embodiment of the invention, said narrowed
section self-expanding to provide said configuration change.
Alternatively, said narrowed section is plastically deformable to
provide said configuration change. Alternatively, said narrowed
section does not expand. Alternatively, said narrowed section is
further expandable after said reducer is in said expanded
configuration.
[0033] In an exemplary embodiment of the invention, said reducer
comprises a ring mounted outside of said narrowed-section, said
ring defining a maximal diameter of said narrowed section.
[0034] In an exemplary embodiment of the invention, said narrowed
section is formed of a pliable material. Alternatively or
additionally, said reducer is formed of at least one of an elastic
material, a shape-memory material and a super-elastic material.
[0035] In an exemplary embodiment of the invention, different parts
of said reducer have different degrees of resistance to deforming.
Optionally, said narrowed section has a greater resistance to
deformation than said flared section. Alternatively, a rim area of
said flared section has a greater resistance to deformation than an
adjacent part of said flared section.
[0036] In an exemplary embodiment of the invention, said narrowed
section has an axial extent of between 1 mm and 5 mm.
[0037] In an exemplary embodiment of the invention, said reducer
has an axial extent of between 10 mm and 30 mm.
[0038] In an exemplary embodiment of the invention, said narrowed
section has a cross-sectional area of less than 70% of a maximum
cross-sectional area of said flared section. Optionally, said
narrowed section has a cross-sectional area of less than 50% of a
maximum cross-sectional area of said flared section. Optionally,
said narrowed section has a cross-sectional area of less than 40%
of a maximum cross-sectional area of said flared section.
Optionally, said narrowed section has a cross-sectional area of
less than 30% of a maximum cross-sectional area of said flared
section. Optionally, said narrowed section has a cross-sectional
area of less than 20% of a maximum cross-sectional area of said
flared section.
[0039] In an exemplary embodiment of the invention, said flared
section has an axial extent of between 4 mm and 10 mm.
[0040] In an exemplary embodiment of the invention, said reducer is
adapted for insertion in a human coronary sinus. Alternatively or
additionally, said reducer is adapted for insertion in a human
coronary vein. Optionally, said adaptation is by size.
[0041] In an exemplary embodiment of the invention, said at least
one flared section comprises at least two flared sections.
[0042] In an exemplary embodiment of the invention, said reducer
describes an hourglass figure.
[0043] In an exemplary embodiment of the invention, said flared
section is dense, to reduce blood flow therethrough. Alternatively
or additionally, said flared section is coated, to reduce blood
flow therethrough.
[0044] In an exemplary embodiment of the invention, said reducer is
formed of a soft material, to reduce contact force against an
enclosing vessel wall.
[0045] In an exemplary embodiment of the invention, said reducer is
operative to release a slow release molecule after it is
deployed.
[0046] In an exemplary embodiment of the invention, said reducer
has an outside surface adapted to attach to a wall of a vein.
[0047] In an exemplary embodiment of the invention, said narrowed
section comprises a valve.
[0048] There is also provided in accordance with an exemplary
embodiment of the invention, a reducer for insertion in a blood
vessel having a diameter, comprising:
[0049] at least one narrowed section having a first diameter;
and
[0050] at least one flared section having a diameter at least 20%
greater than said first diameter,
[0051] wherein said reducer is adapted to be plastically deformed
from a first configuration in which said reducer is unexpanded to a
second configuration in which said reducer is expanded. Optionally,
said narrowing section has a length of at least 10% of a total
axial length of said reducer. Optionally, said narrowing section
has a length of at least 20% of a total axial length of said
reducer.
[0052] There is also provided in accordance with an exemplary
embodiment of the invention, a reducer for insertion in a blood
vessel having a diameter, comprising:
[0053] at least one narrowed section having a first diameter;
and
[0054] at least one flared section having a diameter greater than
said first diameter,
[0055] wherein said reducer is adapted to contact a vein at said
flared section. Optionally, said adaptation comprises forming said
flared section to reduce a probability of damage to said vein.
Alternatively or additionally, said adaptation comprises forming
said reducer of a soft material to reduce a contact force between
said reducer and said vein.
[0056] In an exemplary embodiment of the invention, said reducer is
adapted to cause coagulation in an area defined between said
reducer and a wall of said vein.
[0057] There is also provided in accordance with an exemplary
embodiment of the invention, a reducer for insertion in a blood
vessel having a diameter, comprising:
[0058] at least one narrowed section having a first diameter;
and
[0059] at least one flared section having a diameter at least 20%
greater than said first diameter,
[0060] wherein said flared section is resistant to blood flow
across a wall of said section, such that at least 50% of blood flow
through the reducer passes through a lumen defined by said flared
section and said narrowed section. Optionally, at least 80% of
blood flow through the reducer passes through a lumen defined by
said flared section and said narrowed section. Optionally, at least
90% of blood flow through the reducer passes through a lumen
defined by said flared section and said narrowed section.
[0061] There is also provided in accordance with an exemplary
embodiment of the invention, a reducer for insertion in a blood
vessel having a diameter, comprising:
[0062] at least one narrowed section having a first diameter;
and
[0063] at least one flared section having a diameter substantially
greater than said first diameter,
[0064] wherein said flared section and said narrowed section
cooperate to substantially reduce blood flow through a lumen
defined by said sections, relative to flow through a cylinder
having a maximal diameter of the flared section.
[0065] There is also provided in accordance with an exemplary
embodiment of the invention, a blood vessel reducer delivery kit,
comprising:
[0066] a guide catheter;
[0067] a plastically deformable reducer having an hour-glass figure
when deformed and adapted to ride on said catheter; and
[0068] a balloon having an inflation profile matching said
hour-glass figure.
[0069] There is also provided in accordance with an exemplary
embodiment of the invention, a method of reducer selection,
comprising:
[0070] determining a desired hemodynamic effect in a coronary
vascular system; and
[0071] selecting a reducer having a suitable geometry to achieve
said desired hemodynamic effect, from a set of reducers of
different geometries. Optionally, said desired effect is at least
one of: increase in myocardial perfusion pressure, increase in
myocardial pressure, increase in myocardial perfusion duration,
increase in coronary artery pressure, redistribution of blood flow
in coronary arteries, increase in pressure in a coronary sinus
and/or a restarting of a coronary artery autoregulation
mechanism.
[0072] There is also provided in accordance with an exemplary
embodiment of the invention, a method of affecting hemodynamic
parameters of a coronary system, comprising:
[0073] selecting a reducer for reducing a diameter of a coronary
vein; and
[0074] implanting said reducer in said coronary vein. Optionally,
said coronary vein is a coronary sinus.
[0075] There is also provided in accordance with an exemplary
embodiment of the invention, a kit for reducing blood flow in a
venous system, comprising: a plurality of vascular implants, each
defining a narrowed section, said plurality of implants including
at least two implants with different geometrical properties.
Optionally, said two implants have different degrees of narrowing.
Alternatively or additionally, said two implants have different
outer diameters, for matching different coronary veins.
BRIEF DESCRIPTION OF THE DRAWINGS
[0076] Non-limiting, embodiments of the invention will be described
with reference to the following description of exemplary
embodiments, in conjunction with the figures. The figures are
generally not shown to scale and any measurements are only meant to
be exemplary and not necessarily limiting. In the figures,
identical structures, elements or parts which appear in more than
one figure are preferably labeled with a same or similar number in
all the figures in which they appear, in which:
[0077] FIG. 1 is a schematic showing of a reducer installed in a
coronary sinus vein, in accordance with an exemplary embodiment of
the invention;
[0078] FIG. 2 is a schematic side view of a reducer, in accordance
with an exemplary embodiment of the invention;
[0079] FIGS. 3A and 3B illustrate a plan layout of a reducer, in
accordance with an exemplary embodiment of the invention;
[0080] FIG. 3C shows illustrates the reducer of FIG. 3A in an
unexpanded configuration and mounted on a delivery system, in
accordance with an exemplary embodiment of the invention;
[0081] FIG. 3D illustrates a coil-based reducer, in accordance with
an exemplary embodiment of the invention;
[0082] FIGS. 4A and 4B show a plan layout of a reducer having a
smooth rim when expanded, in accordance with an exemplary
embodiment of the invention;
[0083] FIG. 4C shows a reducer with a smooth rim in an expanded
configuration, in accordance with an exemplary embodiment of the
invention;
[0084] FIG. 5 shows a vascular path to a coronary sinus, in
accordance with an exemplary embodiment of the invention;
[0085] FIG. 6A shows a plastically deforming reducer delivery
system, in accordance with an exemplary embodiment of the
invention;
[0086] FIG. 6B shows a delivery system for delivering a
self-expanding reducer, in accordance with an exemplary embodiment
of the invention;
[0087] FIG. 6C shows a balloon design, in accordance with an
exemplary embodiment of the invention;
[0088] FIG. 7 is a flowchart of a method of reducer delivery, in
accordance with an exemplary embodiment of the invention;
[0089] FIG. 8 shows a portion of a plan layout of a section of a
reducer with selective narrowing control, in accordance with an
exemplary embodiment of the invention; and
[0090] FIGS. 9A-9F illustrate various reducer variations, in
accordance with exemplary embodiments of the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0091] FIG. 1 is a schematic showing of a reducer 100 installed in
a coronary sinus vein 102, in accordance with an exemplary
embodiment of the invention. Coronary sinus 102 drains a plurality
of cardiac veins 106 into a right atrium 104. The cardiac
circulation is generally hierarchical and comprises of stages of
reducing (or increasing) diameter. Thus, veins 106, in turn, drain
a plurality of thin venoules 108, which, after a few stages, drain
a plurality of capillaries 110. Capillary 110 are fed by a
plurality of arterioles 112, which, after a few stages, are fed by
a plurality of coronary arteries 114 and 120. A stenosis 116 is
shown in a coronary artery 114. While the cardiac circulation is
generally hierarchical, some connection exists between different
branches. Occasionally, the existence of stenosis 116 will cause a
collateral connection 118 to spontaneously form (or widen an
existing connection) between coronaries 114 and 120, bypassing
stenosis 116.
[0092] In some cases, however, this spontaneous formation does not
occur. In an exemplary embodiment of the invention, a reducer 100
is placed in coronary sinus 102 and has a narrowing significant
enough to encourage the formation of collateral connection 118. It
is hypothesized that collateral connection 118 is caused by an
increase in venous blood pressure, which, in turn, increases the
pressure in the capillaries and/or causes retro-flow in the
capillaries and/or causes drainage of the capillaries directly into
the heart. However, even if this hypothesis is incorrect, several
studies, that included numerous experiments and actual procedures
have shown that constriction of coronary sinus 102 will generally
cause the formation of collateral circulation and/or otherwise
improve the condition of patients with blocked coronary arteries.
Alternative or additional hypotheses which are optionally used to
select the constrictive effect of reducer 100 include:
[0093] (a) Reducer 100 increases the pressure in the coronary
capillaries, thus increasing perfusion duration.
[0094] (b) An increase in resistance of the venous system causes
redistribution of blood flow in coronary arteries.
[0095] (c) An increase in resistance of venous system increases
intra-myocardial perfusion pressure and/or intra-myocardial
pressure.
[0096] (d) Increasing the arterial diastolic pressure (by
restricting venous drainage) causes the arterial auto-regulation to
start working again, for example, such an auto regulation as
described in Braunwald "Heart Disease: A textbook of Cardiovascular
Medicine", 5th Edition, 1997, W.B. Saunders Company, Chapter 36,
pages 11168-1169.
[0097] It should be noted that the selection of reducer 100 may be
made to achieve one or more of the above suggested effects,
optionally to a desired degree and/or taking into account safety
issues, such as allowing some drainage and maximum pressure allowed
by the coronary venous drainage system. These effects may be
determined using various measurements, as described below with
reference to FIG. 7.
[0098] FIG. 2 is a schematic side view of reducer 100, in
accordance with an exemplary embodiment of the invention. Reducer
100 comprises a narrowed section 204 and at least one funnel shaped
section 200 (and 202) leading into narrowed section 204. Section
200 (and 202) includes portions 210 and 206 that are inclined
relative to the wall of coronary sinus 102 and portions 212 and 208
that are parallel to the wall.
[0099] In the exemplary embodiment and measurements shown, reducer
100 is expandable and shortens somewhat during expansion: having a
length of 20 mm before expansion and about 18.8 mm after expansion.
Optionally, a non-shortening design is used, for example a mesh as
in peristaltic stents, such as described in U.S. Pat. No.
5,662,713, the disclosure of which is incorporated herein by
reference. An exemplary material thickness is 0.15 mm, however,
thinner or thicker materials may be used. Other exemplary lengths
are 5 mm, 12 mm, 24 mm, 35 mm 45 mm and any smaller, intermediate
or larger size. The length is optionally selected to match a
physiological size of the target vein (e.g., length and curves)
and/or to ensure good contact with vein walls. The length of
narrowing 204 may be, for example, 0.5 mm, 1 mm, 2 mm, 3 mm, 5 mm
or any smaller, intermediate or larger length, for example selected
to achieve desired flow dynamics. An exemplary inner diameter of
the flared out sections is between 2 mm and 30 mm, for example, 5
mm, 10 mm, 15 mm, 20 mm or any larger, smaller or intermediate
diameter, for example selected to match the vein diameter. The
inner diameter of the narrowing may be, for example, 1 mm, 2 mm, 3
mm, 5 mm, 10 mm or any smaller, larger or intermediate diameter,
for example selected to achieve desired flow dynamics and/or a
pressure differential across the reducer.
[0100] In an exemplary embodiment of the invention, the ratio
between the cross-section of narrowing 204 and the ends of reducer
100 is 0.9, 0.8, 0.6, 0.4, 0.2 or any larger, smaller or
intermediate ratio, for example selected to achieve desired flow
dynamics and/or a pressure differential across the reducer.
[0101] While a circular cross-section is shown, other
cross-sections may be used, for example, polygonal and ellipsoid. A
potential advantage of non-circular cross-sections is that the
device is less likely to migrate axially. Alternatively or
additionally, the outside of the reducer is roughened and/or
otherwise adapted to adhere to the vein wall. The cross-section
shape and/or orientation optionally changes along the length of
reducer 100.
[0102] FIGS. 3A and 3B illustrate a plan layout of reducer 100, in
accordance with an exemplary embodiment of the invention. FIG. 3B
shows a detail of the plan layout. In this plan layout, the ends of
sections 200 and 202 are caused to be parallel to the vessel wall
when reducer 100 is expanded.
[0103] In an exemplary embodiment of the invention, the outside rim
of reducer 100 is defined by sections 340, 342 and 344, shown in
FIG. 3B. Optionally, the total length of these sections defines the
maximum rim length. Alternatively or additionally, the bending
areas in and between these sections define the relative force
required to expand the rim region relative to the area near the
rim. If the rim region is more difficult to expand and/or is
expanded less than the adjacent regions, the expansion of reducer
100 will tend to cause the rim to bend in, or at least not flare
out. Alternatively, in a self-expanding reducer, the existence of
sections 340, 342 and 344 can be used to endure the final shape of
the rim. Optionally, additional sections 346 are provided around
the circumference of reducer 100, which define outer cells in
reducer 100, which outer cells may have a maximum expansion that is
the same or smaller than that nearby (axially inwards) cells. This
design can also be used to control the shape of the rim.
[0104] In an exemplary embodiment of the invention, a reducer is
characterized by this maximum diameter, which may be used, for
example, for selecting a particular reducer to match a patient.
Optionally, during expansion, the balloon is aligned with reducer
100 so that it only contacts the rim region or only contacts the
non-rim regions of reducer 100.
[0105] FIG. 3C shows reducer 100 in an unexpanded configuration and
mounted on a delivery system 302 (e.g., a balloon catheter).
[0106] In an exemplary embodiment of the invention, reducer 100 is
formed by cutting out of a sheet of metal or a tube, for example,
using laser, water cutting, chemical erosion or metal stamping
(e.g., with the result being welded to form a tube). Alternatively,
reducer 100 is woven (e.g. of metal or plastic fiber), for example,
using methods as well known in the art. Optionally, narrowing
section 204 is made using a different method from flaring sections
200 and 202, for example, the flaring sections being woven and the
narrowing section being cut from sheet metal. In an alternative
embodiment of the invention, reducer 100 includes with a
constraining ring that prevents the expansion of narrowing section
204. Optionally, the restraining ring is plastically expandable,
possibly under a higher pressure than the rest of reducer 100,
which may be plastically deformable or self-expanding.
Alternatively or additionally, the restraining ring is selected to
set the desired degree of narrowing, and then mounted on a reducer,
a stent or a stent graft, for implantation. In a sleeve reducer
(FIG. 9F, below), a similar effect may be achieved by suturing the
stent graft.
[0107] In an alternative embodiment, reducer 100 is cut out of a
sheet and then spirally twisted around a mandrel to form the shape
of reducer 100. Alternatively, reducer 100 is cut out of a tube,
with the flared parts being spiral cuts and the narrowing part
being a ring cut. Alternatively, reducer 100 is formed as a coil
spring, with axially varying relaxation positions. FIG. 3D
illustrates a coil-based reducer 320, in accordance with an
exemplary embodiment of the invention.
[0108] In an exemplary embodiment of the invention, once reducer
100 is formed, it is mounted in a jig having the desired final
expanded shape and heated to train that shape (e.g., for a
super-elastic reducer).
[0109] In an exemplary embodiment of the invention, reducer 100 is
adapted for use in a coronary sinus or other coronary vein. Veins
are typified by having a low degree of elasticity and being
relatively sensitive to tears (as compared to arteries). In one
example, the edges of reducer 100 are curved inwards or curled, for
example as shown by reference 130 in FIG. 1. Alternatively or
additionally, the edges are folded back and/or smoothed to remove
sharp edges. Alternatively, the parallel sections 208 and 212 (FIG.
2) are made long enough to support reducer 100 without harming
coronary sinus 102. Alternatively or additionally, reducer 100 or
at least larger diameter portions thereof, is made soft enough
and/or with a low spring constant, to prevent the reducer from
applying too much pressure on the coronary reducer wall.
Alternatively or additionally, the ends of reducer 100 are coated
with a flexible coating, for example, a soft silicone elastomer or
another soft plastic or rubber material such as Latex, Teflon
and/or Polyurethane.
[0110] Alternatively or additionally, reducer 100 has a smooth rim
at each end. FIGS. 4A and 4B show a plan layout of a reducer 400
having a smooth rim 402 (when expanded).
[0111] In FIG. 413, outer rim 402 is defined by sections 440 and
446. As shown, these sections are designed to provide a relative
smooth rim, possibly with small amounts of distortion (so rim 402
remains smooth) where the sections connect to sections 442 and 444.
Together, sections 442, 444 and 446 define outer cells for rim
402.
[0112] FIG. 4C shows an alternative design for reducer 400, in an
expanded configuration, illustrating smooth rims 402.
[0113] Referring back to FIG. 1, a region 132 is defined between
reducer 100 and the wall of coronary sinus 102. In an exemplary
embodiment of the invention, it is desired that little or no blood
bypass narrowing 204 through region 132. In some types of reducer
100, this is achieved by sections 200 and 202 being dense enough to
slow down blood flow considerably or being practically blood-proof,
for example, in a coil-type reducer. Alternatively or additionally,
an elastic coating is provided on the inside or outside of reducer
100, for example, latex, to cover and prevent flow through openings
in the reducer body. In an exemplary embodiment of the invention,
the coating is a separate, flexible layer, that is attached to the
reducer at several points (e.g., at the center and at either end,
such as to prevent tearing of the layer by the expanding reducer)
and is performed to the shape of the expanded reducer, prior to
expansion, this coating layer is folded and/or pleated.
Alternatively or additionally, one reducer is implanted inside
another reducer, with misaligned mesh patterns, so that the solid
parts of one reducer block apertures defined by the other
reducer.
[0114] Alternatively or additionally, the walls of coronary sinus
102 collapse onto reducer 100, blocking any apertures in the body
of reducer 100 and preventing flow bypassing narrowing section 204.
Optionally, reducer 100 is constructed to encourage such
collapsing, for example, by the pattern of apertures in funnel
section 200 being different from those in funnel section 202, or by
the external diameter of reducer 100 being slightly greater than
that of coronary sinus 102. It should be noted that since veins are
typically soft and are surrounded by tissue, veins typically
collapse when their inner pressure is reduced.
[0115] Optionally, the outer surface of reducer 100 includes means
for attaching the reducer to the collapsed walls, for example,
small barbs, an adhesive and/or a fibrosis-formation encouraging
material. Optionally, during implantation of reducer 100, flow of
blood from the coronary veins to the reducer is blocked for a short
period of time and/or blood in reducer 100 is sucked out, to
encourage the coronary sinus walls to collapse onto reducer 100 and
attached to reducer 100. Optionally, a reducer used for such a
procedure can have very short flaring parts, possible with an outer
diameter smaller than that of the coronary sinus.
[0116] In some embodiments of the invention, a coagulation
enhancing material or geometry (e.g., thrombogenic threads) are
provided in area 132, for example, being attached to reducer 100.
Thus, region 132 will fill with coagulated blood and prevent
further blood flow therethrough. In an exemplary embodiment of the
invention, however, the reducer is made as un-thrombogenic as
possible (e.g., suitable coatings and geometry, as known in the
art), to prevent propagation of clots into the heart. Coagulation
enhancing is optionally provided if the reducer is relatively
impervious to blood flow through its walls, so that clots are not
expected to propagate.
[0117] In an exemplary embodiment of the invention, reducer 100 is
formed of metal, for example, a NiTi alloy (e.g., Nitinol) or
stainless steel (e.g., 316L and 316LS). Alternatively, reducer 100
is formed of--or coated with--other bio-compatible materials, such
as Nylon and other plastics. Optionally, reducer 100 is
bio-absorbable. A reducer made of plastic can be, for example, cast
or injection molded. Depending on the type of material and the
processing applied, reducer 100 may be plastically deformable to
the geometry shown in FIG. 1. Alternatively, reducer 100 may relax
to that geometry, for example, using an elastic, shape-memory or
super-elastic relaxation process.
[0118] Optionally, reducer 100 is formed of two or more materials,
for example, narrowing section 204 being a ring formed of plastic
and the flared sections being formed of metal.
[0119] FIG. 5 shows a vascular path to coronary sinus 102, in
accordance with an exemplary embodiment of the invention.
Desirably, reducer 100 is implanted using a trans-vascular
approach, for example, from the venous system or by crossing
through an intra-chamber wall in the heart. In an exemplary
embodiment of the invention, the delivery system is inserted
through a jugular vein 510 or a subclavian vein 512 to a right
atrium 506 of a heart 500 via a superior vena cava 508 and/or a
femoral vein 502, via an inferior vena cava 504. Once in right
atrium 506, the delivery system is guided (e.g., through a sharp
bend) to an opening 514 into coronary sinus 102. In some patients,
a valve exists at the entrance to coronary sinus 102.
[0120] As noted above, reducer 100 can be, for example, actively
deformed to the implanted configuration or allowed to relax to the
configuration. FIG. 6A shows a plastically deforming reducer
delivery system 600, in accordance with an exemplary embodiment of
the invention. System 600 can be a standard delivery system
designed for deploying a stent over a balloon. Possibly, however,
specialized guide sheaths, adapted to the particular path in the
right atrium, will be provided. In an exemplary embodiment of the
invention, narrowing section 204 of reducer 100 is non-expandable
or is less easily expandable, so that the balloon will not
completely inflate under narrowing section 204. Alternatively, a
non-standard balloon is used, for example, a double balloon,
comprising a first balloon section 602 and a second balloon section
604, each adapted to expand one funnel section of reducer 100.
Optionally, a single balloon or two balloons are used for this
balloon design. Alternatively, in an exemplary embodiment of the
invention, a single balloon, that is moved axially from one part of
the reducer to another, is used. Alternatively or additionally,
after a two-section balloon is used it is replaced with a single
section balloon, for example, for selectively expanding a flared
end or a narrowing of reducer 100.
[0121] FIG. 6B shows a delivery system 620 for delivering a
self-expanding reducer, in accordance with an exemplary embodiment
of the invention. System 620 can be a system generally like that
used for standard self-expanding reducers, for example, including
an outer sheath 622 and an inner mandrel 624 on which reducer 100
is mounted. In an exemplary embodiment of the invention, when
reducer 100 expands, its inner diameter is greater than the outer
diameter of mandrel 624, allowing mandrel 624 to be retracted. In
an exemplary embodiment of the invention, mandrel 624 comprises two
optional end pieces 626 that define between them a depression, in
which reducer 100 is held. End pieces 626 prevent axial migration
of reducer 100.
[0122] Optionally, the delivery system includes a pressure
transducer at its end, for example, for measuring base-line
pressure in the coronary sinus. Alternatively or additionally, the
delivery system includes a contrast injection channel, for example,
for assisting in imaging the coronary sinus before, during and/or
after deployment of reducer 100.
[0123] FIG. 7 is a flowchart 700 of a method of reducer delivery,
in accordance with an exemplary embodiment of the invention. It
should be appreciated that the procedure of FIG. 7 is an exemplary
procedure and other procedures may be applied as well. In
particular, the process of FIG. 7 assumes, for clarity, the use of
a particular sheath-based delivery system, the use of which is not
an essential feature of the invention.
[0124] In an exemplary embodiment of the invention, the coronary
sinus treatment is combined with an arterial treatment, such as
PCTA, stenosis removal (e.g., laser ablation) and/or stenting. The
arterial treatment may be applied, for example, before, during or
after the venous treatment, possibly during a same use of the
catheterization facilities.
[0125] At 702, various pre-implantation tests and procedures are
optionally applied to a patient to be catheterized, for example, a
few weeks, a few days or a few hours before the catheterization.
Such procedures can include, for example, one or more of, tests
typically applied prior to catheterization and/or reducer delivery,
various cardiac function measurements, determination that the
patient suffers from ischemic heart disease, determination of
angina class, performing electrocardiographgy, full blood work,
functional and/or perfusion mapping (e.g., using nuclear medicine
imaging techniques such as PET, Thallium or Technetium), to
determine pre-procedure perfusion state, echo-cardiography,
echo-dobutamin, estimation of micro-cardiological perfusion, Millar
catheterization and physiological measurements, such as cardiac
output, pulse pressure, left ventricular end-diastolic pressure and
stroke volume, left arterial pressure, SVO.sub.2% in the right
atrium and/or coronary sinus, intra-myocardial pressure and/or
stress testing, such as tread-mill exercise testing. Optionally an
imaging technique (e.g., ultrasound, MRI, angiography, or CT) is
used to determine the size and/or shape of the coronary sinus
and/or other coronary veins.
[0126] Just prior to the catheterization, the patient is optionally
attached to various monitoring equipment, for example, one or more
of ECG (especially to detect and/or monitor one or more of heart
rate, ischemic changes, rate disturbances and/or ST segment
changes), an arterial line for measuring blood pressure, a pulse
oxyrneter, a body thermometer and/or apparatus for tracking blood
gases.
[0127] In an optional step 704, a determination is made of
desirable properties of reducer 100 and a reducer and/or an
expansion protocol is selected to reach these properties.
Alternatively, step 704 is performed after catheterization (712).
In an exemplary embodiment of the invention, the selection of the
reducer depends on one or more of:
[0128] (a) coronary sinus length and diameter (e.g., to obtain a
matching reducer geometry);
[0129] (b) coronary sinus change in diameter near the right atrium
(e.g., to obtain a matching reducer geometry);
[0130] (c) desired increase in coronary sinus pressure before
reducer, optionally including a maximum allowed pressure, for
example, 50 mmHg at which coronary sinus is expected to be damaged
and/or fail (e.g., to decide what narrowing to select);
[0131] (d) desired narrowing (e.g., to decide what narrowing to
select);
[0132] (e) desired later further narrowing (e.g., to decide on
reducer type);
[0133] (f) resistance of coronary sinus wall (e.g., how elastic or
stiff should reducer be and/or what inflation pressure to use);
[0134] (g) desired redistribution of coronary blood flow;
[0135] (h) desired retro-flow of blood in coronary arteries;
and/or
[0136] (i) desired reduction in backflow during right atrium
contraction.
[0137] In an exemplary embodiment of the invention, the venous
location of the reducer is selected to match various cardiac
conditions, such as arterial blockage, alternatively or
additionally to selecting the reducing diameter for each such
reducer. In an exemplary embodiment of the invention, a reducer is
implanted in a coronary vein corresponding to a blocked coronary
artery. Alternatively or additionally, the locations of
implantation are selected to achieve a desired redistribution of
coronary artery pressures and/or blood flow, for example, to
increase perfusion of ischemic or hibernating portions of the
heart.
[0138] In an exemplary embodiment of the invention, a database is
maintained, which provides a correlation between one or more
disease state parameters, the degree of narrowing and/or other
reducer parameters, various expansion protocols and/or the expected
side effects and/or beneficial effects of the reducer. This
database is optionally used to assist in selecting which reducer to
use.
[0139] At 706, the insertion site is disinfected, for example, near
a Jugular vein or a Femoral vein. Depending on the diameter of the
delivery system, a smaller vein may be used, possibly allowing the
procedure to be less invasive. At 708, a local anesthetic is
optionally applied. At 710, a port is inserted in to the vein.
Various tests, for example as described above may be performed, for
example, one or more of Atrium and chamber pressures, LVEDP,
functional tests such as echo-dobutamin and/or perfusion tests.
Optionally, Heparin is provided and an ACT (Activated Clotting
time) test is performed.
[0140] At 712, a guide catheter is inserted into the coronary
sinus. In some delivery methods, no separate guide catheter is
needed. Before inserting the reducer, various measurements may be
performed, for example, a base-line coronary sinus pressure (e.g.,
using a pressure transducer at the end of the catheter), an
angiographic mapping of the coronary sinus, for example to assist
in determining what size reducer to use and/or a test obstruction
of the coronary sinus, for example to assist in determining a
desired narrowing dimension of the reducer that will achieve a
desired pressure increase and/or to detect possible side effects in
the patient of such a pressure increase.
[0141] At 714, a guide sheath is inserted over the catheter to the
coronary sinus. However, alternative insertion methods can be used,
for example, guiding reducer 100 over a guide wire or along a
monorail guide wire. The reducer may be provided with the sheath or
it may be inserted through the sheath after the sheath is in place.
The reducer may be guided to the coronary sinus. Alternatively or
additionally, a suitably sized reducer may be inserted in one or
more coronary veins.
[0142] At 716, the reducer is deployed. In an exemplary embodiment
of the invention, deployment comprises delivering the reducer and
expanding the reducer (e.g., self-expanding or
balloon-expanded).
[0143] At 718, various measurements are optionally performed, for
example, coronary sinus pressures and cardiac functions (e.g., as
noted above). Optionally, as described below, the narrowing
diameter is changed in response to results of the measuring.
Optionally, an image is acquired to ensure the reducer is
positioned correctly. Optionally, a measurement of the coronary
sinus pressure is made to ensure that the resulting increase in
pressure (e.g., by 20 mmHg or 30 mmHg) does not go beyond the
holding capacity of the vein or some other safety number (e.g., 50
mmHg). If the pressure exceeds the holding capacity, the narrowing
may be enlarged, to reduce the pressure differential. It should be
noted that such measurements may be performed before, during and/or
after a corresponding arterial treatment that may be performed
concurrently with the venous treatment.
[0144] At 720, the delivery system is retracted. Optionally,
various measurements (e.g., cardiac function) are performed a
short-time after deployment, for example, after half an hour.
[0145] It is expected that one or more of the following effects is
detected (at once and possibly to a greater extent after some
delay): retrograde increase in coronary sinus pressure, with a
possible associated retrograde flow, improvement of perfusion in
some ischemic areas, reduction in venous O.sub.2 saturation (e.g.,
greater extraction of Oxygen by the cardiac muscle) and/or increase
of intra-myocardial pressure, as an indication of possible
redistribution of blood supply in the heart. Alternatively or
additionally, functional improvements may be viewed, for example,
an improvement in segmental contraction, which can be seen using
ECHO methods.
[0146] At 722, an optional short term follow-up, for example after
a few hours, days or weeks is performed. At 724, an optional long
term follow-up, for example, after a few months or years is
performed. In an exemplary embodiment of the invention, follow-ups
are performed after one week, two weeks one month, three months,
six months and then yearly. Such follow-up may include, for
example, tracking of angina class, treadmill stress test, perfusion
estimation (e.g., using SPECT), functional estimation, for example,
using echo-dobutamin and/or any other typically applied tests.
[0147] It is expected that after a few weeks, the myocardial
perfusion and intra-myocardial pressure will increase and
redistribution of myocardial blood flow will improve, even beyond
the immediate result of the insertion of reducer 100. Possibly, the
auto-regulation mechanism of the coronary flow will start working
again, by the pressure in the coronary arteries increasing beyond
the threshold for activation of the autoregulation mechanism and/or
revascularization should start. After a few months,
revascularization is expected to be well established, and
significantly improve the clinical picture.
[0148] Optionally, the above procedure is varied by first placing a
stent or a graft into the coronary sinus and mounting the reducer
inside the stent or the graft.
[0149] Optionally, the reducer includes an integral blood pressure
sensor, or a separate small blood pressure monitor is implanted,
for example as described in U.S. Pat. No. 6,053,873, in WO
00/32092, in WO 99/34731 and in U.S. Pat. No. 6,159,156, the
disclosures of which are incorporated herein by reference. One or
more transducers are optionally implanted, for example, to measure
a pressure differential across the reducer.
[0150] Reducer 100 may be varied in various manners. It should be
noted, that when placing a reducer in a blood vessel it is
generally desirable that the flow through the reducer be smooth.
Alternatively, the flow may be made turbulent, for the express
purpose of reducing the flow rate through the reducer.
[0151] Reducer 100 has been described generally as including
sections which do not reduce blood flow and sections which do
reduce blood flow. In an alternative embodiment of the invention,
the entire reducer reduces blood flow, for example, reducing
diameter, by at least 20%, 30%, 50% or more. In an exemplary
embodiment of the invention, the vein is actively collapsed on the
reducer, so that the vein is engaged by barbs on the outside of
reducer 100. Optionally, a flared shape is maintained for this
version of the reducer, so that flow remains smooth.
[0152] Occasionally, it is not possible to insert a reducer with
exactly the right diameter. One possible solution is to insert a
second reducer, with a smaller diameter in series (e.g., in
coronary sinus or other coronary veins) or inside an existing
reducer. A reducer for installation inside a second reducer may
have a non-standard shape, for example, including only one funnel
section 200 (e.g., to prevent the need for the delivery system to
pass through the narrowing in the existing reducer) or including
ends adapted to engage the reducer rather than to prevent damage to
the coronary sinus. Another possible solution is to insert a
reducer with a small inner diameter and to increase the diameter as
needed, e.g., by progressively inflating a balloon
therethrough.
[0153] FIG. 6C shows a cross-section through fingered balloon 650,
comprising a body 652 and a plurality of fingers 654. When the
balloon is deflated, the shape of the fingers and their elasticity
causes the fingers to wrap down and reduce the diameter of the
balloon. This may prevent the balloon from catching on narrowing
204. Fingers 654 may be axially elongate. Alternatively, the
fingers are axially short, possibly with a plurality of axially
displaced fingers provided. Such fingers may bend out of the way
when the balloon is retracted.
[0154] FIG. 8 shows a portion of a plan layout of a section of a
reducer 800 with selective narrowing control, in accordance with an
exemplary embodiment of the invention. Reducer 800 includes a
narrowing section 804. However, section 804 is also expandable, for
example, having a plurality of thin slits 806 defined therein. This
allows the minimum diameter of reducer 800 to be increased after
deployment. In an exemplary embodiment of the invention, section
804 is stiffer than the rest of reducer 800, so that pressure
suitable for expanding reducer 800 will not expand section 804.
Alternatively, reducer 800 is a self-deploying device and section
804 is plastically deformed using a balloon. Thus, a delivery
system used for reducer 800 may include both a restraining element
and a balloon element. In case the implantation of a reducer fails,
extreme expansion of section 804 will substantially negate the
function of reducer 800 and will allow a new reducer to be
implanted within reducer 800, at a later time.
[0155] Alternatively, as shown, two sizes of slits 806 are
provided, with the degree of resistance to deformation being
determined by the sizes and/or relative sizes of the slits.
[0156] FIGS. 9A-9F illustrate various reducer variations, in
accordance with exemplary embodiments of the invention. While a
sigmoid-like flaring is shown, a linear or other flaring design may
also be provided.
[0157] FIG. 9A shows a reducer 900 with having a narrowing 902 and
only a single flared out portion 904. Narrowing 902 may point
upstream or down stream. One potential advantage of this design, is
that the delivery system is less likely to get caught inside
narrowing 902. Another potential advantage is that a completely
obstructing implant can be provided. In an exemplary embodiment of
the invention, however, even such a completely obstructing implant
has smooth sides, to prevent damage to the coronary sinus.
Possibly, the outer diameter of the completely obstructing implant
or a nearly complete reducer is increased beyond that of the
coronary sinus, to prevent dislodgment of the implant.
Alternatively or additionally, one or more barbs on the outside of
the implant may be provided. Optionally, a cone shaped reducer is
provided with one or more openings for blood flow on the face of
the cone, rather than at its apex as shown.
[0158] Alternately to a plain reducer, the narrowing may be a
valve, for example, a valve which opens, to a full or partial
diameter, after a suitable pressure is achieved in the coronary
sinus distal from the right atrium. For example, a leaflet valve or
other type of vascular valve as known in the heart may be
provided.
[0159] FIG. 9B shows an alternative reducer 910, with two
narrowings 912 and 916 sandwiching a flared out portion 914 between
them. Optionally, the different narrowings have a different inner
diameter. Optionally, the narrowings are selectively expanded using
a balloon to achieve a desired pressure profile.
[0160] FIG. 9C shows an alternative reducer 920 with three
narrowings 922, 926 and 929 and two flared out portions 924 and 928
between the narrowings.
[0161] FIG. 9D is an example of an asymmetric reducer 930, in which
one flared out portion 932 has a smaller diameter than a second
flared out portion 936, but larger than an intermediate narrowing
portion 934. Such a reducer may be useful, for example, for veins
that change in size along their length, such as the coronary sinus
right next to the right atrium.
[0162] In FIG. 9E, a reducer 940 is not symmetric around its axis,
with one flared out portion 946 being distorted relative to an axis
defined by a second flared out portion 942 and a narrowing portion
944.
[0163] Optionally, the reducer is curved. In an exemplary
embodiment of the invention, asymmetric or curved reducers include
special markings, for example, radio-opaque or radio-transparent
areas, to assist correct orientation of the reducer in a blood
vessel.
[0164] FIG. 9F shows a reducer 950, in which a narrowing section
954 is a sleeve, for example, formed of a flexible graft material,
such as Dacron or GoreTex. Reducer 950 further comprises at least
one of two outer rings 952 and 956 that serve to anchor reducer 950
in the blood vessel. A potential advantage of using a sleeve is
that it can bend to conform to the vein geometry and/or dynamics.
Other reducer designs can also bend. Optionally, the graft material
is elastic, so it can serve as a pressure limiting valve, to better
control coronary sinus pressure. Optionally, a constraining ring is
provided on the outside of section 954, to restrict the lumen of
reducer 950. Optionally, the ring is placed on reducer 950 during
the procedure, to achieve a desired narrowing effect. Alternatively
or additionally, the ring is expandable, for example using a
balloon, to allow controlling the narrowing of reducer 950.
Optionally, the ring is sutured to narrowing section 954.
Optionally, section 954 is stiffened, for example, using a wire, as
known in the art of stent-grafts.
[0165] Optionally, the above various reducers use a delivery system
with a matched balloon form (e.g., different diameters of inflation
at different parts). Alternatively, a single balloon with
controllable inflation (e.g., a central part and a plurality of
fingers) is provide, in which the balloon is placed inside the
reducer at a certain axial position and inflated to further expand
that section. Alternatively, different axial sections of the
reducer have different resistance, elasticity, plasticity and/or
other mechanical properties.
[0166] Optionally, the reducer is adapted to release one or more
molecules into the blood flow, for example, angiogenesis causing
molecules, adhesion enhancing molecules (e.g., for adhesion to the
vein wall), anti-coagulation drugs, growth factors, DNA carriers
(e.g., liposomes, plasmids), hormones, and/or other molecules as
known in the art. In an exemplary embodiment of the invention, the
release is towards the vessel wall and/or towards the blood flow.
Optionally, the release is selectively in the part of the flow
before the narrowing or after the narrowing, to take advantage or
to avoid backflow caused by the reducer. Various release mechanisms
are known in the rat and may be used, for example, using a coated
reducer, a porous reducer, a reducer with a drug chamber or a
reducer that includes a channel between the reducer and the vein
wall for holding the drug.
[0167] A reducer, similar to that of FIG. 3, has been tested on
animals (pigs), using the following procedure.
[0168] (a) Anti-Trandelburg of the animal, to increase venous
return in the Jugular.
[0169] (b) Clearing an area over a vein (e.g., Jugular, Femoral,
Subclavian).
[0170] (c) Insert F6 sheath directly into vein.
[0171] (d) Provide heparin 2500 units.
[0172] (e) Insert a catheter to the coronary sinus.
[0173] (f) Insert Amplaz super stiff guide of 180 mm or 200 mm to
coronary sinus.
[0174] (g) Attempt to insert 3.5 mm outer diameter reducer through
an IVC filter sheath.
[0175] (h) Pass a balloon through a 40 cm or 60 cm arrow sheath,
inflate and deflate twice and then place reducer on the deflated
balloon, and check for stability.
[0176] (i) Insert IVC filter sheath to coronary sinus, as distal as
possible and pass reducer through sheath. If reducer moves, inflate
balloon a bit. Then position reducer in coronary sinus.
[0177] (j) Check ACT.
[0178] (k) Advance reducer so that it leaves sheath arrow and
inflate balloon to fix reducer in place.
[0179] (l) Remove balloon (possibly sucking out fluid from balloon
using a syringe). Twist the balloon.
[0180] (m) If arrow sheath gets stuck on narrowing section of
reducer, try rotating sheath and/or using IVC filter sheath as a
contra.
[0181] (n) If reducer did not fit in step (g), put in a peel away
banana sheath.
[0182] (o) Insert reducer of (h) through banana sheath. Since
banana is 14F and sheath arrow is 10F, there may be some bleeding.
Inflate balloon if reducer moves.
[0183] (p) Do (i)-(1)
[0184] (q) Is sheath arrow gets stuck in narrowing section of
reducer, take out banana sheath, cut proximal end of balloon and
sheath arrow and insert IVC filter sheath for use as a contra (as
in (m).
[0185] The effect of inserting reducer 100 in four animals (pigs),
was estimated to be an average increase in coronary sinus mean
pressure from 7.0 mmg to 24.6 mmg. These measurements were made
with a Swan-Ganz catheter including a narrowing balloon mounted on
the catheter to emulate the effect of reducer 100. The amount of
narrowing was estimated to be between 70% and 80% based on an
angiogram using injected contrast material. In another four pigs, a
reducer was implanted the reducer was test implanted and in three
pigs, the reducer was implanted.
[0186] Two of the pigs in which the device was implanted were
sacrificed for assessment of angiogenesis after two and three
months. The cardiac tissue was fixed using Formalin. Both pigs
showed significant proliferation of small-medium sized vessels
containing smooth muscle, which represent coronary collaterals.
This was true of almost all the samples, from various parts of the
heart, including samples form anterior and mid-posterior wall. The
most significant proliferation was evident at the peri-coronary
sinus specimens, both anterior and posterior.
[0187] While the above has been described for use in coronary
veins, a reducer with similar design may also be used in other
veins, for example, popliteal, tibial or saphenous veins. In an
exemplary embodiment of the invention, one or more reducers are
implanted in popliteal veins, to increase back-pressure and
possibly enhance tissue perfusion pressure and/or redistribute
blood flow in the leg. It is expected that pooling will not occur
due to the existence of alternative drainage paths in the leg.
[0188] In another example, the reducer can be adapted to match
other ducts or conduits in the body, for example, with respect to
size, length, degree of narrowing, degree of elasticity and form of
contact with the conduit walls.
[0189] In an exemplary embodiment of the invention, reducer 100 is
provided in kit form, possibly with additional reducers, and
including instructions for use and/or size markings. Optionally,
the reducer is provided inserted into a delivery system or packaged
with a delivery system.
[0190] It will be appreciated that the above described methods of
deploying a reducer implant may be varied in many ways, including,
changing the order of acts, which acts are performed more often and
which less often, the type and order of tools used and/or the
particular timing sequences used. Further, the location of various
elements may be switched, without exceeding the sprit of the
disclosure. In addition, a multiplicity of various features, both
of methods and of devices have been described. It should be
appreciated that different features may be combined in different
ways. In particular, not all the features shown above in a
particular embodiment are necessary in every similar exemplary
embodiment of the invention. Further, combinations of features from
different embodiments into a single embodiment or a single feature
are also considered to be within the scope of some exemplary
embodiments of the invention. In addition, some of the features of
the invention described herein may be adapted for use with prior
art devices, in accordance with other exemplary embodiments of the
invention. The particular geometric forms and measurements used to
illustrate the invention should not be considered limiting the
invention in its broadest aspect to only those forms. Although some
limitations are described only as method or apparatus limitations,
the scope of the invention also includes apparatus designed to
carry out the methods and methods of using the apparatus.
[0191] Also within the scope of the invention are surgical kits,
for example, kits that include sets of delivery systems and reducer
implants. Optionally, such kits also include instructions for use.
Measurements are provided to serve only as exemplary measurements
for particular cases, the exact measurements applied will vary
depending on the application. When used in the following claims,
the terms "comprises", "comprising", "includes", "including" or the
like means "including but not limited to".
[0192] It will be appreciated by a person skilled in the art that
the present invention is not limited by what has thus far been
described. Rather, the scope of the present invention is limited
only by the following claims.
* * * * *