WO1999053862A1 - The balloon expandable sheet stent and technology of its manufacturing - Google Patents

The balloon expandable sheet stent and technology of its manufacturing Download PDF

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Publication number
WO1999053862A1
WO1999053862A1 PCT/IL1998/000189 IL9800189W WO9953862A1 WO 1999053862 A1 WO1999053862 A1 WO 1999053862A1 IL 9800189 W IL9800189 W IL 9800189W WO 9953862 A1 WO9953862 A1 WO 9953862A1
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WO
WIPO (PCT)
Prior art keywords
stent
constructive elements
stencil
strutted
geometrical profile
Prior art date
Application number
PCT/IL1998/000189
Other languages
French (fr)
Inventor
Valerian Voinov
Yuli Glatman
Original Assignee
Brainwave Cardio-Vascular Technologies Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Brainwave Cardio-Vascular Technologies Ltd. filed Critical Brainwave Cardio-Vascular Technologies Ltd.
Priority to PCT/IL1998/000189 priority Critical patent/WO1999053862A1/en
Publication of WO1999053862A1 publication Critical patent/WO1999053862A1/en

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Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/88Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure the wire-like elements formed as helical or spiral coils
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/95Instruments specially adapted for placement or removal of stents or stent-grafts
    • A61F2/958Inflatable balloons for placing stents or stent-grafts
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2002/825Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents having longitudinal struts
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • A61F2002/91533Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other characterised by the phase between adjacent bands
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • A61F2002/9155Adjacent bands being connected to each other
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61FFILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2210/00Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2210/0004Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof bioabsorbable

Abstract

The Balloon Expandable Sheet Stent is intended for the better support of a diseased vessel wall on the basis of securing the very best thromboresistant properties and raise in the serviceability of a stent in a vessel. The stent (19) comprises a cylindrical surface formed by semi-circular bands (20) oppositely located along the stent longitudinal axis and displaced one against another for a calculated step, and arc-shaped links (12) uniting the said semi-circular bands (20) between themselves on their loose diametrical ends (15) over a generating line of the said stent cylindrical surface. The said stent cylindrical surface is preliminary formed on the surface of a thin sheet metallic blank (13) in a shape of a stencil (10) of calculated geometrical profile constructive elements with the final linear and diametrical sizes of the stent design. In a state of the said stencil (10) one group (11) of the said calculated geometrical profile constructive elements is executed with a possibility of bending and shaping of pockets (16) with clearances for a deployment of bioabsorbable components for local drug delivery, the other group (12) of these constructive elements is executed with a possibility of flanging on both sides from the said stencil longitudinal axis and shaping of a lumen for the deployment of an uninflated balloon (18) of the conducting catheter. The proposed stent design could be manufactured with the application of a simple unwasted technology.

Description

- 1 -

THE BALLOON EXPANDABLE SHEET STENT and TECHNOLOGY of its MANUFACTURING

Field and Background of the Invention

The present invention relates generally to medical technology, particularly to expandable cardiovascular stents, which are intended for the radical arterial lumen

recovery with subsequent restoring of the normal blood flow.

In the present application the term "stent" refers to the device designed to expand the blood vessel and to maintain the achieved size of lumen. Traditionally, stents are delivered to the target area in the cardiovascular system on the inflatable

balloon located on the tip of a transluminal catheter. Then, the balloon is inflated leading to the expansion of the stent thereby widening the lumen of the vessel.

Other less common systems for stent delivery also exist.

Most of the existent stents made from metals. The examples of common designs described in patents are: US 4.733.665, US 4.969.458, US 5.102.417, US 5.195.994,

US 5.513.444, WO 91FR013820. Certain properties of any metallic surface lead to thrombogenicity of the stent once it is implanted within the human cardiovascular system. Therefore, one of the important directions in the stent development is the

improvement of the stent thromboresistance because this would reduce the in systemic anticoagulation therapy thereby reducing complication rate after stent implantation. In the present, none of the metallic stents designs have achieved

the delicate balance between the desired durability to sufficiently support the

vessel wall and flexibility to reduce the thrombogenicity and intimal hyperplasia.

Thus, there is a substantial need for anticoagulation and thrombolitic therapy following stent implantation. - 2 -

Utilization of metal in the stent design leads to further flaws. One of limitations of metallic stent is a presence of more or less rigid kinematic link between construc¬

tive elements of radial strength and flexibility. This factor creates additional difficulties during the delivery of the stent to the target area in the coronary artery, especially in distal segments of the vessel. This factor also plays a major role in the shortening of the stent upon stent inflation, which may lead to the suboptimal

implantation of the stent, especially in diseased segments of blood vessels, and also this may activate undesirable postprocedural processes, such as thrombosis and

restenosis.

The rigidity of a kinematic link between the constructive elements of radial

strength and flexibility in already complicated geometrical forms of the stent

structure does not allow to use thin metal plates in the stent manufacturing, on the contrary, it requires high inflation pressures upon the deployment of the stent to prevent the stent from collapsing into the vessel lumen. However, ideally,

a stent structure should combine the longitudinal flexibility and radial rigidity, which would correspond optimally to the characteristics of pulsating coronary

arteries.

Despite the fact the descriptions of most conventional stents claim that these are low profile stents, in fact, all known stents have profiles in the range of 1.3-1.6 mm.

This is due to the limitations of the technology of stent manufacturing. All stents

are placed on balloons with a minimal diameter of 1.6 mm, which already restricts

clinical applications of stents in small vessels. There is no known stent, which

parameters would permit it to be used in vessels 2 mm or less.

The additional advantage of a stent structure is an ability to perform an adjunctive - 3 -

angioplasty after the deployment of the stent. This also permits the better adjus- ment of the stent to the arterial wall due to the deeper penetration of the stent outer elements into the media and the atherosclerotic plaque.

One of the disadvantages, on the other hand, is the metallic surface of a stent in

general, and especially the texture of the surface, which can attract the blood

elements and activate the formation of the thrombus, as well as initiate the exaggerated healing process, which through the proliferation of the smooth muscle

cells results in restenosis. Therefore, the important part of the stent design is the

ability to accommodate various bioabsorbable polymers within itself, which can be

loaded with antithrombotic and/or antiproliferative pharmacologic agents with

high concentrations. Thus, these agents, delivered locally into the arterial wall, can

prevent thrombosis, neointimal proliferation and also avoid unwanted systemic

side effects. However, so far the results of clinical experiments with polymer coated stents show frequent occurrence of inflammatory reactions to the polymers by the vessel wall, which limits their clinical applications.

Another important limitation of the stenting is an expensive technology of the

stents' manufacturing, which involves the laser technology in almost all known

stents, which lowers the cost-effectiveness of the device, and, therefore it's

utilization in clinical practice. This technology also leaves the quality of the stents'

surface suboptimal, with subsequent higher percentage of thrombus formation on

this surface.

In summary, the "ideal" stent should possess the following high quality properties:

flexibility, trackability, non-shortness, ultra-low profile, visibility in the X-rays,

thromboresistance, biocompatability, reliable expandability, wide range of - 4 -

available sizes, optional capability of the local drug delivery, and low cost (see, P. Ruygrok and P. Serruys Intracoronary stenting. "Circulation", 1996, 882-890).

These features will widen clinical applications of stenting, enable the reduction of

unwanted side effects, and ultimately improve the clinical outcome.

The Prior Art

The most effective technical solution for the slotted tube stents, combining both

flexibility and radial durability is proposed in the patent application PCT/TL 96/00148 filed on 12.11.1996.

In the above mentioned invention the constructive element, which provides the

radial strength of the stent, is constructed in a form of a series of circular bands

(2, Fig. 1), disposed over a common longitudinal axis with a number of curvilinear

components (3), which play a role of compensators of the diametrical deformation

(CDDs). CDD comprises of a least two rods (4), conjugated in the apex (5) by a V-shaped connection. The loose ends of the rods (4) are closed by the undefor-

mable segments (6) of the circular bands (2).

Upon the expansion of the stent (1), resulting from the outward forces from the

inflating balloon, CCDs enable the increase of the diameter of each circular bands

(2) up to a certain predetermined size where the degree of the diameter increase is

proportional to the number of the CDDs. The maximal diameter of the circular

band (2) corresponds to the inner diameter of the vessel wall, and the circular band

(2) in this position takes shape of almost ideal circle with width of the one CDD

rod. The number of circular bands varies from 2 to 40 depending on the length of

the stent.

The longitudinal flexibility of the stent is based on the separation of the static and - 5 -

dynamic functions between the circular bands (2) and the constructive elements of flexibility (7) of the stent, which connect the CDDs. Where the circular band (2)

with CDD performs only static function of preventing the vessel wall from collapsing, the constructive element of flexibility (7) of interconnecting zone possesses

the significant dynamic function as well, because it needs to reflect the differences

in the various segments of the vessel. On another hand, the latter element (7) does

not transfer the deformation to the circular bands (2). Therefore, it plays a role of

the compensator of the longitudinal deformation (CLD).

CLD (7) comprises of two rods (8), conjugated at the apex (9) by V-shaped 90 degree oriented connection. All the rods (8) have the same length and their loose

ends are closed by the undeformable segments (6) of the circular bands (2).

The degree of flexibility of the stent depends on the sum of lengths of all CLD rods.

Therefore, the optimal positioning of the CLDs between CDDs during manufacturing becomes very important to achieve the maximum possible number of CLDs

on each stent.

Fig. 2 shows that the expansion of the stent only CDDs change their geometrical

forms, whereas CLDs, connected to the undeformable segments (6), do not receive

the deformation force from the expansion. On another hand, since all junctions (4)

of the CDDs have the same size, the stent maintains the cylindrical shape after

the expansion.

The discussed invention also describes the effective approach to increase the

longitudinal flexibility of a stent to match the changes of the shape of the pulsating

vessel. This can be accomplished by producing CLDs from the bioabsorbable

polymer material. However, that patent application does not describe any - 6 -

particular engineering solution to this idea, probably, because the described model is a slotted tube stent, which almost excludes the possibility of incorporating

biodegradable materials.

Another limitation of the slotted tube stent design comes from certain short-

-comings of manufacturing process, which is most of cases is a laser technology.

Particularly, this technology limits the accuracy of the length of CDD rods, the

radius of the curve in the V-shaped structures, and the optimal position of the

CDDs and CLDs in the original shape of the stent. This may potentially lead upon the expansion of the stent in the moving vessel to the deformation of the stent with subsequent activation of the processes of intimal hyperplasia and thrombosis.

Taking into consideration that the discussed model of the stent is the closest one

the "ideal" stent among slotted tube stents, this design nevertheless contains some

unresolved flaws, which need to addressed to improve the clinical outcome and

minimize such unwanted effects of stenting as thrombosis and restenosis.

Therefore, the future "ideal" expandable stent must possess the following characteristics:

1. Maximal radial strength.

2. Correspondence with the shape of the vessel.

3. Compliance to the pulsating vessel.

4. Non-shortning on expansion.

5. Minimum low profile.

6. Accommodation of additional angioplasty.

7. Visibility in X-rays.

8. Capability of local drug delivery. - 7 -

9. Low manufacturing costs with a high quality easily reproducible manufacturing technology, thus meeting the modern requirements of a cost-effective medical

device.

Summary of the Invention

The purpose of the invention is creation of a stent design with a necessary complex

of thromboresistant properties including those of minimum low profile before

the expansion and non-shortened state upon the expansion of the stent, and

provision of a possibility to manufacture devices according to a simple unwasted

technology.

This aim is achieved by the fact that the Balloon Expandable Sheet Stent comprises

a cylindrical surface formed by a multitude of strutted constructive elements execu¬

ted in a shape of semi-circular bands oppositely located along a stent longitudinal

axis and displaced one against another for a calculated step, and by a multitude of

outlined constructive elements executed in a shape of non-strutted links. The said

outlined constructive elements unite the said semi-circular bands together on their

loose diametrical ends and are located over the generating line of the said stent

cylindrical surface.

The essential different sign of the Balloon Expandable Sheet Stent consists in a fact

that the said strutted and outlined constructive elements of the said stent cylindrical

surface are preliminary formed on the surface of a thin sheet metallic blank in

a shape of a stencil of calculated geometrical profile constructive elements with

the final linear and diametrical sizes of the stent design.

In the said, preliminary formed, stencil of the calculated geometrical profile

constructive elements a prior part of the said sheet metallic blank surface area is - 8 -

occupied by the said strutted constructive elements that have a possibility, upon the execution of the said stencil, of a free relative spatial positioning along the said stent longitudinal axis.

In a state of the said stencil the outlined constructive elements of the calculated geometrical profile are executed with a possibility of bending and shaping pockets

with clearances in the units of their connection with the loose diametrical ends of

the strutted constructive elements of the calculated geometrical profile. Upon the

expansion of the said stent the said outlined constructive elements do not take

the strutted forces from a inflatable balloon, and are only additionally pressed by the said pockets to the generating line of the said stent cylindrical surface,

eliminating the said pockets clearances and integrating into the vessel wall.

In a state of the said stencil the strutted constructive elements of the calculated

geometrical profile are executed with a possibility of flanging along the both sides

from the said stencil longitudinal axis and shaping of a lumen for the deployment

of an uninflated balloon in it. Upon the insignificant inflation of the said balloon

the said strutted constructive elements of the calculated geometrical profile take

up a shape approximating that of a stent non-expanded profile minimum accessible outward diameter. After the expansion of the said stent and the flexible forces

from the pulsating vessel the said strutted constructive elements do not take the

occurring forces.

The said stent can be supplied with the bioabsorbable components for local drug

delivery that are located in the clearances of the said pockets along the said stent

longitudinal axis. In this case the shape, volume and geometrical sizes of the said

bioabsorbable components are predetermined. - 9 -

The technological process of stent manufacturing includes the following steps:

- separation of the thin sheet metallic blank with a multiple unwasted quantity of the stent designs with their final linear and diametrical sizes;

- execution of a stencil of strutted and outlined constructive elements of calculated

geometrical profile on the surface of the said sheet metallic blank;

- bending of the outlined constructive elements of the calculated geometrical profile

and shaping of pockets with clearances in the units of their connection with loose

diametrical ends of the strutted constructive elements of the calculated geometrical

profile;

- flanging of the said strutted constructive elements of the calculated geometrical

profile along the both sides from the stencil longitudinal axis and of shaping a lumen for the deployment of an uninflated balloon in it;

- separation of a ready device;

- conditioning of the said ready device surfaces;

- location in the said pockets clearances along the stent longitudinal axis of

the bioabsorbable components for local drug delivery;

- location of the said ready device on the uninflated balloon of a conductive catheter.

The said stent could also be manufactured in an automatic cycle of the said technological operations.

The proposed Balloon Expandable Sheet Stent possesses the following characte¬

ristics:

1. The unique transformation of the sheet metallic blank into a stent regular cylind¬

rical surface.

2. Kinematic structure of the stent cylindrical surface excluding the mutual force - 10 -

influence of the elements of radial strength and flexibility.

3. Minimum outward diameter of the stent non-expanded profile.

4. Constancy of the linear size both in non-expanded and expanded positions.

5. Accommodation of additional angioplasty.

6. Visibility in X-rays.

7. Capability of bioabsorbable components for local drug delivery.

8. Manufacturing clinical samples with a diameter from 2.0 to 5.5 mm.

9. Manufacturing clinical samples with a length from 3.5 to 80 mm.

10. Manufacturing of the devices with a simple unwasted technology.

Thus, the proposed stent design possesses a complex of the necessary thrombo-

resistant characteristics including ultra-low profile before the expansion and

non-shortened after the expansion of the stent, and secures the possibility of stent manufacturing with a simple unwasted technology.

Brief Description of the Drawings

This invention is herein described with the help of an examples and references

to the accompanying drawings, wherein:

Fig. 1 shows the stent-prototype before the expansion.

Fig. 2 shows the stent-prototype after the expansion.

Fig. 3 shows a stencil of strutted and outlined constructive elements of a calculated

geometrical profile is executed on the surface of a thin sheet metallic blank,

according to the invention.

Fig. 4 shows bend variants of diametrically located outlined constructive elements

with formed pockets having clearances, including:

a) the bend of the outlined constructive elements to one side from the stencil - 11 -

longitudinal axis; b) the same as in Fig. 4a, but with bioabsorbable components located in the clearan¬

ces of the pockets; c) the bend of the outlined constructive elements along the both sides from the

stencil longitudinal axis; d) the bend of the outlined constructive elements along the both sides and situated

in a staggered order along the stencil longitudinal axis;

e) the same as in Fig. 4d, but with several bioabsorbable components located in

the clearances of the pockets.

Fig. 5 shows a stent the strutted constructive elements of which are flanged on

both sides from the stencil longitudinal axis and form a lumen for the location

of an uninflated balloon in it, according to the invention.

where S - a calculated step of displacing opposite strutted constructive elements one against another along stent longitudinal axis.

Fig. 6 shows the same as in Fig. 5, but with bioabsorbable components located in

the clearances of the pockets.

Fig. 7 shows a stent part with several bioabsorbable components in the clearances

of the pockets as shown in Fig. 6.

Fig. 8 shows a stent before the expansion, according to the invention, which is located on the uninflated balloon.

Fig. 9 shows a stent cross-section, according to Fig. 8, after an insignificant

inflation of the balloon and a formation of a stent non-expanded profile,

minimum accessible outward diameter.

Fig. 10 shows a stent after the expansion, according to the invention, - 12 -

Fig. 11 shows a stent part, according to Fig. 10, with bioabsorbable components located in the clearances of the pockets.

Fig. 12 shows a state of strutted and outlined constructive elements before

the expansion (a,b) and after expansion (c,d) of the stent, according to the

invention,

where L - longitudinal size of the outlined constructive elements.

Specific Description

Fig. 3 shows a stencil (10) of strutted (11) and outlined (12) constructive elements

of a calculated geometrical profile formed on the surface of a thin sheet metallic blank ( 13). Whereas the linear and diametrical sizes of the stent design are the final.

The strutted constructive elements (11) are executed, for example, in Z - shaped

geometrical profiles and occupy a prior part of the said stencil (10). When forming

the said stencil (10) the Z - shaped profiles (11) have a possibility of a free relative

spatial positioning along the stencil longitudinal axis. This allows to design minimum

low profile devices and provides a possibility for implantation of a stent into a distant

and most curved parts of diseased vessel. In the proposed stent design a diameter

before the expansion is limited only by the presence of the uninflated balloon with

a corresponding diameter.

The outlined constructive elements (12) are executed, for example, in a form of

non-strutted arc - shaped links, which connect the Z - shaped profiles (11) in units

(14) on their loose diametrical ends (15).

The minimum quantity of the Z - shaped profiles (11) and arc - shaped links (12) in

the said stencil (10) of the calculated geometrical profile is four of every element.

Maximum quantity of such constructive elements is practically unlimited and - 13 -

is determined by the necessary clinical requirements.

In a state of the said stencil (10) the arc - shaped links (12) of the calculated geometrical profile are executed with a possibility of bending and shaping pockets

(16) with clearances for locating some bioabsorbable components for local drug delivery in them. The bend of the arc - shaped links (12) is done in the units (14) of

their connection with loose diametrical ends (15) of the Z - shaped profiles (11) along

one or both sides in relation to the stencil longitudinal axis. In Fig. 4 are shown bend variants of diametrically placed the arc - shaped links (12) with formed pockets (16)

having clearances for locating some bioabsorbable components for local drug

delivery. Fig. 4a corresponds to the bend variant of the arc - shaped links (12) with

formed the pockets (16) along one side in relation to the stencil longitudinal axis.

Fig. 4b corresponds to the bend variant of the arc - shaped links (12) along one side

with bioabsorbable components (17) located in the clearances of the pockets (16). Fig. 4c corresponds to the bend variant of the arc - shaped links (12) with formed

the pockets (16) along the both sides in relation to the stencil longitudinal axis.

Fig. 4d corresponds to the bend variant of the arc - shaped links (12) with formed

the pockets (16) and situated in a staggered order in relation to the stencil

longitudinal axis. Fig. 4e corresponds to the bend variant of the arc - shaped links (12)

with several bioabsorbable components (17) located in the clearances of the pockets

(16).

In a state of the said stencil (10) the Z - shaped profiles (11) are executed with

a possibility of flanging along the both sides of the stencil longitudinal axis and

of displacing one against another for a calculated step S (Fig. 5, 6, 7). With the

flanging of the Z - shaped profiles (11) from the stencil longitudinal axis a lumen is - 14 -

formed, wherein an uninflated balloon (18) of the conducting catheter is located (Fig. 8). Upon the insignificant inflation of the balloon (18) the Z - shaped

profiles (11) take up a shape approximating that of a stent non-expanded profile minimum accessible outward diameter (Fig. 10, pos. 19).

With all this the bended arc - shaped links (12) are situated over a generating

line of the stent (19) cylindrical surface along the stent longitudinal axis and are

compensators of a longitudinal deformation upon the conduction of the stent to

the place of the diseased vessel, and also after the expansion of the stent in the

vessel upon the pulsating dynamical loads.

Some bioabsorbable components (17), located in the clearances of the pockets (16),

are executed, for example, from a polymer thread or film, which can be loaded with

high concentration agents for the sustained local drug delivery. The shape, volume

and geometrical sizes of bioabsorbable components (17) are predetermined.

On the outward surface of the polymer thread (17) the marks are made (not shown

in the Figures), which are visible in X-rays on the stent body upon the implantation.

Figs. 10, 11 show the stent (19), which is expanded in a vessel by the generally

accepted balloon expandable stent method. In can be seen that upon the expanding

load the Z - shaped profiles (11) take up the form of undeformed strutted semi-

-circular bands (20) and displace one against another for a calculated step S. The

outward diameter of such semi-circular bands (20) corresponds to the maximum

vessel inner diameter, and the width of every semi-circular band approaches that

of the Z - shaped profile (11). After the attainment of the semi-circular bands (20)

of the maximum vessel inner diameter, the angular apices (21) on the surface

of the semi-circular bands (20) integrate into a vessel wall, helping the stent (19) - 15 -

to adjoin the vascular tissue more closely.

As is seen from Figs. 10, 12 upon the expansion of the stent (19) only the Z - shaped

profiles (11) deform and change their geometrical sizes. The arc - shaped links (12),

attached to the corresponding undeformed loose diametrical ends (15) of the strutted semi-circular bands (20), do not take the forces and deformations from the expanded

load. The arc - shaped links (12) are closely pressed by the pockets (16) to the

cylindrical surface generating line of the stent (19), eliminating the clearances lumen

and integrating into the vessel wall (additional deformation angioplactic of the

diseased vascular tissue). Due to the absence of kinematic link between the

Z - shaped profiles (11) and the arc - shaped links (12) the stent (19) does not

change its length (L) upon the expansion up to the maximum vessel inner diameter

(Fig. 12). At the same time, the semi-circular bands (20) do not react to the flexible

forces that occur from the pulsating vessel side (after the expansion of the stent).

Upon the heart muscle contraction the installed stent does not violate the natural

dynamics of the vessel function, the fact that creates favorable conditions for the

normal restoration of the traumatic vascular tissue. This should also be effectively

assisted by the reglamented medication therapy with bioabsorbable components

loaded into the polymer thread.

Upon designing the stencil (10) of the calculated geometrical profile constructive

elements there exists a possibility of creation a stent outward surface with cone-

-like shape. This is done upon the stencil formation by way of regulating the

strutted constructive elements geometrical sizes. Besides, due to the possibility of

modifying the volume of the calculated step S between the opposite semi-circular

bands (20) situated along the stent longitudinal axis stents could be implanted - 16 - into the bifurcated coronary artery.

The technology of manufacturing the proposed stent design is a sum total of the developed operations., whose name and sequence of execution are described in the Summary of the Invention.

One of the important advantages of the proposed technological process is

a simple unwasted expenditure of metal, the use of the available operations (as,

for examples, stamping, Fhoto-Chemical Machining, Electro-Chemical Polishing)

for the formation of the stencil of the calculated geometrical profile constructive

elements and a simple transformation of the steet stencil into a cylindrical form

of a regular stent. As a whole, this brings the proposed technological process to

the level of modern industrial production and allows for the creation of comparati¬

vely cheap programme-controlled automatic lines.

Thus, in comparison to the prototype and already the known analogues, the

proposed stent design possesses the best thromboresistant characteristics,

increases the serviceability of the stent in the vessel and can be made according

to the simple unwasted technology. Thanks to this new possibilities are opened

for obtaining effective results in the treatment of coronary artery and for

an essential raise in the volume of stent application in clinical practice.

Industrial Applicability

The proposed balloon expandable sheet stent is a basis for design, production and

application of a wide spectrum of cardiovascular samples. The model is recommended

for bulk serial and massive production. A preferred mode of the balloon expandable

sheet stent production is described above. Still, the construction equivalent elements

can be improved without losing the invention advantages, formulated as follows.

Claims

- 17 - What is claimed is: 1. The Balloon Expandable Sheet Stent for insertion in a lumen of a vessel of a living being, comprising:
- cylindrical surface, formed by a multitute of strutted constructive elements, executed in a shape of semi-circular bands oppositely located along the stent
longitudinal axis and displaced one against another for a calculated step, and
by a multitute of outlined constructive elements, executed in a shape of
non-strutted links, the said outlined constructive elements unite the said semi-
-circular bands together on their loose diametrical ends and are located over
a generating line of the said cylindrical surface, whereas the said strutted and
outlined constructive elements of the said stent cylindrical surface are preliminary
formed on the surface of a thin sheet metallic blank in a shape of a stencil of
a calculated geometrical profile constructive elements with the final linear and diametrical sizes of the stent design;
- in the said, preliminary formed, stencil of the calculated geometrical profile
constructive elements a prior part of the said sheet metallic blank area is taken
by the said strutted constructive elements that have a possibility, upon the
execution of the said stencil, of a free relative spatial location along the stencil
longitudinal axis;
- in a state of the said stencil the outlined constructive elements of the calculated
geometrical profile are executed with a possibility of bending and shaping of
pockets with clearances in the units of their connection with loose diametrical ends
of the calculated geometrical profile strutted constructive elements, whereas upon
the expansion of the said stent the said outlined constructive elements do not take - 18 -
strutted forces from a inflatable balloon, and are only additionally pressed by the said pockets to the generating line of the said stent cylindrical surface,
eliminating the said pockets clearances and integrating into a vessel wall;
- in a state of the said stencil the strutted constructive elements of the calculated geometrical profile are executed with a possibility of flanging along the both sides
from the said stencil longitudinal axis and shaping of a lumen for the deployment
of a uninflated balloon in it, whereas upon the insignificant inflation of the said
balloon the said strutted constructive elements of the calculated geometrical
profile take up a shape approximating that of a stent non-expanded profile minimum accessible outward diameter, and after the expansion of the said stent
and the flexible forces from the pulsating vessel the said strutted constructive
elements do not take the occurring forces.
2. The Balloon Expandable Sheet Stent, wherein a shape, volume and geometri¬
cal sizes of bioabsorbable components for local drug delivery are predetermined.
3. The Balloon Expandable Sheet Stent, technological process of manufacturing
of which includes the following operations:
- separation of a thin sheet metallic blank with multiple unwasted quantity of the
stent designs with their final linear and diametrical sizes;
- execution of a stencil of strutted and outlined constructive elements of
a calculated geometrical profile on the surface of the said sheet metallic blank;
- bending of the outlined constructive elements of the calculated geometrical profile
and shaping of pockets with clearances in the units of their connection with loose
diametrical ends of the strutted constructive elements of the calculated geometrical
profile; - 19 -
- flanging of the strutted constructive elements of the calculated geometrical profile along the both sides from the stencil longitudinal axis and shaping of a lumen for the deployment of an uninflated balloon of the conductive catheter
in it;
- separation of a ready device;
- conditioning of the said ready device surfaces;
- location of bioabsorbable components for local drug delivery in the said pockets
clearances along the stent longitudinal axis;
- location of the said ready device on the uninflated balloon of the conductive
catheter.
4. The Balloon Expandable Sheet Stent as in claim 3, wherein is executed in
an automatic cycle of the said technological operations.
PCT/IL1998/000189 1998-04-21 1998-04-21 The balloon expandable sheet stent and technology of its manufacturing WO1999053862A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IL1998/000189 WO1999053862A1 (en) 1998-04-21 1998-04-21 The balloon expandable sheet stent and technology of its manufacturing

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IL1998/000189 WO1999053862A1 (en) 1998-04-21 1998-04-21 The balloon expandable sheet stent and technology of its manufacturing

Publications (1)

Publication Number Publication Date
WO1999053862A1 true WO1999053862A1 (en) 1999-10-28

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US9023094B2 (en) 2007-06-25 2015-05-05 Microvention, Inc. Self-expanding prosthesis

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Publication number Priority date Publication date Assignee Title
US8221490B2 (en) 1998-10-23 2012-07-17 Boston Scientific Scimed, Inc. Helical stent design
US6488703B1 (en) 1998-10-23 2002-12-03 Scimed Life Systems, Inc. Helical stent design
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EP1176927A1 (en) * 1999-04-25 2002-02-06 Brainwave Cardio-Vascular Technologies Ltd. The double-sheet stent
US20040149294A1 (en) * 2002-12-16 2004-08-05 Gianchandani Yogesh B. Assembly and planar structure for use therein which is expandable into a 3-D structure such as a stent and device for making the planar structure
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US9023094B2 (en) 2007-06-25 2015-05-05 Microvention, Inc. Self-expanding prosthesis

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