Note: Descriptions are shown in the official language in which they were submitted.
~ WO95/25560 2 ~ Q r~ 7~,~
INTRA "' lC BALLOON ~'7~'1'~'r~70~
- This application is a continuation-in-part of co-
pending application Serial No. 08/170,513 filed December
20, 1993.
FTP rn OF Tl~17. INVE~TION
This invention relates to intra-aortic balloon pumps
and particularly to improved intra-aortic balloon pump
catheters .
BACKGROUND OF THE INVENTION
Intra-aortic balloon pumps (IABP) are used to
provide counter pulsation within the aorta of ailing
hearts over substantial periods of time, e.g. to provide
ventricular assistance during cardiogenic shock, low
cardiac output in post-operative care, weaning from
car~ p~ ry bypass, treatment for refractory unstable
angina, and other circumstances of sub-normal cardiac
function. Such pumps of the type involved in this
invention include a flexible intra-aortic balloon (IAB)
which is readily in~latable under low pressure to
substantial size and displ~ ~~ L. The balloon is
mounted on a catheter device used for insertion of the
balloon into a remote artery, typically a femoral artery,
and through the intervening vascular system of the
patient to the aortic pumping site while the balloon is
def lated and furled . This requires insertion of the
furled large capacity balloon through a small insertion
passage, e.g., a small puncture opening or through an
introducer cannula into the selected artery, and then
sliding-threading of the catheter and furled balloon
through tortuous lumen passageways of the patient's
vascular system over a guidewire to the pumping site,
e.g. from insertion into an artery in the groin area to
the patient's ~cc~ntlin~ aorta. At the pumping site, the
W095/25560 21 ~g2.0 PcrluS95/03464 ~
balloon is unfurled and then successively and rapidly
inflated and deflated in synchronism with the patient's
cardiac pulsation rates over extended periods of time in t
a known counterpulsation technique to enhance cardiac
5 output. Thus, use of an IABP requires forceful sliding
insertion of a relatively large balloon through a small
insertion opening and tortuous arterial lumens, which may
be randomly narrowed by arteriosclerotic deposits of
plaque, and sllhceq~l~nt unfurling and reliable pulsation
10 operation at heart-beat rates over substantial periods of
time, e . g . f or several days .
It will be appreciated that the circumstances and
requirements of insertion and use of intra-aortic balloon
pumps provide numerous conf licting parameters .
15 Significant aspects of these conflicting parameters are
related to the fact that the inf lated but unstretched
diameter of the balloon is much larger than the ~l;Ar ~ F~r
of the insertion site, which may be percutaneous, and
larger than at least portions of the lumen of the
20 vascular system through which it is to be threaded. This
requires that the balloons be furled for insertion
through passa~_.. y~ which are of very small inside
diameter lID) relative to the size of the ~alloon when
opened. The related catheter equipment typically must
include dual col,ce.,~L ic lumens, including an inner lumen
passageway to serve functions such as ~n~ i n~ over a
guidewire, sensing values in the aorta, e.g. arterial
. ~S_UL~:I and/or administration of - 'l rAr~ntS. A
~UL r vull-ling annular passageway between the inner and
outer lumens must be of a size adequate to shuttle an
operating gas such as helium at rates to obtain the rapid
repetitious expansion and collapse of the balloon
n~r~qC ~ry for the pumping function in counterpulsation to
the patient's heart.
The aforenoted parameters for intra-aortic balloon
catheters have resulted in these catheters being of
significant complexity of CU-~ LU- Lion and attendant
~ Wo95/2ss60 2 ~ ~59~ r~~ o I 1
6ubstantial size, i.e. substantial effective diameter of
the catheter structure during insertion as well as during
the periods of pumping operation within the patient ' s
vasculature. A significant potential complication during
5 use is associated with limb; ~ h~mi ;I due to size mismatch
between the overall size (diameter) of the counter
pulsation catheter and the effective lumen size of the
patient's vasculature through which the catheter must
pass and in which it must remain during the period of
10 pumping assistance. Heretofore, the full featured IAB
catheter systems available on the market have been of
nominal 9 French (Fr) size or larger. The Fr size
designation of an IABC refers to the approximate size of
the outer lumen. Thus, for example, while 9 Fr literally
is about 0.118" diameter, catheters designated as 9 Fr
may have outer lumens which slightly exceed that
dimension, e.g., up to about .122". Further, such
catheters may include balloons which originally were
furled to about .126" outer t~i~r t,~r and in which the
20 furling has relaxed to about .144" outer diameter in
their packaging sheaths. In any event, reduction in size
of intra-aortic balloon catheters and introducer systems
would improve systemic f low to limbs at risk .
However, as indicated above the insertion of an IAB
25 catheter intrinsically involves pushing the device along
a tortuous path through the patient's vasculature. This
requires applying and transmitting compressive forces
through the very slender "column" ~LU~:LU't: of the
catheter, which requires a significant degree of
30 stiffness in the catheter. The catheter also must flex
or bend to follow the desired path through the patient's
vasculature without undue lateral reactive force which
could cause trauma to the vessels. Thus IAB cathet
ld h e a high degree of stiffneSs over a wide range
35 of bending angles, while providing flexibility to follow
tortuous paths along which the IAB catheter is being
pushed. These characteristics are measures of the
W0 95/25560 2 ~ .D J ~
~pllchAhi1ity~ and ~tri~rk~hi1ity" of the catheter, e.g.,
to follow a guide wire when pushed therealong over a
tortuous path without UVt!~C ing the guiding fitiffness of
that wire and/or otherwise impinging on the vasculature
5 walls with potentially injurious forces.
IAB catheters also must resist kinking , i . e ., sharp
bending collapse of either or both of the lumen tubes
with attendant loss of smooth ~.:UL Vi' ~U' a and closing or
drastic reduction of the respective internal passageway.
lo Resistance to kinking is nPcPc~ Iry to maintain
pushability of the catheter assembly and to avoid binding
on the guide wire. Avoiding kinking also m; n~mi zp~s risks
of cracking of the lumens during insertion and attendant
risks of later leakage during operation, as well as
15 minimi7in~ risks of kink-blockage of the gas shuttle
capacity between the lumens or blockage of medication or
ssnsing operations through the inner lumen during pumping
operation .
It is an object of this invention to provide
20 i ~Jv~=d intra-aortic balloon pump catheters.
It is a more specific object of this invention to
provide such catheters wherein adequate gas shuttling
capacity can be obtained with conventional pump
controllers through cathsters of significantly reduced
25 size.
Similarly, it is an object of this invention to
provide such; uv~d catheters wherein substantially
higher gas f low rates and attendant higher shuttle speeds
Day be obtained in catheters of sizes used heretofore,
30 thereby permitting tracking of heart rhythms not
trackable with conventional previous catheters.
It is a further object to provide; uvt:d IAB
catheters which attain some or all of the aforegoing
object6 and which maintain high degrees of fl~Y;h; l ity,
35 torquability, pushability and trackability for safe and
easy insertion, with minimal risk of trauma to the
patient .
~ wo 95/25560 ~ 1 8 5 ~ 2 ~ I ~ 11 ~,~ 1A7 1~ 1
SUMMA2Y OF THE INVENTION
It has been found that IAB catheters using very
small metal lumen tubes having high degrees of elasticity
and particularly shape restorative elasticity will
5 satisfy the aforementioned parameters. This will allow
flexibility with stiffness over a wide range of bending
angles of IAB catheters, down to quite severe bends and
other temporary deformations which may occur in the
course of insertion or operation. More particularly, it
has been found that by fabricating IAB catheters with at
least the inner lumen being a superelastic thin walled
metal tube such as of nitinol, the inner lumen can have a
very thin wall with an inside diameter (ID) sufficient
for a guidewire and a small outside diameter (OD) which
allows reduction of the outer lumen and related
ts by at least one size Fr while providing gas
shuttle capacity between the lumens for conventional IAB
pump oper2tion. This design also attains excellent
flexibility and stiffness of the catheters for ease of
insertion and assurance of functionality while reducing
the outside ~l i; Pr to signif icantly reduce the risks of
vascular and i c~h~m; ;~ complications.
As used herein, the terms "superelastic alloy" or
"superelastic alloys" and "superelasticity" refer to
those materials, specifically those metal alloys, which
return to their original shape upon unloading after a
substantial deformation. In most if not all instances
superelasticity is related to shape memory. It is
understood that a shape memory alloy is one which
displays a th-:L ~l~ctic martensitic transformation and
is able to absorb several percent shear strain by
preferential orientation of martensite variants, and then
can reverse that shear strain upon being heated, as the
martensite transforms back to the parent (austenite)
phase. Similarly, it is understood that a superelastic
alloy is the same as a shape memory alloy except that it
absorbs strain above the transformation temperature by
W095/~5s6!) 2 i 35~2~ PCTIUS95/03464 1--
the creation of stress-induced martensite variants of
preferential orientation, and then reverts to the parent
phase at the same temperature as reduced stress reverses
the strain. Superelastic alloys can be strained up to
5 ten times more than ordinary spring materials without
6ubstantial permanent deformation, i.e., less than 0.5%.
They provide nearly constant stress f orces over a wide
range of elastic deformation, as repre6ented by typically
"flag shaped" stress-strain curves, without significant
10 change of temperature.
Nitinol (nickel-titanium alloys) is perhaps the best
known of these materials. Its tranformational
superelasticity is about ten times higher than elasticity
in ordinary materials. Further, various nitinol alloys
15 are known which are superelastic within the t ~ Lu~ ~
ranges of the living human body. One further description
of the superelasticity characteristic and of nitenol
alloys which provide this characteristic at human body
t~ eLLuLe8 appears in a publication of Raychem
20 Corporation entitled "Su~erelasticitY - Su~erelastic
Tinel~ Allovs", which is incorporated herein by this
reference and a copy of which is being filed with this
application .
Further, it has been found that improved forms of
25 the outer lumen may be provided of co-extruded plastics
to complement and enhance the size reduction and capacity
goals noted above. In the preferred PTnhOr i-- L this
in,ll-rZP~ a relatively thin major inner nylon portion for
strength and a polyurethane outer portion for
30 biocompatability, flexibility and compatibility for
bonding to the balloon.
T ~ve d techniques f or production of appropriate
balloons and for joining the respective components also
are provided, particularly for joining of each balloon to
35 the distal end of the outer lumen and to the distal end
of the inner lumen while avoiding or minimizing buildup
of ~Ziz LL~1 dimensions. ~JLC:UVe~, it has been found
~ ____ _
W095/25560 21~5~0 r~ /r7lc~
that intra-aortic balloons may be made with thinner walls
than heretofore to further complement the aforenoted
results without C~ ing the integrity of the system.
A radiopaque metal marker ring also has been provided
5 which is compatible with the size reduction goal while
providing;, ov~d imaging capabilities.
Brief De6cri~tion of the Drawinas
Fig. 1 is a simplified top view of an intra-aortic
10 balloon catheter employing this invention.
Fig. 2 is an enlarged ~;~oss-s~ctional view taken
along line 2-2 of Fig. 1.
Fig. 3 is an enlarged cross-sectional view taken
along line 3-3 of Fig. 1, on a lesser scale than Fig. 2.
Fig. 4 is an enlarged side elevation view of the
balloon portion of the catheter with the balloon furled,
such as f or insertion .
Fig. 5 is an enlarged sectional view of a portion of
the catheter assembly at the distal end of the balloon,
taken along an axial ~ir 1~1 plane.
Fig. 6 is an enlarged side view of the outer lumen
and adjacent proximal end portion of the balloon of the
catheter of Fig. 1.
Fig. 7 is an end view of a radiopaque tracer ring
included in~ the catheter of Fig. 1.
Figs. 7A and 7B illustrate alternative
conf igurations of the tracer ring .
Fig. 8 is a side view of a stylet used in forming
the guidewire of the catheter of Fig. 1.
Fig. 9 is an enlarged side view of the outer end of
the guidewire used in the catheter of Fig. 1.
Figs lOA and lOB schematically illustrate the
stripping of intra-aortic h;~l lor~ns: from mandrels on which
they have been formed by dip casting.
Figs. llA-E are schematic illustrations of steps for
reforming the proximal end sleeve portions of such
balloons .
, . . _ . . = . _ . _ _ _ . _ _ _ _ _ _ _
W09~/2556/) 2~ ~9~D r~ 5~
Fig. 12 is a schematic side view of one preferred
apparatus used in the process illustrated by Figs. llA-E.
Fig. 13 is a left-end view of the balloon clamp of
Fig. 12.
Fig. 14 is a right-end view of the apparatus of Fig.
12 .
Fig . 15 illustrates the shape of the cavity def ined
by the balloon clamp, as seen generally along line 15-15
of Fig. 13.
While the invention will be further described in
connection with certain pref erred pmho~l i r ~s, it is not
intended to limit the invention to those ~ Ls. On
the contrary, it is intended to cover all alternatives,
modif ications and equivalents as may be included within
the spirit and scope of the invention.
Detailed DesOEiption of Pref erred Embo-l i r- c
As illustrated in Fig . 1, one ~nho~ i - t of an
intra-aortic balloon pump catheter device 10 includes a
flexible outer lumen tube 12 and a co-axial flexible
inner lumen tube 14 which are attached to a wye ~r~nnr~ct~ r
16. The inner lumen tube 14 extends through the outer
lumen 16 and through a single chamber intra-aortic
balloon 18 to the distal tip end of the catheter. The
proximal end of the balloon la is attached to the distal
end of the outer lumen tube 12. The distal end of the
balloon 18 is attached to a compatible tip element 20 on
the distal end of the inner lumen tube 14. Each of these
balloon-lumen att~` ~~ Ls is a gas-tight solvent bond
connection between an end sleeve section 21,22 of the
balloon and the outer surfaces of the outer lumen 12 and
the tip 20, respectively. As seen in the drawings, these
end atte.~ -nt sleeves are of substantially lesser
diameter than the main disp~ Al- L body section 23 of
the balloon and are joined thereto by short tapered
sections 24, 25.
Wo 95l25560 2 1 8 ~ ~ ;2 0 'J ~ ,n ~ I r I
The wye ro~n~rt~r 16 provides access through the
lateral branch 26 to an appropriate gas supply pump and
control device (not shown) for inflating and deflating
the balloon 20 by sl~r~esively injecting and withdrawing
a gas such as helium through the annular space between
the lumens 12 and 14. As indicated above, this is
sometimes referred to as "6huttling" the inflation gas to
and from the balloon. The controller responds to signals
corrPcprn~lin~ to the pulsing of the heart and effects
inflation and deflation of the balloon in timed
counterpulsation to the pumping action of the heart in a
known manner. The axial section 27 of the wye provides
axial access to the inner lumen for reception of a guide
wire 28 as well as for sensing of arterial ~Le2~uLc:
and/or the injection of medicaments through the inner
lumen. Tie downs 32 are included for affixation to the
skin of the patient by suturing and/or taping for
securing the catheter in its inserted operative pumping
position .
The balloon 18 is a large flexible thin-film balloon
of conventional ~ iate size, i.e., on the order of
about 0 . 5" to about 1. 0" in diameter when in an inflated
but unstretched condition and about 8" to 12" in length.
Typical sizes are of 30cc, 40cc and 50cc displ;lc L.
The balloon may be formed of any 5uitable material, with
polyurethane presently being preferred. A hydrophilic
coating 36 preferably covers the balloon and forms a
lubricous outer surface which is very slippery when
wetted by an aqueous fluid, such as blood, while
permitting processing and furling of the balloon and
hAnrll;n~ of the balloon and related pump chAn;r~ in a
normal manner when dry. Presently preferred coatings and
appropriate modes of applying such coatings are 1; CClOfiPd
in co-pending application No. 08/170,513, filed December
20, 1993, the disclosure of which is incorporated herein
by this reference.
_
W095/2556~) 2
The balloon 18 i5 furled, as illustrated
schematically at 18f in Fig. 4. This min;mi~es its
effective outer diameter during insertion into a
patient's arterial system. The furling may be
S accomplished in a conventional manner. This includes
applying a solution of silicone and freon on the outer
surface such as by spraying to deposit ~i 1 ;rorlP thereon,
then evacuating the air from the balloon thereby causing
the balloon to collapse into flat generally radially
extending "wings", then rolling those wings tightly about
the inner lumen 14 in mutually interleaved relation with
one another. This winds the collapsed balloon "wings"
into tightly packed spirals as viewed in cross-section,
to minimi ~P the effective outer diameter of the balloon
during h In~l in~ and during the insertion process. The
~i l i c~n~ avoids surface-to-surface sticking of the furled
layers. A thin tubular packaging sheath typically is
placed over each furled balloon to maintain its furled
compaction to a minimum effective outside diameter during
shipping and h~n~ll ing~ up to the place and time of
insertion into the patient. Further, the furled balloons
typically are heated, e.g., to a t _La~U~c: on the order
of about 135F for about 12-16 hours, to assist in
setting and thereby sustaining the furling during
insertion following removal from the packaging sheath by
the user. Balloons with the noted hydrophilic coatings
also become very slippery promptly upon being wetted,
with attendant benefits of ease of insertion and
placement as well as reduction of trauma.
The wye connector 16 and related _-nPnts and
equipment may be of any suitable structure and size.
The inner lumen 14 is a very thin-walled tube formed
of a tough and superelastic metal, namely nitinol. For
example, it has been f ound that an inner lumen tube 14 of
such materials having a wall thirknPC~ of only about
0035'l will function satisfactorily in providing a small
IAB catheter, e.g., 8 Fr size. The inner lumen tube 14
WO95/25560 7 ~ ~59;2~ r~ /O~IC~
m;n;mi 5!~C the outside diameter of the inner lumen while
maintaining the n~CF~cs ~ry f-ln~ti-~n 11 in6ide diameter as
- well as providing desirable characteristics of
f 1~Y; h; l; ty and strength throughout the length of the
5 catheter.
An exemplary such inner lumen tube 14 has about
. 0276" ID and . 0345" OD. By comparison, the inner lumen
currently used in the 9 Fr IAB catheters being m-rk~t~
by the Cardiac Assist Division of St. Jude Medical , Inc .,
10 under the trademark RediGuardn', consi6t of a polyurethane
tube of about .008" wall th;rkn~cc ~ULL~Ullded by a coiled
stainless steel wire of .003" diameter generally as in
the arrangement disclosed in US Patent No. 4,646,717,
resulting in an effective overall thickness of the inner
lumen wall of .011" and an attendant OD o~ .054" to
provide an inner lumen ID of . 032" .
The outer lumen tube 12 is formed by coextrusion of
a thin outer polyurethane layer around a thicker nylon
inner layer 12b. The nylon layer provides high
compressive ~LL~I-y~h relative to the ~h;~-kn~,c,c, and it is
believed that the polyurethane layer provides flexibility
as well biocompatability and compatibility for ready
bonding of the polyurethane balloon. One advantageous
combination has been found to be a .002" outer layer of
polyurethane coextruded with a . 006" inner layer of
nylon, with the total wall th;rkn~cc being about .008".
Thus the outer lumen 12 also is a relatively thin-walled
tube, as compared to current commercial polyurethane
outer lumens which are on the order of 0. 010" thick.
3 0 By ut; l; ~; n~ inner and outer lumens 12 and 14 as
described, the annular space therebetween is of ade~uate
1L ~ss -scction to ~ te the gas shuttle capacity
required for normal IABP operations using a conventional
controller while minimizing the outside ~ r of the
catheter, e.g., reduction of the catheter by one full
size Fr, and meeting the other desirable parameters for
IAB catheters. Concomitantly, IAB catheters using this
Wo gs/25560 ~ ¦ 8 5 q 7 ~ P ~ ~ c ~ --
12
construction and of the same nominal size as prior
ou,.aLLu~ions would be capable of higher gas shuttle
rates than those prior devices and thus capable of
tracking higher heart pulsation rates.
The outer lumen also could be f ormed of a thin
walled metal tube having superelasticity, for example
also being formed of nitinol. This alternative would
permit further reduction of the outer diameter of the
outer lumen while maintaining equivalent or even better
operational capabilities, but would add significantly to
the costs at the present price of nitinol tubing.
Ref erring particularly to Figs . 8 and 9, the
guidewire 28 is of a stylet-type with a "floppy J" tip,
similar to some guidewires utilized heretofore in other
applications, e.g. in cholangiography (catheterization of
bile ducts). The stylet 40 is a slim rod or wire which
inrl~ a main body portion 42 normally of uniform
circular cross-section and a distal end portion 44 of
modified configuration for forming the "J" tip. For
example, the distal end portion is significantly reduced
in diameter along the second portion 44, with an annular
~h~ Pr 46 between portions 42 and 44. Sequentially
outward of the section 44 is a third portion 48 which is
tapered to a lesser ~iAr ~r, and an end portion 50 which
is flattened in cross-section. As represented in Fig. 9,
the proximal end of a f ine wire 52 is brazed or welded to
the stylet shaft adjacent the shoulder 46. The wire
extends in closely wound coil fashion about the distal
portion 44, with the distal end being brazed or welded to
the distal tip of the stylet body 42. The distal end
portion 50a is bent approximately 180, preferably being
bent normal to the flattening planes, to form the bight
of the "J" tip, generally as illustrated.
By way of further example, one guidewire 28 for use
in one specif ic '~ L of this invention as described
herein included a stylet 40 formed of 302/304 stainless
6teel, about 150cm in length and with the shoulder 46
2 ~ ~92~
W095/25560 r~l~-JL ~71C1
13
being about 30cm from the distal end. The main body
portion 42 was about .025" in 1;A- Dr, Second portion
- 44 was about .013" in diameter and extended for about
23cm from the shr~ Pr 46. Portion 48 was tapered from
the .013" diameter to about .0055~ r over a length
of about 6cm, and the di6tal end 3cm portion was
flattened to about .0035" thickness. The wire 52 was
about .005" ~li; Pr, also being of 302/304 StAinlPC~
6teel. The distal 3cm was bent to form the bight and
remote leg of the "J" tip. The entire assembly was
coated with Teflon, providing a guidewire with a diameter
not PYrPPflin~ .025" for use through the inner lumen
described above.
As noted above, the balloon 18 may be of the same
material, configuration and size as balloons currently in
use in intra-aortic balloon pumps. An example of a
preferred A ~ -'ir ~ includes a thin-walled polyether
based polyurethane balloon of about 0 . 003"-0. 004" wall
thickness formed by dip molding on an appropriately
shaped mandrel, with a hydrophilic coating as referred to
above. This is a reduction of about . 001 thicknes6 from
balloons currently in commercial use. Such balloons have
satisfactory flexibility and strength, with high
elasticity, e.g., about 525% stretchability without
rupture. One specific commercially available
polyurethane which has proven satisfactory in such
balloons, including those used in practicing this
invention, is sold by B. F. Goodrich under the designation
"Estane 58810".
Referring particularly to Fig. 5 an end tip 20 is
affixed over the outer end of the inner lumen tube 14, as
by being molded thereonto. For this purpose, the outer
surface of the end portion of the tube may be sAn~lhlA~ted
as a preparatory step. The tip 20 preferably is of a
plastic which is compatible with the material of the
balloon, e.g., polyurethane. The outer end surface 62 of
the tip is rounded in a bullet-nose shape to facilitate
wogs/2s~60 ;~ ~59~ r~". 'I!~lc~ --
14
passage through the patient ' s vasculature . The outer end
portion has a central axial passage 64 which provides a
smooth continuation of the central axial passage of the
lumen tube 14 and preferably tapers or flares toward the
5 distal end of the tip, as illustrated in Fig. 5. This
pas6age section 64 may be formed by a core pin being
po6itioned in the outer end of the lumen tube 12 prior to
the molding of the tip 20.
Referring now to Figs. 1, 5 and 6, the cylindrical
10 proximal sleeve portion 21 of the balloon 18 is bonded to
the outer surface of the distal portion of the outer
lumen 12 and the cylindrical distal sleeve portion 22 of
the balloon is bonded to the outer surface of the tip 20.
These bonds must be airtight and effected in a manner to
15 minimi7e the t9i~- L~ll dimension build-up of the catheter
assembly . Such bonding is f acilitated by f orming the tip
20 and at least the outer surface of the outer lumen 12
and the balloon 18 of the same types of materials, namely
polyurethane in the illustrated preferred ~ L. In
20 this: ' -'i L, the sleeve portions 21 and 22 are bonded
to the respective elements by a solvent and ~,L~S~Ur~
bonding technique. It is believed that ~es~,uL~ bonding
with radiofrequency heating to a temperature
approximating the melting temperature of the materials
25 will further enhance this bond and provide even greater
control and minimizing of the final outer dimensions in
these bonding areas. The intervening portion of the
balloon 18, ~ nr~ i n~ the larger body section 23, is
tightly furled about the inner lumen tube 14 between the
30 distal end of the inner lumen 12 and the tip 20. With
the thin-walled balloon referred to above, this multi-
layered furled portion will have an outer diameter which
only slightly exceeds the outer diameter of the sleeve
attA,~ L sections. This is an added factor in
35 maintaining the minimal profile of the entire catheter
assembly during insertion.
Wo gs/25560 2 ~ 5 2 0 F.~ c
Referring to Figs. lOA and lOB, the bi~llonn~ 18 are
made by dip casting on a mandrel 66 having a 6hape
- corresponding to the inf lated unstretched shape of the
balloon 18, including the end sleeve section6 21,22,
5 generally as seen in profile in Fig. 1 and lOA. The
dipping speed and time are adjusted to produce thin-
walled balloons as referred to above. Each of the
balloon blanks as thus formed also includes an end
section S which extends from the sleeve 21 over the
lO mandrel hanger generally as illustrated, and which
subsequently is trimmed from the blank. The formed
balloons are stripped from the respective mandrels by
axial ~ t toward the distal end, whereby the
proximal sleeve 21 and adjacent tapered portion 24, as
15 well as section 5, are stretched in ~ Pr as they
slide over the much larger central portion of the mandrel
on which the main balloon body portion 23 was formed, as
illustrated schematically in Fig. lO~. This stretching
of the proximal ends results in proximal end sleeves that
20 are not reliably of a sufficiently small inner ~l;i Pr
to provide the desired snug fit of the balloon on the
small outer lumen tubes 12 for facile formation of the
nPCPF~ ry air-tight joint at this interface.
Accordingly, the production of the balloons preferably
25 includes reduction of the size of the proximal end
sleeves after removal of the biil l onn~ from the casting
mandrels .
Referring to Figs. llA-llE and 12, the section 5 and
sleeve portion 21 of each balloon blank are mounted over
30 an internal mandrel 70 and secured in place by a collet
72. The balloon is stretched to a predetPrm;nPd length
of the proximal sleeve section 21, as indicated by the
arrow A in Fig. llA. The balloon then is held in the
stretched state to maintain the desired sleeve length, as
35 by a hinged clamp 74 which engages the cone section 24 of
the balloon, as in Fig. llB. The stretching causes the
intervening sleeve to neck down to the desired reduced
Wo 95/2~s60 2
16
diameter, as indicated in Figs. llA and llB. At this
point the neck is in a stre6sed state. At least the
sleeve section of the balloon is heated, as by an
internal heater 76, 78 which i6 positioned with the
5 mandrel 70 (see Fig. llC), to an ~yLu~Llate temperature
over an appropriate dwell time thereby relaxing the
necked-down balloon material in its reduced size
conf iguration . That is, the stress induced by the
stretching is relieved. The balloon then i5 permitted to
10 cool to a normalizing temperature while in the reduced,
n~,n c.~Ltssed configuration, as by turning off the power
to the heater; see Fig. llD. This precludes subsequent
elastic return of the sleeve portion 21 to its previous
oversize ~ LLO~1 dimension. The balloon with the
15 reduced diameter proximal end sleeve 21 then is removed
from the clamp and mandrel, and the end section S is
trimmed off as in Fig. llE.
One ---h;~ni F'n for effecting the foregoing is
illustrated in somewhat greater detail in Figs. 12-15. A
20 mandrel 70 is mounted in a support block 82 which is
pivotally mounted to a fixed support 84 as by an
appropriate pivot pin 86 located adjacent one end of the
block 82, with the pivot pin offset from the mandrel 70.
The heating cable 78 extends through the mandrel 70 to a
25 pin shaped heating element 76. An intervening portion of
the mandrel 70 has a bulbous section 88, with an annular
outer surface 89 which tapers to smaller diameters toward
the support block 82. The collet 72 is of an annular or
washer" shape, having an internal surface which conforms
30 to the tapered surface of the mandrel. The clamp 74
compri6es two hinged mating halves def ining therebetween
a truncated conical open section 90 i c~ting with a
short small cylindrical section 92, which COLLta~ d
generally to the configuration of the transitional
35 section 24 and desired sleeve section 21 of the balloons
being processed.
2 7 ~?3~7~
Woss/2~6o P~IIIJ~3rIO~1CI
17
In operation, to practice the aforedescribed method,
the clamp 74 is opened in preparation for receiving a
balloon to be processed. The collet 72 is retracted
toward the heater cable base block 82. The block 82 is
5 pivoted to an upper position (about 90 counterclockwise)
in Fig. 14, to raise the mandrel/heater further from a
support surface on which the - ^nts are mounted and
thereby providing greater space for the following
described r-nir~ tions. The distal end portion of a
10 balloon then is slid onto the mandrel unit 70, from the
left end in Fig. 12, with the distal end portion of the
sleeve section S over the enlarged section 88 and onto
the tapered section 89. The collet 72 is then moved
towards the enlarged section 88, to provide friction
15 clamping of the balloon end S between the inner surface
of the collet and the outer tapered surface of the
mandrel. The balloon is then stretched, e.g. manually by
the operator, to the point where the tapered end section
24 will match up with the cavity defined by the sections
20 90 of the clamp halves, thereby suitably reducing the
diameter of the neck or sleeve section 21. The heater
cable base block 82 is closed, and the balloon is
positioned with the tapered end section 24 mating into
the cavity defined by the sections 90 of the clamp
25 halve6, with the sleeve section 6tretched over the
intervening internal mandrel and heater 76. The clamp 74
then also is closed to retain the sleeve section of the
balloon in the resulting 6tretched state. Internal to
the balloon at this point is the heater coil 76, which
3 0 extends the entire length of the sleeve area and slightly
into the balloon body area, as seen in Fig. 12.
Sl]hceq~l~ntly~ the heater is activated to thereby relax
the necked down balloon material as described above.
Following heating and subsequent cooling, the clamp 74 is
35 opened and the collet 72 released, and the balloon is
removed. The section S then is cut off. A distal end
portion of the stretched sleeve al60 may be trimmed to
_ _ _ _ , . _ . _ _ . _,,,
Woss/2~s60 ~ ~ ~5~.~D P~l/U~ ~71C1
18
attain the desired length of sleeve 21 which now has the
desired reduced inner diameter. The internal
mandrel/heater may be utilized as the form ~or setting
the size of the reformed sleeve section 21. By way of
5 more specific example, in a typical operation the sleeve
portion 21 has been stretched to about 150% of its
original length in this process, e.g., stretched from
0.5" to 0.75," to effect the desired reduction of the
diameter of the neck in polyurethene bA 11 o~nC as
10 described hereinabove.
It will be appreciated that other gripping and
stretching r- ' An;~mC may be utilized to effect the
sleeve sizing method. For example, one and/or the other
of the clamping r-~hAni~c 74 and 72,88 m2y be movable
15 toward and away from the other whereby the balloon blank
may be clamped therein prior to stretching and then may
be stretched by lateral movement of one or both of the
clamping r - -hAn i ~ relative to the other .
Referring to Figs. 6 and 7, radiopaque marker
20 material is applied to the outer lumen 12 in a position
to be adjacent the proximal end of the balloon in the
final assembly. This permits the user to readily
determine the location of the balloon by fluoroscopy or
X-ray, as nP~cc~ry to attain maximum therapeutic
25 benefit. In a preferred ~ this marker is a thin
short ring 94 of highly elastic metal such as nitinol,
being the same material as the inner lumen. Use of the
same metal for the marker and the lumen avoids any
problems of ir- _tibility of rli~cimilAr metals, such as
30 electrokinetic corrosion of either element, while
providing a highly radiopaque and therefore highly
visible marker for the positioning of the IAB during use.
By using a thin short ring 94 of nitinol, e.g. .003"
thick and .075" long, the marker may be press-fit in
35 place in the outer lumen 12 and the compression of the
lumen will hold the ring in place. The balloon is bonded
over the outer lumen 12, preferably with the sleeve 21 of
WO 95/25560 2 ~ 8 ~
19
the balloon over the marker ring 94, and is furled
tightly over the inner lumen tube 14 as noted above. The
high degree of elasticity of the ring permits the marker
to deform in the process of packaging and insertion
while assuring return to its nominal desired shape and
size in use. Splitting the ring longitll~lin~l ~y so that
it is discontinuous circumferentially, with the ends
either spaced or overlapping as illustrated at 94a and
94b in Figs. 7A and 7B respectively, will enhance its
hoop ~ ~ssibility by a resilient spring action and
thus further complement the size reduction as well as
flexibility of the catheter unit.
In a specific example of the preferred Rmho~ -nt of
this invention, a nominal 8 Fr IAB catheter 10 was
fabricated with an inner lumen tube 14 formed of a
nitinol alloy tubing of Raychem Corporation designated
Tinel Alloy BB formed of only nickel and titanium and
only those trace elements naturally occurring in
commercially available grades of those constituents. The
tube 14 had a nominal inner r~ of . 0276", a nominal
outer diameter of .0345", and a length of 32.775". The
outer tube 12 was a coextrusion of 2363-55D Pellethane
polyurethane (Dow 'h~mici~ Company, Nidland, MI) .002"
thick over Nylon 11 Besno (Elf Atochem, ph;l~d~rhi~, PA)
. 006" thick, as described above, with a nominal inner
diameter of .090" and a nominal outer diameter of .108".
The tip and guide wire used in the catheter were as
described above, and the balloon was of . 003 " nominal
thickness. The balloon was furled to a diameter of .118"
and could relax to about .124" diameter in its packaging
sheath .
Testinq
Rink tests and stiffness tests were conducted on
inner and outer lumens and the combination of the two as
described above, with only slightly different ~ n~:.
The nitinol inner lumens tested had an inner diameter of
, _ _ _ _ _ _ _ .. , . . . _ . _ ... .. ... .. . _
wo 9sl25560 2 1 ~ ~ 92 0 PCTIUS95/03464
.0283" + .0003" and an outer diameter of .0347" + .0003.
The coextruded outer lumens had a nominal inside diameter
of . 090" and a nominal outside diameter of .106" . Crush
tests also were cl~n~ rted on various outer lumens.
The kink tests utilized a template having multiple
circles imprinted thereon, all with a common tangent
point. The circles were 2", 1~", 13~", 1%", 1", %" and 3~"
in diameter. An appropriate length of each tubing being
tested was formed into a larger loop and held against the
template with the ends crossing and tangent to the
circles at the af orenoted common tangent point . While
maintaining this relationship to the template, one end of
the looped tube was pulled to gradually reduce the loop
diameter until the sample kinked. The diameter, also in
inches, at which kinking occurred was recorded. When the
tubing kinked between two circles, the average of those
two circles was used as the kink diameter for
calculations. In the case of outer lumen tubes, notes
also were made of whether the kinking oc- uLl~d guickly,
moderately or slowly.
After ~Y~m;n;n~ a variety of potential 8 Fr outer
lumens, seven coextrusions of polyurethane over nylon
were tested, along with one 9 Fr outer lumen as described
above for comparison ~uL~oses, using five samples of
each. The following table reflects the average diameter,
in inche6, at which kinking oc~ ull.:d in each of these
seven prospective outer lumens, the nature of the kinking
action, and the average diameter, also in inches, at
which the combination of the respective outer lumen tube
3 0 and a nitinol inner lumen as described above kinked:
WO9S125~60 2185920 r~"~ 161
21
OUTEF~ LUIEN ONLY CO~18INED
Lumen-Coextruslon Material~ Diameter Notes Diameter
a. .003" nylon, .005" polyurethi~ne 1.38 ~soderilte 1.5
b. .005" nylon, 003 n polyureth~ne l.53 Quickly l.6
5c. .004" nylon, .004" polyurethime 1.65 Quickly 1.75
d. .001" nylon, .007" polyureth~ne 1.0 Quickly 1.15
. .002" nylon, 006n polyurethAne 1.05 Slowly 1.3
. 004" nylon, 004" polyurethane 1.73 Quickly 1.33
(wLth b~rium ~ulf~te)
g. .006 nylon, .002" polyurethime 1.18 Quickly 1.33
The 9 Fr outer lumen tubes were of the af oredescribed
current commercial design, being polyurethane tubes with
an inner rlii ~Pr of about .101" and an outer fi;; Pr of
15 about .122". The average first kinking ~i;, Pr for the
9 Fr outer lumen tubes was 1", and they kinked "slowly".
The three outer lumens with the best kink test
results, namely coextrusions d, e and g, also were tested
for crush resistance in hemovalves. The ~ue~LLusion g
20 provided the best re5istance to crushing by the valves.
Further samples of- the construction g, namely
coa~,..sion tubes of .002" polyurethane around .006"
nylon, were subjected to further comparative tests with
samples of the aforedescribed 9 Fr catheter lumen tubes,
25 singly and in combination of the respective inner and
outer lumen tubes. The average kink diameters in inches
were as follows:
New 8 Fr Current 9 Fr
Inner Lumen Tube* Less than 0 . 5 Less than 0 . 5
30 Outer Lumen Tube 1. 35 1.15
Combination of the Above 1.19 1.15
* The nitinol tubes tested ; nrl~ ed both extruded tubes
and drawn and r~l~h;nPd tubes, with the results being
substantially the same.
Thirty samples each of the new inner and outer lumen
tubes and ten each of the inner and outer tubes of the
current design were subjected to stiffne55 tests, bûth
Wo ss/2ss60 2 ~ ~ 9 2 ~ C 1
individually and with the respective inner and outer
tubes assembled together, using a Tinius Olsen stiffness
tester. The bending moments were calculated and used for
comparisons. Since the areas of the 8 Fr and 9 Fr parts
5 were different, the values were normalized by multiplying
the 9 Fr results by the ratios of their areas. Selected
comparison angles were chosen within the following
parameters~ All samples achieved the angle; and (2)
the test data had not started to decline, i.e., no
10 indication of a kink forming in the sample. The average
values in inch-pounds were as follows:
Bending Moment
Inner Lumen at 57 Degrees
15New Inner Lumen o . 265
Current Inner Lumen 0. 014
Bending Meoment
Outer Lumen at 2 7 Degrees
20New Outer Lumen 0.168
Current Outer Lumen 0 . 075
Bending Moment Bending Moment
Combined Lumen at 69 Degrees at 57 Degrees
25New Outer/Inner Lumen 0 . 433 0 . 413
Current OutertInner Lumen 0.115 0.144
It will be seen that the constructions in accordance
30 with this invention attained the desired size reduction,
while providing good kink resistance and attendant
ihi 1 ity and increased stiffness.
Thin-walled balloons as alluded to above also were
tested for operational strength, using thirty sample
35 uncoated balloons with an average measured thickness of
.0033" (range of .003" to .004") and thirty such blllonn~
with a hydrophilic coating and therefor having an average
measured thickness of .0037" (range of .003" to .004").
