Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02311977 2000-06-19
METHOD FOR DELIVERING A FLUID INTO A VESSEL OF A
2 HUMAN BODY, AND IMPROVED CANNULA USEFUL FOR
3 CARRYING OUT THE METHOD
4
CROSS-REFERENCES TO RELATED APPLICATIONS
6
7 This application claims the priority of German Patent Applications, Serial
8 No. 199 28 018.5, filed June 18, 1999, and Serial No. 199 33 171.5, filed
July 15,
9 1999, the subject matter of which is incorporated herein by reference.
11 BACKGROUND OF THE INVENTION
12
13 The present invention relates to a method for delivering a fluid into a
14 vessel of a human body, and to a cannula useful to carry out the method.
More
particularly, the present invention relates to the delivery of a fluid, such
as blood,
16 into blood vessel, preferably into an aortic arch.
17
18 Delivery of fluid into body vessels entails the risk that a fluid stream is
19 "jetted" out from a respective cannula and thereby exposes a proximate
vessel
wall to significant stress. In particular in older patients, this stress cause
by the
21 exiting jet stream may dislodge sclerotic deposits which are then flushed
into the
22 blood circulation. This may lead i.a, to a clogging of vessels and to
embolism.
1
. CA 02311977 2000-06-19
1 To counter this, U.S_ Pat. Nos. 5,354,288 and 5,843,226 propose to
2 provide a deflector in the outlet zone of the cannula, whereby the deflector
may
3 have a drop shape or include a deflector plate on the outlet side. Moreover,
U.S.
4 Pat. No. 5,354,288 describes the provision of a diffuser in the outlet zone
of the
cannula in order to further thwart the formation of a pointedly directed jet
stream.
6
SUMMARY OF THE INVENTION
8
9 It is thus an object of the present invention to provide an improved method
for delivering a fluid into a vessel of the human body, obviating the afore-
stated
11 drawbacks.
12
13 In particular, it is an object of the present invention to provide an
improved
14 method for delivering a fluid into a vessel of the human body, by which the
pressure applied by the outgoing fluid stream is significantly reduced
compared
16 to cornentional methods.
17
18 These objects, and others which will becorne apparent hereinafter, are
19 attained in accordance with the present invention by a method for
delivering a
fluid into a vessel, in particular into an aortic arch, which method includes
the
21 step of imposing an axial motion as well as a whirling motion upon each
fluid
22 particle when the fluid enters the vessel.
23
2
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1 Conventional methods are incapable to impose such a whirling motion
2 upon all fluid particles because the encountered velocities are too high in
the
3 relatively short interactive pathway in order to be able to induce a
whirling
4 motion. Moreover, conventional cannulae have parts incorporated therein
which
lead to a cross sectional constriction immediately before of the entry zone,
6 resulting in an increase of the flow velocity. However, a rise of the flow
velocity is,
7 in general, undesired.
8
9 It is another object of the present invention to provide an improved
cannula useful for carrying out the novel and inventive method according to
the
11 present invention.
12
13 This object is attained in accordance with the present invention by
14 providing a tubular body, and a device for imposing a whirling motion upon
each
fluid particle of a fluid which flows through the lumen of the tubular body
into the
16 vessel.
17
18 According to another feature of the present invention, a swirl-inducing
19 device is accommodated in the tubular body and sv positioned that the cross
section of the outlet port of the cannula is not narrowed_ Suitably, the
21 swirl-inducing device should be positioned in an area of the tubular body
which is
22 upstream of the narrower entry zone of the tubular body through an opening
in
23 the vessel wall so as to prevent a further cross sectional constriction by
the
3
CA 02311977 2000-06-19
1 swirl-inducing device in this narrower entry zone.
2
3 Suitably, such a whirling motion of the fluid should be induced before the
4 fluid enters the vessel and should not be generated only through interaction
with
the vessel.
6
7 According to another feature of the present invention, a whirling vector
a associated to the whirling motion has a component which is oriented in the
9 direction of the remaining motion, i.e. linear motion, of the respective
fluid
particle. This results in a tendency of the fluid stream to substantially
spread out,
11 thereby effectively reducing the stream pressure of the outgoing fluid
flow.
12
13 The whirling motion can be induced in a simple and cost-effective manner
14 especially by a swirl-inducing device, whereby a sufficient interactive
zone of the
swirl-inducing device should be ensured to attain that all fluid particles are
16 exposed to the whirling motion. This is true in particular when positioning
the
17 swirl-inducing device at the end of the cannula. On the other hand, it may
be
18 possible to provide an equalizing zone behind the swirl-inducing device in
flow
19 direction of the fluid. Fluid particles, already executing a whirling
motion, can
transmit the whirling motion in the equalizing zone to further fluid
particles. Thus,
21 even a shortened interactive zone or a shorter swirl-inducing device can be
used
22 while still ensuring that all fluid particles carry out a whirling motion.
The
23 equalizing zone may hereby have characteristics that further impact the
flow
4
CA 02311977 2000-06-19
1 guidance.
2
3 It is also possible to provide the swirl-inducing device, as viewed in fluid
4 flow direction, upstream of an angled zone or bend of the cannula, thereby
ensuring an improved flow guidance. Even though, various cannulae, in
6 particular aortic cannulae, may differ in the configuration of their angled
zone, the
7 remaining zones are effectively standardized and identical. Thus, different
8 cannulae may use a same swirl-inducing device, thereby reducing production
9 costs. Of course, the angled zone may be utilized as equalizing zone as
well.
11 According to another feature of the present invention, the swirl-inducing
12 device may be provided upstream of a tapered zone of the cannula, when
viewed
13 in flow direction of the fluid_ This, too, results in a better flow
guidance and an
14 improved inducement of the whirling motion_ Furthermore, the rotation is
accelerated by this tapered configuration so that the whirling motion is
16 significantly higher when the fluid enters the vessel. Of course, such a
tapered
17 zone may be combined with an equalizing zone andlor an angled zone of the
1 B tubular body.
19
BRIEF DESCRIPTION OF THE DRAWING
21
22 The above and other objects, features and advantages of the present
23 invention will be rnore readily apparent upon reading the following
description of
5
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1 preferred exemplified embodiments of the invention with reference to the
2 accompanying drawing, in which:
3
4 FIG. 1 is a schematic illustration of one embodiment of a cannula
according to the present invention for delivering a fluid into a vessel; and
6
7 FIG. 2 is a schematic perspective illustration, on an enlarged scale
8 of another embodiment of a cannula according to the present invention for
9 delivering a fluid into a vessel.
11 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
12
13 Turning now to the drawing, and in particular to F1G. 1, there is shown a
14 schematic illustration of one embodiment of a cannula 2, e.g, an aortic
cannula,
according to the present invention, for delivering a fluid into a vessel 1,
e.g. an
16 aortic arch. The cannula 2 has a generally tubular body which includes a
lower
17 portion inserted through an oval opening 3, made through incision in the
wall of
18 the aortic arch 1, so that an entry zone 4 of the lower portion of the
cannula 2 is
19 positioned inside the aortic arch 1 while a rear portion 5 of the cannula 2
is
positioned outside the aortic arch 1. The lower portion, which includes the
entry
21 zone 4, has a cross section which is narrower than the remaining portion of
the
22 tubular body so that the size of the opening 3 can be kept as small as
possible.
23 The cross sectional constriction also results in an increase of the flow
velocity in
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1 the entry zone 4.
2
3 Non-rotatably positioned in the rear portion 5 of the cannula 2 is a
4 swirl=inducing device 6 which is suitably secured, e.g. press-fitted or
glued, in the
lumen of the tubular body and so configured that a whirling motion, i,e.
swirl, is
6 imposed on each fluid particle, moving in axial direction through the lumen
of the
7 tubular body of the cannula 2. An equalizing zone 7 is provided between the
8 swirl-inducing device 6 and the narrowed entry zone 4 and represents a
9 transition zone between the wider rear portion 5 and the narrower entry zone
4_
11 Approximately in the area of the opening 3 through the vessel wall of the
12 aortic arch 1, the tubular body of the cannula 2 has an angled zone or bend
8 to
13 form an arched configuration of the cannula 2 in this area: As clearly
shown in
14 FIG. '1, the swirl-inducing device fi is disposed upstream of the bend 8,
as viewed
in flow direction of the fluid through the cannula 2. Since the cross section
16 upstream of the bend 8 is also narrowed, the swirl-inducing device 6 is
suitably
17 disposed in fluid flow direction upstream of the tapered zone of the
cannula 2,
18
19 ~ The swirl-inducing device may be of any suitable configuration that is
capable to impose a whirling motion on a fluid stream, e.g., a body having a
21 plurality of guide blades attached to the body in suitable fashion.
22
23 Fluid, e.g, blood, perfusing through the lumen of the cannula 2, is
imparted.
7
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1 a whirling motion by the swirl-inducing device 6, and subsequently flows
through
2 the tapered transition zone into the bend 8. These zones constitute also the
3 equalizing zone 7. When entering the aortic arch or vessel 1, each fluid
particle
4 has therefore a substantially linear direction of motion as a consequence of
the
lumen of the tubular body, and a whirling motion as a consequence of the
6 whirling motion generated by the swirl-inducing device 6_ The whirling
motion is
7 thereby defined by a whirling vector having a component in parallel relation
to the
8 linear motion. This whirling motion results is a rapid spreading out of the
exiting
9 stream without jetting so that the emanating fluid stream is gentle on the
vessel
wall and in particular a dislodging and flushing of sclerotic deposits can be
11 significantly reduced.
12
13 Turning now to FIG. 2, there is shown a schematic perspective illustration,
14 on an enlarged scale, of another embodiment of a cannula 12 according to
the
present invention for delivering a fluid into a vessel (not shown here). The
16 cannula 12 has a tubular body which accommodates a swirl-inducing device 16
17 for imposing a whirling motion, indicated by reference numeral 13, upon the
fluid
18 flowing in direction of arrow ~ 9. In the nonlimiting example of FIG. 2,
the
19 swirl-inducing device 16 has a screw-like or helical configuration, with a
thread 16a extending along a central shaft 16b. Downstream of the swirl body
16,
21 the tubular body has in succession an equalizing zone 17, a tapered zone 11
and
22 an angled zone or bend 18. The bend 18 is suitably part of a plug 20,
sealingly
23 received in the vessel-near end of the tubular body, and has an outlet port
14
8
CA 02311977 2000-06-19
1 through which the fluid stream 15 emanates from the cannula 12 and enters
into
2 the vessel with a whirling motion 13 of the fluid, generated by the swirl-
inducing
3 device 16. As a consequence of the whirling motion, the fluid stream has a
4 tendency to spread out so that the stream pressure is effectively reduced
when
the fluid exits the outlet port 14.
6
? While the invention has been illustrated and described as embodied in a
8 method for delivering a fluid into a vessel of a human body, and improved
9 cannuia useful for carrying out the method, it is not intended to be limited
to the
details shown since various modifications and structural changes may be made
11 without departing in any way from the spirit of the present invention.
12
13 What is claimed as new and desired to be protected by Letters Patent is
14 set forth in the appended claims:
9
