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The present invention relates generally to the field of surgical equipment
and more particularly, to a micro-hemostat for use in vascular surgery.
BACKGROUND OF THE INVENTION
The micro-hemostat of the present invention is particularly useful in
anastomosis which is a surgical technique for forming a passage between
two normally distinct tubes or vessels of the body.
A common operation in which anastomosis is employed is a coronary artery
by-pass operation in which blood is routed about a blocked portion of a
coronary artery to restore and insure adequate blood supply to the heart
muscle. In the normal by-pass operation, a short segment of a vein taken
from another part of the patient's body is used. One end of this vein is
connected to the aorta and the other end is connected to the blocked
coronary artery below the blockage. The anastomosis connection between the
aorta and the artery serves as the by-pass around the blockage.
The standard operative technique for making a coronary artery by-pass
comprises first clamping off the aorta to occlude blood flow to all the
coronary arteries. The by-pass connection is then made by suturing the
veins in place. Many times multiple by-passes are required, and as a
result, it may be necessary for the aorta to be clamped off for an
extended period of time during which there is no blood supply to the
muscle tissue of the heart or the myocardium. The prolonged suspension of
blood supply to the heart can result in life threatening infarcts.
Recently a relatively simple technique for the local occlusion of a
coronary artery without aortic cross-clamping during anastomosis was
described in the literature. Mullen et al, Anals. of Thoracic Surgery,
Vol. 23, No. 1 (July, 1977). In the described technique, the flow of blood
through the artery is stopped with an occluding device made of silicone
rubber and shaped like a T-tube with bulb tips. The occluder is inserted
into the artery through an incision and the bulbs occlude the artery
bi-directionally during the anastomosis. The occluders are soft and
malleable and available in several sizes to fit different sized arteries.
The occluder is removed from the artery just prior to placing the final
stitches joining the vein and artery.
The occluder and technique described in the Mullen et al article are a
significant improvement over the aorta cross-clamping technique previously
used. However, there are surgeons who would prefer a technique in which
the incision required for insertion and withdrawal of the occluding device
would not have to be so large, in which the operating time consumed in
selecting the correct size occluder could be reduced and in which the
tissue supplied by the artery would not be without circulation while
sizing and using the occluder.
SUMMARY OF THE INVENTION
It is an object of the present invention to disclose a micro-hemostat which
requires a relatively small incision for insertion and withdrawal, which
eliminates the time consumed in selecting the correct size device for an
artery and which continues to supply blood to the tissue serviced by the
artery during the time required to perform the anastomosis.
It is a further object to disclose a novel method of preparing the
micro-hemostat.
The micro-hemostat of the present invention includes a T-shaped member
having a highly flexible, double walled tubular bar. The stem of the
T-shaped member is connected at one end to the outer wall of the bar and
it communicates with an annular space between the walls of the bar. The
other end of the stem is connected and communicates with a pressure bulb
containing a pressurizing fluid to form a completely closed fluid system.
The outer wall of the bar includes cuff portions of highly elastic
material adjacent each end of the bar and the inner wall of the bar is a
tube of relatively inelastic material. In use, the highly flexible,
unpressurized bar is introduced into a blood vessel through an incision
using the stem and the pressure bulb as a handle. The bar is then
pressurized by squeezing the pressure bulb to inflate the cuff portions to
form seals with the inner wall of the blood vessel and to rigidize the
normally highly flexible portion of the bar between the cuff portions. As
a result blood can flow through the blood vessel only by passing through
the lumen of the bar. The stem can be closed to prevent fluid from
returning to the pressure bulb and to retain the bar in a pressurized
condition until the surgery is completed.
Because of the extremely small size of the micro-hemostat, a novel method
of preparing the hemostat had to be developed as conventional assembly
techniques proved to be impractical.
In the preferred method of preparation of the micro-hemostat, a T-shaped
tube having a bar portion of highly elastic material is first formed and
then a flexible, relatively inelastic tube inserted within the lumen of
the bar portion of the T-tube. The elastic wall of the bar of the T-shaped
tube serves as the outer wall of the double walled bar of the hemostat and
the relatively inelastic tube forms the inner wall. The outer and inner
walls are sealed at the ends of the bar to form a fluid tight annular
chamber. The elastic outer wall of the hemostat bar is then either sealed
to the inner wall or coated with a less elastic material to prevent if
from expanding or inflating except in the cuff areas adjacent each end of
the tube. The stem of the T-shaped tube which communicates with the
chamber between the walls, is then connected to a pressure bulb for
pressurizing fluid to form a completely closed fluid system. The
pressurizing fluid either can be present in the bulb at the time of
attachment to the stem of the T-tube or the bulb can be filled with the
fluid through a resealable valve after it has been connected to the stem.
The micro-hemostat of the present invention, because of its highly flexible
bar with non-preformed bulb ends can be easily folded and bent, thus it
requires a smaller incision for insertion and withdrawal than do
conventional occluders. Furthermore, since the micro-hemostat is
inflatable once in place, a single size hemostat can be used with any of
the blood vessels normally encountered in coronary surgery. As a result,
the time lost in selecting the proper size occluder is saved. Finally,
when the micro-hemostat of the present invention is used, tissue normally
supplied by the blood vessel is not without circulation.
In one embodiment, the non-cuff areas of the outer wall are spot sealed
with adhesive or welds to the outside of the tube forming the inner wall.
In another embodiment, the outer wall is prevented from inflating or
expanding except in the cuff areas by adhesively sealing the inside of the
non-cuff portions of the outer wall to ribs on the outside of the tube
that forms the inner wall of the bar.
In still another embodiment, the non-cuff areas of the outer wall are
coated sufficiently with elastomer to render them relatively inelastic
although still highly flexible.
The micro-hemostat and its method of use will be further described in
connection with the drawings in the specification which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 through 3 are perspective views showing an embodiment of the
micro-hemostat of the present invention and its use in a surgical
procedure;
FIG. 4 is a cross sectional view of the cuff portion of the bar of the
micro-hemostat shown in FIG. 1;
FIG. 5 is a cross sectional view of the bar portion of the micro-hemostat
of FIG. 1 taken along lines 5--5 in FIG. 4;
FIG. 6 is a perspective view partly in section of a second embodiment of
the micro-hemostat of the present invention;
FIG. 7 is a sectional view of the bar of the micro-hemostat of FIG. 6; and
FIG. 8 is a cross sectional view taken along lines 8--8 of FIG. 7.
In the drawings, the views have been enlarged to facilitate an
understanding of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In the drawings, the micro-hemostat of the present invention is generally
referred to as 10, and it is seen to include a generally T-shaped member
having a tubular bar 11 and a tubular stem 12 which joins the bar to a
pressure bulb 13 containing a pressurizing fluid 14 which is preferably
sterile saline. The bar 11 includes an outer wall 15 and an inner wall 16
which are joined in a fluid-tight system at each end of the bar so that
the space between the two walls forms an annular chamber 17 for receiving
the pressurizing fluid 14. The tubular stem 12 of the hemostat is
connected at its inner end to the outer wall 15 of the bar so that the
lumen of the stem 12 communicates with the chamber 17. The other end of
the stem 12 is connected and communicates with the pressure bulb 13 to
form a completely closed fluid system for the pressurizing fluid 14.
In the embodiment of the invention shown in FIGS. 1 through 5, the outer
wall 15 is highly elastic, the inner wall 16 is relatively inelastic and
the normally annular chamber 17 is deformed by a plurality of spaced seals
18 (seen only in FIGS. 4 and 5). The seals 18 which may be formed with
spot welds or adhesives attach the inner wall 16 to the outer wall 15 and
are arranged so that all areas of the chamber 17 are interconnected. Thus,
when the pressure bulb 13 is squeezed the pressurizing fluid 14 can flow
freely to fill the entire chamber 17. The seals 18 are further arranged so
that the normally, highly elastic outer wall 15 is prevented from
expanding or inflating except for the cuffs 19 adjacent each end of the
bar 11 where the inner wall 16 to the outer wall 15 are not attached by
seals 18.
The inflated shape of the cuffs 19 is shown by broken lines in FIGS. 1, 3
and 4 and by solid lines in FIG. 2. The pressurizing fluid 14 when
introduced into the bar 11 under pressure not only inflates the cuffs 19,
but its presence in the intermediate portions of the bar 11 between the
cuffs 19 causes the normally flexible bar 11 to become more rigid. As seen
in FIGS. 2 and 3, the tubular stem 12 can be closed with an external clamp
20 to retain the pressurizing fluid 14 in the bar so that the cuffs 19
remain inflated and the bar 11 rigid.
In FIG. 6, an embodiment of the micro-hemostat 10 is shown in which there
is a one-way valve 21 in the stem 12. The one-way valve 21 prevents the
return of the pressurizing fluid 14 to the pressure bulb 13 and eliminates
the need to use the external clamp 20 for that purpose. If desired, the
valve 21 may be of the type which can be manually opened to permit the
return of the fluid 14 to the bulb 13. Suitable valves are disclosed in
U.S. Pat. No. 4,009,711 and U.S. Pat. No. 4,060,080.
As seen in FIG. 6, the second embodiment has a safety bulb 22. The safety
bulb 22 provides additional assurance that the cuffs 19 will be fully
inflated, but not over inflated with pressurizing fluid 14. The wall of
the safety tube 22 preferably is made of slightly less elastic material
than the elastic wall of the cuffs 19. Thus, when the pressure bulb 13 is
squeezed and the pressurizing fluid 14 is forced into the chamber 17 of
the bar 11, the cuffs 19 will first expand to form a seal with the blood
vessel wall and then when further expansion of the cuffs 19 is restricted,
but, before the cuffs 19 can cause damage to the walls of the blood
vessel, the safety bulb 22 will expand. Therefore, the user of the second
embodiment can visually determine by observing the expanded safety bulb 22
that the cuffs 19 have been sufficiently inflated to form the desired
seals with the blood vessel wall. The safety bulb 22 also provides a
visual signal when the closed fluid system of the micro-hemostat 10 has
been inadvertently opened, e.g., by nicking with a sharp instrument.
In FIGS. 7 and 8, an embodiment of the hemostat 10 is shown in which the
tube which serves as inner wall 16 of the bar 11 is provided with
longitudinal ribs 23. The ribs 23 cooperate with the walls 15 and 16 to
provide channels 24 which permit the pressurizing fluid 14 to flow from
the stem 12 through the intermediate arm portions of the bar 11 to the
cuffs 19. The presence of the fluid 14 under pressure in the channels 24
renders the flexible bar 11 more rigid. In order to facilitate the flow of
pressurizing fluid 14, portions 23a of the ribs 23 are removed in the cuff
area and where the stem 12 joins the bar 11.
When a ribbed inner tube is employed as the inner wall 16, it is possible,
if desired, to eliminate the use of adhesive or spot welding to prevent
the elastic outer wall 15 from expanding. This can be done by coating the
non-cuff portions of the outer wall 15 with a material that renders them
inelastic. Obviously, the elastic material making up the cuffs 19 must be
either protected during the coating process or formed after the coating
process is completed.
A preferred method of making the embodiment of the micro-hemostat employing
the ribbed tube is to first dip coat a T-shaped mandrel which takes apart
for stripping in a silicone elastomer. The mandrel is dipped to form a
substantial thickness over the stem 12 and intermediate arm portions of
the bar 11 and the silicone material on the mandrel is trimmed off at the
two distal ends where the cuffs 19 will start. The mandrel is then dipped
again to form an additional layer of cuff thickness and cured. The tips
are then trimmed and the material which is to form the cuffs is rolled up
back upon itself. The mandrel is removed and a relatively inelastic inner
tube with longitudinal ribs 23 is inserted into the lumen of the tubular
bar 11 of the thus formed T-tube. The tube preferably has been previously
modified by grinding or cutting off segments 23a of the ribs 23 all around
the circumference at the center and at the end of each arm in the cuff
area to provide the channels 24 for the flow of the pressurizing fluid. If
desired, the tops of the ribs on the tube can then be coated with adhesive
before the tube is positioned inside the bar of the T-tube. Using an
inflatable mandrel the adhesive coated ribs 23 of the inner tube can be
forced against the inner wall of the bar of the T-tube. A tapered mandrel
can also be used for the same purpose. When the adhesive is cured, the
cuffs can be unrolled and the ends of the outer wall 15 and inner wall 16
sealed by dip coating or cementing. Finally, the pressure bulb 13 can be
attached to the stem 12 with adhesive to form the complete micro-hemostat
10.
The pressure bulb is preferably provided with a resealable valve so that it
can be filled after it has been thus assembled. A suitable resealable
valve which is also comprised of silicone material is disclosed in U.S.
Pat. No. 3,919,724.
Although in the preferred embodiments of the invention which have been
described, the entire micro-hemostat has been described as being made of
medical grade silicone, other suitable materials such as polyurethane also
can be used.
In the embodiments of the invention shown in the drawings, the pressurized
bar of the micro-hemostat can be depressurized by either unclamping the
stem, opening the one-way valve or cutting the stem. Since the prepared
pressurizing fluid is sterile saline there is no disadvantage in cutting
the stem and cutting the stem does have its advantage that the hemostat
will not be reused.
A method of using the micro-hemostat 10 will now be described in connection
with FIGS. 1, 2 and 3. Prior to using the micro-hemostat 10 a section of
artery A to be anastomosed is located and a longitudinal incision B is
made. The unpressurized, highly flexible bar 11 of the micro-hemostat is
then easily inserted into the artery A through the incision B using the
bulb 13 and stem 12 as the handle. The bar 11 is positioned in the blood
vessel A so that the ends of the bar 11 extend in opposite directions from
stem 12 past the edges of the incision B. Since the hemostat 10 is
inserted downstream of the blockage in the artery A, the insertion is
normally accomplished without any great loss of blood. The pressure bulb
13 is squeezed to force the pressurizing fluid 14 into the chamber 17 to
inflate the cuffs 19 and rigidize the intermediate arm portions of the bar
11. When the cuffs 19 have been adequately inflated, the blood flowing
through the artery passes through the lumen 11a of the tubular bar 11.
When the hemostat 10 is properly in place and pressurized the stem 12 is
then closed with either a one-way valve 21 or an external clamp 20 as seen
in FIG. 3 to keep the bar 11 pressurized and the cuffs 19 inflated.
The blood vessel C to be connected to artery A is then placed over the
incision B as seen in FIG. 3. Artery A is then lifted from inside by using
the stem 12 and bulb 13 as a handle to stabilize the artery and facilitate
the suturing of the blood vessel C to the artery about the incision B.
Sutures are prepared about the incision through which the stem 12 extends,
but are not drawn tight. The clamp 20 is then removed to permit the
pressurizing fluid to leave the cuffs and the intermediate portion of the
bar 11 and to return to the pressure bulb 13 so that the micro-hemostat 10
can be readily removed from the artery A. Once again, the stem 12 and the
pressure bulb 13 are used as a handle for this purpose. The suturing of
the blood vessel C to the artery A is then quickly completed with a
minimum of blood loss. Because of the flexibility and softness of silicone
rubber the use of the preferred micro-hemostat results in a minimum of
trauma to the site of the anastomosis.
It will be readily apparent to those skilled in the art, that a number of
modifications and changes can be made without departing from the spirit
and scope of the present invention. For example, in some instances it may
be desirable to replace the pressure bulb of the described micro-hemostat
with a resealable cap on the stem. The pressurizing fluid to rigidize the
highly flexible bar and inflate the cuff is then introduced under pressure
from a separate bulb or syringe through a cannula extending through the
resealable cap; the opening in the cap formed by the cannula closes upon
the withdrawal of the cannula. Other conventional means of closing the
stem may also be employed. Therefore, it is intended that the invention
not be limited except by the claims which follow.
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