U.S. patent application number 12/758844 was filed with the patent office on 2011-10-13 for instrument of patterning cusp for cardiac valve reconstruction and component thereof.
Invention is credited to Shigeyuki OZAKI.
Application Number | 20110251598 12/758844 |
Document ID | / |
Family ID | 44761473 |
Filed Date | 2011-10-13 |
United States Patent
Application |
20110251598 |
Kind Code |
A1 |
OZAKI; Shigeyuki |
October 13, 2011 |
INSTRUMENT OF PATTERNING CUSP FOR CARDIAC VALVE RECONSTRUCTION AND
COMPONENT THEREOF
Abstract
In a case of repairing an aortic valve, etc. by forming a valve
cusp with a biomembrane or the like, the shape and the size of a
valve cusp can be determined easily. An instrument including a
valve cusp sizer 2 for measuring the sizer of the valve cusp and a
template 3 for scribing lines for the shape of a valve cusp
conforming to the measured size of the valve cusp, in which the
valve cusp sizer 2 has a plurality of differently-sized sizer
blocks (G.sub.1 to G.sub.8) attached to each of the top ends of
grip members 21 respectively and each sizer block has an arcuate
surface 24 formed by cutting each of differently-sized circular
cylinders 22 at an angle conforming to the central angle for the
commissure portions and, the template 3 is formed with a scribing
portion 31 including a substantially semi-circular valve cusp base
forming portion 33 having a diameter as a sum of a nominal diameter
(D.sub.1 to D.sub.8) defined for the diameter of a circular
cylinder constituting the arcuate surface of a sizer block (G.sub.1
to G.sub.8) whose arcuate surface 24 conforms at both ends thereof
to both of the commissure portions and an allowance for stitching
margin (W), and a coaptation zone forming portion 34 in contiguous
with the valve cusp base forming portion.
Inventors: |
OZAKI; Shigeyuki; (Tokyo,
JP) |
Family ID: |
44761473 |
Appl. No.: |
12/758844 |
Filed: |
April 13, 2010 |
Current U.S.
Class: |
606/1 |
Current CPC
Class: |
A61F 2/2415 20130101;
A61F 2/2496 20130101; A61F 2/2445 20130101 |
Class at
Publication: |
606/1 |
International
Class: |
A61B 17/00 20060101
A61B017/00 |
Claims
1. An instrument of patterning a valve cusp used for aortic valve
reconstruction by stitching a valve cusp patterned from an
artificial membrane or a biomembrane to a portion of a tricuspid
cardiac valve such as an aortic valve from which an abnormal cusp
has been excised, the instrument including; a valve cusp sizer for
measuring the size of a valve cusp conforming to the size of a
cardiac valve, and a template for scribing lines of the shape of
the valve cusp on the artificial membrane or the biomembrane
conforming to the measured size of the valve cusp, in which the
valve cusp sizer has a plurality of differently-sized sizer blocks
for measuring the length of a valve annulus extending from one
commissure portion of a valve cusp to a valve annulus to the other
commissure portion of the valve cusp to the valve annulus of an
excised valve cusp, where each of the seizer blocks is attached to
each of the top ends of grip members respectively and each of the
sizer blocks has an arcuate surface formed by cutting each of
differently-sized circular cylinders at an angle conforming to the
central angle for the commissure portions and, the template is
formed with a scribing portion including a substantially
semi-circular valve cusp base forming portion having a diameter as
a sum of a nominal diameter defined for a diameter of a circular
cylinder constituting the arcuate surface of a sizer block whose
arcuate surface conform at both ends thereof to both of the
commissure portions of the excised valve cusp when the cusp sizer
is inserted to a valve annulus from which the valve cusp has been
excised and an allowance for stitching margins, and a coaptation
zone forming portion in contiguous with the valve cusp base forming
portion.
2. A valve cusp sizer for measuring the size of a valve cusp
conforming to the size of a cardiac valve in a cardiac valve
reconstruction of reconstructing a cardiac valve by stitching a
valve cusp which is formed by pattering an artificial membrane or a
biomembrane, to a portion of a tricuspid cardiac valve, for
example, of an aortic valve from which an abnormal valve cusp has
been excised in which each of a plurality of differently-sized
sizer blocks for measuring the length of a valve annulus extending
from one commissure portion of a valve cusp to a valve annulus to
the other commissure portion of the valve cusp to the valve annulus
of an excised valve cusp is attached to the top end of each of grip
members, and an arcuate surface formed by cutting a circular
cylinder of different radius at an angle conforming to the central
angle for the commissure portion is formed to each of the sizer
blocks.
3. A valve cusp sizer according to claim 2, wherein contact probe
portions for positioning both ends of the arcuate surface of the
sizer block to the commissure portions are formed in parallel with
the central axis of the arcuate surface.
4. A valve cusp sizer according to claim 2, wherein the upper
surface of the sizer block is formed being curved as a concave
shape such that the central point for the valve cusp base between
commissure portions can be observed when both ends of the arcuate
surface of the sizer block are abutted against both of the
commissure portions of the valve annulus from which the valve cusp
has been excised.
5. A valve cusp sizer according to claim 3, wherein the upper
surface of the sizer block is formed being curved as a concave
shape such that the central point for the valve cusp base between
commissure portions can be observed when both ends of the arcuate
surface of the sizer block are abutted against both of the
commissure portions of the valve annulus from which the valve cusp
has been excised.
6. A valve cusp sizer according to claim 4, wherein an index as a
center marker is attached to the upper surface of the sizer block
at a position corresponding to the central point of the valve cusp
base between commissure portions.
7. A valve cusp sizer according to claim 5, wherein an index as a
center marker is attached to the upper surface of the sizer block
to a position corresponding to the central point of the valve cusp
base between the commissure portions.
8. A valve cusp sizer according to claim 2, wherein the grip member
is attached to the center of the circular cylinder that forms the
sizer block and inclined relative to the central axis thereof at a
predetermined angle on the side opposite to the arcuate
surface.
9. A template for scribing lines of a valve cusp shape on an
artificial membrane or a biomembrane conforming to shape of a valve
cusp, in which a valve cusp sizer for measuring the size of the
valve cusp has a plurality of differently-sized sizer blocks for
measuring the length of a valve annulus extending from one
commissure portion of a cusp to a valve annulus to the other
commissure portion of the cusp to the valve annulus of an excised
valve cusp, where each of the seizer blocks is attached to each of
the top ends of grip members respectively and each of the sizer
blocks is formed with an arcuate surface formed by cutting each of
differently-sized circular cylinders at an angle conforming to the
central angle for the commissure portions and, the template is
formed with a scribing portion including a substantially
semi-circular valve cusp base forming portion having a diameter as
a sum of a nominal diameter that is defined for a diameter of a
circular cylinder constituting the arcuate surface of a sizer block
and stitching margins, and a coaptation zone forming portion in
contiguous with the valve cusp base forming portion.
10. A template according to claim 9, wherein the coaptation zone
forming portion is formed into a rectangular shape in which both
end edges thereof are extended from both ends of the valve cusp
base forming portion for a length conforming to the height of the
coaptation.
11. A template according to claim 9, wherein both ends edges of the
coaptation zone forming portion are extended for a length
conforming to the height of the coaptation zone while being widened
gradually from both ends thereof and the free margin portion at the
top end is formed into an angled shape.
Description
TECHNICAL FIELD
[0001] The present invention concerns an instrument for patterning
a valve cusp and a component thereof, used for cardiac valve
reconstruction that stitches a valve cusp formed of an artificial
membrane or a biomembrane to a portion of a tricuspid cardiac valve
such as an aortic valve from which an abnormal valve cusp has been
excised. The instrument includes a valve cusp sizer for measuring
the size of a valve cusp conforming to the size of a cardiac valve
and a template for scribing lines of a valve cusp shape on an
artificial membrane or a biomembrane conforming to the measured
size of the valve cusp.
BACKGROUND ART
[0002] As shown in FIG. 8, a heart 71 has a function of a pump that
sends a blood circulated through the body and flowing from superior
and inferior vena cava 72, 72 into a right atrium 73R from a right
ventricle 74R by way of a pulmonary artery 75 to right and left
lungs and then delivers a blood circulated from the lung by way of
pulmonary veins 76 - - - to a left atrium 73L from the left
ventricle 74L by way of an aorta 10 to the whole body.
[0003] For example, an aortic valve 11 is a cardiac valve that is
formed at the exit where the blood flows out from the left
ventricle 74L to the aorta 10, in which cup-shaped three valve
cusps 12, - - - of a thin membrane are present as shown in the
schematic view of FIG. 9.
[0004] In each of the valve cusps 12, a portion defined along a
commissure portion K of a cusp to a valve annulus on one end of a
free margin F as an ON-OFF end.fwdarw.a bottom end C.sub.L of a
coaptation zone just therebelow.fwdarw.a bottom B of the valve
cusp.fwdarw.a bottom end C.sub.L of the other coaptation
zone.fwdarw.a commissure portion K of a cusp to a valve annulus on
the other end is integrated with the inner wall as valve annulus of
the aorta 10 to constitute a fixed edge 13.
[0005] Then, along with dilation and contraction of the heart 71,
since the pressure in the left ventricle 74L becomes negative
during diastole, coaptation zones Z.sub.c formed on the side of the
free margin F of the valve cusps 12 are jointed to each other to
close the valve 11 as shown in FIG. 9(a), whereas since the
pressure in the left ventricle 74L becomes positive during cardiac
systole, the coaptation zones Z.sub.c of the valve cusps 12, 12, -
- - are spaced apart from each other to open the valve 11 as shown
in Fig. (b).
[0006] However, when atheriosclerosis, etc. proceed along with
aging and calcium is deposited to calcify and harden the valve
cusps, the valve cusps are restricted for the movement and do not
open sufficiently to cause disease such as aortic valve
stenosis.
[0007] According to the recent study, from 2 to 3% of the
population of 26,000,000 aged 65 years or older in Japan suffer
from the disease.
[0008] When the aortic valve stenosis is caused, since pressure
loss is generated at the affected area, the left ventricle intends
to maintain the blood pressure in the aorta at a normal 100 to 120
mmHg (during cardiac systole) contracts at a pressure higher than
that (for example, 150 mmHg).
[0009] As a result, the left ventricle wall becomes thickened and
causes hypertrophy and, when the thickness for the wall of the
cardiac muscle is excessively increased, since the blood flow
supplied from the coronary arteries is no more sufficient, the
heart becomes to a hypoalimentation and insufficient oxygen state
(miocardial ischemia). Particularly, if myocardial ischemia is
caused when the oxygen demand is increased, for example, during
activity, it may possibly cause symptoms such as chest pain and
syncope.
[0010] In a case where the blood pressure difference exceeds, for
example, 50 mmHg, this is judged as surgical indication.
[0011] The most popularized treatment is valve replacement by using
a prosthetic valve.
[0012] The prosthetic valve includes two types, that is, a
mechanical valve formed of carbon, graphite, etc. and a heterogenic
biovalve prepared from biomembranes of animals such as swinery and
cattle and they are operated by the procedures as shown in FIG.
10.
[0013] That is, FIG. 10 is an explanatory view showing the outline
of prosthetic valve replacement. As shown in FIG. 10(a) to 10(b),
all three valve cusps (left coronary cusp, right coronary cusp,
noncoronary cusp) 79, - - - of the aortic valve situated at the
inlet of the aorta 10 are excised while leaving only the valve
annulus in contiguous from the left ventricle 74L to the aorta.
Then, as shown in FIG. 10(c), the inner diameter of the aorta is
measured by a sizer 81 as shown in FIG. 10(c) (refer to Patent
document 1) and a prosthetic valve 82 having a valve annulus outer
diameter equal with the inner diameter of the aorta is stitched to
replace the valve.
[Patent Document 1] JP-T No. 2000-502937
[0014] However, even replacement is conducted by the prosthetic
valve 82, since the prosthetic valve 82 has a shape in which the
valve cusps 84 - - - are attached to a valve annulus 83, when it is
stitched to the aorta 10, the inner diameter of the aorta 10 is
decreased by so much as the thickness of the valve annulus 83 and
the portion forms an orifice to cause pressure loss.
[0015] For example, in a case where the inner diameter of the aorta
10 is 20 mm, when a prosthetic valve 82 having the valve annulus 83
of 3 mm thickness is mounted as the prosthetic valve, the inner
diameter of the prosthetic valve 82 is decreased to 14 mm even when
it is opened fully and the area ratio is decreased to about 1/2.
Then, a pressure loss is caused to the portion and although the
valve is replaced with an aim of decreasing the pressure loss
caused by aortic stenosis, the loss cannot be decreased
sufficiently.
[0016] In a case of using a mechanical valve as the prosthetic
valve 82, it is necessary to continuously take an anti-coagulant
agent such as warfarin for whole life long, which results in a
problem that it is difficult to arrest the bleeding in a case of
injury, as well as, it is also pointed out a risk that
teratogenesis may be caused possibly to a fetus when a pregnant
woman takes the agent.
[0017] On the other hand, there is no requirement of taking
warfarin in a case of using a heterogenic biovalve, but this
involves a problem that the cost is as high as 1,000,000 yen or
more per one valve unit.
[0018] Further, since both the mechanical valve and the heterogenic
biovalve are obstacles after all, they may cause a risk of
rejection.
[0019] Accordingly, as a result of an earnest study, the present
inventor has established, instead of valve replacement, an aortic
valve reconstruction of repairing an aortic valve by decalcifying
hardened valve cusps by using a supersonic surgical aspirator,
etc., thereby leaving valve cusps that can be used as much as
possible, and forming only the valve cusp that is no more usable by
using an autologuous biomembrane, etc.
[0020] In this case, when the valve cusp is formed by incising an
autologuous pericardium, etc., since this comprises an autologuous
biobody tissue, there is no problem of causing the rejection or
blood clotting reaction (thrombus) and there is no requirement of
purchasing an expensive prosthetic valve.
[0021] However, there has been a problem in this case how to cutout
a valve cusp from a planar pericardium in the shape and the size
conforming to the diameter of a patient's aorta.
[0022] It is considered that the diameter (or radius) of the valve
annulus corresponds generally to the shape of the aorta. However,
in a case of measuring the diameter, for example, by a sizer 81
used for attaching the prosthetic valve (refer to FIG. 10(c)), all
valve cusps have to be excised. If a usable valve cusp is left, the
valve cusp hinders measurement for the diameter of the aorta.
[0023] Accordingly, the present inventor has attempted to use a
model for the shape of the valve cusp based on the peripheral
length of the valve cusp as shown in FIG. 11.
[0024] At first, assuming that an aorta is a circular cylinder
having an inner diameter (diameter) D and that the central angle
for a free margin L.sub.F extending from one commissure portion K
of a cusp to a valve annulus, passing through the center P.sub.F of
the aorta to the other commissure portion K of the cusp to the
valve annulus (central angle for the commissure portions K, K) is
120.degree. in a valve-open state, the length of the free margin is
equal to D.
[0025] On the other hand, when assuming that the height from one
commissure portion K to the bottom end C.sub.L of the coaptation
zone Z.sub.c where the valve cusps are joined to each other as h
(usually the height is considered sufficient if h=10 to 12 mm), the
coaptation zone Z.sub.c has a rectangular shape having a width
L.sub.F (=D) and a height h.
[0026] Since the central point P.sub.c for the base B of the valve
cusp is at a position lower than the bottom end C.sub.L of the
coaptation zone, the length L.sub.B for the base of the valve cusp
extending from the bottom end C.sub.L of one commissure portion K,
passing along the base of the valve cusp through the central point
P.sub.c thereof to the bottom end C.sub.L of the other coaptation
zone is larger than the inner peripheral length of the aorta having
the central angle of 120.degree..
[0027] Then, when the shape of the valve cusp is formed as a
semi-circular-square shape comprising a semi-circular cusp base
portion having a length L.sub.B thereof up one-half circumference
(=.pi.r) of the inner periphery of an aorta and a rectangular
portion corresponding to a rectangular coaptation zone Z.sub.c in
contiguous therewith while making an allowance for stitching formed
by cutting out a pericardium conforming to the shape and it is used
for animal experiment of forming the prosthetic valve cusp of an
aortic valve, it showed good result after surgery.
[0028] In this case, if it is possible to easily measure the inner
diameter D of the aorta in a state of excising only one valve cusp,
it is extremely convenient since the aortic valve can be formed
while preparing the valve cusp by cutting out the pericardium
during surgery.
DISCLOSURE OF THE INVENTION
Subject to be Solved by the Invention
[0029] The present invention has been achieved based on the
inventor's finding as described above and, it intends to easily
determine the shape and the size of a valve cusp in a case of
treating a tricuspid cardiac valve such as an aortic valve by
replacing only the valve cusp that can no more be used with an
autologuous biomembrane or the like, thereby reconstructing the
aortic valve.
Means for Solving the Subject
[0030] The present invention provides an instrument of patterning a
valve cusp used for aortic valve reconstruction by stitching a
valve cusp patterned from an artificial membrane or a biomembrane
to a portion of a tricuspid cardiac valve such as an aortic valve
from which an abnormal cusp has been excised, the instrument
including; [0031] a valve cusp sizer for measuring the size of a
valve cusp conforming to the size of a cardiac valve, and [0032] a
template for scribing lines of the shape of the valve cusp on the
artificial membrane or the biomembrane conforming to the measured
size of the valve cusp, in which [0033] the valve cusp sizer has a
plurality of differently-sized sizer blocks for measuring the
length of a valve annulus extending from one commissure portion of
a valve cusp to a valve annulus to the other commissure portion of
the valve cusp to the valve annulus of an excised valve cusp, where
each of the seizer blocks is attached to each of the top ends of
grip members respectively and each of the sizer blocks has an
arcuate surface formed by cutting each of differently-sized
circular cylinders at an angle conforming to the central angle for
the commissure portions and, [0034] the template is formed with a
scribing portion including a substantially semi-circular valve cusp
base forming portion having a diameter as a sum of a nominal
diameter defined for a diameter of a circular cylinder constituting
the arcuate surface of a sizer block whose arcuate surface conform
at both ends thereof to both of the commissure portions of the
excised valve cusp when the cusp sizer is inserted to a valve
annulus from which the valve cusp has been excised and an allowance
for stitching margins, and a coaptation zone forming portion in
contiguous with the valve cusp base forming portion.
Effect of the Invention
[0035] According to the invention, the valve cusp sizer is inserted
to the valve annulus in a state of excising an abnormal valve cusp
of a tricuspid cardiac valve such as an aortic valve and, when the
diameter of the sizer block whose arcuate surface conform at both
ends thereof to the commissure portions of the excised valve cusp,
the diameter is defined as a nominal diameter, and this is used as
an index for deciding the size of the valve cusp.
[0036] Since the scribing portion conforming to the nominal
diameter is formed in the template, when a biomembrane, for
example, a pericardium is extended, the template is put thereon,
the shape of the a valve cusp is drawn along the scribing portion
by using, for example, a sterilized surgery skin marker, etc. and
then the biomembrane is excised along the line, a prosthetic valve
cusp conforming to the shape of the excised valve cusp is
formed.
[0037] Then, when the thus formed prosthetic valve cusp is directly
stitched to the valve annulus where the base of the excised valve
cusp has been joined, a tricuspid cardiac valve such as an aortic
valve can be formed without decreasing the valve annulus
thereof.
BRIEF EXPLANATION OF THE DRAWINGS
[0038] [FIG. 1] is an explanatory view showing an example of a
valve cusp forming instrument according to the invention.
[0039] [FIG. 2] is an explanatory view showing a valve cusp
sizer.
[0040] [FIG. 3] is an explanatory view showing a template.
[0041] [FIG. 4] is an explanatory view showing another embodiment
of a template.
[0042] [FIG. 5(a)] is an explanatory view showing an aortic valve
before excising a valve cusp.
[0043] [FIG. 5(b)] is an explanatory view showing an aortic valve
from which a valve cusp has been excised.
[0044] [FIG. 5(c)] is an explanatory view showing the state of
measuring the size of a valve cusp.
[0045] [FIG. 6] is an explanatory view showing the template in the
state of use.
[0046] [FIG. 7] is an explanatory view showing a petri dish type
vessel for preparing each cusp individually.
[0047] [FIG. 8] is a schematic view of a heart.
[0048] [FIG. 9(a)] is an explanatory view showing an aortic valve
in a closed state.
[0049] [FIG. 9(b)] is an explanatory view showing an aortic valve
in an open state.
[0050] [FIG. 10(a)] is a view showing an aortic valve in which
valve cusps are calcified.
[0051] [FIG. 10(b)] is a view showing an aorta valve from which all
valve cusps are excised.
[0052] [FIG. 10(c)] is a view showing the state of measuring the
inner diameter of an aortic valve by using an existent sizer.
[0053] [FIG. 10(d)] is a view showing an aorta replaced with a
prosthetic valve by existent aortic valve replacement.
[0054] [FIG. 11] is an explanatory view showing a model of a valve
cusp.
PREFERRED EMBODIMENTS OF THE INVENTION
[0055] The present invention intends to easily determine the shape
and the size of a valve cusp in a case of reconstructing, a
tricuspid cardiac valve such as an aortic valve by replacing only
the valve cusp which is no more usable using, an autologuous
biomembrane, etc.
[0056] For this purpose, an instrument of patterning a valve cusp
used for aortic valve reconstruction by stitching a valve cusp
patterned from an artificial membrane or a biomembrane to a portion
of a tricuspid cardiac valve such as an aortic valve from which the
abnormal cusp has been excised includes; [0057] a valve cusp sizer
for measuring the size of a valve cusp conforming to the size of a
cardiac valve, and [0058] a template for scribing lines of the
shape of the valve cusp on the artificial membrane or the
biomembrane conforming to the measured size of the valve cusp.
[0059] The valve cusp sizer has a plurality of differently-sized
sizer blocks for measuring the length of a valve annulus extending
from one commissure portion of a cusp to a valve annulus to the
other commissure portion of the cusp to the valve annulus of an
excised valve cusp, where each of the seizer blocks is attached to
each of the top ends of grip members respectively and each of the
sizer blocks has with an arcuate surface formed by cutting each of
differently-sized circular cylinders at an angle conforming to the
central angle for the commissure portions.
[0060] The template is formed with a scribing portion including a
substantially semi-circular valve cusp base forming portion having
a diameter as a sum of a nominal diameter defined as a diameter of
a circular cylinder constituting the arcuate surface of a sizer
block whose arcuate surface conform at both ends thereof to both of
the commissure portions of the excised valve cusp when the cusp
sizer is inserted to a valve annulus from which the valve cusp has
been excised and an allowance for stitching margins, and a
coaptation zone forming portion in contiguous with the valve cusp
base forming portion.
First Embodiment
[0061] FIG. 1 shows an instrument 1 of this embodiment which
includes a valve cusp sizer 2 for measuring the size of a valve
cusp conforming to the size of a cardiac valve, a template 3 for
scribing lines of a shape of the valve cusp on an artificial
membrane or a biomembrane conforming to the measured size of the
valve cusp, and a base plate 4 for maintaining the artificial
membrane or the biomembrane in a planar state upon scribing the
lines for the shape of the cusp by using the template 3.
[0062] The valve cusp sizer 2, the template 3, and the base plate 4
are contained in a stainless steel case 5, and they can be
sterilized in a state as they are contained therein by an
sterilizing autoclave.
[0063] In the case 5, a main body 51 for containing the valve cusp
sizer 2, and a cover 52 for containing the template 3 and the base
plate 4 are opened and closed by a hinge 53, and a partition plate
54 is disposed therebetween.
[0064] The cusp sizer 2 has a plurality of differently-sized sizer
blocks G.sub.1 to G.sub.8 for measuring the length of the valve
annulus from one commissure portion of a valve cusp to a valve
annulus to another commissure portion of the valve cusp to the
valve annulus of an excised valve cusp, and each of the sizer
blocks is attached to each of the top ends of grip members 21, 21,
- - - .
[0065] Then, as shown in FIG. 2, each of the sizer blocks G.sub.1
to G.sub.8 has, as a basic shape, a partial circular cylinder 23
formed by cutting different-sized circular cylinder 22 at an angle
conforming to the central angle for the commissure portions of the
aortic valve (120.degree. in this embodiment, while assuming that
the central angles for three commissure portions K are equal).
[0066] The outer peripheral surface is formed as an arcuate surface
24 to be abutted against the valve annuls of an aorta from which an
abnormal valve cusp has been excised, and contact probe portions 25
of a predetermined length for positioning and abutting both ends of
the arcuate surface 24 against the commissure portions K, K are
formed in parallel with the central axis of the arcuate surface
24.
[0067] The diameter of the circular cylinder 22 (arcuate surface
24) is used as the nominal diameter (D.sub.1 to D.sub.8) for
defining the size of the valve cusp. In this embodiment, sizer
blocks G.sub.1 to G.sub.8 having eight types of nominal diameters
D.sub.1 to D.sub.8 from 17 to 31 mm on every 2 mm step are used
while considering the personal differences for the diameter of
adult aorta.
[0068] Then, numerical values for the nominal diameters D.sub.1 to
D.sub.8 are indented to the grip members 21 such that the size of
the sizer block D.sub.1 to D.sub.8 attached to the top ends thereof
can be read.
[0069] Further, the central point P.sub.c for the base B of the
valve cusp is at a position lower than the bottom end C.sub.L of a
coaptation zone (refer to FIG. 11). Therefore, the upper surface 26
for each of the sizer blocks G.sub.1 to G.sub.8 is formed being
curved in a concave shape such that the central point P.sub.c for
the base B of the valve cusp between the commissures portions K, K
where the valve cusp is to be stitched can be seen when each of the
contact probe portions 25 is abutted against each of the commissure
portions K, K from which the valve cusp has been excised.
[0070] Further, an index 27 as a center marker for defining the
central point P.sub.c is formed at a position of the upper surface
thereof corresponding to the central point P.sub.c in a case of
starting stitching from the central point P.sub.c.
[0071] Then, the grip member 21 is attached to the center of the
partial circular cylinder 23 that forms each of the sizer blocks
G.sub.1 to G.sub.8 such that it does not hinder the observation of
the valve annulus in a state of abutting the arcuate surface 24 of
each of the sizer blocks G.sub.1 to G.sub.4 to the valve annulus,
and the grip member 21 is inclined by a predetermined angle .theta.
(.theta.=30.degree.) in this embodiment) relative to the central
axis X to the side opposite to the arcuate surface.
[0072] FIG. 3 shows the template 3 which is put over the artificial
membrane or the biomembrane for scribing the lines of the shape of
the valve cusp by using a sterilized surgery skin marker, etc. and
in which a plurality of scribing portions 31 having
differently-sized shapes of the valve cusp are perforated.
[0073] The scribing portion 31 is formed as a
semi-circular-rectangular part comprising a substantially
semi-circular base forming portion 32 and a substantially
rectangular coaptation forming portion 33 in contiguous
therewith.
[0074] When assuming that a valve cusp sizer 2 is inserted to a
valve annulus from which a valve cusp has been excised and that
contact probes 25 formed on both ends of the arcuate surface of a
sizer block Gn (G.sub.1 to G.sub.8) conform to both of the
commissure portions of the excised valve cusp, the valve cusp base
forming portion 32 has a diameter as a sum of the diameter defined
as a nominal diameter Dn of the circular cylinder and an allowance
for stitching margins 2W on both right and left sides (Dn+2w). The
stitching margin is designed as: w=3 mm in this embodiment.
[0075] Further, the coaptation zone forming portion 33 is formed as
a rectangular shape having a width equal with the diameter of the
cusp base forming portion 32 from both ends of the cusp base
forming portion 32 to the free margin portion 34 at the top end,
and having a length h of 12 mm which is necessary and sufficient as
the height for the coaptation zone.
[0076] Then, nominal diameters D.sub.1 to D.sub.8 are described as
guide numbers for respective scribing portions 31. Thus, the
scribing portion 31 conforming to the measured nominal diameter Dn
of the aorta measured by the cusp sizer 2 can be selected
easily.
[0077] FIG. 4 shows another improved template 6, in which the shape
of the scribing portions 61 - - - is improved for further
decreasing the back flow blood.
[0078] This embodiment is identical with the first embodiment in
that a cusp base forming portion 62 is formed of a semi-circle
having a diameter as a sum of the nominal diameter Dn and an
allowance for the stitching margins 2w on both right and left sides
(Dn+2w).
[0079] A coaptation zone forming portion 63 is formed as a
pentagonal shape in which both end edges thereof are extended for a
length h conforming to the height of the coaptation till it reaches
the free margin 64 at the top end while being gradually widened
from both ends of the semi-circular cusp base forming portion 62,
and the center of the free margin portion 64 at the top end thereof
is protruded into an angled shape.
[0080] In this embodiment, the maximum width .alpha. of the
coaptation zone forming portion 62 is designed as: .alpha.=1 mm and
the protrusion length .beta. at the center of the free margin
portion 64 is designed as: .beta.=2 to 3 mm.
[0081] In this embodiment, an allowance is provided for the length
of the free margin portion 64 by gradually increasing the width
thereof while maintaining the substantially rectangular shape as
the coaptation zone forming portion 63, and air tightness is
improved when the valve cusps are closed to reliably prevent
backflow of the blood by increasing the height for the central
portion where three valve cusps are in contact with each other.
[0082] The base plate 4 is formed, for example, of a stainless
steel plate in which perforations 41 are formed at the periphery
thereof for putting and stretching threads 43 that are passed
through the biomembrane or the artificial membrane (refer to FIG.
1, FIG. 6).
[0083] The constitution of the embodiment of the present invention
is as has been described above and the operation thereof is to be
described to an example for the treatment of aortic valve stenosis
with reference to FIG. 5 and FIG. 6.
[0084] Aortic valve reconstruction is applied, for example, by
leaving two valve cusps 12, 12 that can function normally by
removing a calcium component by a supersonic surgical aspirator as
they are and replacing only one valve cusp 12a that cannot be
repaired by decalcification with a prosthetic valve cusp formed of
an autologuous pericardium among three valve cusps 12 of an aortic
valve 11 suffering from aortic valve stenosis caused by deposition
and calcification of calcium.
[0085] In this case, skins, subcutis, and fascia are at first
incised to exteriorize sternum, which is subjected to medium
sternotomy and then the pericardium is incised. Then,
extracorporeal circulation is started by a pump oxygenator in a
state of exposing the heart and, after stopping cardiac activity,
the aortic valve 11 is exposed on the side of the aorta.
[0086] Then, the pericardium is incised into an appropriate size
and the pericardium 42 is extended over the base plate 4 and dipped
in a histological fixture such as glutaraldehyde in a fixed state
by putting around threads 43.
[0087] Then, as shown in FIG. 5(a) to (b), among three valve cusps
12, - - - of the aortic valve 11, one valve cusp 12a is excised by
applying a surgical knife along the fixing edge 13 thereof, a cusp
sizer 2 is inserted to the portion as shown in FIG. 5(c) to measure
the size of the excised valve cusp 12a.
[0088] Specifically, differently-sized sizer blocks G.sub.1 to
G.sub.8 of the cusp sizer 2 are inserted successively and abutted
to the valve annulus of the aorta 10 from which the valve cusp 12a
has been excised, and a sizer block Gn in which the contact probe
portions 25 disposed on both ends of the arcuate surface 24 thereof
conform to both of the commissure portions K, K of the excised
valve cusp 12a is confirmed and the nominal diameter Dn for the
cusp sizer 2 is read.
[0089] When the nominal diameter Dn that determines the cusp size
is decided, the pericardium 42 dipped in glutaraldehyde is taken
out together with the base plate 4, over which the template 3(6) is
placed, and lines for the cusp shape is drawn along the inner
peripheral surface of the scribing portion 31 (61) conforming to
the nominal diameter Dn on the autologuous pericardium 42 by a skin
marker 44. Then, it is detached from the base plate 4 and cut into
the scribed shape by a shear sizer and dipped in physiological
saline for preventing drying.
[0090] In a case of forming, for example, only one valve cusp, the
valve cusp formed of the pericardium 42 may be dipped in a vessel
such as a tray or a Petri dish containing physiological saline.
However, the tricuspid valve of the aortic valve includes three
members of right coronary valve cusp, left coronary valve cusp, and
non-coronary valve cusp. In a case of forming two or more of them
and if the size of respective cusps are different subtly, when they
are happened to be stitched erroneously, this brings about a
trouble in the aortic valve reconstruction.
[0091] In order to prevent this, as shown, for example, in FIG. 7,
a petri dish type vessel 7 for preparing each cusp individually is
used. The vessel is partitioned into three parts of a right
coronary cusp dipping portion 8R, a left coronary cusp dipping
portion 8L, and a non-coronary cusp dipping portion 8N by partition
walls 7a, and identification tags 9R, 9L, 9N are attached for
identifying respective dipping portions 8R, 8L, 8N. By filling the
respective dipping portions 8R, 8L, 8N with physiological saline
and dipping valve cusps formed of the pericardium 42 into
respective dipping portions 8R, 8L, 8N, a risk of erroneously
stitching them during surgery can be prevented.
[0092] Then, when the valve cusp can be formed from the autologuous
pericardium 42, the cusp sizer 2 having the nominal diameter Dn is
again abutted so as to conform the contact probe portions 25
thereof to both commissure portions K, K of the excised valve cusp
12a, a thread is put to a valve annulus at a position indicated by
an index 27 formed to a position corresponding to the central point
P.sub.c of the base B of the valve cusp with reference to the index
27, the central point P.sub.c of the base B of the valve cusp is
stitched and then they are stitched successively toward respective
commissure portions K, K with the point Pc as a reference.
[0093] Thus, the aortic valve can be reconstructed by stitching a
valve cusp formed of the autologuous pericardium to a portion where
the valve cusp 12a has been excised.
[0094] Since the valve cusp formed as described above is made of
the autologuous pericardium, it does not cause rejection. Further,
since the valve annulus of the aortic valve can be utilized as it
is, no additional valve annulus is formed and projected into the
aorta and, accordingly, the pressure loss during opening of the
valve is extremely small.
[0095] While the description has been made to a case of forming the
valve cusp with the pericardium, the present invention can be
applied also to a case of forming the valve cusp with a heterogenic
biomembranes of animals such as cattle, horses and swinery, as well
as with artificial membranes.
INDUSTRIAL APPLICABILITY
[0096] As has been described above, the present invention is
applicable use of forming a valve cusp of optimal size and shape
upon treatment of abnormal valve cusp syndrome by cardiac valve
reconstruction of stitching a valve cusp formed of an artificial
membrane or a biomembrane to a portion of a tricuspid cardiac valve
such as an aortic valve from which an abnormal valve cusp has been
excised.
DESCRIPTION OF THE REFERENCES
[0097] 1 valve cusp forming instrument
[0098] 2 valve cusp sizer
[0099] 3 template
[0100] G.sub.1 to G.sub.8 sizer block
[0101] 21 grip member
[0102] 22 circular cylinder
[0103] 24 arcuate surface
[0104] 25 contact probe portion
[0105] 31 scribing portion
[0106] 32 valve cusp base forming portion
[0107] 33 coaptation zone forming portion
[0108] D.sub.1 to D.sub.8 nominal diameter
* * * * *