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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3683_Библиотеки_им_академика_М_И_Перельмана
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FIG. 6.22 Sutures are placed in the annuloplasty band.
FIG. 6.23 Completed posterior annuloplasty band.
In children, we prefer not to use any ring. Instead, we place multiple sutures in the posterior annulus
buttressed with pericardial pledgets to reduce the size of the posterior annulus. This technique allows growth of
the mitral valve annulus. Alternatively, a fine Prolene double-armed suture is run along the posterior annulus
from commissure to commissure and tied over a dilator equal to the appropriate mitral valve size for that patient.
The expectation is that the Prolene suture will fracture as the child grows, allowing growth of the annulus.
It is generally prudent to choose a smaller size ring or band. It is important for the length of the posterior
mitral annulus from trigone to trigone to be as short as possible without creating mitral stenosis. In fact, the mitral
leaflet should appear redundant and generously fill the mitral orifice when the left ventricle is full for optimal
results.
Reconstruction of the Chordae Tendineae
The most effective way of repairing a ruptured chorade or elongated chordae is creation of the artificial chordae
(see above). Occasionally, chordal shortening may offer an alternative approach. Before chordal shortening can
be initiated, the amount of abnormal lengthening must be established. To do this, the leaflets must be pulled
gently into the left atrium with two fine Prolene traction sutures or nerve hooks. The degree of elongation of the
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chords can be closely estimated by measuring the distance between the plane of the mitral valve annulus and
the attachment of the lengthened chords to the elevated leaflet (Fig. 6.24). This excess length can be sewn to
the undersurface of the leaflet (Fig. 6.25).
Attachment of the Chords to the Mitral Leaflets
A double-armed, 5-0 Prolene suture is used to shorten each elongated chord. The first needle is passed through
the chord at or slightly below the plane of the mitral annulus. The second needle is then placed midway between
the first suture and the undersurface of the leaflet. Both needles are then passed upward through the leaflet,
very close to one another, and tied snugly on the atrial side. This draws up the excess length of chord
underneath the leaflet and pulls it down to the level of the plane of the mitral valve to reestablish apposition with
the other leaflet (Fig. 6.25).
Leaflet Tear
The leaflet must be somewhat thickened or fibrous. The chordal-shortening sutures may injure or tear an
otherwise normal leaflet, thereby interfering with a satisfactory repair and culminating in leaflet tear.
FIG. 6.24 Estimating the degree of elongation of the chords by measuring the distance between the plane of the
mitral valve annulus and the attachments of the lengthened chords to the elevated leaflet.
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FIG. 6.25 Attachment of the elongated chords to the mitral leaflets.
Chordal shortening procedures are mainly performed in children for growth potential possibilities. In adults,
we have adopted the simpler technique of using Gore-Tex artificial chords (see subsequent text).
Ischemic Mitral Regurgitation
Ischemic mitral valve prolapse may occur following myocardial infarction secondary to injury with elongation or
partial or complete rupture of a papillary muscle. Total rupture of a papillary muscle generally requires mitral
valve replacement. Incomplete detachment of a single head may be amenable to repair with chordal replacement
or transfer and/or resection of a portion of the affected leaflet as described in preceding text.
Most patients with ischemic mitral disease have functional regurgitation due to annular and left ventricular
dilation and/or displacement of the papillary muscles. Mitral valve replacement may be the best option in patients
with severe ischemic mitral regurgitation who are undergoing coronary revascularization. In patients with
moderate ischemic mitral regurgitation and heart failure symptoms, or dilated annulus, or nonviable lateral
myocardium, mitral valve repair with an annuloplasty ring may be a good option. Most surgeons use an
undersized complete ring annuloplasty in these patients along with revascularization of all ischemic, viable
myocardium.
MITRAL VALVE REPLACEMENT
Increasing experience with mitral valve repair has allowed most patients with degenerative mitral valve disease
or mitral annular dilation to undergo reconstructive procedures as previously described quite successfully.
However, when reparative procedures do not appear to provide a durable successful outcome, mitral valve
replacement should be considered.
In recent years, experimental and clinical studies have established the importance of the subvalvular apparatus
in retaining the normal geometry of the left ventricle and its function. Therefore, whenever the mitral valve has to
be replaced, every attempt should be made to preserve the native subvalvular apparatus or replace native
chordal structures with Gore-Tex sutures to maintain the mitral annular-papillary muscle continuity.
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Technique
The diseased anterior leaflet is detached from the annulus between the two commissures. If the anterior leaflet is
not extensively diseased, an ellipse of tissue is excised and the rim of the leaflet tissue containing primary chords
is reattached to the anterior annulus using pledgeted mattress sutures to be used subsequently for valve
implantation (Fig. 6.26). If the leaflet is thickened or calcified, it is divided into two to four segments, depending
on the size of the valvular leaflet. Each segment is then trimmed to create a button of leaflet tissue with attached
chords. These buttons are reattached to the anterior annulus with the valve sutures in an anatomic manner
(Figs. 6.27 and 6.28). The normal geometry is probably maintained better if the anterior leaflet is not subdivided.
FIG. 6.26 A: An ellipse of the anterior leaflet is removed. B: The rim of the anterior leaflet is attached to the
anterior annulus.
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FIG. 6.27 A: Anterior leaflet is detached. B: The anterior leaflet is divided into buttons with chordal attachments.
FIG. 6.28 A: Each chordal button is reattached to the anterior annulus, retaining its normal geometric position.
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B: The posterior leaflet is kept intact. Redundant tissue is folded into the left atrium.
The posterior leaflet, when pliable, can usually be retained completely together with the attached chordae
tendineae. Redundant leaflet tissue is folded up into the annulus by placing the valve sutures through the
annulus and bringing them through the leading edge of the leaflet tissue (Fig. 6.28B). Alternatively, incisions or
small wedge resections of leaflet tissue between the chordal attachments are performed if the posterior leaflet is
thickened and fibrotic to allow implantation of a larger valve.
At times, the mitral valve leaflet and the subvalvular apparatus are grossly diseased and calcified and must be
totally resected. The diseased leaflets are then pulled and stretched slightly with a heavy suture or forceps to
bring their annular attachments into view (Fig. 6.29A). With a long-handled no. 15 blade, the mitral leaflets are
divided circumferentially 4 to 5 mm from the annulus (Fig. 6.29B). A traction suture in the annulus adjacent to the
posteromedial commissure allows better exposure and provides countertraction for the complete removal of the
diseased valve (Fig. 6.29C). This suture can subsequently be used in anchoring the prosthesis. The diseased
chordae tendineae are then excised with scissors (Fig. 6.29D).
Excessive Leaflet Excision
A good margin of leaflet tissue should always be left with the annulus to allow secure attachment of sutures for
subsequent placement of a prosthesis. Overzealous excision of leaflets may leave a weakened annulus, making
valve replacement insecure or even resulting in detachment of the left atrium from the left ventricle.
Papillary Muscle Excision
Only the calcified and diseased chords should be excised, leaving the fibrous tips of the papillary muscles
untouched. Removal of an excessive amount of papillary muscle may weaken the ventricular wall, which may
result in hematoma within the wall and possible rupture (see subsequent text).
Excessive Pull on Papillary Muscle
During the process of leaflet excision, the valve tissue should never be pulled overzealously. The heart arrested
with cardioplegia is flaccid, and any excessive pull on the papillary muscle may tear a buttonhole defect through
the weakened left ventricular wall (Fig. 6.30A, B). If such a catastrophe occurs, it must be detected immediately
and repaired with pledgeted mattress sutures (Fig. 6.30C, D). The posterior descending coronary artery is likely
to be in close proximity to this type of ventricular wall tear. Precautions must therefore be taken to avoid
occluding the coronary artery in the process of repairing the defect. Pledgeted, double-armed, atraumatic sutures
are passed deeply, well away from the coronary artery, and tied snugly over another pledget. If bleeding
continues after the application of several well-placed sutures, the whole area of the defect should be covered
with a patch of
bovine pericardium, meticulously sewn to the surrounding normal myocardium with continuous 3-0 Prolene
sutures. Topical application of Bioglue on the repaired wall is most helpful in controlling the bleeding. Some
coronary artery branches may have to be sacrificed within the continuous suturing process. This is inevitable
and must be borne in mind when dealing with this potentially lethal problem.
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FIG. 6.29 Mitral valve excision. A: Diseased leaflets are pulled and stretched with Allis forceps or heavy suture
to expose their annular attachments. B: The mitral leaflets are divided circumferentially with a long-handled no.
15 blade 4 to 5 mm from the annulus. C: A traction suture in the annulus adjacent to the posteromedial
commissure allows better exposure and provides countertraction for the complete removal of the diseased valve.
D: The chordae tendineae and fibrotic tips of the papillary muscles are then removed with scissors.
Mitral Valve Calcification
Calcification of the mitral valve and annulus is quite common. Care should be taken to remove as much calcium
as possible without weakening the annulus. Occasionally, removal of calcium or degenerative material may leave
a hollow cavity in the annulus. This should be immediately irrigated and closed securely with soft tailor-made
pledgeted sutures. These sutures may or may not be used to help anchor the prosthesis (Fig. 6.31).
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FIG. 6.30 A-D: Mechanism of a buttonhole defect through the left ventricular wall and its surgical repair.
Annular Calcification
The mural annulus of the mitral valve may become infiltrated with heavily calcified tissue that may extend into
and involve the full thickness of the atrioventricular groove and wall. Overzealous removal of this excessive
calcium may result in a defect in the atrioventricular groove. Consistency of the surrounding tissues and the
location of the circumflex coronary artery in the atrioventricular groove make any attempt to repair this defect
most hazardous.
Atrioventricular Groove Disruption
Overzealous removal of calcium from the posterior annulus of the mitral valve or forcibly implanting too large a
prosthesis may result in disruption of the atrioventricular groove. This catastrophe is often noted as the patient is
being weaned off cardiopulmonary bypass when the operative field is flooded with bright red blood.
It is dangerous to attempt to repair this injury from outside the heart. Cardiopulmonary bypass is resumed,
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and cardioplegic arrest of the heart is once again accomplished. The left atrium is opened and the mitral
prosthesis is removed. The extent of the defect is fully evaluated. A large patch of autologous pericardium
treated with glutaraldehyde or bovine pericardium is cut to the appropriate size and shape. It is sewn in place,
well away from the margin of the defect, to the left ventricular wall, left atrial wall, and left atrioventricular
junction. The suture line is reinforced with multiple interrupted sutures buttressed with Teflon felt. A smaller mitral
prosthesis is reimplanted in the usual manner except that it is attached to the pericardium
instead of the posterior annulus. The surgery is then continued to its completion.
FIG. 6.31 Removal of degenerative calcific material. The hollow cavity in the annulus formed during removal
should be irrigated and closed with pledgeted sutures.
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FIG. 6.32 A: Papillary muscles are attached to the mitral annulus at the 2, 5, 7, and 10 o'clock positions with
Gore-Tex chordal substitutes. B: Gore-Tex sutures are attached to the papillary muscles. Teflon felt pledgets
may be used to buttress the sutures. C: Anterior chordal replacement with retention of the posterior native
chordal attachments. D: Locking the Gore-Tex suture at the level of the annulus.
Injury to Posterior Left Atrium
Overzealous removal of organized and/or calcified blood clots from the left atrial wall during mitral valve surgery
or a maze procedure may result in a shear injury and serious bleeding. It is always safer to go back on
cardiopulmonary bypass and repair the bleeding site from within the left atrium. This may be tedious but the
experienced surgeon will not be tempted to repair any bleeding from the back of the heart following mitral valve
surgery by displacing the heart upward, no matter how minor the bleeding site may appear to be.
Technique for Chord Replacement
All the native chordal structures are resected if the subvalvular apparatus is markedly diseased, as in patients
with rheumatic disease in whom there is fusion of the chordae tendineae, foreshortening of the chordal
apparatus, and papillary muscle thickening. Continuity between the mitral annulus and the papillary muscle is
then recreated with 4-0 Gore-Tex sutures to produce artificial chordae tendineae that extend from the heads of
the papillary muscle to the annulus (Fig. 6.32).
A suture of 4-0 Gore-Tex on a double-armed needle is sutured to the fibrous tip of the papillary muscle. If there is
no fibrous tissue, the suture is buttressed with a small, soft felt or pericardial pledget and the suture is tied snugly
or locked on itself (Fig. 6.32B). Both needles of each suture are passed through the annulus of the mitral valve at
approximately the 2, 5, 7, and 10 o'clock positions (Fig. 6.32A). The precise length of the Gore-Tex artificial
chord is determined, and each suture is locked on itself and then tied. Locking the stitch prevents any pulling on
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