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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. 6.44 Closure for the transatrial oblique approach.
Depth of Sutures in the Septum
The septum is quite thick at times; the sutures should incorporate the whole thickness, including the
endocardium on both sides of the septum. Otherwise, the suture may tear through the muscular septum,
resulting in a septal defect.
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FIG. 6.45 A: Closing tears in the fossa ovalis. B: Buttressing with adjacent fossa tissue. C: Buttressing with
Teflon felt.
Buttressing the Sutures
At times, fossa ovalis tissue can be friable and may not hold sutures well (Fig. 6.45A). The adjacent fossa tissue
may be used to buttress the sutures (Fig. 6.45B). Alternatively, pericardial strips may be used to reinforce the
suture line (Fig. 6.45C).
Transatrial Longitudinal Septal Approach
After completion of the procedure, the septum is reapproximated with a continuous 4-0 Prolene suture. The right
atrial wall is closed with a second 4-0 Prolene suture line.
7
Surgery of the Tricuspid Valve
The most common indication for surgical intervention on the tricuspid valve is functional tricuspid regurgitation.
Functional or secondary tricuspid insufficiency occurs frequently in patients with advanced mitral valve disease
and pulmonary hypertension. The insufficiency may disappear or improve significantly when successful mitral
valve repair or replacement is accomplished. The current approach is to be more aggressive with secondary
tricuspid disease and to perform an annuloplasty in patients with dilated annuli or more than mild tricuspid
insufficiency.
Rheumatic fever continues to be the most common cause of organic tricuspid valve disease. With rare
exceptions, it is associated with mitral and, in many patients, aortic valve disease as well. Usually, both stenosis
and insufficiency are present. Degenerative tricuspid valve disease is less common, but severe tricuspid
regurgitation can result, requiring surgical repair. Tricuspid valve bacterial endocarditis is seen in intravenous
drug abusers, occasionally in patients with long-standing central venous catheters, and infrequently in patients
with small perimembranous ventricular septal defects. Often, the infection destroys leaflet tissue, causing
tricuspid insufficiency. Iatrogenic causes of tricuspid valve dysfunction include pacemaker lead-induced tricuspid
regurgitation and radiation therapy, which may result in retracted, calcified valve leaflets. Carcinoid affects the
tricuspid and frequently the pulmonic valve, causing stenosis as well as insufficiency.
TECHNICAL CONSIDERATIONS
Surgical Anatomy of the Tricuspid Valve and the Right Ventricle
The tricuspid valve guards the right ventricular orifice. It consists of a septal leaflet, a large anterior leaflet, and a
small posterior leaflet, all three of which are attached to and continuous with the tricuspid ring. These valve
leaflets are folds of endocardium strengthened by fibrous tissue. Small accessory leaflets are often present in the
angles between the major leaflets. The atrioventricular node lies in the atrial septum adjacent to the septal
leaflet, just anterior to the coronary sinus. Its location can be pinpointed at the apex of the triangle of Koch (which
is bordered by the septal leaflet, the tendon of Todaro, and the orifice of the coronary sinus). The atrioventricular
conduction bundle (bundle of His) extends from the atrioventricular node through the central fibrous body into the
ventricles under the membranous part of the interventricular septum. It is approximately 2-mm thick and consists
of bundles of fine muscular fibers. There is normally no muscular continuity between the atria and the ventricles
except through the conducting tissue of the atrioventricular bundle, but aberrations may exist, which can give rise
to rhythm disturbances (Fig. 7.1).
The right ventricular cavity is tubular and triangular in contrast with that of the left ventricle, which is conical. It is
bounded by concave anterior and posterior walls and a convex septal wall. There are at least three groups of
papillary muscles that stem from the inner aspect of the right ventricular cavity. Chordae tendineae, which are
nonelastic chords of tissue, arise from the papillary muscles and fuse to the free edges and the ventricular
surfaces of the leaflets of the tricuspid valve. The chords of each papillary muscle control the contiguous margins
of two cusps. Hence, chords pass from a large anterior papillary muscle to the anterior and posterior leaflets. A
posterior papillary muscle, often represented by two or more components, gives rise to chords that attach to the
posterior and septal leaflets. Finally, from a variable group of small septal papillary muscles, chords fan out and
fasten to the anterior and septal leaflets of the tricuspid valve. A bridge of muscle, the moderator band, stems
from the septum, crosses the cavity of the right ventricle to the free wall, and contributes to the origin of the
anterior papillary muscle. A tract of specialized tissue associated with the conduction system runs through the
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moderator band (Fig. 7.2).
Incision
A median sternotomy is the preferred approach for acquired valvular disease because it offers complete
exposure for exploration of the mitral, aortic, and tricuspid valves. The tricuspid valve can also be approached
through a lower ministernotomy or submammary right thoracotomy (see Chapter 1).
FIG. 7.1 Surgical anatomy of the right atrium and tricuspid valve. AL, anterior leaflet; PL, posterior leaflet; SL,
septal leaflet; CS, coronary sinus; IVC, inferior vena cava; FO, fossa ovalis; SAN, sinoatrial node; SVC, superior
vena cava; AVN, atrioventricular node; AO, aorta.
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FIG. 7.2 Surgical anatomy of the tricuspid valve as seen from the right ventricle. The free wall of the ventricle
has been removed to show the tricuspid subvalvular apparatus and the convex septal wall.
Historically, digital palpation through a purse-string suture on the right atrial appendage was used to assess
tricuspid insufficiency before the initiation of cardiopulmonary bypass. Currently, intraoperative transesophageal
echocardiography is used to evaluate the tricuspid valve. Because tricuspid insufficiency is load dependent,
clinical history, preoperative echocardiography, and/or right heart catheterization data are useful in determining
whether the tricuspid valve should be addressed. Some surgeons advocate exploring the tricuspid valve in all
patients undergoing mitral valve surgery to directly measure annular size.
Cannulation
When surgery on the tricuspid valve is contemplated, both vena cavae are cannulated directly (Fig. 7.3). A
cannula is placed in the ascending aorta, and cardiopulmonary bypass is initiated.
Isolated tricuspid valve surgery can be performed on cardiopulmonary bypass with a warm, beating heart. Most
of the time, repair or replacement of the tricuspid valve is performed as part of a combined procedure that
includes mitral and/or aortic valve surgery with or without concomitant coronary artery bypass grafting. At the
conclusion of these other procedures, the aortic cross-clamp is removed and deairing of the left heart is
completed.
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FIG. 7.3 Direct caval cannulation.
The tricuspid valve is then repaired while the patient is being rewarmed.
Exposure of the Tricuspid Valve
A longitudinal or oblique atriotomy is made approximately 1 cm posterior to and parallel to the atrioventricular
groove. The atriotomy edges are retracted with sutures, and exposure of the tricuspid valve is further facilitated
by means of appropriately sized retractors.
Injury to the Sinoatrial Node
The sinoatrial node is prone to injury during cannulation and passage of a tape around the superior vena cava.
The atriotomy should be well away from the sinoatrial node, and its superior extension should be limited to
approximately 1 cm from the superior margin of the right atrium.
FUNCTIONAL TRICUSPID REGURGITATION
The controversy regarding the management of functional tricuspid insufficiency reflects the difficulty of precisely
distinguishing the two stages of the same disease process, that is, irreversible and reversible tricuspid valve
insufficiency. Irreversible functional tricuspid insufficiency is the outcome of chronic right ventricular dilation, with
a permanent increase in right ventricular volume and tricuspid annular dilation. Certainly, if severe tricuspid
regurgitation is present, significant tricuspid pathology must exist, which is most likely irreversible. However,
even if the tricuspid insufficiency is only mild or moderate, irreversible tricuspid pathology may still be present.
This is because the assessment of the degree of tricuspid regurgitation depends on right ventricular preload and
afterload at the time of the study. A better marker of irreversibility may be annular size. The distance from the
anteroseptal to the anteroposterior commissure is measured directly through the open right atrium. If it is 70 mm
or greater (twice the normal size), the tricuspid annulus will most likely not return to normal and may very well
continue to dilate.
Tricuspid valve repair is recommended when there is severe TR in the setting of left-sided valvular surgery,
or when the annular diameter measures greater than 40 mm (or >21 mm/m2) on transesophageal
echocardiogram.
The preferred technique for functional tricuspid regurgitation is ring annuloplasty. De Vega annuloplasty is
another technique for surgical management of tricuspid regurgitation, but may be associated with a higher
incidence of recurrent tricuspid insufficiency. Bicuspidization of the tricuspid valve can be performed quickly and
may be preferred in patients with mild to moderate insufficiency or a less dilated annulus. Some surgeons have
found that placement of an annuloplasty ring results in a lower incidence of recurrent tricuspid insufficiency
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compared with the De Vega procedure or bicuspidization.
Technique
De Vega Annuloplasty
The right atrium is opened obliquely or longitudinally, and the tricuspid valve is inspected. A double-armed
suture, usually 2-0 Ticron or Prolene, is started on the annulus at the posteroseptal commissure. It is then
extended around the circumference of the valve in a counterclockwise direction, taking deep bites (every 5 to 6
mm) into the endocardium (Fig. 7.4) and into the fibrous ring of the posteroseptal commissure, posterior leaflet,
anteroposterior commissure, anterior leaflet, and anteroseptal commissure. The second needle of the suture
traverses the same route 1 to 2 mm outside the previous suture. At each end of the course of suturing, a small
pledget of felt is used for a buttress, and the
suture is then tied securely around an appropriately sized mitral valve sizer to ensure a predictable annuloplasty.
A strip of autologous pericardium or a C-shaped piece of Teflon felt can be incorporated in the suturing process
for additional stability (Fig. 7.5).
FIG. 7.4 Suturing technique in De Vega annuloplasty.
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FIG. 7.5 Annuloplasty reinforced with a Teflon felt strip.
FIG. 7.6 Ring or band annuloplasty. A: Anchoring mattress sutures. B: Reducing the size of the annulus. C:
Restoring the valve to its normal configuration.
Ring Annuloplasty
Several partial rings and flexible annuloplasty bands are available, which conform to the normal shape of the
tricuspid valve and do not include the area of the septal annulus. The ring size is determined by the length of
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fibrous septal annulus, between commissures along the septal leaflet, with a goal of slight undersizing. The ring
or band is anchored in position by means of multiple simple or mattress sutures of 3-0 Tevdek incorporating the
fibrous annulus of the anterior and posterior leaflets and excluding the septal leaflet (Fig. 7.6A). The sutures are
placed closer together on the ring or band to reduce the size of the annulus (Fig. 7.6B). The device is lowered
onto the annulus and the sutures tied. The completed annuloplasty using either a band or a ring reduces the size
of the tricuspid orifice and attempts to restore the valve to its normal shape (Fig. 7.6C). A potential advantage of
a band annuloplasty is that it allows the tricuspid orifice to flex as ventricular contraction occurs.
Inadequate Suture Depth
The depth of the suture bites at the annulus must be quite substantial; otherwise, the suture will tear through and
result in an inadequate annuloplasty.
FIG. 7.7 Technique for bicuspidizing the tricuspid valve.
Injury to the Atrioventricular Node
Sutures should not be placed in the septal annulus or near the orifice of the coronary sinus to avoid injury to the
atrioventricular node.
Leaflet Tear
Sutures should be limited to the fibrous annulus and must not include the thin and otherwise normal leaflet
tissue, which may tear, resulting in valvular insufficiency and an inadequate repair.
Bicuspidization of the Tricuspid Valve
Annuloplasty at the anteroposterior and posteroseptal commissures can be used to reduce tricuspid valve
insufficiency. Often, it is useful to exclude the entire posterior annulus, converting the tricuspid valve to a
bicuspid valve. This is achieved by multiple figure-of-eight sutures of 2-0 Ticron placed well away from the orifice
of the coronary sinus to avoid producing postoperative heart block (Fig. 7.7). Alternatively, two concentric
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horizontal pledgeted 2-0 Ticron sutures are run from the anteroposterior to the posteroseptal commissure to
exclude the posterior annulus.
ORGANIC TRICUSPID VALVE DISEASE
Rheumatic Tricuspid Disease
Rheumatic involvement of the tricuspid valve generally results in mixed insufficiency and stenosis. Many of these
patients require valve replacement (see subsequent text). Occasionally, stenosis is the predominant finding with
commissural fusion, thickening of the leaflets, and variable fibrosis and shortening of the chordae tendineae.
These patients are candidates for commissurotomy.
Technique of Tricuspid Commissurotomy
Commissurotomy is carried out meticulously with a No. 11 knife blade along the commissures up to 1 to 2 mm
from the annulus. Because of the tricuspid nature of the valve, commissurotomy is limited to one or two
commissures to avoid producing insufficiency (Fig. 7.8).
Anterior Septal Commissure
The anterior septal commissure is rarely incised because this often causes insufficiency.
Remodeling the Tricuspid Valve
If insufficiency occurs, the valve must be remodeled with an annuloplasty procedure (see preceding text).
Frequently, bicuspidization will result in a competent valve.
Degenerative Tricuspid Disease
Tricuspid regurgitation may result from myxomatous disease involving the tricuspid valve. Most often the anterior
leaflet is involved and prolapses secondary to elongated chords or may be flail if chordal rupture occurs. The
mechanism of regurgitation must be ascertained in detail from transesophageal echocardiography to allow for
accurate repair of the valve. Chordal replacement using Gore-Tex sutures as described for mitral valve repair is
often required (see Chapter 6). Every repair is reinforced with an annuloplasty ring or band (see preceding text).
FIG. 7.8 Tricuspid valve commissurotomy.
Edge-to-Edge Tricuspid Valve Repair
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