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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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all four pulmonary veins must be identified, as well as the left atrial appendage and mitral valve. The membrane
is resected, taking care not to extend the incision outside the heart. This membrane can be densely adherent to
the mitral valve apparatus (Fig. 20.8).
FIG. 20.6 Repair of left inferior pulmonary vein obstruction from inside the left atrium.
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FIG. 20.7 The pulmonary vein confluence is opened into each of the vein orifices, but the “sutureless”
connection is created between the left atrium and the area shown in the dotted line; this anastomosis is to the
pericardium (not the underlying pulmonary vein tissue) that lies adjacent to the opening. Particular care must be
made not to enter the left pleural space when opening the veins.
FIG. 20.8 With the first inspection of anatomy, it is important to delineate the location of the pulmonary vein
orifices and the left atrial appendage. A: If the orifice of the appendage is easily visualized, the diaphragm may
represent a supravalvar mitral ring. B: Removing the diaphragm to demonstrate the orifice of the appendage (the
diaphragm separates the appendage from the veins) suggests this is cor triatriatum. C: Pulmonary veins,
appendage, and mitral valve should all be visible at the end of the procedure.
The incision on the atrial septum can then be closed primarily or more often with a patch of autologous
pericardium prepared with glutaraldehyde using a running 5-0 or 6-0 Prolene suture. The incisions on the right
superior pulmonary vein and right atrium are then closed with a running 5-0 or 6-0 Prolene suture. The patient is
rewarmed, the aortic cross-clamp is removed, and deairing is carried out in the usual manner.
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21
Ventricular Septal Defect
A ventricular septal defect can occur as an isolated lesion or in combination with other anomalies.
SURGICAL ANATOMY
The embryologic development of ventricular septal defects is interesting and has been the basis for many
complex classifications. We prefer a classification proposed by Anderson, which is simple and has many clinical
implications, particularly from the surgeon's point of view. Anderson divides ventricular septal defects into
perimembranous, subarterial-infundibular, and muscular types.
The perimembranous variety of ventricular septal defects encompasses subgroups of defects that occur near the
membranous segment of the interventricular septum and includes those septal defects commonly seen in
tetralogy of Fallot and atrioventricular septal defects (Fig. 21.1). Because the path of the conduction tissue is
intimately related to the inferior rim of these defects, an accurate knowledge of the surgical anatomy of this
region is most helpful.
The atrioventricular node is situated in its usual position at the apex of the triangle of Koch, whose boundaries
consist of the septal attachment of the tricuspid valve, tendon of Todaro, and the coronary sinus as its base (Fig.
21.2). The conduction tissue passes from the atrioventricular node as the bundle of His through the central
fibrous body and the tricuspid annulus into the ventricular septum, following a course along the inferior rim of the
defect toward the left ventricular side of the septum.
SURGICAL APPROACH
All forms of ventricular septal defects are approached through a median sternotomy although some have used
right thoracotomy.
Cannulation
Cardiopulmonary bypass with moderate systemic hypothermia is used in most patients. In very small infants (<2
kg), deep hypothermic arrest using a single venous cannula through the right atrial appendage for cooling and
warming may be preferred. In all others, the superior and inferior venae cavae are cannulated directly; tapes are
then passed around both cavae.
Myocardial Preservation
Cardioplegic arrest of the myocardium is maintained by intermittent infusion of cold blood cardioplegia into the
aortic root (see Chapter 3).
TRANSATRIAL APPROACH TO A VENTRICULAR SEPTAL DEFECT
Almost all the perimembranous and atrioventricular canal types of ventricular septal defects and many of the
muscular variety can be exposed and closed through the right atrium. The subarterial-infundibular type is best
approached through pulmonary arteriotomy.
The aorta is cross-clamped, and cardioplegic solution is administered into the aortic root. The venae caval
snares are then snugged down. A longitudinal or oblique atriotomy is made, starting at a point 0.5 to 1 cm
anterior and parallel to the sulcus terminalis, and is extended toward the orifice of the inferior vena cava. The
edges of the incision are then retracted to provide a good exposure of the tricuspid valve and the triangle of
Koch (Fig. 21.3).
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Coexisting Patent Ductus Arteriosus
If a patent ductus arteriosus is present, it should be occluded before the initiation of cardiopulmonary bypass to
prevent pulmonary overcirculation and suboptimal systemic perfusion (see Chapter 14).
Sinoatrial Node Injury
The sinoatrial node is vulnerable to injury from the snare around the superior vena cava. It can also be injured if
the atriotomy is extended too far superiorly.
FIG. 21.1 Types of ventricular septal defects.
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FIG. 21.2 Surgical anatomy of the right atrium.
FIG. 21.3 Exposure of a ventricular septal defect by retracting the tricuspid valve leaflets.
Technique for Closure
The anterior leaflet of the tricuspid valve is retracted with a 6-0 Prolene suture or small vein retractor to expose
the defect and its margins for identification (Fig. 21.3). The defect can be closed with a continuous suture
technique using 5-0 Prolene, or multiple interrupted sutures of buttressed with Teflon felt pledgets, or a
combination thereof.
Continuous Suture Technique
With a double-armed, half-circle needle of 5-0 Prolene, the suturing is started at the 12 o'clock position along the
muscular rim. The needle is then passed through a patch of Gore-Tex slightly larger in size than the defect,
again through the muscular rim, and then again through the patch, which is subsequently lowered into position
(Fig. 21.4).
FIG. 21.4 Patch closure of a ventricular septal defect using a continuous suture technique.
FIG. 21.5 Interrupted suture technique for closure of a ventricular septal defect.
The suturing is continued in a counterclockwise direction along the superior rim, which overlies the aortic valve,
until the central fibrous junction of the septum, aortic root, and tricuspid annulus is reached. The needle is
passed through the septal leaflet of the tricuspid valve. During the procedure, the placement of each stitch is
facilitated by the assistant applying slight traction on the Prolene suture.
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Buttressing the Sutures
Occasionally, the muscular rim of the ventriculoseptal defect may be very friable, allowing the fine Prolene to cut
through. Multiple interrupted sutures buttressed with pledgets are then substituted for the continuous suture
technique (Fig. 21.5).
Injury to the Aortic Valve
The aortic valve leaflets are immediately below the superior margin of the defect and can be punctured during
suturing if deep needle bites are taken in this area (Fig. 21.6).
Residual defects
Particular care should be taken along the superior aspect of the defect adjacent to the aortic valve, specifically
the area near the infundibular septum. The trabeculations within the muscle can be the source of residual
defects; this is less likely if the suture line follows the aortic annulus quite closely.
Transitional Sutures
The junction of the tricuspid annulus, aortic root, and septum is a vulnerable area where a residual defect may
occur.
A transitional stitch incorporating the tricuspid leaflet, the rim of the defect, and the patch will ensure a more
secure closure (Fig. 21.7). This can be satisfactorily accomplished with either an interrupted or a continuous
suturing technique.
FIG. 21.6 Proximity of an aortic valve leaflet to the rim of the septal defect.
The other arm of the Prolene suture is then continued in a clockwise direction; superficial bites that include only
endocardium are taken along the inferior rim of the defect, until the tricuspid leaflet is reached (Fig. 21.7).
Alternatively, the other arm of the suture is continued, moving outward to a distance of 3 to 5 mm from the rim of
the defect to avoid the underlying conduction tissue (Fig. 21.8).
FIG. 21.7 Continuous suture technique for closure of a ventricular septal defect. Note upper needle passing
through patch, muscular rim, and then tricuspid leaflet to complete transitional stitch.
FIG. 21.8 Sutures are placed 3 to 5 mm from the rim of the defect inferiorly to avoid the conduction tract.
Prevention of Heart Block
As already described, the bundle of His pierces the central fibrous body and the tricuspid annulus before
penetrating the ventricular septum, where it follows a course along the inferior margin of the defect toward the
left ventricular side of the septum. Because suturing along this course can be hazardous and culminate in heart
block (Fig. 21.9A), shallow superficial bites are taken that include only the whitish endocardium close to the rim
of the defect. In fact, the needle should be visible through the translucent endocardium (Fig. 21.9B). A more
conservative and safer approach is to place sutures 3 to 5 mm from the inferior rim of the defect (Fig. 21.8).
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FIG. 21.9 A and B: Shallow bites of endocardium prevent the occurrence of heart block.
FIG. 21.10 A: Line of detachment of septal and anterior leaflet to provide improved exposure. B: Retraction of
detached leaflets. C: Completing closure of ventricular septal defect and reattaching leaflets to annular rim.
Interference by Chordae Tendineae and Papillary Muscles
If the view of the ventricular septal defect is obscured by chordae tendineae or papillary muscles, the septal
leaflet and a portion of the anterior leaflet of the tricuspid valve may be detached, leaving a 2- to 3-mm rim of
tissue along the annulus (Fig. 21.10A). Retraction of these leaflets provides an unobstructed view of the
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