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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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Just above the sinus venarum in the center of the medial wall is the fossa ovalis, an elliptic or horseshoe-shaped
depression. The true interatrial septum consists of the fossa ovalis with variable contributions from the superior,
anterior, and inferior limbic muscle bundles that surround it. The aortic root is hidden behind the anteromedial
atrial wall between the fossa ovalis and the termination of the heavily trabeculated right atrial appendage.
Segments of the noncoronary and right sinus of Valsalva are in close apposition to the atrial wall in this area.
Their locations may be manifested by the aortic mound, a bulge above and slightly to the left of the fossa ovalis.
The presence of the aortic valve here can be more clearly visualized if one takes into consideration its continuity,
through the central fibrous body, with the adjacent tricuspid valve annulus.
Also invisible to the surgeon is the artery to the sinoatrial node, which runs through this same area. Although its
origin and exact location are unpredictable, the artery to the sinoatrial node takes a variable course toward the
superior cavoatrial angle and the sinus node.
The tricuspid valve is located anteroinferiorly in the right atrium, where it opens widely into the right ventricle.
The annulus of the tricuspid valve crosses over the membranous septum, dividing it into atrioventricular and
interventricular segments. The membranous, or fibrous, septum is a continuation of the central fibrous body,
through which the tricuspid, mitral, and aortic valves are connected.
Immediately below the upper or atrioventricular section of the membranous septum lies the hidden
atrioventricular node. It is situated at the apex of the triangle of Koch, the boundaries of which are the annulus of
the septal leaflet of the tricuspid valve, the tendon of Todaro (running intramyocardially from the central fibrous
body to the Eustachian valve of the inferior vena cava), and its base, the coronary sinus. Anderson describes the
tendon of Todaro as a fibrous extension of the commissure between the Eustachian valve (of the inferior vena
cava) and the thebesian valve (of the coronary sinus). Conduction tissue passes from the atrioventricular node
as the bundle of His below the membranous septum and
down into the muscular interventricular septum. The coronary sinus, draining the cardiac veins, is situated
alongside the tendon of Todaro, between it and the tricuspid valve.
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FIG. 25.2 Surgical anatomy of the right atrium.
THE ARTERIAL SWITCH OPERATION
Incision
A median sternotomy is performed, and the thymus is removed.
Preparation
A rectangular piece of pericardium is harvested and treated with glutaraldehyde. The relationship of the great
vessels and coronary anatomy can be confirmed at this point.
Cannulation
The ascending aorta is cannulated as far distally as possible. Direct bicaval cannulation is carried out where
possible, or single atrial cannulation for small weight babies. With initiation of cardiopulmonary bypass, the
ductus arterious is occluded at its aortic end with a heavy tie or metal clip. The ductus arteriosus is later divided,
oversewing the pulmonary artery side with 6-0 or 7-0 Prolene suture. A vent can be placed through the right
superior pulmonary vein if necessary. During cooling, the ascending aorta is dissected free from the main
pulmonary artery, and the right and left pulmonary arteries are extensively mobilized out to the first branches in
the hilum of each lung. Most or all of the dissection is accomplished with an electrocautery on low current.
Flooding of the Pulmonary Bed
As soon as cardiopulmonary bypass is instituted, the ductus arterious must be occluded to prevent runoff of
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aortic cannula flow into the lungs.
Mobilization of the Pulmonary Arteries
It is essential to fully mobilize the branch pulmonary arteries beyond their hilar bifurcation so as to reduce tension
on the Lecompte.
Transection of the Great Arteries
The aortic cross-clamp is applied just proximal to the aortic cannula. A dose of cold blood cardioplegic solution is
administered through a needle into the ascending aorta at the mid ascending aorta. The aorta is then transected
at this level, and traction sutures are placed just above the three commissures of the aortic valve and tagged
(Fig. 25.3). The pulmonary artery is transected at the level of the takeoff of the right pulmonary artery, and
traction sutures are placed at the commissures and tagged. The pulmonary valve is inspected to rule out
significant abnormalities because this will be the new aortic valve.
FIG. 25.3 The ascending aorta has been transected. Note the divided ductus arteriosus and line of transection
on the main pulmonary artery.
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FIG. 25.4 By dividing the ascending aorta at or just beyond its midpoint, and the pulmonary artery closer just
above the commissures, the neoaorta will be foreshortened (and somewhat posteriorly directed) and the
neopulmonary root slightly longer to reduce the chance of stenosis from stretching after Lecompte.
Pulmonary Valve Abnormalities
The status of the pulmonary valve is usually defined by the preoperative transthoracic echocardiogram and
intraoperative transesophageal echocardiogram. A sufficiently competent and nonstenotic valve must be
confirmed before excising the coronary arteries.
Division of the Aorta
It can be helpful to divide the aorta slightly above the midpoint so as to procure more ascending aorta
(neopulmonary root) and thereby reduce tension on the Lecompte. By design, this maneuver also places the
aortic root more posteriorly (Fig. 25.4).
The pulmonary artery confluence is brought anterior to the distal ascending aorta (Fig. 25.5). The most proximal
portion of the transected distal aorta is then grasped with a forceps or straight vascular clamp. The initial cross-
clamp
is then reapplied proximal to the pulmonary artery confluence as high as possible on the ascending aorta. This
technique, referred to as the Lecompte maneuver after the surgeon who originally described it, avoids the need
for an interposition conduit to connect the new pulmonary artery base to the pulmonary artery confluence.
FIG. 25.5 The Lecompte maneuver: Pulmonary artery confluence is brought in front of the aorta and a second
aortic clamp is applied. Arrow shows distal aortic clamp reapplied below the pulmonary artery confluence. Dotted
lines indicate excision for the coronary tongues.
Distorting the Distal Ascending Aorta
When repositioning the aortic cross-clamp, care must be taken not to twist the aorta and create torsion at the
aortic suture line.
Excision of the Coronary Ostia
The coronary ostia and at least 2 to 3 mm of surrounding aortic wall are excised as tongues of tissue (Fig. 25.5)
or as buttons. The proximal coronary arteries are mobilized from the epicardium for several millimeters using an
electrocautery on low current.
Kinking of Coronary Arteries
Adequate dissection of the coronary arteries must be carried out to allow successful translocation of each
coronary ostium to the corresponding sinus of the pulmonary artery. Insufficient mobilization may lead to tension
on the coronary anastomosis or kinking of the coronary artery.
Mobilization of the Right Coronary Artery
Conal branches may rarely need to be ligated and divided to allow adequate mobilization of the right coronary
artery.
Juxtacommissural Ostia
When one or both coronary ostia arise immediately adjacent to the commissure, the adjacent commissure must
be excised along with the coronary ostia. This may lead to mild neopulmonary valve insufficiency.
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Intramural Coronary Artery
A generous cuff of aortic wall must be included in the tongue of tissue containing the coronary ostium to avoid
injury to the intramural portion of the coronary artery.
Coronary Artery Reimplantation
The reimplantation sites for the coronary ostia are determined by holding the mobilized coronary arteries up
against the anterior facing sinuses of the pulmonary root, ensuring that no distortion of the proximal course of the
coronary arteries is created. The coronary arteries can be reimplanted into the pulmonary root as tongues of
tissue by making a U-shaped incision in the appropriate location (Fig. 25.6). Alternatively, the coronary flaps are
reattached
as buttons of tissue, trimming the distal end of the flap before completing the suture line. In this case, a small slit
is made at the appropriate location for coronary reimplantation in the pulmonary root. This site may be enlarged
free hand, or with a small aortic punch. The coronary artery is sutured to the opening in the pulmonary root using
7-0 or 8-0 Prolene suture (Fig. 25.7). After each coronary anastomosis, cold blood cardioplegic solution is
infused directly into each coronary ostium with a 2-mm olive-tipped cannula, allowing assessment of any kinking
or distortion of the coronary artery. If any problems are detected, they should be rectified now by either freeing
up any restrictive adventitial or epicardial bands or redoing the anastomosis.
FIG. 25.6 Reattachment of the coronary tongues to the pulmonary root.
Coronary Implantation
Many surgeons favor creating the incisions for coronary implantation with the aortic root filled. To achieve this,
the Lecompte maneuver is performed, and the neoaorta is anastomosed with marking sutures placed on the
outside exactly at the site of the three commissures. The cross-clamp can either be removed, or a cardioplegia
catheter placed and the root filled to demonstrate the orientation and extent of the root prior to choosing sites for
coronary implantation. The incision into the root is done with the root fully distended to reduce the chance of
injury to the neoaortic valve (Fig. 25.8).
FIG. 25.7 Reattachment of the coronary ostia as buttons to the pulmonary root.
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FIG. 25.8 “Closed” technique for coronary reimplantation. Note the angulation of the incisions slightly toward the
midline. The “X” marks the location of the top of the commissure, and is marked on the outside of the neoaorta
with a marking suture.
Torsion of the Coronary Artery
Some surgeons prefer to excise the coronary ostia as buttons, instead of tongues of tissue from the aortic root.
When this technique is used, extreme care must be taken to prevent rotation and distortion of the coronary artery
button during reimplantation.
Circumflex Coronary Artery Arising from the Right Coronary Artery
If the circumflex coronary artery arises from the right coronary artery, a trapdoor may be created in the neoaorta
to prevent kinking of the takeoff of the circumflex branch (Fig. 25.9). Alternatively, the right coronary artery ostium
may be implanted higher on the neoaorta. When the circumflex arises from the right coronary artery, the
pulmonary artery should be transected as far distally as possible to allow a high reimplantation of the right
coronary button. Occasionally, the anastomosis must be performed on the ascending aorta distal to the suture
line joining the neoaortic root to the distal aorta (Fig. 25.10).
Intramural Coronary Artery
A shallow, U-shaped incision is made in the proximal neoaorta adjacent to the location of the previously prepared
aortic tongue of tissue containing the involved coronary ostium
or ostia. The upper edge of the aortic tongue is sutured to the lower portion of this U-shaped opening in the
neoaortic root with a 7-0 Prolene suture (Fig. 25.11A). The suture line is secured at both ends. The neoaortic
root is anastomosed to the ascending aorta posteriorly, securing the suture line on both sides where it meets the
coronary artery anastomosis. A piece of autologous pericardium is cut in the appropriate shape, and sewn into
place to create a convex roof over the remaining opening (Fig. 25.11B). This technique allows the coronary
artery to maintain its original orientation, and
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minimizes the risk of twisting or tension on the proximal course of the coronary artery.
FIG. 25.9 Trapdoor technique when the circumflex coronary artery arises from the right coronary artery.
FIG. 25.10 Placing an anastomosis of the right coronary artery above the anastomosis of the neoaortic root to
the ascending aorta.
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FIG. 25.11 A: Anastomosing a single intramural coronary artery to the neoaorta maintaining the native
orientation of the coronary ostium. B: Using a pericardial hood to complete the anastomosis.
FIG. 25.12 Anastomosis of the neoaortic root to the distal aorta.
Injury to the Neoaortic Leaflets
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