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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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Care must be taken when making the opening in the neoaortic root first with the knife blade and then with the
punch to protect the valve leaflets from injury. The assistant may gently retract the leaflet with the back of a fine
forceps.
Reconstructing the Aorta
The distal ascending aorta is anastomosed to the neoaortic root with running 6-0 or 7-0 Prolene suture (Fig.
25.12).
Size Difference between the Neoaortic Root and Ascending Aorta
If a discrepancy between the diameter of the distal ascending aorta and neoaortic root exists, the excess tissue
can usually be gathered in the posterior suture line. Gathering tissue anteriorly can distort the coronary artery
anastomoses. This is especially true if the coronary arteries have been reimplanted as flaps.
Hemostasis of the Posterior Suture Line
Care must be taken to ensure hemostasis of the aortic suture line, especially posteriorly, because this is
relatively inaccessible after the repair is completed.
Side-by-Side Great Vessels
When the aorta and pulmonary artery are side by side, the Lecompte maneuver may not be performed. The
distal ascending aorta is mobilized laterally and anastomosed to the neoaortic base.
Intracardiac Repair
The atrial septal defect or balloon atrial septostomy and a ventricular septal defect, if present, are closed through
a right atriotomy incision (see Chapters 19 and 21). Alternatively, a ventricular septal defect can be closed
through one of the semilunar valves. If this is done through the posterior (pulmonary) valve, great care must be
taken to avoid the conduction system. After closing the right atrium, the aortic cross-clamp may be removed or
left in place until the pulmonary artery reconstruction is finished. If it is left in place, another dose of cardioplegia
is given through a butterfly needle in the neoaortic root, allowing the surgeon to check the lie and filling of the
coronary arteries as well as the suture lines for bleeding.
Reconstructing the Pulmonary Artery
If the aorta is to remain clamped, the clamp must now be moved to the ascending aorta above the pulmonary
artery confluence. The defect created in the neopulmonary base is filled either with two separate patches, or with
a rectangular patch of glutaraldehyde-treated pericardium (“pantaloon”). The patch should be approximately
twice as long as the remaining neopulmonary sinus. A slit-like or V-shaped incision is made halfway along the
long edge of this rectangular patch. This fits into the posterior commissure of the neopulmonary base. The patch
is sewn into place with a running 6-0 or 7-0 Prolene suture. The resultant neopulmonary root is then
anastomosed to the pulmonary artery confluence with a 6-0 Prolene suture (Fig. 25.13).
Supravalvular Pulmonary Stenosis
A well-recognized late complication of arterial switch procedures is supravalvular pulmonary stenosis. This can
be minimized by leaving a generous cuff of pericardium when reconstructing the neopulmonary root.
Side-by-Side Great Vessels
When the Lecompte maneuver is not performed, the pulmonary artery confluence is oversewn with a 6-0 Prolene
suture. A longitudinal opening is made on the underside of the right pulmonary artery. The reconstructed
neopulmonary artery base is anastomosed to this opening in the right pulmonary artery with a 6-0 Prolene
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suture.
Completing the Operation
The aortic cross-clamp is removed, and deairing carried out through the cardioplegic needle hole, which is
subsequently closed with a 7-0 Prolene horizontal mattress suture. When rewarming is completed, the patient is
weaned off cardiopulmonary bypass, taking care not to overfill the heart.
FIG. 25.13 Reconstruction of the neopulmonary root with pericardium and its attachment to the pulmonary artery
confluence.
Examining Coronary Perfusion
After the aortic cross-clamp is removed, the heart is examined for perfusion in all coronary distributions.
Abnormalities of perfusion must be corrected. Further mobilization of the coronary artery in question may be
required, or a coronary anastomosis may need to be repositioned. If it is determined that the coronary anatomy is
not suitable for further revision, or that the patient will not tolerate an additional period of cross-clamping, a
bypass procedure should be performed. Most often, this consists of mobilizing the left or right internal thoracic
artery from the chest wall as an in situ conduit. It is anastomosed to the involved coronary artery. Occasionally,
the left subclavian artery may be ligated distally, transected, and the distal end anastomosed to the proximal left
anterior descending or circumflex coronary artery.
Dysrhythmias
Rhythm disturbances during rewarming or soon after cardiopulmonary bypass is discontinued are most often
secondary to coronary perfusion problems in the absence of preoperative tachyarrhythmias. The cause must be
determined and corrected promptly.
Stretching of the Coronary Arteries
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Overdistention of the heart in the immediate postbypass period may stretch the transposed coronary arteries.
This can lead to decreased coronary flow. Therefore, volume should be administered carefully to these patients
for the first 24 to 48 hours postoperatively to avoid this potentially fatal complication.
Suture Line Bleeding
Bleeding can be a problem because of the extensive suture lines. Hemostasis should be checked after removing
the aortic cross-clamp. Bleeding sites should be carefully sutured with adventitial horizontal mattress 7-0 Prolene
sutures. If bleeding from the aorta is noted after discontinuation of cardiopulmonary bypass, reinstitution of
bypass may be required. Takedown of the pulmonary artery anastomosis to allow access to the aortic suture line
may be necessary.
Coronary Artery Spasm
The transposed coronary arteries are susceptible to spasm in the postbypass and early postoperative periods.
Intravenous nitroglycerin infusion is indicated in these patients. Intravenous calcium solution should be given
very cautiously to prevent coronary artery spasm.
CONGENITALLY CORRECTED TRANSPOSITION OF THE GREAT ARTERIES
Congenitally corrected transposition of the great arteries is a congenital heart defect in which both
atrioventricular
discordance and ventriculoarterial discordance are present. Physiologically, this combination allows for a normal
circulation if other defects are not present. Most of these patients also have ventricular septal defects, pulmonary
valve abnormalities, and/or Ebsteinoid changes of the tricuspid valve. The traditional surgical approach
(“functional repair”) has been to repair the associated lesions only. This leaves the patient with a morphologic
right ventricle and tricuspid valve as the systemic ventricle and atrioventricular valve. More recently, some
centers have advocated an anatomic repair, the “double switch” procedure, in certain subgroups of these
patients. Patients with two adequate ventricles and a normal pulmonic valve undergo an arterial switch
procedure combined with a Senning or Mustard atrial switch. If the pulmonic valve is not suitable for an arterial
switch, a Senning and Rastelli procedure may be an option if there is an appropriate ventricular septal defect for
baffling the morphologic left ventricle to the aortic valve. Theoretically, a double switch procedure should improve
the long-term outcome of these patients, who often develop progressive tricuspid regurgitation and right
ventricular failure, by making the morphologic left ventricle the systemic ventricle and placing the abnormal
tricuspid valve in the lower pressure pulmonary circulation. However, proper patient selection is critical, and
many patients require a multistaged pulmonary banding procedure to train the left ventricle.
When performing the double switch operation, either the arterial switch or the atrial switch can be performed first.
Some modifications to both procedures may be required because of previous pulmonary artery banding and
anatomic considerations.
Closure of Ventricular Septal Defect
The ventricular septal defect is closed through the mitral valve. Sutures are placed on the morphologic right
ventricular side of the septum to avoid the conduction system.
Previous Pulmonary Banding
Dissection between the aorta and pulmonary artery should be carried out carefully in the presence of a
previously placed pulmonary band. The proximal pulmonary root (neoaorta) may be dilated. This may require V-
shaped excisions of tissue from the sinuses before coronary transfer to ensure a competent valve. In addition,
the area of the band must be excised or enlarged to prevent supravalvar stenosis and distortion of the
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sinotubular junction.
THE SENNING PROCEDURE
Cannulation
The distal ascending aorta is cannulated and direct superior and inferior vena caval cannulation is achieved
with right-angled cannulas. The site of the superior vena cava cannula should be as high as possible above
the cavoatrial junction (Fig. 25.14). Individual caval cannulation must be done carefully to minimize
interference with venous return and avoid hypotension and serious dysrhythmias. Partial cardiopulmonary
bypass may be initiated after one cannula is inserted to facilitate placement of the second cannula. Under
moderate hypothermia, the aorta is cross-clamped and cardioplegia is delivered into the aortic root.
Atrial Incision
Access to the inside of the right atrium is gained through a longitudinal incision made 3 to 4 mm anterior and
parallel to the sulcus terminalis (Fig. 25.15).
Incision Length
The incision should be well away from the sinoatrial node, and its superior extension should be limited to
0.5 cm from the superior margin of the right atrium. If additional length is required, the incision can be
extended onto the right atrial appendage (Fig. 25.15).
Direction of the Incision
Only after the surgeon has inspected the inside of the right atrium should the incision be extended inferiorly
so that it can be directed toward the lateral insertion of the valve of the inferior vena cava (Eustachian
valve) (Fig. 25.15).
The Atrial Septum
The fossa ovalis is usually torn if a balloon septostomy has been performed earlier. The trapezoid septal
flap is developed starting in the most anterior part of the foramen ovale and is incised superiorly for a
distance of approximately 7 mm. The direction of the incision is then changed posteriorly toward the
superior margin of the right superior pulmonary vein and extends to the base of the interatrial septum.
Similarly, an incision from the lower part of the fossa ovalis is continued downward toward the inferior
margin of the right inferior pulmonary vein (Fig. 25.16). The raw margins of the septum are then
endothelialized with interrupted sutures of 6-0 or 7-0 Prolene taking superficial bites and approximating the
endothelium (Fig. 25.16, inset). This atrial septal flap is now connected only at its base, which corresponds
outside the atria to the interatrial groove.
Injury to the Sinoatrial Node Artery
The artery to the sinoatrial node traverses the anterosuperior quadrant of the medial wall of the right atrium.
Development of the atrial septal flap should spare the vascular supply of the sinoatrial node by not deviating
the superior extension of the incision anteriorly.
Perforation of the Medial Wall of the Right Atrium
Similarly, the direction of the superior incision in the septum is significant. If this incision is deviated
anteriorly toward the muscular aortic mound, it may lead into the
pericardium outside the heart. If this happens, it must be immediately detected and the defect
reapproximated with multiple fine Prolene sutures.
FIG. 25.14 Technique for caval cannulations. Inset: Direct cannulation using a right-angled cannula.
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FIG. 25.15 Atriotomy.
Preferential Conduction Tracts
There are three main preferential conduction tracts or muscle bands joining the sinoatrial node to the
atrioventricular node (Fig. 25.17). These probably correspond to the crista terminalis and limbic muscle
bundles. The anterior conduction tract passes anterior to both the fossa ovalis and coronary sinus. The
middle tract also lies anterior to the fossa ovalis but may pass through or just posterior to the coronary
sinus. The posterior preferential tract crosses the posterior wall of the right atrium between the venae cavae
and then curves forward toward the coronary sinus. During the development of the flap, the middle tract will
be sacrificed in
most cases. Great care should be taken to prevent injury to the other conduction pathways.
FIG. 25.16 Preparation of the atrial septal flap. Inset: Endothelial approximation.
The defect in the flap from the fossa ovalis is filled by attaching an appropriately sized patch of Gore-Tex or
glutaraldehyde-treated autologous pericardium. The size of the atrial septal flap thereby developed is
remarkably constant and has a base of approximately 3 cm, a height of 2 cm, and an anterior side of 1.5 to
2 cm in infants 6 to 12 months of age.
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FIG. 25.17 The three main preferential conduction tissue pathways joining the sinoatrial node to the
atrioventricular node.
Inadequate Flap Size
The flap often must be enlarged by attaching a patch of appropriately sized Gore-Tex or glutaraldehyde-
treated autologous pericardium with a continuous suture of 6-0 Prolene (Fig. 25.18).
Tearing the Fossa Ovalis
A segment of the fossa ovalis is usually torn open by an earlier balloon septostomy. It is also thin and
sometimes full of perforating holes. This segment should be excised because it may tear at the suture line
and produce a defect in the newly constructed atrial septum.
The interatrial groove is dissected to free as much of the posterior atrial wall as possible. Traction on the
septal flap brings the left atrium and pulmonary veins into view. A longitudinal incision is made parallel with
and posterior to the groove into the left atrium (Fig. 25.18).
Small Left Atrial Opening
A transverse incision may be made down into the right superior pulmonary vein or between the right
superior and inferior pulmonary veins to ensure a larger left atrial opening.
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FIG. 25.18 Enlarging the septal flap with a patch of autologous pericardium or Gore-Tex.
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FIG. 25.19 Direction of the suture line to prevent injury to the atrioventricular node. Inset: Close-up of the
suture line below the coronary sinus.
The Septal Flap
The septal flap must be mobile enough so that it can be slightly rotated without causing any tension. The
midpoint of the anterior margin of the flap is sutured to the left atrial wall behind the left atrial appendage
beginning just in front of and between the left superior and inferior pulmonary veins with a double-armed
continuous suture of 6-0 Prolene. The suture line is continued both superiorly and inferiorly along the
posterior wall of the left atrium to the base of the flap.
Obstruction of the Left Pulmonary Veins
The flap must be of adequate size or it will be under tension and cause obstruction of the left pulmonary
veins at their orifices.
Suture Line Leaks
The suture line should be checked for leaks with a nerve hook to prevent any postoperative shunting.
Sewing the Anterior Edge of the Posterior Segment
The anterior edge of the posterior segment of the right atrium is sutured to the anterior part of the septal
defect between the mitral and tricuspid valves. Suturing is continued superiorly and inferiorly around the
lateral margins of the orifices of the superior and inferior venae cavae (Fig. 25.19).
Injury to the Atrioventricular Node
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The suture line, when continued down toward the inferior vena cava, should pass behind the coronary
sinus to avoid any injury to the atrioventricular node.
Obstruction of the Inferior Vena Cava
The medial aspect of the Eustachian valve of the inferior vena cava, when well developed, is an important
landmark because it signifies the medial limit of the orifice of the inferior vena cava. The approximation of
the atrial wall flap to the medial margin of the Eustachian valve ensures an adequate inflow channel for the
inferior vena cava.
Underdeveloped or Absent Eustachian Valve
If the Eustachian valve is absent or underdeveloped, a venous cannula of appropriate size may be
introduced through the left atrial appendage and the newly constructed atrial septal defect into the inferior
vena cava. The atrial wall flap is then sutured in place using the cannula as a stent (Fig. 25.20).
Caval Obstruction
If suturing impinges on the orifices of the superior or inferior vena cava, the resultant constriction may cause
obstruction to the venous return. This can be particularly troublesome with the superior vena cava (Fig.
25.21).
FIG. 25.20 Introduction of a venous cannula into the inferior vena cava when the Eustachian valve is absent
or underdeveloped to ensure adequate flow.
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