A Fontan operation is used for patients who have a variety of anomalies with single ventricle including, but not limited to, tricuspid atresia or hypoplastic left heart syndrome. After the repair is complete, the single ventricle is in continuity with the systemic circulation, and the systemic venous return flows to the lungs without passing through a functional ventricle.
Historically, the operation was performed by using a variety of right atrial to pulmonary arterial connections. Currently, most centers use the modified Fontan procedure as a single- or a two-stage operation. This technique incorpo- rates division of the superior vena cava and a direct end-to-side anastomosis to the right pulmonary artery. This should provide for unobstructed flow from the superior vena cava into the right and left pulmonary circulation. The tunnel used to direct inferior vena caval flow to the pulmonary arteries as part of this procedure is constructed with an intra-atrial tunnel baffle or with an extracardiac tube graft.
The two-stage repair is always used in the presence of risk factors and most centers stage the procedure in all patients. A bidirectional cavo-pulmonary shunt is constructed with or without cardiopulmonary bypass. At a later operation the intra-atrial baffle or extracardiac conduit procedure is performed.
6-1. First-Stage Fontan Procedure
Before cardiopulmonary bypass, extensive dissection is performed. The ascend- ing aorta and main pulmonary artery are freed from surrounding tissue to allow division of the proximal main pulmonary artery. The left pulmonary artery is mobilized, and the right pulmonary artery is dissected to facilitate the superior vena cava-right pulmonary arterial anastomosis. The entire superior vena cava is dissected to near the inominate vein, allowing high caval cannulation and lower caval exposure for the proposed anastomosis. The cava is marked with a suture at the site of division of this vessel, which will allow for an anastomosis without tension or redundancy. The azygos vein is usually sacrificed. The inferior vena cava is cannulated at the inferior cava-atrial junction, saving direct caval cannulation for the stage 2 procedure. Usually aortic cross-clamping is not used. Air embolization is prevented by use of a large caliber ventricular vent placed across the systemic atrio-ventricular (AV) valve and systemic hypothermia to depress ventricular function. To facilitate the stage 2 operation, the pericardium is closed primarily or a Gore-Tex® pericardial membrane is left in place.
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being divided
proximal closed portion of main pulmonary artery
FIGURE 6-1. After cardiopulmonary bypass is established, the main pulmonary artery is divided near the pulmonary valve. The valve leaflets are sutured closed to prevent release into the circulation of any clot that might later form in this blind pouch. The proximal pulmonary artery is then closed with continuous sutures in two layers. The suture line is supported with three interrupted sutures with Teflon® felt pledgets. The superior vena cava is divided at a point determined before cardiopulmonary bypass, when the vessel is naturally distended. If an atrial septectomy is required, this can be performed working through the retracted proximal superior vena cava orifice.
superior vena cava
proximal right pulmonary artery
open distal portion of main pulmonary artery
FIGURE 6-2. After a right pulmonary arteriotomy of appropriate size along the cephalad
surface of this vessel, an end-to-side caval-pulmonary artery anastomosis is constructed
with a continuous suture posteriorly. Care is taken to avoid twisting the cava before the
anastomosis.
R ^
distal portion of main pulmonary artery
FIGURE
6-3. The anterior row of the anastomosis is completed with a continuous suture only interrupting it with three or four sutures to allow for anastomatic growth.
occluded anastomosis between main pulmonary artery and superior vena cava
FIGURE
6-4. The open distal portion of the main pulmonary artery is closed primarily. The
open lower portion of the superior vena cava is anastomosed circumferentially around the
adjacent intact pulmonary artery segment. This establishes tissue continuity that will be
useful at the time of the second-stage or completion Fontan operation.
ceph R < - - • L
caud
superior caval segment
FIGURE
6-5. In another patient, the open distal main pulmonary artery is anastomosed end-to-end to the open lower superior caval segment. A pericardial patch is inserted in the anastomosis between the two vessels, closing the connection to occlude blood flow.
In many patients this helps to maintain patency of the two blind pouches. At the later completion Fontan operation, the blind pouches are opened and the pericardial patch is simply excised.
ceph R < - - • L
caud
open distal main pulmonary artery
pericardial patch
FIGURE
6-6. The anterior row of this anastomosis is completed with a continuous suture
picking up pulmonary artery wall, pericardial patch, and caval wall with each stitch.
R ^
pulmonary artery
superior vena cava segment
FIGURE 6-7. The anastomosis is complete and the blind caval and main pulmonary artery pouches, respectively, are in continuity.
caud
superior vena cava
blind pouch of main pulmonary artery
right pulmonary artery
FIGURE 6-8. The postoperative angiogram shows a well positioned and functioning bidi-
rectional caval pulmonary shunt. The blind main pulmonary artery pouch is also visual-
ized.
FIGURE
6-9. With the child on bypass, a short anterior right atriotomy is made. A right-
angle clamp is passed into the blind caval pouch and the tip exposes the area posterior to
the sinoatrial (SA) node region.
ceph R « - - > L
caud
tip of clamp
FIGURE 6-10. A longitudinal incision is made laterally in the blind pouch.
ceph R < - - • L
caud
region of SA node
incision
FIGURE 6-11. This incision is located posterior to the SA node region.
ceph R < - - • L
caud
eustachian valve
FIGURE 6-12. Looking through the atriotomy, an atrial septal defect (ASD) is identified.
The eustachian valve is prominent and will be used in the repair.
R ^
patch
caud
FIGURE 6-13. A rectangular-shaped patch is cut from a large tubular Gore-Tex® graft.
ceph R < - - • L
caud
eustachian valve
FIGURE
6-14. The lower rim of the patch is stitched to the eustachian valve using a con- tinuous Gore-Tex® suture. The medial margin of the patch is stitched to the atrial septum adjacent to the ASD.
fenestration
FIGURE
6-15. The right margin of the patch is stitched to the lateral wall of the atrium. A
5- to 6-mm fenestration is cut at the mid portion of the patch.
R ^
exteriorized purse string stitch
FIGURE
6-16. A large polypropylene stitch is placed as a mattress suture around the rim of the fenestration and then is exteriorized.
exteriorized purse string stitch
stitches at corners of fenestration
FIGURE
6-17. Gore-Tex® sutures placed at the two corners of the fenestration are exteri-
orized and tied.
R <
tourniquet on purse string stitch
FIGURE 6-18. A tourniquet is placed around the exteriorized purse string stitch and pulled tight.
R ^
fenestration snared closed
tourniquet
FIGURE 6-19. The fenestration is checked to be sure that it is obliterated by tightening the
purse string stitch.
ceph
R<- - • L t caud
additional stitch used to open fenestration
FIGURE 6-20. A second smaller polypropylene stitch is placed around the original purse string stitch and also exteriorized. By pulling this second suture, the original purse string stitch can be loosened if necessary after closing all cardiotomies.
R ^
sulcus terminalis
FIGURE 6-21. The intra-atrial baffle is completed by attaching the upper rim of the patch
to the sulcus terminalis.
R <
Gore-Tex baffle
FIGURE
6-22. The completed intracardiac baffle is in good position and will direct all infe- rior caval flow to the blind superior caval pouch.
ceph R < - - • L
caud
main pulmonary artery pouch
superior vena cava pouch
FIGURE
6-23. To establish continuity between the heart and the pulmonary arteries, a lon-
gitudinal incision is made laterally in the blind main pulmonary artery pouch that is con-
tiguous with the incision in the superior vena caval pouch. In this patient, the two vessels
had previously been approximated by direct anastomosis. The result is a thick layer of scar
tissue that separates the endothelial lining. This lining will be approximated with multiple
fine interrupted polypropylene sutures.
ceph R < - - • L
caud
FIGURE 6-24. In another patient, the blind main pulmonary artery pouch is opened and the previously placed pericardial patch is seen occluding the opening with the intracar- diac structures.
area of exised pericardial patch
FIGURE 6-25. This patch is excised to establish continuity with the blind superior caval
pouch.
ceph R « - - • L
caud
lateral Gore-Tex patch
FIGURE
6-26. A Gore-Tex® patch is stitched over this area to connect the intra-atrial lateral tunnel to the pulmonary artery. The superior margin of this Gore-Tex® patch extends onto the inferior rim of the right pulmonary artery. This patch is placed on the lateral aspect of the cardiac structures for optimal blood flow dynamics and to avoid placing stitches in the SA node.
R<-
LA line
RA line
FIGURE
6-27. A snare around the exteriorized fenestration suture is positioned along the
atrium. If hemodynamics allow, the fenestration stitch can be tied during this surgery but
after separation from cardiopulmonary bypass. If the fenestration is to be left patent, the
tourniquet is stitched to the area behind the right rectus muscle. Some months or years
later, cardiac catheterization is performed and the fenestration is test occluded. If it can
be closed at that procedure, a small incision is made below the xiphoid and the end of
the tourniquet exposed. The tourniquet is pulled tight and fixed in order to occlude the
fenestration.
ceph R < - - • L
caud
FIGURE
6-28. A postoperative angiogram shows the lateral tunnel with flow primarily to the left pulmonary artery.
ceph A R « - - • L ,,?-
caud
fenestration
FIGURE
6-29. On the lateral view of this angiogram, the patent fenestration is visualized.
erative atrial arrhythmias with the latter technique as a result of avoidance of damage to the SA node.
right atrium
FIGURE 6-30. The heart is widely
dissected of adhesions and there is ample space between the right atrium and pericardium for place- ment of the conduit.
FIGURE 6-31. The heart is lifted
to expose a long inferior caval
segment.
R +
atriotomy
inferior vena cava
FIGURE 6-32. To place the patient on cardiopulmonary bypass, the inferior vena cava is cannulated directly. The cava with an attached rim of right atrial wall is excised.
R ^
right atrium closed
FIGURE 6-33. The atriotomy is closed primarily.
FIGURE
6-34. A large Gore-Tex® tubular conduit is stitched end-to-end to the inferior vena cava.
ceph R < - - • L
caud
opening in pulmonary artery branches
FIGURE
6-35. A generous opening is made in the pulmonary artery branches.
ceph A
R<-
- • Lcaud
FIGURE
6-36. The conduit is stretched to conform with the right heart border to avoid redundancy when the heart is filled after completing the surgery. The cephalad end of the graft is stitched to the pulmonary arteries with a continuous suture.
R ^
anastomosis
FIGURE
6-37. The completed anastomosis with the pulmonary arteries is seen.
ceph R * - - • L
caud
FIGURE
6-38. A 5- to 6-mm fenestration is created in the medial aspect of the conduit using an aortic punch.
ceph R < - - • L
caud
fenestration
FIGURE
6-39. The fenestration is adjacent to the mid part of the right atrium.
ceph R < - - • L
caud
FIGURE 6-40. A small atriotomy is made and the conduit fenestration is stitched to this opening with a continuous polypropylene suture. After completing the posterior row of this anastomosis, a fenestration snare stitch will be placed.
R ^
purse string stitch
FIGURE 6-41. A large polypropylene continuous mattress purse string suture is placed pos-
teriorly and will be continued along the anterior margin of the atriotomy.
fenestration
purse string stitch
6-1-4. Intra-Atrial Conduit
In a few patients with complex and unusual anatomy, neither an intra-atrial lateral tunnel nor an extracardiac conduit repair can be safely accomplished. In these cases, an intra-atrial conduit may be useful. Working within the atrial cham- bers, a tubular conduit is stitched to the internal orifice of the inferior vena cava.
It then passes cephalad to an atriotomy on the superior surface of the atrial cham- bers, through which it is anastomosed to the pulmonary arteries.
FIGURE 6-43. The conduit has been placed and a fenestration created with a flap opening in the lateral aspect of the conduit.
A mattress suture is placed in the rim of the fenestration and through the flap, after which it is exteriorized through the lateral atrial wall.
intra-atrial tubular conduit
fenestration
mattress stitch in fenestration
>post
6-2. Obstruction of Bulboventricular Foramen
In the presence of single ventricle with d- or 1-transposition of the great arteries and obstruction of a bulboventricular foramen that separates the ventricle and aorta, ventricular hypertension occurs that must be relieved to preserve ventric- ular function. Two techniques are used. In the first, the proximal-divided main pulmonary is attached to the ascending aorta (Damus procedure), creating a double outlet ventricle to bypass the obstruction. With the second technique, subaortic obstruction is resected and/or septal tissue is removed to enlarge the bulboventricular foramen.
ascending aorta
restrictive bulbo- ventricular foramen
ceph ant<- -•post
caud
FIGURE
6-45. This lateral view of a single ven-
tricular injection shows the restrictive bulboven-
tricular foramen that separates the ventricle
from the subaortic chamber.
pulmonary artery band
FIGURE
6-46. The great vessels are transposed with an anterior ascending aorta and a pos- terior main pulmonary artery. The pulmonary artery band constricts the mid main pul- monary artery.
ascending aorta
main pulmonary artery divided FIGURE
6-47. Cardiopulmonary bypass is established, and the aorta is clamped. Profound
local cardiac cooling and cardioplegia are used. The main pulmonary artery and its
branches are dissected; the vessel is divided at the pulmonary artery band, and the band
is removed.
R ^
proximal main pulmonary artery
FIGURE 6-48. A longitudinal incision is made in the proximal main pulmonary artery segment to near the annulus and adjacent to the ascending aorta. The ascending aorta is opened proximally and then to a point more distal than the pulmonary artery segment.
R ^
ascending aorta
Gore-Tex hood
proximal main pulmonary artery caud
FIGURE 6-49. A side-to-side anastomosis is constructed between the posterior margin of
the proximal aortotomy and the proximal pulmonary arterotomy. A triangular shaped
Gore-Tex® hood is stitched over the distal end of the main pulmonary artery segment
and then attached to the distal aortotomy.
FIGURE
6-50. The anterior rim of the aortotomy is stitched to the anterior rim of the pul- monary artery to complete the repair.
6-2-2. Enlargement of Bulboventricular Foramen by Resection of Septal Tissue
This is an alternative technique to relieve ventricular outlet obstruction in patients with a single ventricle. A complication of this procedure is complete heart block caused by injury to conduction tissue during septal resection. In patients with d-looping, the His' bundle is located in septal tissue along the right and caudal margin of the bulboventricular foramen. In patients with 1-looping, the His' bundle is normally found along the cephalad and left margin of the bul- boventricular foramen. Resection is carried out in the obstructing septum on the border of the foramen remote from conductive tissue.
Procedures are performed using cardiopulmonary bypass. In small infants, ade-
quate exposure may be gained working through a small incision in the ventricu-
lar wall of the subaortic outflow chamber. The ventriculotomy is remote from the
systemic ventricle and should not adversely affect ventricular performance. In
older children, resection of septal tissue can be easily performed through a prox-
imal ascending aortotomy while retracting the aortic valve or a right atriotomy
while retracting the AV valve. It is useful to pass a large nerve hook or a right-
angle clamp into the bulboventricular foramen for retraction, facilitating expo-
sure of the area to be resected.
FIGURE
6-51. After placing the infant cardiopulmonary bypass with aortic cross-clamping and cardioplegic arrest, a short incision is made in the anterior wall of the subaortic chamber. In some cases it may be difficult to define the best location for the ventriculo- tomy. In this case, an aortotomy is made and a small clamp is passed into the subaortic chamber, pressing it against the anterior wall so the precise location for the ventriculo- tomy can be determined. The restrictive bulboventricular foramen is seen. Conductive tissue is near the right border of the bulboventricular foramen, and the area of resection is identified to the infant's left.
caud
enlarged bulboventricular foramen
FIGURE
