atrial septal defect

2 Secundum Atrial Septal Defect

Diagnosis of secundum atrial septal defect (ASD) is made by echocardiography and cardiac catheterization is reserved for the rare case in whom evaluation of hemodynamics is needed. If the ASD measures 5 mm or more, repair is recom- mended. In those defects that are smaller, repair is indicated with associated right ventricular (RV) dilatation or other evidence of RV volume load. In most centers today, closure of this anomaly beyond infancy is offered by the invasive cardiol- ogist using one of a variety of prosthetic devices. Long-term results are being evaluated for this technique. Certain anatomical features contraindicate device closure and complications, including early failure of closure or residual ASD, early or late thromboembolism, serious arrhythmias, aortic insufficiency, inter- ference with mitral valve function, or erosion of the device with catastrophe, con- vince many families to use the long-tested and reliable technique of surgical repair.

The operation is performed using cardiopulmonary bypass. When the defect is isolated and time on the heart-lung machine is expected to be short, core cooling to 32°C is used. In the presence of partial anomalous pulmonary venous con- nection or other intracardiac anomalies, when intracardiac repair requires a longer time, core cooling to 26°C to 30°C is used. In all cases, the operation is performed with aortic clamping, cardioplegia, profound local cardiac cooling, and left ventricular venting to maximize safety against air embolization during bypass.

9

atrial septal defect

FIGURE 2-1. The child has been placed on cardiopulmonary bypass, and a mid right atriotomy is made.

The region of the cavoatrial junc- tion is spared to avoid injury to the sinoatrial (SA) node. A large secun- dum atrial septal defect can be seen in the region of the fossa ovalis.

A metal sucker is in the defect.

Because the septal tissue that sur- rounds the ASD is substantial, it can be closed primarily. It is important to inspect the atrial chambers to rule out other anomalies and the orifices of all pulmonary veins should be identified to ensure that they enter the left atrium normally.

> L

closure stitch

tricuspid valve

coronary sinus

FIGURE 2-2. Primary closure of the ASD has been performed using a continuous suture

of monofilament polypropylene. The closure is started at the caudad margin of the ASD

because this is usually the area of poorest exposure. The surgeon should avoid stitching

together the posterior and anterior rims of the defect remote from the lower edge of the

ASD; if this is done, the surgeon can create a tunnel for inferior vena caval blood to flow

directly into the left atrium, causing a right-to-left shunt postoperatively. After the closure

stitch is completed, a small probe should be used to check for residual openings in the

suture line, which can be closed with interrupted sutures.

ceph R < - - • L

caud

atrial septal defect

FIGURE 2-3. When the ASD is extremely large, primary closure with a continuous suture may cause excessive tension on and tearing of the rim of the defect, resulting in a recur- rent ASD postoperatively. It is safer to close this atrial defect with a patch to avoid suture line tension. Here, the anterior cephalad septum is poorly formed. Stitches in this area should be placed in the endocardium only because the aortic valve is located beneath this area and can be injured by deeply placed sutures.

ceph R < - - • L

caud

Dacron patch

FIGURE 2-4. A Dacron® patch is stitched over the ASD with a continuous monofilament

suture. The rim of the patch should be probed to check for residual openings, which can

be closed with individual sutures. Endothelial growth covers the Dacron® patch within 4

to 6 weeks postoperatively, and postoperative anticoagulants are not used. I prefer

Dacron® material for a patch in the atrium because it encourages tissue ingrowth; also,

it will not contract as will pericardium, so there is less chance for tension on the suture

line and reduced possibility of tearing the septum with recurrence of the ASD.

ceph R^- - • L

caud

atrial septal defect

coronary sinus orifice

FIGURE 2-5. The child has been placed on cardiopulmonary bypass and a mid right atri- otomy performed. Looking through the orifice of the coronary sinus there is an atrial septal defect in the roof of this structure. If small the defect can be closed primarily;

however, most will be closed with a patch to avoid undue tension on closure sutures.

2-7-2. Atrial Septal Defect after Failed Device Closure

Sideris occluder

residual atrial septal defect

ceph

R<- ^{- • L}

caud

FIGURE 2-6. The child has been placed on cardiopulmonary bypass and a mid right

atriotomy made. The Sideris occluder, which was placed previously, is shown with the

residual ASD.

ceph

A

R « - - • L caud

Sideris occluder

FIGURE 2-7. The occluder is attached to the septum by gelatinous material along the posterior rim of the ASD.

R ^

Sideris occluder explanted

FIGURE 2-8. The occluder is explanted by incising and excising free-floating gelatinous

material.

ceph R « - - • L

caud

atrial septal defect

coronary sinus

tricuspid valve

FIGURE 2-9. The remaining atrial septal defect is in the mid part of the septum.

ceph R < - - • L

caud

stitch closure of atrial septal defect

FIGURE 2-10. The atrial septal defect is closed with a continuous stitch and a few addi-

tional buttressing stitches across the original suture line.

2-2. Atrial Septal Defect with Partial Anomalous Pulmonary Venous Connection

When partial anomalous pulmonary venous connection is present, abnormal pul- monary veins from the right upper and middle lobes commonly drain to the supe- rior vena cava or the right atrium near the caval atrial junction. This is usually associated with a sinus venosus ASD located opposite the anomalous pulmonary veins.

ceph R < - - > L

caud

aorta

superior vena cava

cava-atrial junction

anomalous pulmonary veins

FIGURE 2-11. Anomalous pulmonary veins are seen entering the high and lateral right atrium and low superior vena cava adjacent to the cava atrial junction.

FIGURE 2-12. The superior vena caval cannula is passed through the right atrial appendage and into the mid superior vena cava. The supe- rior caval snare is placed above the azygos vein to allow wide exposure of the anomalous pulmonary veins with a high cardiotomy to the mid superior vena cava. A separate tape for snaring is passed around the azygos vein for hemostasis. The atriotomy is made posterior to the sulcus terminalis and the SA node to avoid damage to the latter structure.

atrial septal defect normal pulmonary vein entering left atrium ceph

caud

ceph R^- - • L

caud

atrial septal excision

FIGURE 2-13. In some cases the atrial septal defect is too small to freely accept all flow from the tunnel constructed around the anomalous pulmonary veins. To avoid obstruction of the tunnel at this site, the atrial septal defect should be enlarged by resecting the adja- cent septum. Adequate exposure of the ASD and anomalous veins is gained by retracting the superior vena caval cannula.

ceph R < - - • L

caud

Dacron patch

FIGURE 2-14. A thin Dacron® patch is cut in a pear shape, and the smaller end is stitched around the orifices of the anomalous pulmonary veins. The patch should not be too narrow in this area because minimal obstruction anywhere in the Dacron® tunnel can result in pulmonary venous obstruction. The Dacron® patch tunnel is completed by stitching it to the rim of the ASD. Flow from the anomalous pulmonary veins is now diverted behind the patch through the atrial septal defect and to the left atrium. Posteriorly, the Dacron®

patch is near the rim of the posterior right atriotomy.

ceph R < - - • L

caud

pericardial patch

FIGURE 2-15. To avoid superior vena caval obstruction by the intracardiac Dacron® patch, a gusset of pericardium is always placed over the lower superior vena cava and adjacent right atrium to widen the cava-atrial junction. When sutures are placed to attach the ante- rior rim of the gusset, care should be exercised to avoid damage to the SA node. Peri- cardium is preferable to synthetic material for the gusset because of its ease of handling and hemostatic qualities.

2-2-1. High Superior Caval Drainage of Partial Anomalous Pulmonary Venous Connection

When repair is performed using an intracaval baffle or patch tunnel, there is a high risk of superior caval and/or pulmonary vein tunnel obstruction. Repair using a right atrial pedicle flap tunnel is indicated when anomalous veins enter the superior cava near or above the azygos vein entrance.

ceph R < - - • L

caud

anomalous pulmonary

area of azygos vein

FIGURE 2-16. The anomalous pulmonary veins are located high in the cava near the

innominate vein.

ceph R««- - > L

caud

pedicle flap of right atrium

cannula in superior vena cava

FIGURE 2-17. The child is placed on cardiopulmonary bypass with bicaval cannulation.The purse string stitch for the superior vena caval cannula is placed in the wall of the mid right atrium, and a straight cannula is used. Alternatively, a small right-angle cannula can be placed directly in the cava above the anomalous pulmonary veins and near the innomi- nate vein. A wide pedicle flap of right atrial wall is developed, with the base of the flap in the transverse plane, near the cava atrial junction. Care is taken to avoid injury to the SA node during development of this flap. The straight cannula is seen passing into the supe- rior vena cava. The superior cava is divided around the cannula in the area above the insertion of the anomalous veins. The superior caval cannula is momentarily clamped, removed from its position in the superior vena cava, and passed through the large atri- otomy at the site of pedicle flap and again passed into the upper superior vena cava through the caval tourniquet.

R ^

cannula in superior vena cava

Gore-Tex patch

lower segment of superior vena cava

FIGURE 2-18. A Gore-Tex® patch is stitched over the lower end of the divided superior

vena cava, immediately above the anomalous pulmonary veins. Other patch material, such

as pericardium or homograft pulmonary artery wall, can be used.

ceph R««- - • L

caud

upper segment of superior vena cava

Gore-Tex patch

lower segment of superior vena cava

FIGURE 2-19. The cava above the pulmonary veins is closed with the Gore-Tex® patch, and the caval cannula is seen passing through the tourniquet in the upper superior vena cava.

ceph R«*- - > L

caud

intra atrial Dacron patch

FIGURE 2-20. A Dacron® patch is stitched over the high ASD, bringing the upper margin

of the patch in front of the native superior caval orifice. The lower superior cava segment

now functions as a conduit for anomalous pulmonary vein flow to the left atrium behind

the Dacron® patch.

ceph R^- - • L

caud

superior vena cava

superior

caval

cannula right atrial pedicle flap tunnel

right atriotomy

FIGURE 2-21. The atrial wall pedicle flap is wrapped around the caval cannula and anas- tomosed end-to-end to the upper caval segment.

ceph R < - - • L

caud

pericardial patch

right atrium

FIGURE 2-22. The deficient area in the anterior wall of the new superior vena cava is closed with a pericardial autograft. A patch of different material, that is, homograft pulmonary artery wall, can be used. I prefer a tissue patch of some variety for better hemostasis.

2-2-2. Scimitar's Syndrome

All right pulmonary veins drain to the right atrium through a common vein that

enters the atrium or cava near the inferior caval atrial junction. There is usually

an associated secundum ASD and a large left-to-right shunt through both the

anomalous pulmonary veins and the ASD. Anomalous systemic arteries from the

abdominal aorta to the right lung are usually present and pierce the diaphragm

to enter the lower lung region. These vessels must be closed at the time of sur-

gical correction.

2-2-3. Intracardiac Tunnel Repair

ceph R < - - • L

caud

right atrium

anomalous right pulmonary

FIGURE 2-23. By retracting the heart, the inferior vena cava can be seen in a normal posi- tion. The large anomalous right pulmonary vein is immediately adjacent to the cava and enters the right atrium in this area. Care must be used when the inferior vena cava is iso- lated with a tape for snaring because it may be adherent to the anomalous vein. The diaphragmatic surface of the pericardium is incised so that the inferior vena cava can be isolated beneath the diaphragm.

R<*

atrial septum

orifice of anomalous pulmonary vein

FIGURE 2-24. After the child is placed on cardiopulmonary bypass, a low posterior right

atriotomy is made. The inferior vena caval cannula is retracted anteriorly, and the orifice

of the anomalous pulmonary vein can be seen posteriorly.

ceph R « - - • L

•

caud

atrial septal defect

FIGURE 2-25. An ASD is located in the region of the fossa ovalis. If it is restrictive, the surrounding atrial septum should be excised to enlarge the ASD.

ceph R « - - • L

caud

Dacron patch

FIGURE 2-26. A thin Dacron® patch is stitched inferiorly around the orifice of the anom-

alous pulmonary vein and then in a cephalad direction along the posterior atrial septum

and the mid atrial septum, respectively. The patch creates a tunnel to divert anomalous

pulmonary vein flow to the ASD septal defect and the left atrium. The stitch around the

orifice of the anomalous pulmonary vein is placed to separate the anomalous vein from

the inferior vena cava without narrowing the cava.

ceph R < - - • L

caud

pericardial patch

FIGURE 2-27. To avoid obstruction of the inferior vena cava by the intra-atrial Dacron®

patch, a pericardial gusset is stitched over the upper inferior vena cava and low right atrium.

pericardial patch

inferior vena cava

FIGURE 2-28. After completing the repair, the inferior cava-right atrial gusset will distend

when the blood fills the right atrium. The effect of this gusset is to widen the upper infe-

rior cava and low right atrium.

ant

present. In the presence of an ASD, for example, repair on cardiopulmonary bypass can be carried out through this incision.

pericardium

ceph^- -•caud post

Scimitar's vein entering inferior vena cava

right lower lobe

FIGURE 2-29. Working through a right fifth or sixth intercostal space thoracotomy, the infe- rior portion of the right lung is retracted to expose the Scimitar's pulmonary vein, which drains the entire lung to the upper inferior vena cava. If anomalous systemic arteries are present they can easily be divided through this exposure.

ant ceph^- -•caud

post

phrenic nerve

pericardial opening

left atrium

Scimitar's vein

FIGURE 2-30. The pericardium is opened over the left atrium immediately anterior to the

hilum and usually posterior to the phrenic nerve.

FIGURE 2-31. The Scimitar's vein is divided at its connection to the cava and the caval end is closed.

Prior to clamping the Scimitar's vein, the right pulmonary artery is occluded by a snare to avoid right lung engorgement during the procedure. Using a partially oc- cluding side biting clamp on the left atrium, the Scimitar's vein is shifted cephalad and anastomosed directly to the left atrium.

right pulmonary artery

left atrium

anastomosis

>caud post

2-2-5. Anomalous Left Upper Lobe Pulmonary Venous Connection with Intact Atrial Septum

2-2-5-1. Extracardiac Repair

Repair is carried out by working through a left fourth or fifth intercostal space thoracotomy without cardiopulmonary bypass.

ant c a u d ^ - -^•ceph

post

innominate vein

ascending connecting

left subclavian artery

left upper lobe pulmonary

left lower lobe pulmonary vein

FIGURE 2-32. Working through a left thoracotomy the lung is retracted posteriorly. Here,

the large ascending pulmonary vein drains all left lung flow to the innominate vein. The

ascending vein is dissected as are the upper and lower pulmonary veins.

ant caud<- ->-ceph

post

ascending connecting vein

left upper lobe pulmonary vein

left lower lobe pulmonary vein

FIGURE 2-33. The pericardium is opened immediately in front of the hilum to expose the left atrial appendage.

ant caud<- -•ceph

post

excluding side biting clamp

left atrial appendage

vein to atrium anastomosis

FIGURE 2-34. The left pulmonary artery is occluded with a snare to stop inflow into the

lung to avoid lung engorgement during the anastomosis. The two pulmonary veins are

then occluded with snares. The upper end of the ascending vein is divided and the upper

segment is closed primarily. The left atrial appendage is retracted and a side biting clamp

is placed on the base of the appendage. The surgeon should avoid constructing the anas-

tomosis on the tip of the appendage, which may result in partial obstruction to flow

through a narrow appendage internal orifice. A large incision is made in the pulmonary

vein confluence near the base of the appendage and an adjacent incision made in the

appendage. A side-to-side anastomosis is constructed with fine polypropylene suture.

ant c a u d ^ - ->ceph

post

left atrial appendage

anastomosis

pulmonary vein

closed stump of ascending

FIGURE 2-35. The completed anastomosis is shown with no tension on the pulmonary vein.

The upper end of the divided ascending vein was closed primarily.

2-2-6. Repair with Cardiopulmonary Bypass

Repair of this anomaly can be performed working through a median sternotomy, which is necessary when associated intracardiac anomalies are repaired. This is carried out using cardiopulmonary bypass.

ceph R<- - * L

caud

ascending connecting pulmonary vein

left atrial appendage

main pulmonary artery

ascending aorta

FIGURE 2-36. The ascending connecting pulmonary vein is exposed in the left upper

mediastinum.

ceph

R^- ->L

caud

vein

posterior anastomosis

opened left atrial appendage

FIGURE 2-37. After placing the child on cardiopulmonary bypass, the upper end of the ascending left pulmonary vein is divided and the end near the innominate vein closed pri- marily. The lower segment of the ascending vein is shifted caudad. The base of the left atrial appendage is opened and an anastomosis between the vein and atrium constructed.

R +

turned down ascending vein

anastomosis

left atrium

FIGURE 2-38. The anastomosis is complete and the vein is attached to the left atrium

without tension or obstruction to flow.