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Congenital Heart Disease in Adults

Due to major advances in both diagnosis and treatment of congenital heart disease in children, many are living into adulthood. There are almost one million such patients this year.

Congenital heart disease can be divided into two types:

1. The acyanotic ones in which the oxygen level in the blood is high enough to keep the patients' color pink;

2. The cyanotic ones in which the oxygen level in the blood is low enough for the lips and skin to show varying degrees of bluish discoloration.

1. Acyanotic congenital heart consist of the following:

a) atrial septal defect ( figures 112a, 112b )
b) ventricular septal defect ( figure 112c )
c) patent ductus arteriosus ( figure 22 )
d) aortic stenosis ( figures 24a, 24b, 46a, 46b, 46c, 47 )
e) pulmonary stenosis ( figure 25a, 25b )

f) parachute mitral valve ( figures 44g-1 and 44g-2 )
g) coronary artery fistula
h) anomalies of the great veins

Brickner,M.E. and others,Congenital Heart Disease inAdults,N.Engl.J.Med.,Vol.342.N.4,Jan.27,2000

 

2. Cyanotic Congenital Heart
Disease
features bluish discoloration of the skin and lips as opposed to the normal pink appearance. The cyanosis is due to the shunting of systemic venous blood to the arterial circulation causing arterial blood desaturation of oxygen. The size of the shunt determines the degree of desaturation. In adults the most common causes of cyanotic congenital heart disease are tetralogy of Fallot and Eisenmenger's syndrome.

a) Tetralogy of Fallot ( figure 23d )
b) Ebstein's Anomaly ( figure 23e )
c) Transposition of the Great Arteries ( figure 23h )
d ) Eisenmenger's syndrome ( figure 23j )
Brickner,M.E. and others,Congenital Heart Disease in Adults,N.Engl.J.Med.,Vol.342.N4,2000,pp.334-342

e) Hypoplastic Left Heart Syndrome

a) Tetralogy of Fallot

It is characterized by a large ventricular septal defect (VSD, figure 112c), an aorta that overrides the left and right ventricles, obstruction of the right ventricular (RV) outflow tract, and RV hypertrophy (increased wall thickness). As obstruction in RV outflow tract increases, more blood is shunted through the VSD to the left side of the heart to cause more cyanosis (see figure 23d). Increases in resistance to flow in the general arteries of the body causes less shunting, and decreases cause more shunting to the left.

Symptoms in adults include shortness of breath and limited exercise tolerance. Complications include brain abscesses, strokes and heart infections (see figures 48a, 48c, 48d). Such patients may have enlargement of the distal ends of their fingers called clubbing. Most patients without surgical correction die in childhood.

Echocardiography can establish the diagnosis. Color Doppler can visualize the VSD. Heart catherterization can confirm the diagnosis.

Surgical repair is recommended to relieve symptoms and to improve survival. Complete surgical correction (closure of the VSD and relief of RV outflow obstruction is performed currently when patients are very young. Patients are at risk for heart infections and should thus receive prevention with antibiotics before dental or elective surgical procedures.

Even with repair these patients have a poorer survival rate (apparently due to cardiac causes such as arrhythmias) than that of an age-matched control population. Ventricular arrhythmias can be detected with Holter monitoring in 40 to 50 percent of patients with repaired tetralogy and are most likely to occur in patients who are older at the time of surgical repair and those with moderate or severe pulmonary regurgitation,systolic and diastolic ventricular dysfunction, prolonged cardiopulmonary bypass, or prolongation ot the QRS intreval (to greatwer than 180msec). Patients with repaired tetralogy of Fallot often have atrial fibrillation or flutter, which may cause considerable morbidity.

Patient with repaired tetralogy are at risk for other chronic complications. Pulmonary regutgitation may develop as a consequence of surgical repair of the right ventricular outflow tract. Although even substantial regurgitationcan be tolerated for long periodds, enlargement of the right ventricle eventually occurs, with resultant right ventricular dysfunction, and repair orreplacement of the pulmonary valve may be in required. An aneurysm may form at the site where the right ventricular outflow was repaired;rupture has occurred rarely.

Alternatively, patients may have residual or recurrent obstruction of the right ventricular outflow tract, requiring repeated surgery. Approximately 10 to 20 percent of patients with repaired tetralogy of Fallot have residual ventricular septal defects, and such patients may require repeated sirgery if the defects are of sufficient size. RBBB is common after repair of tetralogy of Fallot, but complete heart block is rare. Finally, aortic regurgitation may occur but is usually mild.

Brickner,M.E. and others,Congenital Heart Disease in Adults,N.Engl.J.Med.,Vol.342.N4,2000,pp.334-342

Late survival is excellent, even in patients who underwent repair during the very early years of open heart surgery. Surgery can not be considered curative,since survival,even in excelllent series is slightly but significantly worse than for a matched control population. The risk factors for an adverse late outcome include older age at surgery, preopoerative congestive heart failure, a previous Potts operation, persistent right ventricular systolic hypertension, and a residual ventricular defect. Late death may be sudden, due to tachyarrhythmias or, very rarely in the current era to conduction disease. Left and right ventricular failure due to right ventricular overload or left ventricular volume overload is another important cause of late death in older patients.
The late functional outcome is excellent for the mayority of patients. Most live normal lives, but the results appear to be better in those undergoing surgery at a younger age. Pulmonary valve replacement can be accomplished with low risk.
Exercise performance is usually impaired when surgery is undertaken in adolescence or adulthood.

 

b) Ebstein's Anomaly

This anomaly is due to a defect in the tricuspid valve (TV) with the septal and posterior leaflets displaced down into the right ventricle, while the anterior leaflet is malformed and abnormally attached to the RV free wall (see figure 23e). This valve often allows blood to regurgitate from the small RV back into the large RA.

Eighty percent of these patients have ASD's through which right-to-left shunting of blood may occur with cyanosis. Such patients are at risk for a paradoxical embolus (blood clot) from the RA through the LA to the brain with abscess(instead of the normal route of an embolus from the legs to the lungs via the right ventricle through the pulmonary valve)and sudden death.

There is usually a heart murmur. EKG abnormalities are often present including WPW syndrome, an atrial tachycardia or rapid heart beat (see figures 2, 3a). Twenty percent have an accessory electrical pathway between the atrium and ventricle (see figure 1) to account for the cardiac arrhythmias.

An echocardiogram can define the abnormalities, and a color Doppler imaging study can determine the presence and size of interatrial shunting.

Management involves prevention of complications, such as heart infection, prevented with antibiotic prophylaxis. Heart failure is treated with diuretics (diuril, lasix, etc) (to eliminate fluid) and digoxin (a heart drug to improve heart muscle contractions). Arrhythmias may be treated with medication or catheter ablation (see figures 3b, 11).

Repair or replacement of TV in conjunction with closure of the interatrial communication is recommended in older patients with severe symptoms despite medical therapy and heart enlargement.

Brickner,M.E. and others,Congenital Heart Disease in Adults,N.Engl.J.Med.,Vol.342.N4,2000,pp.334-342

 

c) Transposition of the Great Arteries

In d-transposition of the great arteries, the aorta arises in an anterior position from RV and the pulmonary artery arises from LV (see figure 23f). In two thirds of cases the ductus arteriosus (see figure 22) and foramen ovale allow communication between the aortic and pulmonary circulations. Severe cyanosis is present. The one third with other defects that permit intracardiac mixing (i.e. ASD figures 112a and 112b, VSD figure 112c, PDA figure 22) are less critically ill with loss of severe cyanosis, but they are at risk of LV failure.

Findings include cyanosis and heart murmur. RVH (increased RV wall thickness) or LVH (increased LV wall thickness) may be present. Chest X ray shows heart enlargement.

Immediate management involves creating intracardiac mixing or increasing its extent:
1) use of infusing of medication, prostaglandine E, to maintain or restore patency of ductus arterioses, 2) the creation of an ASD or both.

Also, oxygen is administered to most patients (to decrease pulmonary [lung] vascular (blood vessel) resistance and to increase lung blood flow), as are digoxin and diuretic drugs like diuril or lasix (to treat heart failure).

Two surgical operations have been used (see figure 23f regarding the atrial switch operation). The atrial switch operation as shown in figure 23f has been replaced by the arterial switch operation in which the pulmonary artery and ascending aorta are transected above the semilunar valves and coronary arteries (see figure 23i), and then switched, so that the aorta is connected to the neoaortic valve (formerly the pulmonary valve) arising from the left ventricle (LV), and the pulmonary artery is connected to the neopulmonary valve (formerly the aorta valve) arising from the RV (see figure 23i). The coronary arteries are relocated to the neoaorta to restore normal coronary circulation. This operation can be performed in neonates (newly born) and is associated with a low operative mortality and an excellent long-term outcome.

Brickner,M.E. and others,Congenital Heart Disease in Adults,N.Engl.J.Med.,Vol.342.N4,2000,pp.334-342

 

The Arterial Switch Operation


Surgical Repair of d-Transposition of the Great Vessels Arterial switch operation for d-TGA with intact ventricular septum

Cardiopulmonary bypass can be conducted in a number of ways, depending on the surgeon's preference or the time required to accomplish complete repair, particularly in the presence of a ventricular septal defect or other anomalies such as coarctation of the aorta or a hypoplastic or interrupted aortic arch. In a patient with D-transposition of the great arteries and an intact ventricular septum, the operation is preferably performed with the patient under either total circulatory arrest or continuous low-flow (50 ml/kg/min) hypothermic perfusion, limiting circulatory arrest time to the few minutes necessary to close the atrial septal defect. In the presence of a ventricular septal defect or other complex associated lesions, two periods of deep hypothermic circulatory arrest are used, interposing 10 to 15 minutes of hypothermic reperfusion is between them, or the arterial switch itself may be performed under continuous low-flow cardiopulmonary bypass, with profound hypothermic circulatory arrest for closure of the ventricular septal defect and other procedures such as repair of an interrupted aortic arch.

Stage I: Preparation

o Aprotinin, solumedrol (30 mg/kg), Regitine (0.1 mg/kg), and prophylactic antibiotics are given preoperatively.
o The sternum is opened, the patient heparinized, and a large segment of pericardium is harvested and prepared with 0.6% glutaraldehyde.
o The coronary arteries and great vessels are inspected.
o The arterial duct is dissected free, as are the left and right pulmonary arteries, including the first pulmonary artery branches in the hilum of each lung. The right pulmonary artery can be dissected prior to bypass, and the left dissected while on bypass.
o The ascending aorta is cannulated as far distally as possible to allow adequate length for the aortic anastomosis. A single venous cannula is placed within the right atrium. The left ventricle is vented with a catheter placed in the right superior pulmonary vein.

Stage II: Cardiopulmonary

o Cardiopulmonary bypass is begun, and the patient cooled for a minimum of 20 minutes to 20°C rectal temperature.
o The arterial duct is doubly ligated and divided, and the branch pulmonary arteries are completely mobilized.
o The site of aortic transection is marked before the cross clamp is applied. This is just distal to the pulmonary artery bifurcation, as best judged by the take-off of the left pulmonary artery.
o At 20°C rectal temperature, the distal ascending aorta is clamped, and cold blood cardioplegia is delivered into the proximal ascending aorta.
o The aorta is divided at the previously marked site, and the main pulmonary artery is divided just proximal to its bifurcation.
stage, adhesions do not usually present a problem. In the unusual situation in which the origin of the left coronary artery cannot be visualized after the banding, the arterial switch operation is deferred (for about 12 months) at which time clear delineation of the coronary anatomy can be made by coronary arteriography and/or magnetic resonance imaging.
o The aortic and pulmonary valves are careftilly inspected, as is the presence of left ventricular outflow tract obstruction.
o The Lecompte maneuver is performed, and the pulmonary artery is held in position anterior to the ascending aorta by moving the aortic cross clamp.
o The anterior commissure of the neoaorta is marked with a silk suture. Alternatively, the exact positions of the implantation sites are identified by juxtaposing the explanted coronary arteries or by placing marking sutures before cardiopulmonary bypass, when the aortic and pulmonary roots are distended.

Stage III: Coronary Transfer

o The ostium, the initial course of the left and right coronary arteries, and the presence of infundibular branches are identified.
o The coronary ostia are excised along with a large segment of surrounding aortic wall, extending the incision well into the base of the sinus of Valsalva.
o The proximal coronary arteries are mobilized sufficiently to avoid tension or distortion. Infundibular branches are very rarely sacrificed.
o The distal aorta is anastomosed to the proximal neoaorta with a continuous 6-0 Prolene or Maxon.
o The coronary implantation sites are prepared by making a neoaortotomy into the left and right anterior aspects of the neoaorta while the aortic cross-clamp is temporarily removed, angling the incisions from posterior to anterior, and using the commissural marking stitch as a guide.
o The coronary ostia are transferred by sewing the coronary flaps to these incisions with a continuous 7-0 Maxon suture.

o When the circumflex coronary artery arises from the right coronary artery, the site of right coronary implantation must be placed either higher than usual on the proximal neoaorta or, occasionally, above the suture line on the distal ascending aorta to avoid distortion of the circumflex artery.
o Adequate mobilization of the right coronary artery is frequently necessary to avoid distortion of the circumflex coronary artery. If the two coronary arteries originate from the same sinus, they can often be included in the same aortic flap (provided there is not an intramural course for one of the coronaries).
o If the coronary ostia are located closely adjacent (paracommissural) to the posterior commissure, excision of a segment of the posterior commissure of the native aortic valve (neopulmonary valve) is often necessary; the resultant neopulmonary regurgitation is generally mild and well tolerated.

Stage IV: Circulatory Arrest

o At this point, the pump is turned off and the venous cannula removed. The atrial communication is closed through a right atriotomy, which, as a rule, can be accomplished by suture closure after balloon septostomy, as there is usually no tissue deficiency.

Stage V: Right Ventricular Outflow Reconstruction

o The atriotomy is closed, and the aortic and venous cannula replaced.
o Cardiopulmonary bypass is resumed and the aortic cross-clamp removed.
o The left ventricular vent is turned on.o The aortic and pulmonary valves are careftilly inspected, as is the presence of left ventricular outflow tract obstruction.
o The Lecompte maneuver is performed, and the pulmonary artery is held in position anterior to the ascending aorta by moving the aortic cross clamp.
o The anterior commissure of the neoaorta is marked with a silk suture. Alternatively, the exact positions of the implantation sites are identified by juxtaposing the explanted coronary arteries or by placing marking sutures before cardiopulmonary bypass, when the aortic and pulmonary roots are distended.

Stage III: Coronary Transfer

.The ostium, the initial course of the left and right coronary arteries, and the presence of infundibular branches are identified.
.The coronary ostia are excised along with a large segment of surrounding aortic wall, extending the incision well into the base of the sinus of Valsalva.
.The proximal coronary arteries are mobilized sufficiently to avoid tension or distortion. Infundibular branches are very rarely sacrificed.
.The distal aorta is anastomosed to the proximal neoaorta with a continuous 6-0 Prolene or Maxon.
.The coronary implantation sites are prepared by making a neoaortotomy into the left and right anterior aspects of the neoaorta while the aortic cross-clamp is temporarily removed, angling the incisions from posterior to anterior, and using the commissural marking stitch as a guide.
.The coronary ostia are transferred by sewing the coronary flaps to these incisions with a continuous 7-0 Maxon suture.

. When the circumflex coronary artery arises from the right coronary artery, the site of right coronary implantation must be placed either higher than usual on the proximal neoaorta or, occasionally, above the suture line on the distal ascending aorta to avoid distortion of the circumflex artery.
o Adequate mobilization of the right coronary artery is frequently necessary to avoid distortion of the circumflex coronary artery. If the two coronary arteries originate from the same sinus, they can often be included in the same aortic flap (provided there is not an intramural course for one of the coronaries).
o If the coronary ostia are located closely adjacent (paracommissural) to the posterior commissure, excision of a segment of the posterior commissure of the native aortic valve (neopulmonary valve) is often necessary; the resultant neopulmonary regurgitation is generally mild and well tolerated.

Stage IV: Circulatory Arrest

.At this point, the pump is turned off and the venous cannula removed. The atrial communication is closed through a right atriotomy, which, as a rule, can be accomplished by suture closure after balloon septostomy, as there is usually no tissue deficiency.

Stage V: Right Ventricular Outflow Reconstruction

.The atriotomy is closed, and the aortic and venous cannula replaced.
.Cardiopulmonary bypass is resumed and the aortic cross-clamp removed.
.The left ventricular vent is turned on.
.Full-flow and rewarming are begun. An additional dose of Regitine 0.1 mg/kg is given in the pump.
.The coronary explantation sites in the neopulmonary artery are then filled, using a single, long, inverted bifurcated patch of 0.6% glutaraldehyde-pretreated, autologous pericardium. An incision is made into the pericardium to fit into the posterior commissure, and the free pericardial edge is sutured to the area of the aorta (neopulmonary artery) corresponding to the explanted coronary flaps, using a continuous 6-0 suture. When the anterior remnant of the aortic wall is reached, the pericardium, at this point cylindrically shaped, is tailored to bridge the distance between the proximal neopulmonary artery and the distal pulmonary artery without tension. Discrepancies in caliber between the proximal neopulmonary artery and the distal pulmonary artery are reconciled with this pericardial extension.
o Alternatively, two separate pericardial patches can be used, one for the site of each coronary donor.
o The relationship of the great vessels will require other certain modifications. With side-by-side great vessels, for example, a Lecompte maneuver is not always performed, and the central stoma in the transverse pulmonary artery is moved to the right pulmonary artery.
o The proximal neopulmonary artery is anastomosed to the bifurcation of the native pulmonary artery. Some authors prefer to place the bifurcated pericardial patch as the first maneuver after removing the coronary arteries from the aorta and before coronary reimplantation in some cases.

Stage IV: Completing the Operation

. Pleural tubes, along with left atrial, right atrial, and pulmonary artery lines are placed and secured, as are atrial and ventricular temporary pacemaker leads. Ventilation is resumed, and the patient is weaned off cardiopulmonary bypass. Neuromuscular blockade, continuous fentanyl sedation, mechanical ventilation, and moderate inotropic support are customarily maintained during the first 12 to 18 hours or until hemodynamic stability is achieved.


Rapid Two-Stage Repair of d-TGA with intact ventricular septum

The First Stage

Through either a right thoracotomy or a midline sternotomy, a 3.5- or 4-mm polytetrafluoroethylene (GoreTex) graft is used to connect the right subclavian artery to the right pulmonary artery. Subsequently, and after minimal dissection, a Dacron-reinforced Silastic band is tightened around the main pulmonary artery to achieve a left ventricular pressure that is approximately 75% of systemic pressure. The pericardium is then loosely closed after thoroughly irrigating the pericardial space with heparinized saline to flush out any residual blood or fibrin clots.

The Second Stage

The only modification required relative to the standard operative approach for the arterial switch operation is to first divide and oversew the modified Blalock-Taussig shunt, and to remove the pulmonary artery band. Because the second stage is carried out an average of 7 days after the first stage,adhesions do not usually present a problem. In the unusual situation in which the origin of the left coronary origin cannot be visualized after the banding,the arterial switch operation is deferred( for about 12 months) at which time clear delineation of the coronary anatomy can be made by coronary arteriography and /or magnetic resonance imaging.

Repair of d-TGA with ventricular septal defect and left ventricular outflow tract obstruction

The conventional treatment for neonates and infants with D-transposition of the great arteries, a ventricular septal defect, and hemodynamically significant left ventricular outflow tract obstruction has been an initial Blalock-Taussig shunt. However, either direct relief of the obstruction is attempted, accompanied by ventricular septal defect closure and an arterial switch operation, or, in the case of a long-segment hypoplastic left ventricular outflow tract obstruction or valvar pulmonary stenosis, a Rastelli operation using a cryo-preserved valved aortic or pulmonary homograft is performed (particularly in the neonate or young infant in whom the severe cyanosis is due in part to poor mixing, in spite of the possibility of adequate or even over circulation of the pulmonary vascular bed).

Arterial switch operation, ventricular septal defect closure, and direct resection of LVOTO

The occasional discrete subpulmonary membrane or excrescence of endocardial cushion tissue is easily resected through the posterior (pulmonary) semilunar valve. More common, and surgically more demanding, is left ventricular outflow tract obstruction caused by a posteriorly deviated outlet septum.

Once the ascending aorta and main pulmonary artery are divided in the course of an arterial switch operation, the obstructing muscle is more safely exposed through the pulmonary semilunar valve. Although exposure of the outlet septum is often easier through the anterior (aortic) semilunar valve, in patients with D-transposition of the great arteries, incision and excision of the outlet septum via the aortic valve run the risk of damaging the pulmonary valve, because the pulmonary semilunar valve originates at a lower level than the aortic semilunar valve. Therefore, the trans-pulmonary approach allows a more aggressive excision of the posteriorly deviated outlet septum, at the same time leaving sufficient muscle to anchor the ventricular septal patch. It helps to engage the outlet septum with a skin hook and to deliver it further into the left ventricular outflow tract before excising the muscle mass.

Rastelli operation for d-TGA

Often, in the case of a long, hypoplastic left ventricular outflow tract, resection is not feasible. In such cases a Rastelli operation is preferred to a palliative shunt operation, regardless of the patient's age. After opening the chest through a midline sternotomy, an appropriate-size valved homograft (aortic or pulmonary) is selected, usually varying in size from 9 mm for a neonate to 14 mm for an older infant. In addition, a patch of pericardium is harvested and pretreated with 0.6% glutaraldehyde for later use to augment the anastomosis from the right ventricle to the homograft. Depending on the age and size of the child, either circulatory arrest or cardiopulmonary bypass with low-flow hypothermic perfusion is used. The main pulmonary artery commonly lies posterior and to the left of the ascending aorta, and its branches are dissected and the ligamentum arteriosum divided. If continuous cardiopulmonary bypass is used, the aorta is cross clamped at 25°C, and cold cardioplegia is injected. A vertical right ventriculotomy is then made to expose the aortic valve, the ventricular septal defect and the tricuspid valve. Unless the malaligned septal defect is larger than the diameter of the aortic valve, it is enlarged by making two incisions (at 2 o'clock and 4 o'clock) into the anterosuperior limb of the septal band. The intervening muscle is excised. This maneuver is important to achieve an unobstructed pathway between the left ventricle and the aorta. Interrupted horizontal mattress sutures, reinforced with Teflon pledgets, are placed first along the posteroanterior rim of the defect in a manner similar to the technique used for closure of a malaligned ventricular septal defect in tetralogy of Fallot. Additional interrupted stitches are then placed within the remaining circumference of the pathway from the left ventricle to the aortic valve. A baffle is then tailored from a tubular Dacron conduit (retaining approximately 50% of the circumference of the conduit), measuring the distance from the enlarged ventricular septal defect to the aortic valve rim. The sutures placed along the anterior border of the ventricular septal defect and the posteroanterior aspect of the ventricular defect are first threaded through the Dacron baffle and then tied in place. This partial fixation of the baffle offers the opportunity for adjustments in its length or width. The remainder of the sutures are then passed through the Dacron patch and tied. The Dacron baffle should contribute approximately 50% to the circumference of the pathway from the left ventricle to the ascending aorta, the remainder being composed of the patient's own tissue. Next, either the aortic or the pulmonary valve homograft is prepared to cover the distance between the distal main and proximal left pulmonary artery and the right ventriculotomy. To avoid extrinsic compression of the homograft, the conduit is aligned along the left heart border; the left mediastinal pleura is opened to gain additional space for the conduit. After doubly ligating the main pulmonary artery proximally, the distal conduit-to-pulmonary artery anastomosis is fashioned with a 6-0 continuous suture. At this point the aortic cross clamp is removed. During rewarming, the anastomosis between the right ventricle and the homograft is begun at the most distal part of the ventriculotomy incision and is extended to include approximately 50% of the circumference of the proximal homograft stoma. At that point, the glutaraldehyde-preserved pericardial patch is sewn to the remaining part of the right ventriculotomy and to the free edge of the proximal homograft. This technique eliminates distortion of the anastomosis and ensures unobstructed flow through the homograft. After the air is vented and effective cardiac action has resumed, the infant is weaned from cardiopulmonary bypass. Catheters are routinely placed in the left and right atria and also in the trans-homograft pulmonary artery for postoperative monitoring.

The Arterial Switch Operation for Double Outlet Right Ventricle

An arterial switch operation is indicated for double outlet right ventricle which is at the dtransposition end of the spectrum - when there is little to no pulmonary or subpulmonary stenosis. It may be possible to resect muscular or fibrous tissue from the subpulmonary region as long as there is no important straddling mitral valve chordae. Similarly, a bicuspid pulmonary valve should not be considered an absolute contraindication to an arterial switch, particularly since both an atrial inversion procedure or a complex intraventricular repair with a conduit may result in a lesser quality of life

The general principles of the arterial switch operation for double outlet right ventricle are identical to those employed in the operation for d-transposition. The procedure is generally performed using low-flow hypothermic bypass for the extracardiac portion of the procedure while the intracardiac steps (i.e., closure of the atrial and ventricular septal defects) are conveniently performed during a period of circulatory arrest. Division of the great arteries is followed by inspection of the pulmonary valve and left ventricular outflow tract to ensure that there is no important outflow tract obstruction that might increase the risks from an arterial switch. Coronary mobilization and transfer are performed, followed by the aortic anastomosis. It is preferable not to undertake closure of the intracardiac communications before these steps are taken, as they will allow venting of left heart

The Arterial Switch Operation for Double Outlet Right Ventricle

An arterial switch operation is indicated for double outlet right ventricle which is at the dtransposition end of the spectrum - when there is little to no pulmonary or subpulmonary stenosis. It may be possible to resect muscular or fibrous tissue from the subpulmonary region as long as there is no important straddling mitral valve chordae. Similarly, a bicuspid pulmonary valve should not be considered an absolute contraindication to an arterial switch, particularly since both an atrial inversion procedure or a complex intraventricular repair with a conduit may result in a lesser quality of life

The general principles of the arterial switch operation for double outlet right ventricle are identical to those employed in the operation for d-transposition. The procedure is generally performed using low-flow hypothermic bypass for the extracardiac portion of the procedure while the intracardiac steps (i.e., closure of the atrial and ventricular septal defects) are conveniently performed during a period of circulatory arrest. Division of the great arteries is followed by inspection of the pulmonary valve and left ventricular outflow tract to ensure that there is no important outflow tract obstruction that might increase the risks from an arterial switch. Coronary mobilization and transfer are performed, followed by the aortic anastomosis. It is preferable not to undertake closure of the intracardiac communications before these steps are taken, as they will allow venting of left heart return to the single right atrial cannula. The single cannula is preferred to two caval cannulae for the same reason, as well as for the improved exposure provided by one cannula as compared with two.

The ventricular septal defect may be approached through the anterior semilunar valve, through the right atrium, or through a right ventriculotomy, as determined by the specific anatomic situation. Often there is some element of subaortic narrowing, so a right ventricular infundibular incision serves a dual purpose: access for closure of the ventricular septal defect and access for placement of an infundibular outflow patch to relieve outflow tract obstruction Approach through the semilunar valve or ventriculotomy often allows continuation of bypass throughout closure of the ventricular septal defect. The atrial septal defect is closed through a short, low right atriotomy, with the left heart filled with saline to exclude air before tying the suture.

With bypass re-established, the aortic cross clamp is released. Perfusion of all areas of the myocardium is checked. A single large pericardial patch is used to reconstruct the coronary donor areas, although to obtain optimal exposure, this step may be performed before the intracardiac steps. It is important that the pericardial patch actually supplement the neopulmonary artery (i.e., the patch needs to be quite a bit larger than the excised coronary buttons, because the aorta is frequently somewhat smaller than the pulmonary artery, particularly if there is a long and somewhat narrow subaortic conus). The pulmonary anastomosis is fashioned, and the patient is weaned from bypass. Specific variations of the arterial switch operation for double outlet right ventricle include:

Coronary patterns.

Unusual coronary patterns are much more common with side-by-side great arteries than in standard transposition with anteroposterior great arteries. A common pattern is an anterior origin of the right and left anterior descending coronary arteries from a single ostium, with the circumflex originating from a posterior facing sinus. Extensive mobilization of the right coronary is necessary to prevent tethering of the anterior coronary, which must be transferred directly away from the line of the right coronary. Infundibular and right ventricular free wall branches of the right and anterior descending coronaries should be extensively mobilized from their epicardial beds to prevent tension on the arteries and on the anastomosis. On occasion, an autologous pericardial tube extension of the coronary artery can be used to avoid excessive tension. Excessive tension will be manifested by persistent bleeding from the coronary anastomosis and early or late coronary insufficiency. Another common coronary pattern with side-by-side great arteries is origin of the right and circumflex coronaries from the posterior sinus, with the left anterior descending artery originating from the anterior-facing sinus. It is important to guard against compression of the anteriorly transferred coronary by the posterior wall of the main pulmonary artery.

Closure of the ventricular septal defect.

Exposure of the ventricular septal defect associated with double outlet right ventricle may present special difficulties. The defect may be quite leftward and anterior in what almost appears, from the surgeon's perspective, to be a separate, leftward, blind-ending infundibular recess Exposure through the anterior semilunar valve and right atrium is particularly difficult, and even through a right ventriculotomy it may not be easily seen. Although exposure may be achieved through the original pulmonary valve, this is usually not recommended because of the risk of damage to the conduction system and the neoaortic valve. An additional complication to ventricular septal defect closure in this setting is the tendency for the very leftward ventricular septal defect to extend into the anterior trabeculated septum - that is, there appears to be no clear leftward and anterior margin to the defect. By taking large bites with pledgetted sutures, the size of any residual ventricular septal defect can be minimized. Catheter-delivered devices have been useful for ultimate closure of residual ventricular septal defects in this area.

Multiple ventricular septal defects.

Surgical closure of multiple muscular ventricular septal defect as well as large subpulmonary ventricular septal defect may be difficult and may consume an excessive amount of circulatory arrest time. One approach to this problem is intraoperative delivery o a double-clamshell device. After division of the two great vessels, an excellent view is obtained of both sides of the ventricular septum. The sheath loaded with the device is introduced through the right atrium and tricuspid valve into the right ventricle A right-angled instrument is passed through the original pulmonary valve into the left ventricle through the ventricular septal defect, and into the right ventricle, where it grasps the delivery pod The pod is drawn into the left ventricle, and the lei ventricular arms are released under direct vision The pod is then carefully pulled back into the right ventricle, and, viewing through the original aortic valve into the right ventricular arms are released. If necessary, multiple devices may be placed. Although this system has worked well for children weighing more than 4 to 5 kg, the delivery pod requires further modification for neonates and infants weighing less than 4 kg.

Pulmonary artery anastomosis.

Although the Lecompte maneuver is uniformly useful for patients with standard transposition in which the great arteries are positioned antero-posteriorly (or relatively close to this), for side-by-side great arteries judgment is required in deciding whether translocation of the right pulmonary artery anterior to the aorta will be useful in decreasing tension on the right pulmonary artery. In general, if the aorta is the slightest bit anterior to the pulmonary artery a Lecompte maneuver should be performed. Another consideration in this decision, other than just the tension on the right pulmonary artery, is the relationship of the transferred coronary arteries to the pulmonary artery. Care must be taken to ensure that there is no compression of the coronary arteries. A useful maneuver to minimize the risk of coronary compression, as well as to decrease the tension on the pulmonary artery anastomosis, is to shift the anastomosis somewhat from the original distal divided main pulmonary artery into the right pulmonary artery. The leftward end of the main pulmonary artery is closed (usually by direct suture, although the pericardial patch used to fill the coronary donor areas may be extended here), and the orifice is extended into the right pulmonary artery. In other respects the anastomosis is performed in the usual fashion. This maneuver has the effect of shifting the main pulmonary artery rightward so that it will not lie anterior to the aorta where it would likely cause compression of the anteriorly transferred coronary artery.

Repair of subaortic stenosis and arch anomalies.

The long subaortic conus associated with double outlet right ventricle toward the D-transposition end of the spectrum may cause some degree of subaortic stenosis. Not surprisingly, aortic arch hypoplasia and coarctation often accompany such subaortic stenosis. There is likely to be considerable disparity between the diameters of the great vessels. During the preliminary phase of the arterial switch procedure tourniquets should be loosely applied around the head vessels. The coronary transfer should be undertaken in the usual fashion, using low-flow bypass. The circulation is then arrested, the tourniquets are tightened, and the aortic cross clamp is removed. An incision is made along the lesser curve of the ascending aorta and arch, extending across the coarctation. A long patch of pericardium is sutured into this aortotomy, which serves to minimize the disparity between the proximal neoaorta and the distal ascending aorta. The aortic cross clamp is reapplied, and bypass may be recommended. The remainder of the procedure is undertaken as described previously. Coarctation repair and pulmonary artery banding are not favored as preliminary maneuvers.

http://www.pediheart.org/practitioners/operations/ASO.html

d) Eisenmenger's Syndrome

This consist of a large left (L) to right (R) shunt, which causes severe pulmonary (lung) vascular disease and high blood pressure (in the lungs) with resulting reversal of the direction of shunting (figure 23j). This shunting with increase pressure causes the lung arteries to narrow due to thickening of their walls (especially the middle wall, called tunica media, (see figure 23j) and cause obstruction. Initially the changes may be reversible, but ultimately they become irreversible due to inflammation of the arteries. Hence, much of the lung arteries are occluded, leading to increase pulmonary blood vessel resistance. Ultimately the resistance in the lungs may exceed the resistance in the arteries of the rest of the body, which leads to a reversal of flow from left-to-right to right-to-left shunt.

The reversal of the shunt leads to cyanosis, as well as shortness of breath, coughing up blood, reduced exercise tolerance, syncope (fainting), palpitations, and atrial fibrillation (see figures 15A, 15B). Brain events such paradoxical embolus, thrombosis (stroke) and hemorrhage may occur. Heart failure suggest a poor prognosis, and sudden death is possible.

Digital swelling (clubbing) may occur. Heart murmurs may occur.

EKG may show RVH and atrial arrhythmias (see figures 2, 3a, 5a, 5b, 14, 15a, 15b).

Echocardiogram shows RV pressure overload, pulmonary high blood pressure, and the underlying heart defect. Using intravenous contrast injections along with echocardiogram will visualize the intracardiac defect. Heart catherterization is necessary to assess the lung hypertension and the size of the defect.

Rate of survival is 80% 10 years after diagnosis, 77% at 15 years, and 42% at 25 years. Death is usually sudden, presumably due to arrhythmias, but some die of the above mentioned complications.

Lung transplantation with repair of the cardiac or combined heart-lung transplantation is an option for patients with a poor prognosis (failing to respond to medical therapy).

Brickner,M.E. and others,Congenital Heart Disease in Adults,N.Engl.J.Med.,Vol.342.N4,2000,pp.334-342

 

e) Hypoplastic Left Heart Syndrome (Article by P.Syamasundar Rao,MD and Others, E-Medicine from WebMD, August 15,2006,Pages 1-24).

Hypoplastic Left Heart Syndrome

Background:

Hypoplastic left heart syndrome (HLHS) describes a spectrum of cardiac abnormalities characterized by marked hypoplasia of the left ventricle and ascending aorta(see figures and video clips below). The aortic and mitral valves are atretic, hypoplastic, or stenotic (figures 44g-1, 44g-2 and figure 23a). The ventricular septum is usually intact. A large patent ductus arteriosus supplies blood to the systemic circulation. Systemic desaturation may be present because of complete mixing of pulmonary and systemic venous blood in the right atrium via an atrial septal defect or patent foramen ovale. Coarctation of the aorta commonly coexists (figure 23a).

Figure 44g-3: HLHS 4 chamber echocardiographicview slide showing the small left ventricle (star), the large right atrium, right ventricle and the left atrium.

 

Figure 44g-4: Still frame long axis view of aortic arch showing the small ascending aorta and arch serving only to deliver blood in a retrograde fashion to the coronary arteries, an echobright coarctation shelf is seen at the insertion of the ductus arteriosus.

 

Figure 44g-4: Echocardiograhic view of small undeveloped ascending aorta in HLH.

 

Figure 44g-5: Hypoplastic left heart syndrome in a fetus with a cephalic presentaton, Transabdominal US image(four-chamber view) shows that the left ventricle is small relative to the right ventricle and the left atrium is small relative to the right atrium. Arrow= spine.

 

Figure 44g-6: Large right atrium and ventricle compared to the left side. (From Dr. Philippe Jeanty and others, 2004).

 

Figure 44g-7: HLHsyndrome. From Dr. Philippe Jeanty, 1999.

 

Figure 44g-8: HLH with VSD change. From Dr. Philippe Jeanty, 1999.

Hypoplastic left heart syndrome is a uniformly lethal cardiac abnormality if not surgically corrected. In 1979, Norwood performed the first successful surgical palliation on a neonate. Currently, this approach consists of a series of 3 operations: the Norwood procedure (stage I), the hemi-Fontan or bidirectional Glenn procedure (stage II), and the Fontan procedure (stage III). Orthotopic heart transplantation provides an alternative therapy, with results similar to those of the staged surgical palliation. Currently, the survival rate of infants treated with these surgical approaches is similar to that of infants with other complex forms of congenital heart disease in which a 2-ventricle repair is not possible.

Pathophysiology:

The newborn infant with hypoplastic left heart syndrome has a complex cardiovascular physiology. Fully saturated pulmonary venous blood returning to the left atrium cannot flow into the left ventricle because of atresia, hypoplasia, or stenosis of the mitral valve. Therefore, pulmonary venous blood must cross the atrial septum and mix with desaturated systemic venous blood in the right atrium. The right ventricle then must pump this mixed blood to both the pulmonary and the systemic circulations that are connected in parallel, rather than in series, by the ductus arteriosus. Blood exiting the right ventricle may flow (1) to the lungs via the branch pulmonary arteries or (2) to the body via the ductus arteriosus and descending aorta. The amount of blood that flows into each circulation is based on the resistance in each circuit.

Blood flow is inversely proportional to resistance (Ohm law); that is, when resistance in blood vessels decreases, blood flow through these vessels increases. Following birth, pulmonary vascular resistance decreases, which allows a higher percentage of the fixed right ventricular output to go to the lungs instead of the body. Although increased pulmonary blood flow results in higher oxygen saturation, systemic blood flow is decreased. Perfusion becomes poor, and metabolic acidosis and oliguria may develop. Coronary artery and cerebral perfusion also are dependent on systemic blood flow through the ductus arteriosus. Therefore, increased pulmonary blood flow results in decreased flow to the coronary arteries and brain, with a risk of myocardial or cerebral ischemia.

Alternatively, if pulmonary vascular resistance is significantly higher than systemic vascular resistance, systemic blood flow is increased at the expense of pulmonary blood flow. This may result in profound hypoxemia. A careful delicate balance between pulmonary and systemic vascular resistance ensures adequate oxygenation and tissue perfusion.

Hypoplastic left heart syndrome with color to show various degrees of oxgenated blood in various chambers of heart

Most patients with hypoplastic left heart syndrome also demonstrate coarctation of the aorta (figure 23a). This can be significant enough to interfere with retrograde flow to the proximal aorta.

Frequency:

* In the US: Incidence of hypoplastic left heart syndrome is 0.16-0.36 per 1000 live births. Hypoplastic left heart syndrome accounts for 7-9% of all congenital heart disease diagnosed in the first year of life. Before surgical treatment was available, hypoplastic left heart syndrome was responsible for 25% of cardiac deaths in the neonatal period. The rate of occurrence is increased in patients with Turner, Noonan, Smith-Lemli-Opitz, or Holt-Oram syndrome. Certain chromosomal duplications, translocations, and deletions also are associated with hypoplastic left heart syndrome.

* Internationally: Frequency is similar to that in the United States.

Mortality/Morbidity:

* Without surgery, hypoplastic left heart syndrome is uniformly fatal usually within the first 2 weeks of life. Survival for a longer period occurs rarely and only with persistence of the ductus arteriosus.

* Following the Norwood procedure (stage I), overall success (survival to hospital discharge) is approximately 75%. Success rates are higher (85%) in patients with low preoperative risk and lower (45%) in patients with important risk factors. Some centers have reported stage I survival rates in excess of 90%. This appears to be related, in part, to institutional surgical volume. The overall success following the hemi-Fontan procedure (stage II) approaches 95%. Success after completing the Fontan procedure (stage III) approaches 90%. Orthotopic heart transplantation results in early and long-term success similar to that of staged reconstruction. Among low-risk patients who undergo staged reconstruction or transplantation, actuarial survival at 5 years is approximately 70%.

* Most studies report neurodevelopmental disabilities in a significant number of patients who survive either staged surgical reconstruction or cardiac transplantation.

Sex:

Hypoplastic left heart syndrome is more common in males than in females, with a 55-70% male predominance.

Age:

Hypoplastic left heart syndrome typically presents within the first 24-48 hours of life. Presentation occurs as soon as the ductus arteriosus constricts, thereby decreasing systemic blood flow, producing shock, and, without intervention, causing death. Infants with pulmonary venous obstruction (absent or restrictive patent foramen ovale) may present sooner. Very rarely, an infant with persistence of high pulmonary vascular resistance and the ductus arteriosus may present later because of balanced pulmonary and systemic blood flow.

History:

* Although hypoplastic left heart syndrome can easily be detected on fetal echocardiography (see below figures and video clips including fetal cardiovascular anatomy and standard 2D ultrasound examination of the heart, movie- 1, HLH, and ultrasound.zip item), many infants are not identified prenatally because routine obstetric ultrasound examination may not concentrate on cardiac anatomy. Pregnancies are typically uncomplicated, and fetal echocardiography is not indicated routinely. The fetus grows and develops normally because the fetal circulation is not altered significantly. Most neonates are born at term and initially appear normal.

Fetal Echocardiography by Gregory R. DeVore, M.D. describing cardiovascular anatomy, and standard two dimensional ultrasound examination of the heart, including some abnormal conditions.

Video clip 1: Fetal echocardiogram showing a four chamber view of the heart with the aorta and pulmonary arteriy visualized.

 

 

Video clip 2: HLH:

 

 

 

 

Ultrasound video clip: From Phillipe Jeanty,M.D., PhD, Chiatali Shah,M.D., Crine Jeanty: Hypoplastic Left Heart Syndrome at www.The fetus.net showing the smaller left ventricle , the markedly reduced size of the ascending aorta, the normal pulmonary artery and the normal right ventricle, the enlarged right atrium and smaller left artium.

* Occasionally, respiratory symptoms and profound systemic cyanosis are apparent at birth (2-5% of cases). In these infants, significant obstruction to pulmonary venous return (a congenitally small or absent patent foramen ovale) is usually present.

* As the ductus arteriosus begins to close normally over the first 24-48 hours of life, symptoms of cyanosis, tachypnea, respiratory distress, pallor, lethargy, metabolic acidosis, and oliguria develop. Without intervention to reopen the ductus arteriosus, death rapidly ensues.

Physical:

* Before the initiation of prostaglandin E1 infusion to reestablish patency of the ductus arteriosus, infants exhibit signs of cardiogenic shock, including the following:

o Hypothermia

o Tachycardia

o Respiratory distress

o Central cyanosis and pallor

o Poor peripheral perfusion with weak pulses in all extremities and in the neck

o Hepatomegaly

* After reestablishment of systemic blood flow via the ductus arteriosus, signs of shock resolve, leaving the stable infant with tachycardia, tachypnea, and mild central cyanosis. If a coarctation of the aorta is present, arterial pulses in the legs may be more prominent than those in the arms, particularly the right arm.

* Cardiac examination

o Palpable right ventricular impulse

o Normal first heart sound

o Loud single second heart sound

o Nonspecific, soft, systolic ejection murmur at the left sternal border (not always present)

o High-pitched holosystolic murmur at the lower left sternal border, indicating tricuspid regurgitation (not always present)

o Diastolic flow rumble over the precordium, indicating increased right ventricular diastolic filling (not always present)

Causes:

* The exact cause of hypoplastic left heart syndrome is unknown. Most likely, the primary abnormality occurs during aortic and mitral valve development. During cardiac development, adequate flow of blood through a structure is largely responsible for the growth of that structure. With little or no blood flow because of aortic and mitral valve atresia, growth of the left ventricle does not occur.

* Similarly, growth of the ascending aorta does not occur because of lack of left ventricular output. The ascending aorta is perfused in retrograde manner from the ductus arteriosus functioning only as a common coronary artery.

* Premature closure or absence of the foramen ovale represents another theoretical cause of hypoplastic left heart syndrome, as it eliminates fetal blood flow from the inferior vena cava to the left atrium. Fetal pulmonary blood flow is not sufficient for normal development of the left atrium, left ventricle, and ascending aorta.

DIFFERENTIAL DIAGNOSIS:

Aortic Stenosis, Valvar
Atrioventricular Septal Defect, Unbalanced
Cardiac Tumors
Coarctation of the Aorta
Interrupted Aortic Arch
Myocarditis, Viral
Total Anomalous Pulmonary Venous Connection


Other Problems to be Considered:


Associated cardiac abnormalities

Anomalous pulmonary venous connection
Coarctation of the aorta
Complete atrioventricular canal
Coronary artery abnormalities (especially in patients with aortic atresia and mitral stenosis)
Persistent left superior vena cava
Endocardial fibroelastosis (especially in patients with aortic atresia and mitral stenosis)

Associated noncardiac abnormalities

Genetic disorders

Significant noncardiac abnormalities

Central nervous system malformation
Diaphragmatic hernia
Necrotizing enterocolitis

Lab Studies:

* Complete blood count

o Measure hemoglobin levels, because severe neonatal anemia can cause high-output congestive heart failure (CHF) and cardiogenic shock. The hemoglobin level is usually normal.

o Obtain a total white blood cell (WBC) count with differential. Sepsis can cause symptoms of shock. The WBC count is typically normal.

* Electrolytes

o Electrolyte abnormalities may be present in infants with poor oral intake secondary to CHF. Use carbon dioxide to assess acid-base status.
o Electrolyte levels are usually normal. The carbon dioxide level may be low if a metabolic acidosis is present.

* BUN/creatinine

o Infants with critical illness and significantly reduced systemic perfusion may show evidence of renal failure.
o The creatinine may be elevated transiently.

* Liver function tests

o Infants with critical illness and significantly reduced systemic perfusion and CHF may show evidence of hepatocellular damage.
o Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels may be elevated transiently.

* Arterial blood gases and lactic acid

o Assessing acid-base status is paramount, especially to rule out metabolic acidosis. Most infants have some evidence of metabolic acidosis, which should be corrected immediately. Elevated levels of serum lactic acid generally precede a fall in pH, as acidosis develops.

o Assessment of PaO2 and PaCO2 is important for respiratory management and manipulation of pulmonary vascular resistance by mechanical ventilation and the addition of supplemental inhaled nitrogen. The PaO2 is optimally 30-45 mm Hg, and the PaCO2 is ideally 45-50 mm Hg.

* Ultrasound of the head

o An ultrasound of the head is necessary only if the infant has had a significantly long period in shock with potentially poor cerebral perfusion.
o Most often, no abnormalities are observed on the ultrasound scan of the head.

* Karyotype

o Chromosomal analysis is indicated for infants with dysmorphic features.
o Nearly 25% of infants have chromosomal abnormalities.

Imaging Studies:

* Chest radiograph

o Chest radiographic findings are not specific for hypoplastic left heart syndrome.
o Cardiomegaly and increased pulmonary venovascular markings are typically present.
o Marked pulmonary edema may be noted in infants with obstructed pulmonary venous return.

* Echocardiogram

o The echocardiogram is the test of choice for diagnosing hypoplastic left heart syndrome. Two-dimensional imaging clearly shows the hypoplastic left ventricle and ascending aorta. The right atrium, tricuspid valve, right ventricle, and main pulmonary artery are larger than usual.

o Other structural abnormalities should be excluded.

o Doppler and color Doppler imaging are also important.

o Evaluate tricuspid regurgitation, a preoperative risk factor for the Norwood procedure, and blood flow across the atrial septum. Observe retrograde blood flow from the ductus arteriosus into the transverse aortic arch and ascending aorta.

o Evaluate the aortic arch and thoracic aorta for evidence of coarctation.

Other Tests:

* Electrocardiogram

o The electrocardiogram typically shows sinus tachycardia, right-axis deviation, right atrial enlargement, and right ventricular hypertrophy with a qR configuration in the right precordial leads.

o A paucity of left ventricular forces is noted in the left precordial leads.

Procedures:

* Cardiac catheterization

o Pre?Norwood procedure
+ Routine diagnostic catheterization is not necessary because 2-dimensional and Doppler echocardiography can provide the necessary anatomic and hemodynamic data.
+ Perform interventional catheterization with blade/balloon atrial septostomy to relieve pulmonary venous hypertension if blood flow from left atrium to right atrium is severely restricted at the atrial septum.

o Pre?hemi-Fontan (stage II) procedure
+ Perform routine catheterization before the operation to obtain hemodynamic data and several important angiograms.
+ Calculate pulmonary vascular resistance to ensure the patient's suitability for the stage II procedure.
+ Perform an angiogram in the right ventricle to show ventricular function and tricuspid regurgitation.
+ Perform another angiogram in the transverse aortic arch near the shunt to show pulmonary artery size and distribution and to rule out recurrent aortic coarctation

? Perform another angiogram in the transverse aortic arch near the shunt to show pulmonary artery size and distribution and to rule out recurrent aortic coarctation or significant aortopulmonary collateral vessels.

? If collateral vessels are found, they may be occluded with coils at the same catheterization.

o Pre-Fontan (stage III) procedure
+ Accomplish routine catheterization before completing the operation.
+ Calculate pulmonary vascular resistance and perform a right ventricular angiogram.
+ Delineate pulmonary artery anatomy by performing an angiogram at the superior vena cava?pulmonary artery anastomosis via an internal jugular approach.
+ Recurrent coarctation of the aorta and significant collateral vessels are excluded again.

o Postcatheterization precautions include hemorrhage, vascular disruption after balloon dilation, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm.

TREATMENT:

Medical Care:

* Successful preoperative management depends on providing adequate systemic blood flow while limiting pulmonary overcirculation.
* Open the ductus arteriosus

o Blood flow to the systemic circulation (coronary arteries, brain, liver, kidneys) is dependent on flow through the ductus arteriosus. If a diagnosis is suspected, start prostaglandin E1 infusion immediately to establish ductal patency and ensure adequate systemic perfusion.
o If the diagnosis is made prenatally or when the infant is relatively asymptomatic, a smaller dose of prostaglandin E1 may be sufficient to keep the ductus arteriosus patent while limiting its side effects.
o A larger dose of prostaglandin E1 is often required to reopen the ductus arteriosus if an infant has cardiovascular collapse and shock due to ductal closure.
o Ideally, prostaglandin E1 is administered centrally via an umbilical venous catheter.

* Correct metabolic acidosis

o Metabolic acidosis indicates inadequate cardiac output to meet the metabolic demands of the body. Acidosis adversely affects the myocardium.
o Correction of metabolic acidosis with sodium bicarbonate infusion is essential in early management. This therapy is futile if the ductus arteriosus remains constricted.

* Manipulate pulmonary vascular resistance
o The pulmonary vascular resistance of a newborn is slightly less than the systemic vascular resistance and begins to fall soon after birth. In the patient with hypoplastic left heart syndrome, decreased pulmonary vascular resistance causes increased pulmonary blood flow and an undesirable obligatory decrease in systemic blood flow. Increased alveolar oxygen decreases pulmonary vascular resistance, leading to increased pulmonary blood flow. Therefore, most infants should remain in room air with acceptable oxygen saturation (pulse oximeter) in the low 70s. An exceptional circumstance would be in the infant with severe hypoxemia caused by pulmonary venous hypertension.
o Achieving a slightly higher PaCO2, in the range of 45-50 mm Hg, can increase pulmonary vascular resistance. This can be accomplished by intubation, sedation, mechanical hypoventilation, or the addition of nitrogen or carbon dioxide to the infant's inspired gas via the endotracheal tube or hood. It is preferable not to intubate these infants.
o Serial blood gas analysis is necessary. Initially, an umbilical arterial catheter is useful to obtain frequent blood samples.

* Inotropes
o Inotropic support is indicated only in severely ill neonates with concurrent sepsis or profound cardiogenic shock and acidosis.
o The administration of inotropes can adversely affect the balance between pulmonary and systemic vascular resistance.
o If needed, wean from inotropic support as soon as the infant is clinically stable.

* Diuretics
o Consider diuretics to manage pulmonary overcirculation before surgery.
o Agents commonly used include furosemide and spironolactone.

* Antibiotics
o Antibiotics are indicated if the infant is at risk for antepartum infection.
o Discontinue antibiotics after obtaining negative blood cultures.

Surgical Care:

* The goal of surgical reconstruction is to eventually separate the pulmonary and systemic circulations by completing a Fontan operation. The right ventricle remains the systemic ventricle while blood flows to the lungs passively. This ultimate reconstruction is accomplished in 3 stages.

o Norwood procedure (stage I)
+ This procedure is usually performed during the first weeks of life, after the infant has been stabilized in the neonatal intensive care unit (ICU). The goals of the procedure are (1) to establish reliable systemic circulation in the absence of the ductus arteriosus and (2) to provide enough pulmonary blood flow for adequate oxygenation, while simultaneously protecting the pulmonary vascular bed in preparation for stages II and III.
+ The Norwood procedure includes (1) performing an atrial septectomy to provide unrestricted blood flow across the atrial septum, (2) ligating the ductus arteriosus, (3) creating an anastomosis between the main pulmonary artery and the aorta to provide systemic blood flow, (4) eliminating coarctation of the aorta, and (5) placing an aorta?to?pulmonary artery shunt to provide pulmonary circulation.
+ At hospital discharge, most infants remain on digoxin to augment cardiac function, on diuretics to help manage right ventricular volume overload, and on aspirin to prevent thrombosis of the shunt. If tricuspid regurgitation is present, use afterload reduction with captopril. Oxygen saturation is typically 70-80% in room air.

o Hemi-Fontan procedure (stage II)
+ The hemi-Fontan procedure is performed approximately 6 months after the Norwood procedure. Before surgery, perform a cardiac catheterization to assess right ventricular function, pulmonary artery anatomy, and pulmonary vascular resistance. If results are favorable, schedule elective surgery.
+ The hemi-Fontan procedure includes creating an anastomosis between the superior vena cava and the right pulmonary artery, so that venous return from the upper body can flow directly into both lungs. The superior vena cava?right atrial junction is closed with a patch that is removed during the next stage. Blood from the inferior vena cava continues to drain into the right atrium. The aorta?to?pulmonary artery shunt that was placed at stage I is ligated.
+ At discharge, infants usually remain on digoxin, diuretics, aspirin, and captopril for the reasons mentioned above.

o Fontan procedure (stage III)
+ The Fontan procedure is done approximately 12 months after the hemi-Fontan procedure. Again, catheterization is necessary to ensure that the child is a candidate for surgery.
+ Completion of the Fontan procedure includes directing blood flow from the inferior vena cava to the pulmonary arteries by placing a tube within the right atrium. At the conclusion of the procedure, systemic venous blood returns to the lungs passively without passing through a ventricle.
+ At discharge, most children remain on digoxin, diuretics, aspirin, and captopril if necessary. In an uncomplicated case, most of these medications can be weaned over the 6 months following the Fontan operation. Some researchers advocate using aspirin indefinitely.

* Orthotopic cardiac transplantation

o Heart transplantation is another surgical option. The infant must remain on prostaglandin E1 infusion to keep the ductus arteriosus patent while waiting for a donor heart to become available. Approximately 20% of infants listed for heart transplantation die while waiting for a suitable donor organ.

o After successful cardiac transplantation, infants require multiple medications for modulation of the immune system and prevention of graft rejection. Perform frequent outpatient surveillance to identify rejection early and prevent lasting damage to the transplanted heart. Periodic endomyocardial biopsy usually is performed for more precise monitoring.

Consultations:

* Consult a pediatric cardiologist.

* Consult a pediatric cardiovascular surgeon.

* Consult a genetic specialist if a chromosomal abnormality is suspected.

Diet:

* Adequate nutrition is important before and after surgery. Many infants require nasogastric feeding with increased-calorie breast milk or formula after the Norwood procedure. However, normal oral feeding is reestablished with time. Adequate oral iron intake prevents development of iron deficiency anemia.

* After completion of the Fontan operation, specific dietary restrictions are not necessary.

Activity:

* Specific activity restrictions are not imposed on children after completion of the Fontan operation. In general, encourage children to participate in activities that they are able to tolerate.

* Studies have shown that these children may have impaired exercise performance when compared to age-matched peers. Perform an exercise stress test when the child is old enough.

* Neurodevelopmental abnormalities occur often in patients with hypoplastic left heart syndrome.

Medications:

Before the Norwood procedure or cardiac transplantation, treat infants with prostaglandin E1 infusion, diuretics, inotropes, and afterload reduction. The medical management after cardiac transplantation is not discussed in this article.

Drug Category: Prostaglandins -- Prostaglandin E1 promotes dilatation of the ductus arteriosus in infants with ductal-dependent cardiac abnormalities.

Drug Name
Alprostadil (Prostaglandin E1, Prostin) -- Causes relaxation of smooth muscle, primarily within the ductus arteriosus. Used in infants with ductal-dependent congenital heart disease due to restricted systemic blood flow.

Pediatric Dose
0.01-0.1 mcg/kg/min IV infusion

Contraindications
Documented hypersensitivity; respiratory distress syndrome or persistent fetal circulation

Interactions
Coadministration with heparin may increase PTT or PT

Pregnancy
X - Contraindicated in pregnancy

Precautions
Closely monitor respiratory status, cardiovascular status, and coagulation; apnea, fever, irritability, and cutaneous flushing are common; inhibits platelet aggregation

Drug Category: Diuretic agents -- These agents decrease preload by increasing free-water excretion. Decreasing preload may improve systolic ventricular function.

Drug Name
Furosemide (Lasix) -- Loop diuretic that blocks sodium reabsorption in the ascending limb of loop of Henle.

Adult Dose
20-80 mg IV/IM/PO up to tid

Pediatric Dose
0.5-2 mg/kg IV/IM/PO up to tid

Contraindications
Documented hypersensitivity; hepatic coma, anuria, and severe electrolyte depletion

Interactions
Antagonizes muscle-relaxing effect of tubocurarine; auditory toxicity appears to be increased with coadministration of aminoglycosides and furosemide; hearing loss of varying degrees may occur; anticoagulant activity of warfarin may be enhanced when taken concurrently with this medication

Pregnancy

C - Safety for use during pregnancy has not been established.

Precautions
Profound diuresis and electrolyte loss may result; metabolic alkalosis; use caution withother medications known to decrease renal function; may cause hypercalciuria and renal stones, especially in premature infants

 

Drug Name
Spironolactone (Aldactone) -- This drug is a potassium-sparing loop diuretic.

Adult Dose
25-100 mg PO divided bid/qid

Pediatric Dose
2-3 mg/kg PO qd or divided bid

Contraindications
Documented hypersensitivity; anuria, renal failure or hyperkalemia

Interactions
May decrease effect of anticoagulants; potassium and potassium-sparing diuretics may increase toxicity of spironolactone

Pregnancy
D - Unsafe in pregnancy

Precautions
Electrolyte imbalance, especially hyperkalemia, may result; concomitant use with indomethacin or ACE inhibitors may cause hyperkalemia

Drug Category: Cardiac glycosides -- These medications improve ventricular systolic function by increasing the calcium supply available for myocyte contraction.

Drug Name
Digoxin (Lanoxin) -- This form inhibits the sodium-potassium ATPase pump in cardiac myocytes.

Adult Dose
Total digitalizing dose (TDD): 1-1.5 mg PO given in divided doses over 1 d
Maintenance dose: 0.125-0.375 mg PO in 1-2 doses

Pediatric Dose
TDD: Premature infants: 0.02 mg/kg PO divided q8h for 3 doses
Full-term infants: 0.03 mg/kg PO divided q8h for 3 doses
1-24 months: 0.04-0.05 mg/kg PO divided q8h for 3 doses
>2 years: 0.03-0.04 mg/kg PO divided q8h for 3 doses
Maintenance dose:
Infants: 6-8 mcg/kg/d PO
2-5 years: 10-15 mcg/kg/d PO
5-10 years: 7 to 10 mcg/kg/d PO
>10 years: 3-5 mcg/kg/d PO
<10 years: bid dosing recommended

Contraindications
Documented hypersensitivity; beriberi heart disease, idiopathic hypertrophic subaortic stenosis, constrictive pericarditis, and carotid sinus syndrome

Interactions
Medications that may increase digoxin levels include alprazolam, benzodiazepines, bepridil, captopril, cyclosporine, propafenone, propantheline, quinidine, diltiazem, aminoglycosides, oral amiodarone, anticholinergics, diphenoxylate, erythromycin, felodipine, flecainide, hydroxychloroquine, itraconazole, nifedipine, omeprazole, quinine, ibuprofen, indomethacin, esmolol, tetracycline, tolbutamide, and verapamil
Medications that may decrease serum digoxin levels include aminoglutethimide, antihistamines, cholestyramine, neomycin, penicillamine, aminoglycosides, oral colestipol, hydantoins, hypoglycemic agents, antineoplastic treatment combinations (including carmustine, bleomycin, methotrexate, cytarabine, doxorubicin, cyclophosphamide, vincristine, procarbazine), aluminum or magnesium antacids, rifampin, sucralfate, sulfasalazine, barbiturates, kaolin/pectin, and aminosalicylic acid

Pregnancy
C - Safety for use during pregnancy has not been established.

Precautions
Hypokalemia may reduce positive inotropic effect of digitalis; IV calcium may produce arrhythmias in digitalized patients; hypercalcemia predisposes patient to digitalis toxicity, and hypocalcemia can make digoxin ineffective until serum calcium levels are normal; magnesium replacement therapy must be instituted in patients with hypomagnesemia to prevent digitalis toxicity; patients with incomplete AV block may progress to complete block when treated with digoxin; exercise caution in hypothyroidism, hypoxia, and acute myocarditis

Drug Category: Inotropic agents -- These agents stimulate alpha-adrenergic and beta-adrenergic and beta-dopaminergic receptors in the heart and vascular bed.

Drug Name
Dopamine (Intropin) -- At lower doses, stimulation of beta1-adrenergic and beta1-dopaminergic receptors results in positive inotropism and renal vasodilatation; at higher doses, stimulation of alpha-adrenergic receptors results in peripheral and renal vasoconstriction.

Adult Dose
2-20 mcg/kg/min IV infusion

Pediatric Dose
Administer as in adults

Contraindications
Documented hypersensitivity; pheochromocytoma or ventricular fibrillation

Interactions
Phenytoin, alpha- and beta-adrenergic blockers, general anesthesia, and MAOIs increase and prolong effects of dopamine

Pregnancy
C - Safety for use during pregnancy has not been established.

Precautions
Use caution with intravascular volume depletion; administration via a central venous catheter is recommended; the umbilical artery should not be used; doses higher than 20 mcg/kg/min generally are not helpful and other agents should be considered; subcutaneous infiltration may cause tissue sloughing; prompt treatment with subcutaneous phentolamine (Regitine) is recommended

Drug Name
Dobutamine (Dobutrex) -- This drug primarily stimulates the beta1-adrenergic receptor and has less alpha-adrenergic stimulation, leading primarily to increased myocardial contractility.

Adult Dose
2-20 mcg/kg/min IV infusion

Pediatric Dose
Administer as in adults

Contraindications
Documented hypersensitivity; idiopathic hypertrophic subaortic stenosis and atrial fibrillation or flutter

Interactions
Beta-adrenergic blockers antagonize effects of dobutamine; general anesthetics may increase toxicity

Pregnancy
B - Usually safe but benefits must outweigh the risks.

Precautions
Use caution with intravascular volume depletion; administration via a central venous catheter is recommended; the umbilical artery should not be used; doses higher than 20 mcg/kg/min generally are not helpful, and other agents should be considered; subcutaneous infiltration may cause tissue ischemia

Drug Category: Afterload-reducing agents -- Afterload reduction improves myocardial performance and theoretically reduces atrioventricular and semilunar valve insufficiency.

Drug Name
Captopril (Capoten) -- ACE inhibitor, which decreases the production of angiotensin II, a potent vasoconstrictor, resulting in peripheral vasodilatation and afterload reduction, improving myocardial performance and theoretically reducing AV and semilunar valve insufficiency. Administer a test dose of 0.1 mg PO to assess initial response

Adult Dose
6.25-12.5 mg PO tid; not to exceed 150 mg tid

Pediatric Dose
0.1-1 mg/kg PO tid

Contraindications
Documented hypersensitivity; renal impairment

Interactions
NSAIDs may reduce hypotensive effects of captopril; ACE inhibitors may increase digoxin, lithium, and allopurinol levels; rifampin decreases captopril levels; probenecid may increase captopril levels; the hypotensive effects of ACE inhibitors may be enhanced when given concurrently with diuretics

Pregnancy
C - Safety for use during pregnancy has not been established.

Precautions
Pregnancy category D in second and third trimesters; caution in renal impairment, valvular stenosis, or severe congestive heart failure; profound hypotensive response is observed rarely after the initial dose in smaller children; an initial test dose should be given and blood pressure should be monitored carefully; dose should be titrated based on clinical response and tolerance; use caution with decreased renal function; ACE inhibitors have a potassium-sparing effect when administered with furosemide; simultaneous administration of spironolactone should be done with caution

Drug Category: Antiplatelet agents -- These agents are used in the treatment or prevention of thrombo-occlusive disease mediated by the action of platelets. They inhibit platelet function by blocking cyclooxygenase and subsequent aggregation.

Drug Name
Aspirin (Anacin, Ascriptin, Bayer Aspirin) -- Inhibits the enzyme cyclooxygenase that reduces production of thromboxane A2, which is a potent vasoconstrictor and platelet-aggregating agent. Antiplatelet effects of aspirin last the entire life of the platelet (6-10 d) and are not reversible.

Adult Dose
325 mg PO qd

Pediatric Dose
5-10 mg/kg PO qd

Contraindications
Documented hypersensitivity; liver damage, hypoprothrombinemia, vitamin K deficiency, bleeding disorders, asthma; because of association of aspirin with Reye syndrome, do not use in children (<16 y) with flu

Interactions
Effects may decrease with antacids and urinary alkalinizers; corticosteroids decrease salicylate serum levels; additive hypoprothrombinemic effects and increased bleeding time may occur with coadministration of anticoagulants; may antagonize uricosuric effects of probenecid and increase toxicity of phenytoin and valproic acid; doses >2 g/d may potentiate glucose-lowering effect of sulfonylurea drugs

Pregnancy
D - Unsafe in pregnancy

Precautions
May cause transient decrease in renal function and aggravate chronic kidney disease; avoid use in patients with severe anemia, with a history of blood coagulation defects, or who are taking anticoagulants

Followup:

Further Inpatient Care:

* Initial preoperative management and postoperative care take place in the neonatal, pediatric, or cardiac ICUs.

* When postoperative patients are clinically stable, transfer them to the general cardiac unit for adjusting oral medications, addressing feeding issues, and completing discharge teaching.

* Involve a pediatric cardiologist during any noncardiac hospital admission of a patient who is status post (S/P) Norwood procedure. This is because of the complex cardiovascular physiology in infants after this surgery.

Further Outpatient Care:

* Schedule outpatient follow-up care 2 weeks after discharge in the typical postoperative patient.

* Schedule those who are S/P cardiac transplantation earlier for necessary laboratory studies.

* Earlier follow-up care is also necessary if a pericardial effusion is discovered on the discharge echocardiogram.

* Individualize further outpatient follow-up care based on the needs of each patient.

In/Out Patient Meds:

* Inpatient medications

o Prostaglandin E1

o Dopamine/dobutamine

o Furosemide (Lasix/Aldactone)

o Captopril

o Digoxin

* Outpatient medications

o Furosemide (Lasix/Aldactone)

o Captopril

o Digoxin

Transfer:

* Transfer the infant to a hospital with appropriate ICUs. Pediatric cardiology and cardiovascular surgery services must be immediately available.

* Carefully monitor the infant for apnea during transfer while on prostaglandin E1 therapy. If prostaglandin E1 has been started, consider elective endotracheal intubation before transfer.

Complications:

* Preoperative complications include acidosis, CHF, renal failure, liver failure, necrotizing enterocolitis, sepsis, and death.

* Postoperative complications include acidosis, CHF, renal failure, liver failure, necrotizing enterocolitis, sepsis, pericardial or pleural effusion, phrenic or recurrent laryngeal nerve damage, stroke, coarctation of the aorta, and death. Early graft rejection and opportunist infection may occur after cardiac transplantation.

* Major complications following the Norwood procedure include aortic arch obstruction at the site of surgical anastomosis and progressive cyanosis caused by limited blood flow through the shunt. An inadequate atrial communication contributes to progressive cyanosis.

* Major complications following the hemi-Fontan procedure include transient superior vena cava syndrome and persistent pleural or pericardial effusion. The development of systemic venous to pulmonary venous collateral vessels is possible.

* Major complications following the Fontan procedure include persistent pleural or pericardial effusion. Neurodevelopmental abnormalities are reported and may be inherent in some patients with hypoplastic left heart syndrome.

Prognosis:

* Overall survival to the time of hospital discharge after the Norwood procedure is nearly 75%. Success rates are higher in uncomplicated cases and lower in cases in which important preoperative risk factors are present, such as age greater than 1 month, significant preoperative tricuspid insufficiency, pulmonary venous hypertension, associated major chromosomal or noncardiac abnormalities, and prematurity.

* Survival after the hemi-Fontan and Fontan operations is nearly 90-95%.

* The actuarial survival rate after staged reconstruction is 70% at 5 years.

* Institutional success rates vary.

* Neurodevelopmental prognosis is not known; however, abnormalities are reported.

* Approximately 20% of infants listed for cardiac transplantation die while waiting for a donor heart. After successful transplantation, the survival rate at 5 years is approximately 80%.

* When the preoperative mortality is considered, the overall survival rate after cardiac transplantation is approximately 70%, or similar to the results for staged reconstruction.

Patient Education:

* Medication

o Educate parents regarding the doses and side effects of their child's cardiac medications.
o Discuss interactions with other medications with the family and the infant's general pediatrician.

* Feeding

o Many infants require nasogastric tube feeding after discharge from the hospital. Parents must become comfortable with placement of the nasogastric feeding tube.

o Frequently, increased-calorie formula is required for adequate growth. Provide the formula recipe or a source for purchasing it to the caregiver.

* Follow-up care

o Stress the importance of follow-up care. If necessary, provide cab or bus vouchers to ensure compliance.
o If noncompliance becomes a critical issue, physicians are required to report to the appropriate family services agency.

Medical/Legal Pitfalls:

* Misdiagnosis

* Failure to recognize the infant with hypoplastic left heart syndrome and the obstruction to pulmonary venous return

Special Concerns:

* The newborn with hypoplastic left heart syndrome dies rapidly if untreated. Surgical techniques, both reconstruction and heart transplantation, offer an opportunity to preserve the newborn's life. Survival rates given above represent the best results and reflect only survival, not quality of life. Mortality rates in many centers exceed those mentioned. Incidence of neurodevelopmental abnormalities in hypoplastic left heart syndrome appears to exceed that of other single-ventricle conditions.

* Hypoplastic left heart syndrome affects family structure. For example, reproductive studies indicate that the incidence of subsequent pregnancy is significantly lower in mothers of a living patient with hypoplastic left heart syndrome than in mothers after death of an infant with hypoplastic left heart syndrome. For these reasons, most pediatric cardiologists continue to offer no treatment as an acceptable option to parents of a newborn with hypoplastic left heart syndrome. It is incumbent on physicians caring for a newborn with hypoplastic left heart syndrome to clearly communicate all of this information to the parents. An ethically appropriate consent for surgery requires this. Allowing an affected infant to die without surgical intervention is a difficult decision, but it is still chosen by some families.