Cyanotic Congenital Heart Defects




Most cyanotic congenital heart defects (CHDs) manifest during the neonatal period, requiring a correct diagnosis for appropriate management. Detection of cyanosis has been made much easier in recent years by routine use of pulse oximetry in asymptomatic newborns. Pulse oximetry helps detect most cyanotic CHDs as well as some noncyanotic critical CHDs. Critical CHDs include defects that depend on the patency of the ductus arteriosus for survival, such as hypoplastic left heart syndrome (HLHS), aortic arch atresia, critical aortic stenosis (AS), pulmonary stenosis (PS) or atresia, tricuspid atresia, and others.


However, pulse oximetry cannot detect all cases of critical CHDs or cyanotic CHDs. Hypoxemia may not be present in some patients with HLHS, AS, and coarctation of the aorta (COA) before discharge from the hospital. In addition, not all cyanotic CHDs manifest with detectable hypoxemia in the nursery. For example, some patients with double outlet right ventricle (RV), Ebstein’s anomaly, and acyanotic tetralogy of Fallot (TOF) may not manifest with detectable hypoxemia in early days of life. Therefore, a negative test result does not exclude the possibility of serious heart defects.


Many investigators believe that pulse oximetry in newborns should be done after 24 hours of life and before hospital discharge and be taken in lower extremities to be able to detect defects with right-to-left ductal shunt and that the cutoff point of abnormal oxygen saturation be set at 95% or less. Arterial saturation is expected to be lower in high altitudes (especially above 5000 ft), but the cutoff point has not been established ( Mahle et al, 2009 ).


Hypoxemia does not necessarily mean a heart defect is present; it may be caused by pulmonary disease or central nervous system (CNS) depression. After hypoxemia (or central cyanosis) is detected, the cause of hypoxemia must be determined.


Approach to a Cyanotic Neonate


Three common causes of central cyanosis (or hypoxemia) are cardiac disease, pulmonary disease, and CNS depression. Clinical findings often direct physicians to the correct system that causes cyanosis. Table 14-1 lists some of the differentiating clinical findings of central cyanosis associated with the three common causes of cyanosis. Crying may improve the cyanosis caused by lung diseases or CNS depression; however, crying usually worsens cyanosis in patients with cyanotic heart defects.



TABLE 14-1

CAUSES AND CLINICAL FINDINGS OF CENTRAL CYANOSIS




















Systems Causes Clinical Findings
CNS depression Perinatal asphyxia
Heavy maternal sedation
Intrauterine fetal distress
Shallow irregular respiration
Poor muscle tone
Cyanosis that disappears when the patient is stimulated or oxygen is given
Pulmonary disease Parenchymal lung disease (e.g., hyaline membrane disease)
Pneumothorax or pleural effusion
Diaphragmatic hernia
PPHN
Tachypnea and respiratory distress with retraction and expiratory grunting
Crackles or decreased breath sounds on auscultation
Chest radiography may reveal causes (e.g., those listed under causes in this table)
Oxygen administration may improve or abolishes cyanosis
Cardiac disease Cyanotic CHD with right-to-left shunt Tachypnea usually without retraction
Lack of crackles or abnormal breath sounds unless CHF supervenes
Heart murmurs may be absent in serious forms of cyanotic CHD
A continuous murmur (of PDA) is audible in a cyanotic neonate
Chest radiography may show cardiomegaly, abnormal cardiac silhouette, increased or decreased pulmonary vascular markings
Little or no increase in Po 2 with oxygen administration

CHD, congenital heart defect; CHF, congestive heart failure; CNS, central nervous system; PDA, patent ductus arteriosus; PPHN, persistent pulmonary hypertension of the newborn.


Box 14-1 lists some of the traditional tools used in the investigation of cyanotic newborns. Some of the steps could be skipped when cardiology consultation is readily available, but they are discussed for the sake of completeness.



  • 1.

    Electrocardiography (ECG) and chest radiography. Although the routine tools of cardiac evaluation (physical examination, ECG, and chest radiography) are not very helpful in diagnosing a specific cyanotic heart defect, these tools are often useful in reducing the diagnostic possibilities. Besides being cyanotic, a neonate may have dyspnea, tachypnea, abnormal heart sounds, heart murmurs, or abnormal peripheral pulses. A midline liver may be palpable (or seen on radiography). Chest radiography may show abnormal lung fields (e.g., increased vascularity, oligemic lung fields, or other abnormalities) and abnormal cardiac shadow (abnormal size or abnormal silhouette). The ECG findings may include abnormal rhythm and rate, abnormal QRS axis, atrial hypertrophy, or ventricular hypertrophy. The more of these abnormalities the patient has, the greater the chance of having CHDs. Cardiology consult should be considered at this time.


  • 2.

    Hyperoxitest. This test helps differentiate cyanosis caused by cardiac disease from that caused by pulmonary diseases. When central cyanosis has been confirmed by arterial Po 2 , one tests the response of arterial Po 2 to 100% oxygen inhalation (hyperoxitest). Oxygen should be administered through a plastic hood (e.g., an Oxyhood) for at least 10 minutes to completely fill the alveolar space with oxygen. With pulmonary disease, arterial Po 2 usually rises to greater than 100 mm Hg. When there is a significant intracardiac right-to-left shunt, the arterial Po 2 does not exceed 100 mm Hg, and the rise is usually not more than 10 to 30 mm Hg (see Chapter 11 for details). Exceptions exist in patients with large pulmonary blood flow and those with severe lung pathology.


  • 3.

    Arterial Po 2 in preductal and postductal arteries. It is important that one obtain arterial blood samples from the right upper body (right radial, brachial, or temporal artery), rather than from the descending aorta, to detect (true) cyanotic CHDs. If a low arterial Po 2 is obtained from an umbilical artery line (or from a lower extremity site), another sample from the right upper body should be obtained, and the Po 2 values from the two sites should be compared to see if there is a right-to-left ductal shunt. Arterial P o 2 from the right radial artery that is 10 to 15 mm Hg higher than that from an umbilical artery catheter is significant. In severe cases of right-to-left ductal shunt, differential cyanosis may be noticeable, with a pink upper and a cyanotic lower body. Such a right-to left ductal shunt is caused not only by persistent pulmonary hypertension of the newborn (PPHN) but also by other serious cardiovascular conditions, including severe obstructive lesions of the left ventricle (LV) (e.g., severe AS) or aortic obstructive lesions (e.g., interrupted aortic arch, COA).


  • 4.

    Prostaglandin E 1 (PGE1) infusion. If a cyanotic CHD or a ductus-dependent cardiac defect (e.g., pulmonary atresia with or without ventricular septal defect [VSD], tricuspid atresia, HLHS, interrupted aortic arch, severe COA) is suspected or confirmed, a PGE 1 (Prostin VR Pediatric) intravenous (IV) infusion should be started. At the same time, cardiology consultation should be requested on an urgent basis. The starting dose of Prostin is 0.05 to 0.1 μg/kg per minute administered in a continuous IV drip. When the desired effects (increased Po 2 , increased systemic blood pressure, improved pH) are achieved, the dose should be reduced step by step to 0.01 μg/kg per minute. When the initial starting dose has no effect, it may be increased up to 0.4 μg/kg per minute. Three common side effects of IV infusion of PGE 1 are apnea (12%), fever (14%), and flushing (10%). Less common side effects include tachycardia or bradycardia, hypotension, and cardiac arrest.



BOX 14-1




  • 1.

    Chest radiography




    • Chest radiography may reveal pulmonary causes of cyanosis and the urgency of the problem.



    • It can also hint at the presence or absence of cardiac defects and the type of defect.



  • 2.

    ECG if cardiac origin of cyanosis is suspected.


  • 3.

    Arterial blood gases in room air




    • Arterial blood gases in room air confirm or reject central cyanosis.



    • An elevated PCO 2 suggests pulmonary or CNS problems.



    • A low pH may be seen in sepsis, circulatory shock, or severe hypoxemia.



  • 4.

    Hyperoxitest: Repeating arterial blood gases while the patient breathes 100% oxygen helps separate cardiac causes of cyanosis from pulmonary or CNS causes.


  • 5.

    Umbilical artery line: A Po 2 value in a preductal artery (e.g., the right radial artery) that is 10 to 15 mm Hg higher than that in a postductal artery (an umbilical artery line) suggests a right-to-left ductal shunt.


  • 6.

    PGE 1 : If a cyanotic defect is suspected that depends on the patency of the ductus for survival, PGE 1 (Prostin VR Pediatric) should be started or made available.



CNS, central nervous system; ECG, electrocardiography; PGE 1 , prostaglandin E 1 .


Suggested Steps in The Management of Cyanotic Newborns




Complete Transposition of the Great Arteries


Prevalence


Complete transposition of the great arteries (TGA) occurs in about 5% to 7% of all CHDs. It is more common in males than in females (male-to-female ratio of 3:1).


Pathophysiology




  • 1.

    In complete TGA, the aorta arises anteriorly from the RV carrying desaturated blood to the body, and the pulmonary artery (PA) arises posteriorly from the LV carrying oxygenated blood back to the lungs. In the classic complete TGA, the aorta is located anteriorly and to the right (dextro) of the PA. This is why the prefix D is used and thus the condition is called D-transposition (D-TGA). (When the transposed aorta is located to the left of the PA, it is called L-transposition, to be discussed later in this chapter.)


  • 2.

    The result of D-TGA is complete separation of the pulmonary and systemic circulations. This results in hypoxemic blood circulating throughout the body and hyperoxemic blood circulating in the pulmonary circuit, which is not compatible with survival (see Fig. 11-4 ). Defects that permit mixing of the two circulations (e.g., atrial septal defect [ASD], VSD, and patent ductus arteriosus [PDA]) are necessary for survival.


  • 3.

    About half of these infants do not have associated defects other than a patent foramen ovale (PFO) or a small PDA (i.e., simple TGA).


  • 4.

    In about 5% of the patients, left ventricular outflow tract (LVOT) obstruction (or subpulmonary stenosis) occurs. The obstruction may be dynamic or fixed. Dynamic obstruction of the LVOT, which occurs in about 20% of such patients, results from bowing of the interventricular septum to the left because of a high RV pressure. Anatomic (or fixed) subpulmonary stenosis or abnormal mitral chordal attachment rarely causes obstruction of the LVOT.


  • 5.

    VSD is present in 30% to 40% of patients with D-TGA and may be located anywhere in the ventricular septum. A combination of VSD and significant LVOT obstruction (or PS) occurs in about 10% of all patients with D-TGA. Infants with TGA and VSD more commonly have associated defects than those without associated VSD. Such associated defects may include COA, interrupted aortic arch, pulmonary atresia, and an overriding or straddling of the atrioventricular (AV) valve.



Overriding is an abnormal relationship between the AV valve annulus and the ventricular septum. The AV valve annulus commits to both ventricular chambers, and it is the result of malalignment of the atria and ventricular septa. Straddling is present when the chordae tendineae insert into the contralateral ventricle through a septal defect. Type A straddling is a mild form in which the chordae insert near the crest of the ventricular septum. In type B, the insertion is along the ventricular septum. In type C straddling, the chordae insert into the free wall of the contralateral ventricle. Overriding and straddling may occur independently or coexist in the same valve.


Clinical Manifestations


History




  • 1.

    History of cyanosis from birth is always present.


  • 2.

    Signs of congestive heart failure (CHF) with dyspnea and feeding difficulties develop during the newborn period.



Physical Examination ( Fig. 14-1 )




  • 1.

    Moderate to severe cyanosis is present, especially in large male newborns. Such an infant is tachypneic but without retraction unless CHF supervenes.




    FIGURE 14-1


    Cardiac findings of transposition of the great arteries. Heart murmur is usually absent, and the S2 is single in the majority of patients.


  • 2.

    The S2 is single and loud. No heart murmur is heard in infants with an intact ventricular septum. An early or holosystolic murmur of VSD may be audible in less cyanotic infants with associated VSD. A soft midsystolic murmur of PS (LVOT obstruction) may be audible.


  • 3.

    If CHF supervenes, hepatomegaly and dyspnea develop.



Laboratory Studies




  • 1.

    Severe arterial hypoxemia usually with acidosis is present. Hypoxemia does not respond to oxygen inhalation. (See the discussion of the hyperoxitest in an early section of this chapter.)


  • 2.

    Hypoglycemia and hypocalcemia are occasionally present.



Electrocardiography ( Fig. 14-2 )




  • 1.

    Right ventricular hypertrophy (RVH) is usually present after the first few days of life. The QRS voltages and the QRS axis may be normal in many newborns with the defect. After 3 days of life, an upright T wave in V1 may be the only abnormality suggestive of RVH.




    FIGURE 14-2


    Electrocardiographic tracing from a 6-day-old male infant with complete transposition of the great arteries. The QRS axis is +140 degrees. Note the deep S waves in V5 and V6 and an upright T wave in V1 are consistent with right ventricular hypertrophy.


  • 2.

    Biventricular hypertrophy (BVH) may be present in infants with large VSD, PDA, or pulmonary vascular obstructive disease because all of these conditions produce an additional left ventricular hypertrophy (LVH).


  • 3.

    Occasionally, right atrial hypertrophy (RAH) is present.



Radiography




  • 1.

    Cardiomegaly with increased pulmonary vascularity is typically present.


  • 2.

    An egg-shaped cardiac silhouette with a narrow, superior mediastinum is characteristic ( Fig. 14-3 ).




    FIGURE 14-3


    Posteroanterior view of the chest radiograph from a 2-month-old infant with complete transposition of the great arteries. Note the cardiomegaly (cardiothoracic ratio, 0.7), “egg-shaped” heart with narrow waist, and increased pulmonary vascular markings, which are characteristic of this condition.



Echocardiography


Two-dimensional echocardiography and color-flow Doppler studies usually provide all the anatomic and functional information needed for the management of infants with D-TGA.



  • 1.

    In the parasternal long-axis view, the great artery arising from the posterior ventricle (LV) has a sharp posterior angulation toward the lungs, which suggests that this artery is the PA ( Fig. 14-4 , A ). In contrast to the normal intertwining of the great arteries, the proximal portion of the great arteries runs parallel. Unlike in a normal heart, there is a fibrous continuity between the pulmonary and mitral valves, and subaortic conus is present. (In normal hearts, there is aortic–mitral fibrous continuity with subpulmonary conus.)




    FIGURE 14-4


    Parasternal echocardiographic views in complete transposition of the great arteries. A, In this parasternal long-axis view, the great arteries are seen in parallel alignment. The posterior artery is directed posteriorly, bifurcates into two branches, and is therefore a pulmonary artery (PA). There is a continuity between the pulmonary valve and the mitral valve. B, In the parasternal short-axis view, the aorta (AO) and the PA are seen in cross section as double circles. The aorta is anterior to and right of the PA. LV, left ventricle; RV, right ventricle.

    (From Snider AR, Serwer GA: Echocardiography in Pediatric Heart Disease. St. Louis, Mosby, 1990.)


  • 2.

    In the parasternal short-axis view, the “circle and sausage” appearance of the normal great arteries is not visible. Instead, the great arteries appear as “double circles” ( Fig. 14-4 , B ). The PA is in the center of the heart, and the coronary arteries do not arise from this great artery. The aorta is usually anterior and slightly to the right of the PA, and the coronary arteries arise from the aorta.


  • 3.

    In the apical and subcostal five-chamber views, the PA (i.e., the artery that bifurcates) is seen to arise from the LV, and the aorta arises from the RV.


  • 4.

    The status of atrial communication, both before and after balloon septostomy, is best evaluated in the subcostal view. Doppler examination and color-flow mapping should aid in the functional evaluation of the atrial shunt.


  • 5.

    Frequently, associated defects such as VSD, LVOT obstruction (dynamic or fixed), or pulmonary valve stenosis are found. Subaortic stenosis or COA rarely occurs.


  • 6.

    The coronary arteries can be imaged in most patients in the parasternal and apical views ( Fig. 14-5 ).




    FIGURE 14-5


    Diagram of the coronary artery anatomy in 32 patients with transposition of the great arteries (TGA). The orientation of the figures is that of a parasternal short-axis echocardiographic view. LAD, left anterior descending artery; LCCA, left circumflex coronary artery; RCA, right coronary artery.

    (From Pasquini L, Sanders SP, Parness IA, et al: Diagnosis of coronary artery anatomy by two-dimensional echocardiography in patients with transposition of the great arteries. Circulation 75:557–564, 1987.)



Other Studies


Cardiac catheterization is performed only for the purpose of balloon atrial septostomy to improve mixing at the atrial level. Rarely, it is performed to look for associated anomalies such as abnormal coronary artery, collateral circulation, or a small aortic isthmus.


Natural History




  • 1.

    Progressive hypoxia, acidosis, and heart failure result in death in the newborn period. Without surgical intervention, death occurs in 90% of patients before they reach 6 months of age.


  • 2.

    Infants with an intact ventricular septum are the sickest group but demonstrate the most dramatic improvement after Rashkind balloon atrial septostomy.


  • 3.

    Infants with VSD are the least cyanotic group but the most likely to develop CHF and pulmonary vascular obstructive disease. Many infants with TGA and a large VSD develop moderate pulmonary vascular obstructive disease by 3 to 4 months of age. Thus, surgical procedures are recommended before that age.


  • 4.

    Infants with a significant PDA are similar to those with a large VSD in terms of their development of CHF and pulmonary vascular obstructive disease.


  • 5.

    The combination of VSD and PS allows considerably longer survival without surgery because the pulmonary vascular bed is protected from developing pulmonary hypertension, but this combination carries a high surgical risk for correction.



Management


Medical




  • 1.

    The following measures should be carried out to stabilize the patient before an emergency cardiac catheterization (if performed) or a surgical procedure is carried out:



    • a.

      Arterial blood gases and pH should be obtained, and metabolic acidosis should be corrected. Hypoglycemia and hypocalcemia, if present, should be treated.


    • b.

      PGE 1 infusion should be started to improve arterial oxygen saturation by reopening the ductus (see Appendix E for the dosage). This should be continued throughout the cardiac catheterization or until the time of surgery.


    • c.

      Oxygen should be administered for severe hypoxia. Oxygen may help lower pulmonary vascular resistance (PVR) and increase pulmonary blood flow (PBF), which in turn increases systemic arterial oxygen saturation.



  • 2.

    Before surgery, cardiac catheterization and a balloon atrial septostomy (i.e., the Rashkind procedure) are often carried out to have some flexibility in planning surgery. If adequate interatrial communication exists and the anatomic diagnosis of TGA is clear by echocardiographic examination, the patient may go to surgery without cardiac catheterization or the balloon atrial septostomy. The need for the balloon septostomy may be determined by inadequate atrial mixing through the PFO (evidenced with a high Doppler flow velocity of >1 m/sec) or a lack of readiness for surgical intervention.



In the balloon atrial septostomy, a balloon-tipped catheter is advanced into the left atrium (LA) through the PFO. The balloon is inflated with diluted radio-opaque dye and abruptly and forcefully withdrawn to the right atrium (RA) under fluoroscopic or echocardiographic monitoring. This procedure creates a large defect in the atrial septum through which an improved intracardiac mixing occurs. An increase in the oxygen saturation of 10% or more and a minimal interatrial pressure gradient are considered satisfactory results of the procedure.



  • 3.

    CHF may be treated with diuretics (and digoxin).



Surgical


Palliative Procedure


No palliative procedure is performed unless an arterial switch operation (ASO) cannot be performed early in life.


Definitive Repair


Historically, definitive surgeries performed for TGA were procedures that switched right- and left-sided blood at three levels: the atrial level (intraatrial repair surgeries such as the Senning or Mustard operation), the ventricular level (i.e., Rastelli operation), and the great artery level (ASO). At this time, ASO is clearly the procedure of choice, and intraatrial repair surgeries are very rarely performed only under unusual situations. The Damus-Kaye-Stansel operation in conjunction with the Rastelli operation can be performed in patients with VSD and subaortic stenosis. Because of a relatively poor long-term result of the Rastelli operation, other options such as the Nikaidoh operation or REV ( réparation à I’étage ventriculare ) procedure have become more popular recently.


Procedures




  • 1.

    Atrial baffle operations (Mustard and Senning operations)



These procedures reroute pulmonary and systemic venous returns at the atrial level with resulting physiologic correction. The pulmonary venous blood eventually goes to the aorta, and the systemic venous blood goes to the PA (see Fig. 14-6 for the hemodynamic results of atrial baffle operation). The Mustard operation uses a pericardial or a prosthetic baffle, and the Senning operation uses the patient’s own atrial septal flap and the RA free wall to redirect the venous returns.




FIGURE 14-6


Atrial baffle operation. The hemodynamic results of the Mustard and Senning operations are shown. Systemic venous blood (shaded) is redirected at the atrial level to the anatomic left atrium (LA) and left ventricle (LV) and eventually to the pulmonary circulation. Pulmonary venous blood is redirected at the atrial level to the anatomic right atrium (RA) and right ventricle (RV) through the tricuspid valve and to the aorta. AO, aorta; IVC, inferior vena cava; PA, pulmonary artery; P.V. atrium, pulmonary venous atrium; S.V. atrium, systemic venous atrium; SVC, superior vena cava.


A number of long-term problems have been reported, including superior vena cava (SVC) obstruction (<5% of all cases), baffle leak (<20%), absence of sinus rhythm (>50%), frequent atrial and ventricular arrhythmias with occasional sudden death, tricuspid valve insufficiency (rare), and RV (i.e., systemic ventricular) dysfunction or failure. The ASO has largely replaced the atrial baffle operation. There are, however, rare indications for atrial baffle operations, including a situation in which relative contraindications of the ASO exist (e.g., coronary arteries that are difficult to transfer).



  • 2.

    Rastelli operation. In patients with VSD and severe PS, redirection of the pulmonary and systemic venous blood is carried out at the ventricular level. The LV is directed to the aorta by creating an intraventricular tunnel between the VSD and the aortic valve. A valved conduit or a homograft is placed between the RV and the PA ( Fig. 14-7 ). Most surgeons prefer to delay this procedure until after the first year of life. The mortality rate is between 10% and 29%.




    FIGURE 14-7


    The Rastelli operation. A, In patients with D-transposition of the great arteries (D-TGA), ventricular septal defect (VSD) and severe pulmonary stenosis (PS), the pulmonary artery (PA) is divided from the left ventricle (LV), and the cardiac end is oversewn (arrow). B, An intracardiac tunnel (arrow) is placed between the large VSD and the aorta (AO) so that the LV communicates with the aorta. C, The right ventricle (RV) is connected to the divided PA by a valved conduit or an aortic homograft. RA, right atrium.



Complications after the Rastelli operation include conduit obstruction (especially in those containing porcine heterograft valves) and complete heart block (which rarely occurs). The conduit needs to be replaced as the child grows. Occasionally, LVOT obstruction occurs at the level of the VSD or at the level of the intraventricular tunnels. More importantly, the long-term results are not optimal, with the 20-year survival rate at about 50%. Two alternative procedures are now available, the REV procedure and the Nikaidoh procedure (see later discussion of these procedures).



  • 3.

    Arterial switch operation



The ASO is now firmly established as the procedure of choice. There are almost no situations which would justify the performance of a Senning or Mustard procedure for D-TGA. The coronary arteries are transplanted to the PA, and the proximal great arteries are connected to the distal end of the other great artery, resulting in an anatomic correction ( Fig. 14-8 ). This procedure has advantages over the atrial baffle operations because it is an anatomic (not physiologic) correction, and long-term complications are infrequent. This procedure is indicated not only for simple TGA but also TGA with other associated anomalies (e.g., VSD or PDA) and the Taussig-Bing type of double outlet right ventricle (DORV) with subpulmonary VSD. The operative mortality rate for neonates with TGA and intact ventricular septum is down to around 6%.




FIGURE 14-8


Arterial switch operation. A, The aorta (AO; unshaded) is transected slightly above the coronary ostia, and the pulmonary artery (PA; shaded) is also transected at about the same level. The ascending aorta is lifted, and both coronary arteries are removed from the aorta with triangular buttons. B, Triangular buttons of similar size are made at the proper position in the PA trunk. C, The coronary arteries are transplanted to the PA trunk. The ascending aorta is brought behind the PA (called the Lecompte maneuver) and is connected to the proximal PA to form a neoaorta (Noe-AO). D, The triangular defects in the proximal aorta are repaired, and the proximal aorta is connected to the distal portion of the divided PA. Note that the neo-PA is in front of the neoaorta.


Complications after the ASO are infrequent. Normal sinus rhythm is usually present, arrhythmias are extremely rare, and LV function is usually normal. The following complications may occur after the ASO:



  • a.

    Coronary artery obstruction, which may lead to myocardial ischemia, infarction, and even death, is a serious but a rare complication.


  • b.

    Supravalvular PS at the anastomosis site (∼12%) is the most common cause for reoperation, although the incidence has decreased.


  • c.

    Neoaortic valvular regurgitation and supravalvular neoaortic stenosis are rare complications.


    The following factors are important for a successful ASO.



    • 1)

      LV pressure. An LV that can support the systemic circulation after surgery must exist. The LV pressure should be near systemic levels at the time of surgery so that the ASO should be performed shortly after birth. The time limit is 3 weeks of age (although some suggest an upper limit of 8 week of age).


    • 2)

      Coronary artery anatomy. Almost all coronary artery patterns in TGA are amenable to the ASO. However, the risk is slightly higher when either one or both coronary arteries passes between the great arteries. The single coronary artery is transferable by various surgical techniques.




Currently, other associated anomalies are repaired at the time of the ASO in the neonatal period.



  • a.

    For patients with associated VSD, the VSD is repaired through the atrial approach or through the pulmonary valve. The mortality rate is around 6%.


  • b.

    For patients with PDA and VSD, the PDA is ligated, and the VSD is closed.


  • c.

    Mild pulmonary valve stenosis or dynamic subpulmonary stenosis does not preclude a successful ASO.



Two-stage switch operation. In patients whose LV pressure is low (because of missing the chance for an early ASO), it can be raised by PA banding, either with or without a shunt procedure, for 7 to 10 days (in cases of a “rapid two-stage switch operation”) or for several months before undertaking the switch operation. LV pressure greater than 85% of the RV pressure appears to be satisfactory for the switch operation. The rapid switch is preferable to a longer waiting period, which results in scarring and adhesions of the PA after PA banding. Scarring makes PA reconstruction and anastomosis of the great arteries difficult, and adhesions obscure coronary artery anatomy.


Staged conversion to ASO. Some patients who received an atrial baffle operation develop RV failure with severe tricuspid valve regurgitation. For these patients, staged conversion to ASO can be done. Initially, a PA band is placed to raise the LV pressure. This is followed by an ASO with a higher mortality rate (≈25%–33%). Alternatively, after PA band, the Damus-Kaye-Stansel operation can be performed, which does not require transfer of coronary arteries. Transfer of coronary arteries is much more difficult in these patients because of dense adhesions.



  • 4.

    REV procedure. This procedure, first reported by Lecompte, may be performed for patients with D-TGA associated with VSD and severe PS, instead of the Rastelli operation. The procedure consists of (1) infundibular resection to enlarge the VSD, (2) intraventricular baffle to direct LV output to the aorta, (3) aortic transection to perform the Lecompte maneuver (by which the right pulmonary artery (RPA) is brought anterior to the ascending aorta), and (4) direct RV-to-PA reconstruction by using an anterior patch ( Fig. 14-9 ). This may require fewer reoperations than the Rastelli procedure. Lecompte reported 50 cases (4 mo–15 yr) with an 18% operative mortality rate.




    FIGURE 14-9


    Réparation à I܀étage Iventriculare (REV) procedure for patients with D-transposition of the great arteries (D-TGA), ventricular septal defect (VSD), and severe pulmonary stenosis (PS). A, A schematic drawing of D-TGA with VSD and severe PS (with a relatively small pulmonary artery [PA]). The broken lines indicate the planned aortic and right ventricular (RV) incision sites. The broken circle indicates a VSD. B, The aorta and PA have been transected, and the right pulmonary artery (RPA) is brought anterior to the aorta (Lecompte maneuver). The proximal PA has been oversewn. The VSD is exposed through the right ventriculotomy. (Note that these figures have expanded ventriculotomy to allow visualization of intracardiac structures.) Dotted hemi-circular lines indicate the portion of the infundibular septum to be excised to enlarge the VSD. C, The aortic valve is well shown by retractors. The broken line indicates the planned site of a patch placement for the LV–aorta (AO) connection. The transected aorta has been reconnected behind the RPA. D, The completed LV-to-AO tunnel is shown (marked LVOT [left ventricular outflow tract] patch). The superior portion of the right ventriculotomy is sutured directly to the posterior portion of the main PA. E, A pericardial or synthetic patch is used to complete the RV-to-PA reconstruction (marked RVOT [right ventricular outflow tract] patch).


  • 5.

    Nikaidoh procedure. This procedure is another surgical option for patients with D-TGA, VSD, and severe PS. In this procedure, the aortic root is mobilized and translocated to the pulmonary position. The repair consists of the following: (1) harvesting the aortic root from the RV (with attached coronary arteries in the original procedure), (2) relieving the LVOT obstruction (by enlarging the VSD by means of dividing the outlet septum and excising the pulmonary valve), (3) reconstructing the LVOT (with posteriorly translocated aortic root and the VSD patch), and (4) reconstructing the right ventricular outflow tract (RVOT) (with a pericardial patch or a homograft). In the modified Nikaidoh procedure, one or both coronary arteries are moved to a more favorable position as necessary (not shown), and the Lecompte maneuver is also performed ( Fig. 14-10 ). The hospital mortality is less than 10%.




    FIGURE 14-10


    Nikaidoh procedure (for patients with D-transposition of the great arteries [D-TGA], ventricular septal defect [VSD], and severe pulmonary stenosis [PS]). A, Schematic drawing of D-TGA with VSD and severe PS (with relatively small pulmonary artery [PA]) is shown. The circular broken line around the aorta is the planned incision site for aortic root mobilization. The smaller broken circle indicates a VSD. B, The aortic root has been mobilized by a circular incision around the aortic root, which leaves an opening in the right ventricular (RV) free wall. The main PA is also transected. Through the opening, part of the VSD, the ventricular septum, and the hypoplastic PA stump are seen. The dotted vertical line in the ventricular septum (in the smaller inset in B ) is the planned incision through the infundibular septum. C, In the inset, the incision in the infundibular septum has created a large opening, which includes the PA annulus and stump and the VSD. D, In the large inset, the posterior portion of the aorta is directly sutured to the PA stump, which results in a large VSD. This completes translocation of the aorta to the original PA position. The thick oval-shaped broken line that goes through the front of the transected aortic root is the planned site for placement of the left ventricular (LV) outflow tract (LVOT) patch, which will direct the LV flow to the aorta. E, The completed tunnel is shown (marked LVOT patch, which directs the LV flow to the aorta). The distal segment of the main PA is fixed to the aorta. Some surgeons use the Lecompte maneuver to bring the right pulmonary artery (RPA) in front of the ascending aorta (as shown here). F, A pericardial patch is oversewn to complete the RV-to-PA connection (marked RVOT [RV outflow tract] patch).


  • 6.

    Damus-Kaye-Stansel operation. Infants with a large VSD and significant subaortic stenosis may receive the Damus-Kaye-Stansel operation at 1 to 2 years of age. In this procedure, the coronary arteries are not transferred to a neoaorta. Instead, the subaortic stenosis is bypassed by connecting the proximal PA trunk to the ascending aorta. The VSD is closed, and a conduit is placed between the RV and the distal PA ( Fig. 14-11 ). The mortality rate is considerable, ranging from 15% to 30%.




    FIGURE 14-11


    Damus-Kaye-Stansel operation for complete transposition of the great arteries (D-TGA) + ventricular septal defect (VSD + subaortic stenosis. A, D-TGA with VSD and subaortic stenosis is illustrated. The main pulmonary artery (MPA) is transected near its bifurcation. An appropriately positioned and sized incision is made in the ascending aorta (AO). B, The proximal MPA is anastomosed end to side to the ascending aorta using either a Dacron tube or Gore-Tex. This channel will direct left ventricular blood to the aorta. The aortic valve is either closed or left unclosed. The VSD is closed (through a right ventriculotomy). C, A valved conduit is placed between the right ventricle (RV) and the distal pulmonary artery (PA). This channel will carry RV blood to the PA. LV, left ventricle; RA, right atrium.



The Damus-Kaye-Stansel operation is also applicable in patients with single ventricle and TGA with an obstructive bulboventricular foramen (BVF) or DORV with subaortic stenosis (see Fig. 14-62 ).


Surgical management for patients with TGA and various associated defects is summarized in Figure 14-12 .




FIGURE 14-12


Surgical approaches to transposition of the great arteries with various associated defects. ASO, arterial switch operation; BT, Blalock-Taussig; PDA, patent ductus arteriosus; PS, pulmonary stenosis; REV, réparation à I܀étage ventriculare ; TGA, transposition of the great arteries; VSD, ventricular septal defect.


Follow-up After Arterial Switch Operation


Although the complication rate is much lower for arterial switch than for atrial baffle repair, regular follow-up is needed to detect possible complications, such as stenosis of the PA or aorta in the supravalvular regions, coronary artery obstruction with myocardial ischemia or infarction, ventricular dysfunction, arrhythmias, and semilunar valve regurgitation. These complications are, for the most part, hemodynamically insignificant or infrequent.


Coronary artery obstruction after the surgery is a concern. In one study, about 5% of postoperative arterial switch patients had coronary arterial abnormalities by coronary angiography; some of them had no signs of ischemia by history, ECG, and echocardiographic studies. A periodic follow-up is recommended with ECG, echocardiography, exercise stress test (in older children), magnetic resonance imaging (MRI) or computed tomography (CT), or coronary angiography. MRI can provide a comprehensive anatomic and functional evaluation for coronary ischemia noninvasively, including myocardial perfusion and viability information.




Congenitally Corrected Transposition of the Great Arteries


Prevalence


Congenitally corrected transposition of the great arteries (or L-TGA) occurs in fewer than 1% of all patients with CHDs.


Pathology




  • 1.

    In this condition, the visceroatrial relationship is normal, but there is ventricular inversion. The RA is to the right of the LA and receives systemic venous blood. The RA empties into the anatomic LV through the mitral valve, and the LA empties into the RV through the tricuspid valve. For this to occur, the RV is located to the left of the LV (or the LV is located to the right of the RV), which is called ventricular inversion ( Fig. 14-13 ). The great arteries are transposed, with the aorta rising from the RV and the PA rising from the LV. The aorta is located anterior to and left of the PA; thus, the prefix of L is used, and the condition is called L-TGA (see Fig. 17-4 , D ). The result is functional correction in that oxygenated blood coming into the LA goes to the anatomic RV and then flows out to the aorta. This is why the term corrected is used to describe this condition.




    FIGURE 14-13


    Diagram of congenitally corrected transposition of the great arteries (L-TGA). There is an inversion of ventricular chambers with their corresponding atrioventricular valves. The great arteries are transposed, but functional correction results, with oxygenated blood going to the aorta. Unfortunately, a high percentage of the patients with L-TGA have associated defects, some of which may cause cyanosis. AO, aorta; LA, left atrium; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle.


  • 2.

    Theoretically, no functional abnormalities exist, but unfortunately, most cases are complicated by associated intracardiac defects, AV conduction disturbances, and arrhythmias.



    • a.

      VSD occurs in 80% of all cases.


    • b.

      PS, both valvular and subvalvular, occurs in 50% of patients and is usually associated with VSD.


    • c.

      Systemic AV valve (tricuspid valve) regurgitation occurs in 30% of patients.


    • d.

      Occasionally, complex associated defects are present with hypoplastic ventricle, AV valve abnormalities, or multiple VSDs.


    • e.

      Both varying and progressive degrees of AV block and paroxysmal supraventricular tachycardia (SVT) frequently occur.



  • 3.

    The cardiac apex is in the right chest (dextrocardia) in about 50% of cases.


  • 4.

    The coronary arteries show a mirror-image distribution. The right coronary artery supplies the anterior descending branch and gives rise to a circumflex; the left coronary artery resembles a right coronary artery.



Clinical Manifestations


History




  • 1.

    Patients are asymptomatic when L-TGA is not associated with other defects.


  • 2.

    During the first months of life, most patients with associated defects become symptomatic with cyanosis resulting from VSD and PS or CHF resulting from a large VSD.


  • 3.

    Exertional dyspnea and easy fatigability may develop with regurgitation of the systemic AV valve (i.e., anatomic tricuspid valve).



Physical Examination




  • 1.

    The patient is cyanotic if PS and VSD are present.


  • 2.

    Hyperactive precordium occurs in the presence of a large VSD. Systolic thrill occurs in the presence of PS with or without VSD.


  • 3.

    The S2 is loud and single at the upper left or right sternal border. A grade 2 to 4 of 6 harsh, holosystolic murmur along the lower left sternal border indicates the presence of VSD or systemic AV valve regurgitation. A grade 2 to 3 of 6 ejection systolic murmur is present at the upper left or right sternal border if PS is present. An apical diastolic rumble may be audible if a large VSD or significant tricuspid regurgitation (TR) is present.


  • 4.

    Bradycardia, tachycardia, or irregular rhythm requires an investigation for AV conduction disturbances or arrhythmias.



Electrocardiography




  • 1.

    The absence of Q waves in V5 and V6 or the presence of Q waves in V4R or V1 is characteristic of the condition ( Fig. 14-14 ). This is because the direction of ventricular septal depolarization is from the embryonic LV to RV.




    FIGURE 14-14


    Tracing from an 8-year-old girl with congenitally corrected transposition of the great arteries, ventricular septal defect, and pulmonary stenosis. Note that no Q waves are seen in leads V5 and V6. Instead, the Q waves are seen in V4R and V1. This suggests ventricular inversion. The electrocardiogram also suggests hypertrophy of the right-sided ventricle (anatomic left ventricle).


  • 2.

    Varying degrees of AV block are common. First-degree AV block is present in about 50% of patients. Second-degree AV block may progress to complete heart block.


  • 3.

    Atrial arrhythmias and Wolff-Parkinson-White (WPW) preexcitation are occasionally present.


  • 4.

    Atrial or ventricular hypertrophy (or both) may be present in complicated cases.



Radiography




  • 1.

    A straight, left upper cardiac border, formed by the ascending aorta, is a characteristic finding ( Fig. 14-15 ).




    FIGURE 14-15


    Posteroanterior view of an actual chest roentgenogram ( A ) and a diagrammatic representation ( B ) from a 10-year-old child with congenitally corrected transposition of the great arteries. Note the straight left cardiac border formed by the ascending aorta. Ao, aorta; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle.


  • 2.

    Cardiomegaly and increased pulmonary vascular markings are present when the condition is associated with VSD.


  • 3.

    Pulmonary venous congestion and LA enlargement may be seen with severe left-sided AV valve regurgitation.


  • 4.

    Positional abnormalities (e.g., dextrocardia, mesocardia) may be present.



Echocardiography


With use of the segmental approach (see Chapter 17 ), the diagnosis of L-TGA can be made easily, and associated anomalies can be detected and quantitated.



  • 1.

    The parasternal long-axis view is obtained from a more vertical and leftward scan than with a normal heart. The aorta, which arises from the posterior ventricle, is not in fibrous continuity with the AV valve.


  • 2.

    In the parasternal short-axis scan, a “double circle” of the semilunar valves is imaged instead of the normal “circle and sausage” pattern. The posterior circle is the PA without demonstrable coronary arteries. The aorta is usually anterior to and left of the PA. The LV, which has two well-defined papillary muscles, is seen anteriorly and on the right and is connected to the characteristic “fish mouth” appearance of the mitral valve.


  • 3.

    In the apical and subcostal four-chamber views, the LA is connected to the tricuspid valve (which has a more apical attachment to the ventricular septum than the other) and the RA is connected to the mitral valve. The anterior artery (aorta) arises from the left-sided morphologic RV, and the posterior artery with bifurcation (PA) arises from the right-sided morphologic LV.


  • 4.

    The situs solitus of the atria is confirmed by the drainage of systemic veins (i.e., inferior vena cava [IVC] and SVC) to the right-sided atrium and the drainage of pulmonary veins to the left-sided atrium.


  • 5.

    The following associated abnormalities should be looked for, and their functional significance should be assessed by the Doppler and color-flow studies: type and severity of PS, size and location of VSD, straddling of the AV valve, and so on.



Other Studies


Occasionally, angiography may be necessary to image coronary artery anatomy, although CT or MRI may provide this information noninvasively.


Natural History


The clinical course is determined by the presence or absence of associated defects and complications.



  • 1.

    Some palliative surgeries are usually needed in infancy when L-TGA is associated with other defects (e.g., PA banding for a large VSD or a systemic-to-PA shunt for severe PS). Without these procedures, 20% to 30% of patients die in the first year. CHF is the most common cause of death.


  • 2.

    Regurgitation of the systemic AV valve (anatomic tricuspid valve) develops in about 30% of patients. This is often associated with dysplastic or Ebstein-like tricuspid valves.


  • 3.

    Progressive AV conduction disturbances may occur, including complete heart block in up to 30% of cases. These disturbances occur more often in patients without VSD than in those with VSD. Sudden death rarely occurs.


  • 4.

    Occasional adult patients without major associated defects are asymptomatic.



Management


Medical




  • 1.

    Treatment with anticongestive agents is necessary if CHF develops.


  • 2.

    Antiarrhythmic agents are used for arrhythmias.



Surgical


Palliative Procedures




  • 1.

    A modified Blalock-Taussig (BT) shunt is necessary for patients with severe PS (usually associated with VSD).


  • 2.

    PA banding may be needed for uncontrollable CHF in early infancy.



Definitive Procedures


There are two major approaches to surgical management of L-TGA, classic repair and anatomic repair. Patients with regurgitation of the tricuspid valve (systemic AV valve) or RV dysfunction need the anatomic repair in which the LV is made the systemic ventricle. The surgical approach for L-TGA is summarized in Figure 14-16 .



  • 1.

    Classic repair leaves the anatomic RV as the systemic ventricle. A competent tricuspid valve (or left AV valve) and good RV function are required. Even after repair, progressive TR and RV failure may develop.



    • a.

      In patients with VSD, the VSD is closed through an atrial approach. Complete heart block is a complication of the surgery, occurring 15% to 30% of the time. The mortality rate is 5% to 10%, which is higher than that for a simple VSD.


    • b.

      In patients with VSD and PS (or LVOT obstruction), the VSD is closed and an LV-to-PA conduit is placed. The surgical mortality rate is higher (10%–15%).



  • 2.

    Anatomic repair makes the anatomic LV the systemic ventricle, which may reduce the likelihood of TR and RV failure. This repair is technically more difficult than the classic repair and carries a higher risk, but this procedure is a better choice for patients with TR or RV dysfunction.



    • a.

      A combination of Senning procedure (which is an atrial switch operation; see Fig. 14-6 ) and ASO (see Fig. 14-8 ), called a “double switch” operation, is performed in patients with VSD. A PA banding is initially placed to delay the procedure until after 1 year of age. Closure of VSD, if present, is performed through the RA. The hospital mortality rate for the “double switch” operation is approximately 10%, with complete heart block occurring 0% to 23% of the time.


    • b.

      In patients with VSD and PS (or LVOT obstruction), a combination of the Senning operation and Rastelli operation is performed. VSD is closed through a right ventriculotomy in such a way to connect the VSD to the aorta. Enlargement of the VSD is often necessary. RV-to-PA continuity is established with an extracardiac valved conduit. The hospital mortality rate is around 10%. TR improves after the procedure.



  • 3.

    Fontan-type operation. In patients with complex intracardiac anatomies, including hypoplasia of one ventricle, straddling AV valves, or multiple VSDs, bidirectional Glenn operation or a full Fontan procedure is indicated.


  • 4.

    Other p rocedures



    • a.

      Valve replacement. For patients with significant TR, valve replacement is required in about 15%, including those without other associated defects.


    • b.

      Pacemaker implantation is required for either spontaneous or postoperative complete heart block.


    • c.

      Cardiac transplantation. Some patients with complex L-TGA eventually become candidates for cardiac transplantation.





FIGURE 14-16


Surgical summary of congenitally corrected transposition of the great arteries (L-TGA). AO, aorta; ASO, arterial switch operation; PA, pulmonary artery; RV, right ventricle; PS, pulmonary stenosis (= LV outflow tract obstruction); TGA, transposition of the great arteries; TR, tricuspid regurgitation (= left-sided AV valve regurgitation); VSD, ventricular septal defect.


Postoperative Follow-up




  • 1.

    Follow-up every 6 to 12 months is required for a possible progression of AV conduction disturbances, arrhythmias, or worsening of anatomic tricuspid valve regurgitation.


  • 2.

    Routine pacemaker care, if a pacemaker is implanted, should be conducted.


  • 3.

    Activity restriction is indicated if significant hemodynamic abnormalities persist.





Tetralogy of Fallot


Prevalence


Tetralogy of Fallot occurs in 5% to 10% of all CHDs. This is probably the most common cyanotic heart defect.


Pathology




  • 1.

    The original description of TOF included the following four abnormalities: a large VSD, RVOT obstruction, RVH, and overriding of the aorta. In actuality, only two abnormalities are required, a VSD large enough to equalize pressures in both ventricles and an RVOT obstruction. The RVH is secondary to the RVOT obstruction, and the overriding of the aorta varies ( Fig. 14-17 ).




    FIGURE 14-17


    Pathologic anatomy of tetralogy of Fallot viewed with the right ventricular (RV) free wall removed. A large ventricular septal defect (VSD) is present underneath the aortic valve. Hypertrophied parietal and septal bands produce infundibular stenosis (marked x). A stenotic and hypoplastic main pulmonary artery (PA) is shown. The RV muscle is hypertrophied. TV, tricuspid valve.

    (Hirsch JC, Bove EL. Tetralogy of Fallot. In Mavroudis C. Pediatric Cardiac Surgery, 3rd ed. Philadelphia, Mosby, 2003. Reproduced with permission).


  • 2.

    The VSD in TOF is a large perimembranous defect with extension into the subpulmonary region.


  • 3.

    The RVOT obstruction is most frequently in the form of infundibular stenosis (45%). The obstruction is rarely at the pulmonary valve level (10%). A combination of the two may also occur (30%). The pulmonary valve is atretic in the most severe form of the anomaly (15%), which is discussed under a separate heading in this chapter.


  • 4.

    The pulmonary annulus and main PA are variably hypoplastic in most patients. The PA branches are usually small, although marked hypoplasia is uncommon. Stenosis at the origin of the branch PAs, especially the left PA, is common. Occasionally, systemic collateral arteries feed into the lungs, especially in severe cases of TOF.


  • 5.

    Right aortic arch is present in 25% of cases, with some of them having symptoms of vascular ring.


  • 6.

    In about 5% of TOF patients, abnormal coronary arteries are present. The most common abnormality is the anterior descending branch arising from the right coronary artery and passing over the RVOT, which prohibits a surgical incision in the region.


  • 7.

    Complete AV canal defect occurs in approximately 2% of patients with TOF, more commonly among patients with Down syndrome, called “canal tet.” In these patients, the VSD has a large outlet component in addition to the inlet portion associated with the AV canal.



Clinical Manifestations


History




  • 1.

    A heart murmur is audible at birth.


  • 2.

    Most patients are symptomatic with cyanosis at birth or shortly thereafter. Dyspnea on exertion, squatting, or hypoxic spells develop later even in mildly cyanotic infants (see Chapter 11 ).


  • 3.

    Occasional infants with acyanotic TOF may be asymptomatic or may show signs of CHF from a large left-to-right ventricular shunt.



Physical Examination ( Fig. 14-18 )




  • 1.

    Varying degrees of cyanosis, tachypnea, and clubbing (in older infants and children) are present.




    FIGURE 14-18


    Cardiac findings in cyanotic tetralogy of Fallot. A long ejection systolic murmur at the upper and mid left sternal border and a loud, single S2 are characteristic auscultatory findings of TOF. EC, ejection click.


  • 2.

    An RV tap along the left sternal border and a systolic thrill at the upper and mid-left sternal borders are commonly present (50%).


  • 3.

    An ejection click that originates in the aorta may be audible. The S2 is usually single because the pulmonary component is too soft to be heard. A long, loud (grade 3 to 5 of 6) ejection-type systolic murmur is heard at the mid-and upper left sternal borders. This murmur originates from the PS but may be easily confused with the holosystolic regurgitant murmur of a VSD. The more severe the obstruction of the RVOT, the shorter and softer the systolic murmur.


  • 4.

    In the acyanotic form, a long systolic murmur, resulting from VSD and infundibular stenosis, is audible along the entire left sternal border, and cyanosis is absent. Thus, auscultatory findings resemble those of a small-shunt VSD (but, unlike VSD, the ECG shows RVH or BVH).



Electrocardiography




  • 1.

    Right-axis deviation (RAD) (+120 to +150 degrees) is present in cyanotic TOF. In the acyanotic form, the QRS axis is normal.


  • 2.

    RVH is usually present, but the strain pattern is unusual (because RV pressure is not suprasystemic). BVH may be seen in the acyanotic form. RAH is occasionally present.



Radiography


Cyanotic Tetralogy of Fallot




  • 1.

    The heart size is normal or smaller than normal, and pulmonary vascular markings are decreased. “Black” lung fields are seen in TOF with pulmonary atresia.


  • 2.

    A concave main PA segment with an upturned apex (i.e., “boot-shaped” heart or coeur en sabot) is characteristic ( Fig. 14-19 ).




    FIGURE 14-19


    Posteroanterior view of chest roentgenogram in tetralogy of Fallot. The heart size is normal, and pulmonary vascular markings are decreased. A hypoplastic main pulmonary artery segment contributes to the formation of the “boot-shaped” heart.


  • 3.

    RA enlargement (25%) and right aortic arch (25%) may be present.



Acyanotic Tetralogy of Fallot


Radiographic findings of acyanotic TOF are indistinguishable from those of a small to moderate VSD (but patients with TOF have RVH rather than LVH on the ECG).


Echocardiography


Two-dimensional echocardiography and Doppler studies usually make the diagnosis and quantitate the severity of TOF.



  • 1.

    A large, perimembranous infundibular VSD and overriding of the aorta are readily imaged in the parasternal long-axis view ( Fig. 14-20 ).




    FIGURE 14-20


    Parasternal long-axis view in a patient with tetralogy of Fallot. Note a large subaortic ventricular septal defect (arrow) and a relatively large aorta (AO) overriding the interventricular septum (IVS). AV, aortic valve; LA, left atrium; LV, left ventricle; MV, mitral valve; RV, right ventricle.


  • 2.

    Anatomy of the RVOT, the pulmonary valve, the pulmonary annulus, and the main PA and its branches is imaged in the parasternal short-axis and subcostal short-axis views. These views allow systematic evaluation of the severity of obstruction at different levels.


  • 3.

    Doppler studies estimate the pressure gradient across the RVOT obstruction.


  • 4.

    Anomalous coronary artery distribution can be imaged accurately by echocardiographic studies ( Fig. 14-21 ). The major concern is to rule out any branch of the coronary artery crossing the RVOT. Thus, preoperative cardiac catheterization solely for the diagnosis of coronary artery anatomy is not necessary.




    FIGURE 14-21


    Patterns of coronary artery anatomy in tetralogy of Fallot (TOF) as imaged from the parasternal short-axis view. The percentage of each pattern seen in 598 patients with TOF is indicated in the lower left corner of each box. Ant, anterior; CX, left circumflex branch; L, left; LAD, left anterior descending coronary artery; R, right; RCA, right coronary artery; Post, posterior.

    (From Need LR, Powell AJ, del Nide P, Geva T: Coronary echocardiography in tetralogy of Fallot: Diagnostic accuracy, resource utilization and surgical implications over 13 years. J Am Coll Cardiol 36:1371–1377, 2000.)


  • 5.

    Associated anomalies such as ASD and persistence of the left superior vena cava (LSVC) can be imaged.



Other Studies


Two-dimensional echocardiographic and Doppler studies are the primary methods of evaluation before surgery. Cardiac catheterization is reserved only for patients with specific unanswered questions after echocardiographic study.


Natural History




  • 1.

    Infants with acyanotic TOF gradually become cyanotic. Patients who are already cyanotic become more cyanotic as the infundibular stenosis worsens and polycythemia develops.


  • 2.

    Polycythemia develops secondary to cyanosis.


    This occurs in all types of cyanotic CHDs.



  • 3.

    Physicians need to watch for the development of relative iron-deficiency states (i.e., hypochromia) (see Chapter 11 ).


  • 4.

    Hypoxic spells may develop in infants (see Chapter 11 ).


  • 5.

    Growth retardation may be present if cyanosis is severe.


  • 6.

    Brain abscess and cerebrovascular accident rarely occur (see Chapter 11 ).


  • 7.

    Subacute bacterial endocarditis (SBE) is occasionally a complication.


  • 8.

    Some patients, particularly those with severe TOF, develop aortic regurgitation (AR).


  • 9.

    Coagulopathy is a late complication of a long-standing cyanosis.



Hypoxic Spell


Hypoxic spells (also called cyanotic spells, hypercyanotic spells, “tet” spells) of TOF are not as common as they used to be because many of the patients with TOF receive surgery before they develop the spells. However, it is very important for physicians to be able to immediately recognize and treat the spells appropriately because they can lead to serious complications of the CNS.


Hypoxic spells are characterized by a paroxysm of hyperpnea (i.e., rapid and deep respiration), irritability and prolonged crying, increasing cyanosis, and decreasing intensity of the heart murmur. Hypoxic spells occur in infants, with a peak incidence between 2 and 4 months of age. These spells usually occur in the morning after crying, feeding, or defecation. A severe spell may lead to limpness, convulsion, cerebrovascular accident, or even death. There appears to be no relationship between the degree of cyanosis at rest and the likelihood of having hypoxic spells (see Chapter 11 ).


Treatment of the hypoxic spell strives to break the vicious circle of the spell (see Fig. 11-11 ). Physicians may use one or more of the following to treat the spell.



  • 1.

    The infant should be picked up and held in a knee–chest position.


  • 2.

    Morphine sulfate, 0.2 mg/kg administered subcutaneously or intramuscularly, suppresses the respiratory center and abolishes hyperpnea (and thus breaks the vicious cycle).


  • 3.

    Oxygen is usually administered, but it has little demonstrable effect on arterial oxygen saturation.


  • 4.

    Acidosis should be treated with sodium bicarbonate (NaHCO 3 ), 1 mEq/kg administered IV. The same dose can be repeated in 10 to 15 minutes. NaHCO 3 reduces the respiratory center–stimulating effect of acidosis.



With the preceding treatment, the infant usually becomes less cyanotic, and the heart murmur becomes louder, which indicates an increased amount of blood flowing through the stenotic RVOT. If the hypoxic spells do not fully respond to these measures, the following medications can be tried:



  • 1.

    Ketamine, 1 to 3 mg/kg (average, 2 mg/kg) administered IV over 60 seconds, works well. It increases the systemic vascular resistance (SVR) and sedates the infant.


  • 2.

    Propranolol, 0.01 to 0.25 mg/kg (average, 0.05 mg/kg) administered by slow IV push, reduces the heart rate and may reverse the spell.



Management


Medical




  • 1.

    Physicians should recognize and treat hypoxic spells (see the preceding section and Chapter 11 ). It is important to educate parents to recognize the spells and know what to do.


  • 2.

    Oral propranolol therapy, 0.5 to 1.5 mg/kg every 6 hours, is occasionally used to prevent hypoxic spells while waiting for an optimal time for corrective surgery in the regions where open heart surgical procedures are not well established for small infants.


  • 3.

    Balloon dilatation of the RVOT and pulmonary valve, although not widely practiced, has been attempted to delay repair for several months.


  • 4.

    Relative iron-deficiency states should be detected and treated. Iron-deficient children are more susceptible to cerebrovascular complications. Normal hemoglobin or hematocrit values or decreased red blood cell indices indicate an iron-deficiency state in cyanotic patients.



Surgical


Palliative Shunt Procedures


Indications


Shunt procedures are performed to increase PBF ( Fig. 14-22 ). Indications for shunt procedures vary from institution to institution. Many institutions, however, prefer primary repair without a shunt operation regardless of the patient’s age. However, when the following situations are present, a shunt operation may be chosen rather than primary repair.



  • 1.

    Neonates with TOF and pulmonary atresia


  • 2.

    Infants with hypoplastic pulmonary annulus, which requires a transannular patch for complete repair


  • 3.

    Children with hypoplastic PAs


  • 4.

    Unfavorable coronary artery anatomy


  • 5.

    Infants younger than 3 to 4 months old who have medically unmanageable hypoxic spells


  • 6.

    Infants weighing less than 2.5 kg




FIGURE 14-22


Palliative procedures that can be performed in patients with cyanotic cardiac defect with decreased pulmonary blood flow. The Gore-Tex interposition shunt (or modified Blalock-Taussig shunt) is the most popular systemic–to–pulmonary artery (PA) shunt procedure. AO, aorta; LV, left ventricle; RA, right atrium; RV, right ventricle.


Procedures, Complications, and Mortality


Although several other procedures were performed in the past (see Fig. 14-22 ), a modified BT (Gore-Tex interposition) shunt is the only procedure performed at this time.



  • 1.

    Classic BT shunt, anastomosed between the subclavian artery and the ipsilateral PA, is usually performed for infants older than 3 months because the shunt is often thrombosed in young infants. A right-sided shunt is performed in patients with left aortic arch; a left-sided shunt is performed for right aortic arch.


  • 2.

    With a modified BT shunt, a Gore-Tex interposition shunt is placed between the subclavian artery and the ipsilateral PA. This is the most popular procedure for any age, especially for infants younger than 3 months of age. Whereas a left-sided shunt is preferred for patients with left aortic arch, a right-sided shunt is preferred for patients with a right aortic arch. The surgical mortality rate is 1% or less.


  • 3.

    The Waterston shunt, anastomosed between the ascending aorta and the right PA, is no longer performed because of a high incidence of surgical complications. Complications resulting from this procedure included too large a shunt leading to CHF or pulmonary hypertension and narrowing and kinking of the right PA at the site of the anastomosis. This created difficult problems in closing the shunt and reconstructing the right PA at the time of corrective surgery.


  • 4.

    The Potts operation, anastomosed between the descending aorta and the left PA, is no longer performed either. It may result in heart failure or pulmonary hypertension, as in the Waterston operation. A separate incision (i.e., left thoracotomy) is required to close the shunt during corrective surgery, which is performed through a midsternal incision.



Complete Repair Surgery


Timing of this operation varies from institution to institution, but early surgery is generally preferred.


Indications and Timing




  • 1.

    Oxygen saturation less than 75% to 80% is an indication of surgery by most centers. The occurrence of hypoxic spells is generally considered an indication for operation.


  • 2.

    Symptomatic infants who have favorable anatomy of the RVOT and PAs may have primary repair at any time after 3 to 4 months of age, with some centers performing it even before 3 months of age. Most centers prefer primary elective repair by 1 to 2 years of age even if they are asymptomatic, acyanotic (i.e., “pink tet”), or minimally cyanotic.



Advantages cited for early primary repair include diminution of hypertrophy and fibrosis of the RV, normal growth of the PAs and alveolar units, and reduced incidence of postoperative ventricular arrhythmias, and sudden death.



  • 3.

    Mildly cyanotic infants who have had previous shunt surgery may have total repair 1 to 2 years after the shunt operation.


  • 4.

    Asymptomatic children with coronary artery anomalies may have the repair after 1 year of age, because a conduit placement may be required between the RV and the PA.



Procedure


Total repair of the defect is carried out under cardiopulmonary bypass, circulatory arrest, and hypothermia. The procedure includes patch closure of the VSD, preferably through transatrial and transpulmonary artery approach (rather than right ventriculotomy, which is shown in Fig. 14-23 ); widening of the RVOT by division or resection of the infundibular tissue; and pulmonary valvotomy, avoiding placement of a fabric patch whenever possible (see Fig. 14-23 ). Widening of the RVOT without placement of patch is more likely to be accomplished if the repair is done in early infancy. However, if the pulmonary annulus and main PA are hypoplastic, transannular patch placement is unavoidable. Whereas some centers advocate placement of a monocusp valve at the time of initial repair, others advocate pulmonary valve replacement at a later time if indicated.




FIGURE 14-23


Total correction of tetralogy of Fallot (TOF). A, Anatomy of TOF showing a large ventricular septal defect (VSD) and infundibular stenosis seen through a right ventriculotomy. Note that the size of the ventriculotomy has been expanded to show the VSD. B, Patch closure of the VSD and resection of the infundibular stenosis. C, Placement of a fabric patch on the outflow tract of the right ventricle (RV). AO, aorta; PA, pulmonary artery; RA, right atrium.


The surgical approach in patients with TOF is summarized in Figure 14-24 .




FIGURE 14-24


Surgery approaches for tetralogy of Fallot (TOF). BT, Blalock-Taussig; RVOT, right ventricular outflow tract; RV-PA, right ventricle–to–pulmonary artery; VSD, ventricular septal defect.


Mortality


For patients with uncomplicated TOF, the mortality rate is 2% to 3% during the first 2 years. Patients at risk are those younger than 3 months and older than 4 years, as well as those with severe hypoplasia of the pulmonary annulus and trunk. Other risk factors may include multiple VSDs, large aortopulmonary collateral arteries, and Down syndrome.


Complications




  • 1.

    Bleeding problems may occur during the postoperative period, especially in older polycythemic patients.


  • 2.

    Pulmonary valve regurgitation may occur, but mild regurgitation is well tolerated.


  • 3.

    Right bundle branch block (RBBB) on the ECG caused by right ventriculotomy, which occurs in more than 90% of patients, is well tolerated.


  • 4.

    Complete heart block (i.e., <1%) and ventricular arrhythmia are both rare.



Anomalous coronary artery


Anomalous anterior descending coronary artery arising from the right coronary artery is considered a contraindication to a primary repair because it may require placement of a conduit between the RV and PA, which is usually performed after 1 year of age. However, it is often possible to enlarge the outflow tract through a transatrial approach and by placing a short outflow patch either above or below the anomalous coronary artery. Alternatively, when a small conduit is necessary between the RV and the PA, the native outflow tract should be made as large as possible through an atrial approach, so that a “double outlet” (the native outlet and the conduit) results from the RV.


Postoperative Follow-up




  • 1.

    Long-term follow-up with office examinations every 6 to 12 months is recommended, especially for patients with residual VSD shunt, residual obstruction of the RVOT, residual PA obstruction, arrhythmias, or conduction disturbances.


  • 2.

    Significant pulmonary regurgitation (PR) may develop after repair of TOF. Although the PR is well tolerated for a decade or two, moderate to severe PR may eventually develop with significant RV dilatation and dysfunction, requiring surgical insertion of a homograft pulmonary valve. Severe PR left untreated may result in irreversible anatomic and functional changes in the RV, but the ideal timing of the valve replacement has been controversial. RV function is best investigated by MRI; if MRI is contraindicated because of the presence of metallic objects or cardiac pacemaker, CT should be used. The following are suggested criteria for surgical pulmonary valve replacement.



    • a.

      Recommended criteria by Geva T (2006) is primarily based on RV regurgitant fraction:



      • 1)

        RV regurgitation fraction ≥25% PLUS


      • 2)

        Two or more of the following criteria



        • a)

          RV end-diastolic volume index ≥160 mL/m 2 (normal, <108 mL/m 2 )


        • b)

          RV end-systolic volume index ≥70 mL/m 2 (normal, <47 mL/m 2 )


        • c)

          LV end-diastolic volume index ≥65 mL/m 2


        • d)

          RV ejection fraction ≤45%


        • e)

          RV outflow tract aneurysm


        • f)

          Clinical criteria: exercise intolerance, syncope, presence of heart failure, sustained ventricular tachycardia, or QRS duration ≥180 msec (two last ones are known risk factors for sudden death)



      • 3)

        The following are modifiers to the above criteria.



        • a)

          Presence of moderate to severe TR, residual ASD or VSD, and severe AR may trigger valve replacement.


        • b)

          If the PR is associated with the stenosis of the main or branch pulmonary arteries (natural or secondary to shunt operations), the PA stenosis should be relieved first by a balloon and/or stent procedure, which may improve PR.


        • c)

          In patients who underwent TOF repair at age 3 years or older, the valve replacement may be indicated in the presence of less severe RV dilatation and dysfunction than those 6 listed above. [Old age at surgery is an independent risk factor for impaired clinical status.]




    • b.

      Recently, Lee C. et al (2012) have recommended the following cutoff values for optimal outcome. They found the systolic volume index to be more important than the diastolic volume index in determining the outcome of surgery.



      • 1)

        RV end-systolic volume index ≥80 mL/m 2 and


      • 2)

        RV end-diastolic volume index ≥163 mL/m 2 .




  • 3.

    Some patients, particularly those who had Rastelli operation using valved conduit, develop valvular stenosis or regurgitation. Valvular stenosis may improve after balloon dilatation, but PR may worsen. A nonsurgical percutaneous pulmonary valve implantation technique developed by Bonhoeffer et al (2000) has been used successfully. It is marketed as the Melody transcatheter pulmonary valve (Medtronic, Minneapolis, MN) (see further discussion under TOF with pulmonary atresia in this chapter).


  • 4.

    Some children develop late arrhythmias, particularly ventricular tachycardia, which may result in sudden death. Arrhythmias are primarily related to persistent RVH as a result of unsatisfactory repair.


  • 5.

    Pacemaker therapy is indicated for surgically induced complete heart block or sinus node dysfunction.


  • 6.

    Varying levels of activity limitation may be necessary.


  • 7.

    For patients who have residual defects or have prosthetic material for repair, SBE prophylaxis should be observed throughout life.





Tetralogy of Fallot with Pulmonary Atresia (Pulmonary Atresia and Ventricular Septal Defect)


Prevalence


Pulmonary atresia occurs in about 15% to 20% of patients with TOF.


Pathology




  • 1.

    The intracardiac pathology resembles that of TOF in all respects except for the presence of pulmonary atresia, the extreme form of RVOT obstruction. The atresia may be at the infundibular or valvular level.


  • 2.

    The PBF is most commonly mediated through a PDA (70%) and less commonly through multiple systemic collaterals (30%), which are referred to as multiple aortopulmonary collateral arteries (MAPCAs). Both PDA and collateral arteries may coexist as the source of PBF.


  • 3.

    The central PAs are usually confluent in patients with PDA (70%). In patients with MAPCAs, the central PA is frequently nonconfluent, with the right upper lobe frequently supplied by a collateral from the subclavian artery and the left lower lobe by a collateral from the descending aorta. The subgroup of the patients with MAPCAs is designated as pulmonary atresia and ventricular septal defect (PA-VSD).


  • 4.

    PA anomalies are common in the form of hypoplasia, nonconfluence, and abnormal distribution.



    • a.

      The central PAs are confluent in 85% of patients; they are nonconfluent in 15%.


    • b.

      The central and branch PAs are hypoplastic in most patients, but this occurs more frequently in patients with MAPCAs than in those with PDA. The degree of PA hypoplasia is importantly related to the success of surgery (see below for further discussion of PA hypoplasia.


    • c.

      Incomplete arborization (distribution) of one or both PAs is found in 50% of patients with confluent PAs and in 80% of patients with nonconfluent PAs.



  • 5.

    Collateral arteries arise most commonly from the descending aorta (occurring in two thirds of patients), less commonly from the subclavian arteries, and rarely from the abdominal aorta or its branches.


  • 6.

    The ductus is small and long and arises from the transverse aortic arch and courses downward (“vertical” ductus) ( Fig. 14-25 ).




    FIGURE 14-25


    Anatomy of the ductus arteriosus in pulmonary atresia. The size and direction of the ductus arteriosus are different between a normal fetus and a fetus with pulmonary atresia. A, In a normal fetus, the ductus is large and joins the aorta (AO) at an obtuse angle. The aortic isthmus (the portion of the aorta between the left subclavian artery and the ductus) is narrower than the descending aorta. B, In pulmonary atresia, the ductus is small because flow to the descending aorta does not go through the ductus. Furthermore, because flow is from the aorta to the pulmonary artery, the connection of the ductus with the aorta has an acute inferior angle (sometimes called “vertical” ductus). The aortic isthmus has the same diameter as the descending aorta. This type of ductus arteriosus is also found in some patients with tricuspid atresia. LPA, left pulmonary artery; MPA, main pulmonary artery; RPA, right pulmonary artery.


  • 7.

    The McGoon ratio and the Nakata index are used to quantitate the degree of PA hypoplasia. Small values of these measurements may adversely affect the outcome of surgeries in patients with small pulmonary arteries.



    • a.

      The McGoon ratio is the ratio of the sum of the diameter of the immediately prebranching portion of the RPA plus left pulmonary artery (LPA) divided by the diameter of the descending aorta just above the diaphragm. Normal values of the McGoon ratio are 2.0 to 2.5. Most survivors of TOF with pulmonary atresia have a ratio greater than 1. Good Fontan candidates should have a ratio greater than 1.8.


    • b.

      The Nakata index is the cross-sectional area of the RPA and LPA (in mm 2 ) divided by the body surface area (BSA). The average diameter of both RPA and LPA are measured at the points immediately proximal to the origin of the first lobar branches at maximal and minimal during one cardiac cycle in the anteroposterior view of the pulmonary arteriogram. The cross-sectional area is calculated by using the formula, π × r 2 × magnification coefficient (where r is the radius or 1/2 of the measured PA diameters). A normal Nakata index is 330 ± 30 mm 2 /BSA. Patients with TOF with PS should have an index greater than 100 for survival. A good Fontan candidate should have an index greater than 250, and a good Rastelli candidate should have an index greater than 200. (Those with an index less than 200 should have a shunt operation rather than the Rastelli.)




Clinical Manifestations




  • 1.

    These patients are cyanotic at birth. The degree of cyanosis depends on whether the ductus is patent and how extensive the systemic collateral arteries are.


  • 2.

    Usually a heart murmur cannot be heard. However, a faint, continuous murmur may be audible from the PDA or collaterals. The S2 is loud and single. A systolic click is occasionally present.


  • 3.

    The ECG shows RAD and RVH.


  • 4.

    Chest radiography shows a normal heart size. The heart often appears as a boot-shaped silhouette (see Fig. 14-19 ), and the pulmonary vascularity is usually markedly decreased (i.e., “black” lung field). Rarely, children with MAPCAs have excessive PBF, and CHF may develop.


  • 5.

    Echocardiographic studies show all the anatomic findings of TOF plus the absence of a direct connection between the RV and the PA. In this case, a careful examination of the central PA is necessary with measurements of the size of central and branch PAs. The small branch PAs and “vertical ductus” (see Fig. 14-25 ) are well imaged from a high parasternal or suprasternal transducer position. Some of the multiple collateral arteries are also imaged by echocardiography and Doppler.


  • 6.

    Cardiac catheterization and angiograms are sometimes needed for a complete delineation of the collaterals. Alternatively, MRI, rather than CT, is chosen for complete anatomic delineation of the aortic collaterals and PA branches.



Natural History




  • 1.

    Without immediate attention to the establishment of PBF during the newborn period, most neonates who have this condition die during the first 2 years of life; however, infants with extensive collaterals may survive for a long time, perhaps for more than 15 years.


  • 2.

    Occasionally, patients with excessive collateral circulation develop hemoptysis during late childhood.



Management


Medical




  • 1.

    PGE1 infusion should be started as soon as the diagnosis is made or suspected to keep the ductus open for additional studies and to prepare for surgery. The starting dose of alprostadil (Prostin VR Pediatric) solution is 0.05 to 0.1 μg/kg per minute. When the desired effect is obtained, the dosage should be gradually reduced to 0.01 μg/kg per minute.


  • 2.

    Emergency cardiac catheterization or MRI study is usually needed to delineate the anatomy of the PAs and systemic arterial collaterals.



Surgical


A connection must be established between the RV and true PA as early in life as possible. This may allow tiny central PAs to enlarge rapidly during the first year of life with improved arborization (distribution) of the pulmonary arteries with concurrent development of alveolar units. To achieve this goal, some centers initially use a central shunt procedure, and others proceed with an RV–PA connection.



  • 1.

    Central shunt operation. Some centers use a central shunt directly connecting the ascending aorta and the hypoplastic main PA to achieve growth of the peripheral PAs (Mee procedure) ( Fig. 14-26 ). A classic or modified BT shunt is avoided because it is difficult to perform on tiny PAs and may cause stenosis or distortion. This is then followed by unifocalization (see below for explanation), RV-PA connection, and closure of VSD. Other centers skip the shunt procedure and proceed with the connection of the RV and the main PA (see below).




    FIGURE 14-26


    Central end-to-side shunt (Mee procedure). A, Diagram of tetralogy of Fallot with pulmonary atresia. B, The hypoplastic pulmonary artery (PA) is anastomosed to the ascending aorta (AO) as posteriorly as possible. LV, left ventricle; RA, right atrium; RV, right ventricle; SVC, superior vena cava.

    (From Watterson KG, Wilkinson JL, Karly TR, Mee RBB: Very small pulmonary arteries: Central end-to-side shunt. Ann Thorac Surg 52:1131–1137, 1991.)


  • 2.

    RV-to-PA connection



    • a.

      Single-stage repair. Complete, primary surgical repair in patients with TOF and pulmonary atresia is possible only when (1) the true PAs provide most or all PBF (with O 2 saturation of >75%) or (2) the central PA connects without obstruction to sufficient regions of the lungs (i.e., at least equal to one whole lung). If additional major collaterals are identified, test the level of arterial O 2 saturation after occlusion of the collateral in the catheterization laboratory. If the O 2 saturation remains greater than 70% to 75%, coil occlusion of the collaterals is then carried out.




Primary repair of this condition consists of closing the VSD, establishing a continuity between the RV and the unifocalized PA (see below for unifocalization procedure) using either aortic or pulmonary homograft (9- to 10-mm internal diameter), and interrupting collateral circulation. The mortality rate varies between 5% and 20%. Good candidates for the repair are those with a Nakata index above 200. If the index is below 200, a shunt procedure is preferable.



  • b.

    Multiple-stage repair. When the requirements for single-stage repair are not met, three consequential steps are used to repair this condition. These steps are summarized in Figure 14-27 .



    • (1)

      Stage 1. RV-to-hypoplastic PA conduit, using a relatively small homograft conduit (6- to 8-mm internal diameter) (see Fig. 14-27 ). The major goal of this operation is to make the central PA grow to an adequate size for eventual repair surgery. Interventional catheterization is carried out 3 to 6 months later to identify and coil occlude remaining aortic collaterals, to define PA distribution, and to identify if certain bronchopulmonary segments are receiving a duplicate blood supply.


    • (2)

      Stage 2. A unifocalization procedure is carried out. Unifocalization is a surgical procedure in which aortopulmonary collaterals are divided from their aortic origin and are anastomosed to the true pulmonary arteries or main PA conduit (see Fig. 14-27 ).



    • Post-unifocalization catheterization is carried out 3 to 6 months later (a) to identify multiple peripheral stenosis in both the true as well as the unifocalized collaterals and to do balloon dilatation with or without stenting and (b) to assess the need for further unifocalization procedures.


    • (3)

      Stage 3. Closure of VSD with or without fenestration, usually at 1 to 3 years of age (see Fig. 14-27 ). The homograft conduit may need to be replaced at the same time. If the RV pressure is 10% to 20% greater than systemic pressure, a central fenestration 3 to 4 mm is created. Multiple ballooning and stenting procedures are often necessary to reduce RV pressure to less than 50% systemic if possible.




    FIGURE 14-27


    Diagram of multiple-stage repair. Upper row (confluent pulmonary artery [PA] and collaterals): A, A hypoplastic but confluent central PA and multiple other collateral arteries are shown. B , A small right ventricle–to–PA (RV-to-PA) connection is made with pulmonary homograft (shown shaded), with collaterals left alone. C, The pulmonary arteries have grown to a larger size, and a larger pulmonary homograft has replaced the earlier small one. Collateral arteries are now anastomosed (unifocalized) to the originally hypoplastic PA branches. The ventricular septal defect (VSD) may be closed at a later time usually 1 to 3 years of age. The pulmonary homograft is usually replaced with a larger graft at this time.

    Bottom row (nonconfluent PA and multiple collaterals): A, Absent central PA and multiple aortic collaterals are shown. B, A small pulmonary homograft (6–8 mm internal diameter, shown shaded) is used to establish the RV-to-PA connection with some collaterals connected to it (unifocalized) (performed at 3–6 mo). Some collaterals are not unifocalized at this time. C, The homograft conduit has been replaced with a larger one. Remaining collateral arteries are anastomosed to the pulmonary homograft to complete unifocalization procedure. The VSD is closed with or without fenestration, usually at 1 to 3 years.



Surgical steps used in patients with TOF with pulmonary atresia are summarized in Figure 14-28 .




FIGURE 14-28


Surgical approaches for tetralogy of Fallot with pulmonary atresia (or pulmonary atresia and ventricular septal defect [VSD]). MAPCAs, multiple aortopulmonary artery collaterals; PA, pulmonary artery; PBF, pulmonary blood flow; RV-PA, right ventricle–to–pulmonary artery.


Postoperative Follow-up




  • 1.

    Frequent follow-up is needed to assess the palliative surgery and decide on appropriate times for further surgeries.


  • 2.

    Valved conduits or homografts may develop valve degeneration requiring conduit replacement at a later time. Valvular stenosis can be dilated with a balloon to reduce the pressure gradient but often result in significant valve regurgitation, eventually leading to RV dysfunction. Many of these patients require surgical replacement of the conduit.


  • 3.

    Recently, Bonhoeffer and his colleagues (2000) have developed a technique in which a dysfunctional conduit or homograft valve can be replaced by percutaneous replacement of pulmonary valve, and more children and adults have successfully had this procedure done ( Khambadkone et al, 2005 ). A bovine jugular venous valve was mounted into the platinum stent and loaded in the delivery system. The assembly was delivered (implanted) in the RVOT according to standard stent-placing technique using an 18-Fr long sheath through a right femoral approach. This valve is marketed as the Melody transcatheter pulmonary valve. The other commercially available valve for use in the RVOT is the Edwards SAPIEN valve (Edwards Lifescience, Irvine, CA), a balloon-expandable stainless steel stent containing a bovine pericardial valve. Experience with this valve is extremely limited.


  • 4.

    Survivors of the defect may need antibiotic prophylaxis for SBE for an indefinite period.


  • 5.

    A certain level of activity restriction is needed because many of these children have exercise intolerance. Most survivors after complete repair are in New York Heart Association (NYHA) class I or II symptomatically.


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Apr 15, 2019 | Posted by in CARDIOLOGY | Comments Off on Cyanotic Congenital Heart Defects

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