Tetralogy of Fallot With Pulmonary Atresia 

Updated: Nov 22, 2015
Author: Michael D Pettersen, MD; Chief Editor: Howard S Weber, MD, FSCAI 

Overview

Background

Because of the wide variability of pulmonary blood supply, diagnosis and surgical management of tetralogy of Fallot (TOF) with pulmonary atresia (PA) is more difficult than that of classic tetralogy of Fallot,[1] and therefore, it is worthy of separate consideration. 

Tetralogy of Fallot is composed of a malaligned ventricular septal defect (VSD), anterior shift of the aorta over the VSD (overriding aorta), obstruction of the right ventricular outflow tract, and right ventricular hypertrophy (see the following video). Pulmonary atresia with VSD is considered the extreme end of the anatomic spectrum of tetralogy of Fallot.

Parasternal long axis two-dimensional echocardiographic image demonstrating a large malalignment ventricular septal defect with overriding of the aorta over the ventricular septum.

See also Tetralogy of Fallot, Tetralogy of Fallot With Pulmonary Stenosis, and Tetralogy of Fallot With Absent Pulmonary Valve.

Epidemiology

Tetralogy of Fallot with pulmonary atresia accounts for about 2% of congenital heart disease. The Baltimore Washington Infant study reported an incidence of tetralogy of Fallot with pulmonary atresia of 0.07 case per 1000 live births. Tetralogy of Fallot with pulmonary atresia accounted for 20.3% of all forms of tetralogy of Fallot.[2]

There is no known race or sex predilection for tetralogy of Fallot with pulmonary atresia. This condition may become symptomatic at birth in most cases as the ductus arteriosus closes, although a delayed diagnosis may occur when additional sources of pulmonary blood flow besides the ductus arteriosus are present.

Anatomy

The lungs develop from the foregut and carry their nutrient supply from the paired dorsal aortae. The paired sixth aortic arches also give rise to branches that form an anastomosis with the pulmonary vascular tree at 27 days' gestation. Over time, the branches from the descending thoracic arch become smaller, and the sixth aortic arch becomes larger.

The aorta and pulmonary arteries form from the distal bulbus cordis and the truncus arteriosus, which are positioned above the right ventricle. The bulbotruncal ridges separate the great arteries, and the aortic component posteriorly rotates. However, faulty rotation of the bulbus-truncus in tetralogy of Fallot (TOF) results in incomplete transfer of the aorta above the left ventricle. Malalignment of the infundibular septum to the trabecular septum is present, resulting in a malalignment ventricular septal defect (VSD).

Anterior displacement of the bulbotruncal region has been postulated to cause the infundibular stenosis. Another theory that has been suggested to cause tetralogy of Fallot is underdevelopment of the subpulmonic infundibulum that results in maldevelopment of the conal septum. Little or no evidence supports this hypothesis.

The anatomy of the pulmonary arteries and the source of pulmonary artery blood supply may widely vary in tetralogy of Fallot with pulmonary atresia (TOF-PA).[3] Persistence of descending thoracic branches accounts for the abnormal pulmonary arterial supply in this condition. Major aortopulmonary collateral arteries (MAPCAs) may anastomose at any site in the pulmonary vascular tree. Most frequently, the right and left pulmonary arteries are patent and maintain free communication with each other and are therefore termed confluent pulmonary arteries. The pulmonary arteries may also be hypoplastic and nonconfluent with no antegrade pulmonary blood flow present from the right ventricle to the pulmonary arteries. The ductus arteriosus is an important source of blood supply to the central branch pulmonary arteries—and when absent indicates the present of MAPCAs.[4]

Classification of pulmonary atresia with VSD depends on the predominant source of blood supply to the bronchopulmonary segments. These range from the native confluent, and possibly absent, central pulmonary arteries supplied solely by the ductus arteriosus to nonconfluent pulmonary arteries, with multiple major aortopulmonary collateral vessels supplying pulmonary blood flow.

Rare sources of pulmonary blood flow include an aortopulmonary window, a persistent fifth aortic arch, and coronary–to–pulmonary artery fistulae. Identification of the pulmonary arterial supply is essential in planning the type of surgical repair.

Etiology

Many patients with tetralogy of Fallot with pulmonary atresia (TOF-PA) have associated syndromes and extracardiac malformations.

CATCH22 syndrome

Conotruncal cardiac malformations associated with a chromosome arm 22q11 deletion have been incorporated under an acronym of CATCH22 (cardiac defect, abnormal face, thymic hypoplasia, cleft palate, hypocalcemia, microdeletion of band 22q11). Patients with tetralogy of Fallot with pulmonary atresia have a higher incidence of this syndrome than patients with classic tetralogy of Fallot. The prevalence of deletion 22q11 is 16% in tetralogy of Fallot with pulmonary atresia with confluent pulmonary arteries and 41% in patients with tetralogy of Fallot with pulmonary atresia and multiple aortopulmonary collateral arteries.[5] Surgical mortality has been reported to be greater among patients with tetralogy of Fallot with pulmonary atresia with a 22q11 deletion compared with patients with normal chromosomes, perhaps due to depressed immunologic status or other factors.[6]

Other syndromes

Other syndromic associations include VATER syndrome (vertebral defects, anal atresia, tracheoesophageal fistula with esophageal atresia, and renal and radial anomalies); CHARGE syndrome (coloboma, heart disease, atresia choanae, retarded growth and retarded development and/or central nervous system [CNS] anomalies, genital hypoplasia, and ear anomalies and/or deafness); Alagille syndrome; cat's eye syndrome; Cornelia de Lange syndrome; Klippel-Feil syndrome; and trisomy 21.[7]

Maternal diabetes mellitus; maternal phenylketonuria; and maternal ingestion of retinoic acid, trimethadione, serotonin reuptake inhibitors, or sex hormones increase the risk of conotruncal abnormalities. Infants of mothers with diabetes mellitus have a 20-fold higher risk of these anomalies than infants of mothers without diabetes mellitus.

The recurrence risk of siblings with tetralogy of Fallot is 3-4%. The recurrence risk increases further if syndromic variants are present.

Variable patterns of inheritance may be observed.

Prognosis

The prognosis of tetralogy of Fallot with pulmonary atresia (TOF-PA) depends on the specific anatomy and type of intervention. Survival before the advent of modern surgical techniques rarely occurred, with less than 5% of patients reaching age 25 years.[8, 9] Survival into late adulthood without surgical intervention has been reported.[10] Surgical morbidity and mortality and long-term survival have steadily improved into the current era, with most of these patients now surviving into adulthood.[11] In patients with operable pulmonary arteries, survival rates with satisfactory quality of life reach 90%.

Long-term follow up data are not widely available; however, recent outcome does seem to be more favorable. Most patients who undergo placement of a right ventricle-to-pulmonary conduit require numerous conduit replacements throughout their lifetime, owing to progressive stenosis or insufficiency of the bioprosthetic valve.[12, 13]

Patients with inadequate pulmonary blood flow and marked cyanosis develop complications affecting multiple organ systems, including hematologic, skeletal, renal, and neurologic, causing significant morbidity and mortality.

In patients with large aortopulmonary collaterals and excessive pulmonary blood flow, congestive heart failure (CHF) may result in failure to thrive (FTT) within the first few months of life.[14]

Patients with tetralogy of Fallot and nonconfluent pulmonary arteries are subject to increased morbidity and mortality related to the frequent need for multiple cardiac surgeries. The risks of cardiopulmonary bypass and anesthesia are also present at each stage of the repair.

Surgical mortality has been reported to be greater among patients with tetralogy of Fallot with pulmonary atresia with a 22q11 deletion compared with patients with normal chromosomes.[6]

In a retrospective observational study (1997-2014) of 48 adult patients with congenital heart disease who underwent heart transplantation, investigators reported that death was significantly associated with a minimum of 3 sternotomies and a MELD-XI (model of end-stage liver disease excluding international normalized ratio [INR]) score greater than 18.[15]  Both 1- and 5-year survival were 77%. The diagnoses included in the study included TOF-PA/double-outlet right ventricle (n=15), D-transposition of the great arteries (TGA) (n=10), tricuspid atresia/double-inlet left ventricle (n=9), ventricular or atrial septal defect (n=4), heterotaxy (n=3), congenitally corrected TGA (n=2), and other diagnoses (n=5).[15]

Complications

Complications may include the following:

  • Residual right ventricular dysfunction from hypoplastic pulmonary arteries, conduit stenosis, or pulmonary valve insufficiency

  • Cyanosis, hypoxemia, and polycythemia, if not surgically corrected

  • Atrioventricular conduction abnormalities, right bundle branch block, ventricular arrhythmias in the postoperative patient

Patient Education

Educate patients and/or their families about anatomic details and long-term prognosis, the potential need for multiple surgeries and catheterizations, and postoperative complications. Moreover, at all patient care visits, emphasize the need for bacterial endocarditis prophylaxis if clinically indicated.

Genetic counseling is strongly recommended in patients of childbearing age; the chance that patients with tetralogy of Fallot could have an offspring with congenital heart disease is as high as 15%. Patients with signficant residual hemodynamic abnormalities are advised to avoid pregnancy, because it carries significant mortality risk to both the mother and fetus.

Exercise tolerance and need for restrictions on physical activity depend on the type of repair and hemodynamic state of the patient. Exercise recommendations must be tailored to individual patients by considering the presence of cyanosis, right ventricular hypertension, right ventricular dysfunction, or dysrhythmias. Patients with cyanosis have significantly limited exercise capacity.

Children and adults who have had complete repair of tetralogy of Fallot with pulmonary atresia may have limited exercise tolerance due to ventricular dysfunction, chronotropic impairment, right ventricular outflow tract obstruction/valve insufficiency, or distal pulmonary artery stenoses.

For patient education information, see Tetralogy of Fallot.

 

Presentation

History and Physical Examination

Clinical presentation in tetralogy of Fallot with pulmonary atresia (TOF-PA) depends on the source and volume of pulmonary blood flow. This usually occurs via the ductus arteriosus and/or aortopulmonary collaterals.

Infants and older children

The newborn infant, in whom the ductus arteriosus is the sole source of pulmonary blood flow, is often symptomatic within the first hours to days of life and becomes increasingly cyanotic as the ductus closes. In the presence of significant aortopulmonary collaterals, cyanosis may be absent. If adequate collaterals or additional sources of pulmonary blood flow are lacking, closure of the ductus may produce hypoxemia too severe for survival. Thus, early recognition of the diagnosis along with prompt institution of prostaglandin E1 (PGE1) infusion is life saving in this instance.

Conversely, when the aortopulmonary collaterals constitute the only source of pulmonary blood flow, the clinical presentation may vary from cyanosis with inadequate pulmonary blood flow to no cyanosis with increased pulmonary blood flow. Uncommonly, pulmonary blood flow is sufficiently increased to cause symptoms due to pulmonary overcirculation (poor feeding, excessive sweating, rapid breathing).

Older infants and children commonly present with cyanosis as the child outgrows the source(s) of pulmonary blood flow. The presence and degree of cyanosis depends on the adequacy of pulmonary blood flow and may range from none to severe. Peripheral pulses are normal in most patients, but they may be bounding in patients with exuberant pulmonary blood flow.

On rare occasions, patients with well-developed aortopulmonary collaterals or persistent patency of the ductus arteriosus may present with heart failure. Symptoms develop several weeks after birth as pulmonary vascular resistance (PVR) decreases and pulmonary blood flow increases.

Peripheral pulses and blood pressures are usually normal during the first few days of life. Patients with increased pulmonary blood flow may be noted to have bounding pulses.

Auscultation reveals a normal first heart sound with a single second heart sound. A systolic murmur may be audible along the lower left sternal border. Because the right ventricular outflow tract is atretic, there is no separate loud systolic ejection murmur at the upper left sternal border that is typical of the usual form of tetralogy of Fallot. If a patent ductus arteriosus is present, a continuous murmur usually is heard after the first 4-6 weeks of life. If systemic-to-pulmonary collateral vessels are present, continuous murmurs can be heard over the back or in the axillae.

Patients with palliative surgical history

Patients who have undergone palliative surgical procedures may also present with variable symptomatology. Most palliative procedures are intended to augment pulmonary blood flow and improve growth of the central branch pulmonary arteries by placement of a systemic-to-pulmonary artery shunt. These shunts may distort the pulmonary vasculature, resulting in branch pulmonary artery stenosis, or they may cause stenosis.

Pulmonary artery hypertension and elevated pulmonary vascular resistance has been noted in the presence of large systemic-to-pulmonary connections. This problem was prevalent with the Waterston (direct anastomosis of the ascending aorta to the pulmonary artery) and the Potts (direct anastomosis of the descending aorta to the pulmonary artery) shunts, both of which have been largely abandoned.

 

DDx

Diagnostic Considerations

Because inadequate collaterals (major aortopulmonary collateral arteries [MAPCAs]) may produce hypoxemia too severe for survival for newborn infants with closure of the ductus arteriosus, early recognition of tetralogy of Fallot with pulmonary atresia (TOF-PA) is critical.

Associated syndromes and extracardiac malformations are not uncommon in patients with TOF-PA (see Etiology). Thus, also consider conditions such as asplenia and polysplenia heterotaxy, double-outlet right ventricle with severe pulmonary stenosis or atresia, and single ventricle with severe pulmonary stenosis or atresia.

Differential Diagnoses

 

Workup

Approach Considerations

Pulse oximetry in the newborn, now the standard of care prior to discharge, is critical in determining the degree of systemic desaturation, which might not be obvious on clinical examination. An abnormal newborn screening pulse oximetry evaluation would result in additional diagnostic testing by a pediatric cardiologist.  In older, unrepaired cyanotic patients, obtain a complete blood cell (CBC) count to determine hemoglobin and hematocrit levels. In infants, arterial blood gas (ABG) measurement can assess their partial pressure of oxygen (PO2) and acid-base status, although at this age it is very unusual to demonstrate a metabolic acidosis.

Electrocardiographic (ECG) findings are similar to those of other patients with tetralogy of Fallot. Right ventricular hypertrophy with right-axis deviation is usually present. Biventricular hypertrophy may occur in infants with cardiac failure from excessive pulmonary blood flow.

Fluorescent in situ hybridization (FISH) analysis may be performed to detect a chromosome arm 22q deletion.

Radiologic Studies

Although chest radiography, magnetic resonance imaging (MRI), and multidetector computed tomography (MDCT) scanning can be helpful in the evaluation of a patient with tetralogy of Fallot and pulmonary atresia (TOF-PA), 2-dimensional (2-D) ultrasonography (echocardiography and Doppler) is the most important imaging modality for this condition.

Radiography, MRI, and MDCT scanning

Chest radiography demonstrates a normal-sized, boot-shaped heart with decreased pulmonary vascular markings in cyanotic patients. A concavity in the region of the main pulmonary artery is evident, and approximately 26-50% of these patients have a right-sided aortic arch. Increased pulmonary vascularity may be observed in the presence of large aortopulmonary collaterals (major aortopulmonary collateral arteries [MAPCAs]).

In centers with expertise, MRI may be used as a noninvasive method of visualizing the pulmonary arteries and their collateral supply.[16, 17] MDCT scanning can also provide excellent delineation of the pulmonary arterial circulation.[18, 19]

O'Meagher et al suggest that right ventricular mass is associated with exercise capacity in adults with repaired tetralogy of Fallot and, thus, right ventricular mass as measured on cardiac MRI may be a novel marker for clinical progress in this patient population.[20] In their study of 82 adults with repaired tetralogy of Fallot, including 9 patients with repaired TOF-PA with ventricular septal defect, peak work was significantly and positively associated with right ventricular mass, independent of other cardiac MRI variables.[20]

2-D Ultrasonography

2-D echocardiography with color flow and 2-D Doppler is the most important tool in the diagnosis of tetralogy of Fallot with pulmonary atresia.

Parasternal long-axis view

The parasternal long axis view reveals a large aortic valve that overrides a large malalignment ventricular septal defect (VSD). 2-D and color flow imaging demonstrates lack of patency of the right ventricular outflow tract (see the videos below).

Parasternal long axis two-dimensional echocardiographic image demonstrating a large malalignment ventricular septal defect with overriding of the aorta over the ventricular septum.
Parasternal long axis two-dimensional echocardiographic image in a patient status post complete repair of tetralogy of Fallot with pulmonary atresia. A patch is visualized closing the ventricular septal defect.
Parasternal long axis color compare echocardiographic image showing the pulmonary artery conduit arising from the right ventricle.

Suprasternal and high parasternal views

The suprasternal and high parasternal views provide information regarding the pulmonary trunk, right and left pulmonary artery size, and their confluence (see the following video). The pulmonary arteries usually appear hypoplastic and may not be visualized at all.

Suprasternal long axis color flow echocardiographic image showing a large patent ductus arteriosus supply confluent pulmonary arteries.

Other

Color-flow imaging may help to identify sources of pulmonary artery blood flow, including the ductus arteriosus (DA) and aortopulmonary collaterals (MAPCAs). Significant hypoplasia of the central pulmonary arteries is highly predictive of an absent or very small DA prenatally and the presence of aortopulmonary collaterals (MAPCA's).[21] If collaterals are suspected, echocardiography alone is inadequate for complete delineation of pulmonary blood flow, and further imaging by MRI or angiography is recommended.[22]

See the videos below for the presence of aortopulmonary collaterals and pulmonary valve atresia, respectively.

Aortopulmonary view angiogram, with injection in the descending thoracic aorta demonstrating multiple aortopulmonary collaterals supplying pulmonary blood flow.

Determination of aortic arch sidedness and the branching pattern of the brachiocephalic vessels is important, particularly if an initial aorta-pulmonary artery shunt is planned.

Subcostal sagittal plane two-dimensional echocardiographic image showing pulmonary valve atresia, with confluent and well-developed pulmonary artery branches.

Cardiac Catheterization and Angiography

Cardiac catheterization with angiography is recommended in most patients before surgical repair. Careful delineation of all sources of pulmonary blood supply is necessary to facilitate surgical planning. This includes determination of the presence, size, and confluence of the native pulmonary arteries and the presence of major aortopulmonary collaterals that may need to be either ligated or incorporated into the repair.

Technique

A femoral venous approach may be used to perform the right heart catheterization. The catheter does not pass across the pulmonary valve but can easily pass across the ventricular septal defect (VSD) into the left ventricle and aorta.

Coronary artery anatomy is delineated by an aortic root injection, although this is usually not necessary in newborns unless a complete surgical repair via a Rastelli procedure (right ventricle to central pulmonary artery conduit) is being considered.

Angiographic depiction of the pulmonary arteries may be performed either via a transvenous or retrograde arterial approach. This also allows easier access to imaging of both surgical shunts and aortopulmonary collaterals. Biplane angiography that includes both lung fields is important in defining the complete anatomy of both pulmonary arteries. Determining the confluence and patency of pulmonary arteries is of utmost importance. Further selective angiograms may be obtained to delineate the systemic-to-pulmonary collateral flow and anatomy.

In some patients, ventriculography and aortography do not demonstrate central true pulmonary arteries. In these patients, pulmonary vein reverse wedge angiography may provide this information. An end-hole catheter is passed across the atrial septum and wedged into a pulmonary vein. (Bilateral injections may be necessary.) A forceful injection of contrast medium by hand causes the contrast to flow retrograde through the pulmonary veins, reaching the central pulmonary arteries.

Findings

Venous catheterization usually reveals normal right atrial pressures. Right and left ventricular pressures are equal and systemic because of the presence of a large VSD. The aortic pressure is normal if pulmonary blood flow is normal or decreased. A wide pulse pressure may be observed in the presence of a large ductus arteriosus or large MAPCAs. Pulmonary artery pressures are difficult to delineate in view of the multiple sources of pulmonary blood flow.

Systemic arterial saturation is dependent on the amount of pulmonary blood flow.

The pulmonary arteries may be depicted as confluent or nonconfluent, and areas of stenoses or hypoplasia in the pulmonary arteries may be observed. Special attention is necessary to determine the presence of a dual supply of a particular lung segment. Intercommunications between the different collateral vessels and the peripheral pulmonary artery segments may be observed.

Postprocedure precautions

Taking appropriate precautions often avoids the potential complications of cardiac catheterization, including blood vessel injury, perforation, tachyarrhythmias, bradyarrhythmias, and vascular occlusion.

General postcatheterization precautions include monitoring for hemorrhage, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm. Pay special attention to the hydration status of infants who require multiple angiograms to outline their pulmonary arterial anatomy. Attempt to limit the amount of contrast medium to 5-6 mL/kg. These patients are hypoxemic, requiring continuous pulse oximetry, and may require oxygen during and after the procedure. Give special attention to obtaining hemostasis and applying a pressure dressing at the access sites postcatheterization.

 

Treatment

Approach Considerations

Admit patients with tetralogy of Fallot with pulmonary atresia (TOF-PA) for testing and potential surgical intervention. Transfer to a tertiary care center is indicated for complete diagnostic evaluation and surgical intervention.

Newborn infants with cyanosis due to congenital heart disease almost always benefit from administration of prostaglandin E1 (PGE1) to maintain ductal patency while a definitive diagnosis is made. Once the diagnosis of TOF-PA is made, the need for a PGE1 infusion is dependent on whether a ductus arteriosus is, in fact, present. If the only sources of pulmonary blood flow are major aortopulmonary collateral arteries (MAPCAs), then a PGE1 infusion is not necessary.

Older infants with increased pulmonary blood flow may require treatment for heart failure.

All patients with TOF-PA who have undergone either palliative surgical intervention (shunt procedure) or complete repair (conduit placement) are required to take appropriate prophylactic antibiotics to avoid bacterial endocarditis.

Findings from a retrospective study of 12 patients with TOF-PA and MAPCAs suggest that use of pulmonary hypertension medications may provide symptomatic improvement and are well tolerated.[14] It remains unknown whether these medications confer any long-term survival benefit in those with complex congenital heart disease.[14]

Nutritional support

Infants who are born with multiple systemic-to-pulmonary collaterals and are in cardiac failure because of pulmonary overcirculation require caloric supplementation to establish a normal growth pattern. Caloric intake as high as 130-150 kcal/kg/d may be required to ensure adequate growth.

Children that undergo palliative procedures also require optimization of their caloric intake. Adequate nutritional supplementation in the form of total parental nutrition must also be ascertained in the perioperative period. These patients often have a prolonged postoperative recovery course.

Surgical Intervention

Neonates with adequate-sized confluent pulmonary arteries may be amenable to primary definitive surgical repair. A palliative procedure with a systemic–to–pulmonary artery shunt may be performed to promote central pulmonary artery growth prior to complete repair at a later date. The ultimate surgical goals are: (1) to incorporate as many pulmonary artery segments as possible into a pulmonary artery confluence, (2) to place a conduit from the right ventricle to the pulmonary artery confluence, and (3) to close the ventricular septal defect (VSD). While the primary intervention in the majority of patients is surgical, selected cases may be amenable to transcatheter perforation of the right ventricular outflow tract followed by balloon dilation.[23]

Hypoplastic pulmonary arteries

When the pulmonary arteries are hypoplastic, nonconfluent, and supplied by aortopulmonary collaterals, a multistaged repair is often required.[24] Hypoplastic pulmonary arteries generally require palliative shunting to induce enlargement and growth of these vessels so they can be successfully incorporated into the complete repair. The shunts used may be a modified Blalock-Taussig or central shunt and may be unilateral or bilateral. Another important strategy to maximize the long-term outcome in this group of patients is the early unifocalization of as many of the aortopulmonary collaterals as possible into a central pulmonary artery confluence.[25, 26, 27, 28] This maximizes the recruitment of lung segments, increasing the cross-sectional area of the pulmonary vascular bed, and it may increase the likelihood of performing a definitive repair.

Complete repair following palliation

For complete repair to be performed in a child who has undergone palliation: (1) The central pulmonary arterial area must be greater than 50% of normal; (2) predominantly left-to-right shunting at the ventricular level (VSD) must be present; (3) the equivalent of an entire lung must be supplied by the central pulmonary artery confluence; and (4) stenotic lesions in the pulmonary artery outflow must be addressed.

The choice of the optimal type of conduit for a growing child remains controversial. Current options include cryopreserved aortic or pulmonary homografts, glutaraldehyde fixed bovine jugular vein grafts, and synthetic conduits, with variable intermediate-term results reported in the medical literature.[29, 30, 31] Patients with membranous pulmonary atresia may be amenable to repair using a pulmonary transannular patch. These patients have an improved freedom from reintervention compared with patients who receive right ventricle-to-pulmonary artery conduits.[32]

Significant pulmonic valve regurgitation often occurs regardless of the type of conduit placed between the right ventricle and the pulmonary arteries. Some patients develop substantial right ventricular dilation and right ventricular dysfunction. Surgical placement of a pulmonic valve may significantly benefit these patients. More recently, a transcatheter-placed pulmonary valve comprising a valved segment of bovine jugular vein sewn within a balloon-expandable stent has been made commercially available. This valve can be placed in patients with postoperative conduit dysfunction consisting of pulmonary regurgitation, obstruction, or both. However, the existing conduit has to be approximately 16 mm in diameter at the time of its original implantation. Early and midterm results with this valve suggest a high rate of procedural success and encouraging valve function.[33]

Single-stage repair

Some centers have shifted toward performing a single-stage repair, wherein all the multiple aortopulmonary collaterals (MAPCAs) are ligated at the aorta.[34, 35] These MAPCAs are then mobilized toward the posterior mediastinum to construct a pulmonary artery confluence, followed by insertion of a pulmonary allograft to establish continuity between these neopulmonary arteries and the right ventricle. The ventricular septal defect (VSD) is closed.

These centers have reported good results. Infants with postunifocalization pulmonary arteries that, combined, are only mildly hypoplastic (> 200 mm2/m2) have a lower mortality rate and acceptable right ventricular pressures. However, many patients require repeat catheterizations for balloon dilation or stent placements in stenotic pulmonary artery segments to alleviate elevated right ventricular pressures.[36]

Consultations

The following consultations are advised:

  • Pediatric cardiology consultation

  • Geneticist consultation to evaluate the presence of syndromic associations and gene deletions, especially in the presence of associated anomalies or dysmorphic features

  • Cardiovascular surgical consultation, once the anatomy of a child with tetralogy of Fallot with pulmonary atresia (TOF-PA) is determined by echocardiography and angiography findings (see Workup);the caregivers need to be aware of the possibility of a multistage repair and repeated surgeries and catheterizations

  • Consultations and follow-up with the appropriate specialists for anomalies involving other systems

Long-Term Monitoring

Infants with multiple aortopulmonary collaterals may require outpatient medical management of heart failure.

Residual right ventricular hypertension with right ventricular dysfunction from hypoplastic pulmonary arteries may be present.

After each stage of surgical reconstruction, echocardiographic evaluation of hemodynamic adequacy should be performed. After complete repair and during clinical follow-up, the patient needs to be evaluated for the development of right ventricle–to–pulmonary artery conduit stenosis as well as pulmonary valve regurgitation.

Some patients may never reach the stage of complete repair because of very hypoplastic and discontinuous pulmonary arteries. These patients are often hypoxemic and polycythemic, requiring oxygen supplementation. Patients who are chronically cyanotic should be carefully monitored for complications related to polycythemia and iron deficiency anemia.

 

Medication

Medication Summary

Newborns with tetralogy of Fallot with pulmonary atresia (TOF-PA) may require the ductus arteriosus (DA) as the main source of pulmonary blood flow. A prostaglandin E1 (PGE1) (Alprostadil) infusion maintains patency of the ductus.

Infants with multiple systemic pulmonary collaterals may develop symptomatic heart failure requiring medical therapy.

Prostaglandins

Class Summary

Prostaglandin E1 (PGE1) (Alprostadil) is a vasodilating agent that also promotes dilatation of the ductus arteriosus (DA) in infants with ductal-dependent cardiac abnormalities.

Alprostadil IV (Prostin VR Pediatric Injection)

Alprostadil is first-line palliative therapy to temporarily maintain patency of the ductus arteriosus (DA) before surgery. This agent is beneficial in infants who have congenital defects that restrict pulmonary or systemic blood flow and who depend on a patent DA for adequate oxygenation and lower body perfusion. Alprostadil produces vasodilation and increases cardiac output. Each 1-mL ampule contains 500 mcg/mL.

Diuretic agents

Class Summary

Diuretic agents promote excretion of water and electrolytes by the kidneys. These drugs are used to treat heart failure or hepatic, renal, or pulmonary disease when sodium and water retention results in edema or ascites. Children who have congestive heart failure (CHF) symptoms often require multiple diuretics for effective control.

Furosemide (Lasix)

Furosemide increases excretion of water by interfering with the chloride-binding cotransport system, which in turn inhibits sodium and chloride reabsorption in the ascending loop of Henle and distal renal tubule. Individualize the drug dose to the patient. Depending on the clinical response, administer adult doses at increments of 20-40 mg, no sooner than 6-8 hours after the previous dose, until the desired diuresis occurs. When treating infants, titrate with 1-mg/kg/dose increments, until a satisfactory effect is achieved.

Spironolactone (Aldactone)

Spironolactone is used for management of edema resulting from excessive aldosterone excretion. This agent competes with aldosterone for receptor sites in the distal renal tubules, increasing water excretion while retaining potassium and hydrogen ions.

Hydrochlorothiazide (Microzide)

Hydrochlorothiazide inhibits the reabsorption of sodium in the distal tubules, causing an increased excretion of sodium and water, as well as potassium and hydrogen ions.

Inotropic agents

Class Summary

Positive inotropic agents increase the force of contraction of the myocardium and are used to treat acute and chronic congestive heart failure (CHF). Poor ventricular function may necessitate the use of inotropic medications.

Digoxin (Lanoxin)

Digoxin is a cardiac glycoside with direct inotropic effects and indirect effects on the cardiovascular system. This agent acts directly on cardiac muscle, increasing myocardial systolic contractions. Indirect actions result in increased carotid sinus nerve activity and enhanced sympathetic withdrawal for any given increase in mean arterial pressure.