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Tetralogy of Fallot With Pulmonary Atresia
Article Last Updated: Jul 17, 2006
AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Michael Pettersen, MD, Director of Echocardiography, Department of Pediatrics, Children's Hospital of Michigan, Assistant Professor, Wayne State University School of Medicine
Michael Pettersen is a member of the following medical societies: American Academy of Pediatrics
Coauthor(s):
Aparna Kulkarni, MBBS, MD, Fellow, Department of Cardiology, Children's Hospital of Michigan
Editors: Ira H Gessner, MD, Professor Emeritus, Pediatric Cardiology; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; Ameeta Martin, MD, Associate Professor, Department of Pediatrics, Section of Pediatric Cardiology, University of Nebraska College of Medicine; Gilbert Herzberg, MD, Assistant Professor, Department of Pediatrics, Section of Pediatric Cardiology, New York Medical College; Stuart Berger, MD, Professor of Pediatrics, Division of Cardiology, Medical College of Wisconsin; Chief of Pediatric Cardiology, Medical Director of Pediatric Heart Transplant Program, Medical Director of The Heart Center, Children's Hospital of Wisconsin
Author and Editor Disclosure
Synonyms and related keywords:
tetralogy of Fallot, TOF, tetralogy of Fallot with pulmonary atresia, TOF-PA, pulmonary atresia with ventricular septal defect, VSD, end-stage tetralogy of Fallot, Fallot tetralogy, Fallot's tetralogy, Fallot tetrad, Fallot's tetrad
Background
Tetralogy of Fallot (TOF) is comprised 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. Pulmonary atresia (PA) with VSD is considered the extreme end of the anatomic spectrum of TOF. TOF-PA is worthy of separate consideration. Because of the wide variability of pulmonary blood supply, diagnosis and surgical management of TOF-PA is more difficult than that of classic TOF.
Embryology
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 on day 27 of 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 rotates posteriorly. However, faulty rotation of the bulbus-truncus in 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 VSD. Anterior displacement of the bulbotruncal region has been postulated to cause the infundibular stenosis. Another theory that has been suggested to cause TOF is underdevelopment of the subpulmonic infundibulum that results in maldevelopment of the conal septum. Little or no evidence exists to support this hypothesis, however.
Anatomy
Anatomy of the pulmonary arteries and the source of pulmonary artery blood supply may be highly variable in TOF-PA. Persistence of descending thoracic branches accounts for the abnormal pulmonary arterial supply in this condition. Major aortopulmonary collateral arteries 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; they are termed confluent pulmonary arteries. The pulmonary arteries may also be hypoplastic and nonconfluent. No antegrade blood flow is present from the right ventricle to the pulmonary arteries. The ductus arteriosus (DA) often is an important source of blood supply, although occasionally it is absent.
Classification of PA-VSD depends on the predominant source of blood supply to the bronchopulmonary segments. These range from the native confluent pulmonary arteries supplied solely by the DA to nonconfluent pulmonary arteries with multiple major aortopulmonary collaterals supplying pulmonary blood flow[took out for consistency]. 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.
Pathophysiology
Clinical presentation in TOF-PA depends on the source and volume of pulmonary blood flow. This usually occurs via the DA and/or aortopulmonary collaterals. The newborn infant, in whom the DA is the sole source of pulmonary blood flow, becomes increasingly cyanotic as the DA closes. 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 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 increased sufficiently to cause symptoms due to pulmonary overcirculation. Older infants and children commonly present with cyanosis. Hypoxia usually progresses further as the child outgrows the source of pulmonary blood flow. Early surgical intervention has improved survival in these patients.
Frequency
United States
The Baltimore Washington Infant study reported an incidence of 0.07 per 1000 live births for TOF-PA. This condition accounts for 1.5% of all forms of congenital heart disease and 20% of all forms of TOF.
Mortality/Morbidity
Survival before the advent of modern surgical techniques occurred rarely, with less than 5% of patients reaching age 25 years. In patients with operable pulmonary arteries, survival rates with satisfactory quality of life now reach 90%.
- 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, CHF may result in failure to thrive.
- Patients with TOF-PA and nonconfluent PAs are subject to increased morbidity and mortality related to the frequent need for multiple cardiac surgeries. The risks of cardiopulmonary bypass and anesthesia are present at each stage of the repair.
Race
No known race predilection exists.
Sex
No specific male or female preponderance of TOF-PA has been noted.
Age
TOF-PA becomes symptomatic at birth in most cases. Diagnosis usually occurs at this time.
History
Clinical presentation is variable and largely dependent on the source and volume of pulmonary blood flow.
- An infant with tetralogy of Fallot with pulmonary atresia (TOF-PA) is often symptomatic within the first hours to days of life.
- Severe cyanosis becomes apparent immediately after birth as the DA begins to close. In the presence of significant aortopulmonary collaterals, cyanosis may be mild to moderate. If adequate collaterals or additional sources of pulmonary blood flow are lacking, closure of the DA may produce hypoxemia too severe for survival.
- On rare occasions, patients with well-developed aortopulmonary collaterals or persistent patency of the DA may present with heart failure. Symptoms develop several weeks after birth as pulmonary vascular resistance decreases and pulmonary blood flow increases.
- The older infant and child with adequate pulmonary blood flow supplied by aortopulmonary collaterals presents with a history of cyanosis. Impaired exercise tolerance and growth failure may occur.
- Patients who have undergone palliative surgical procedures may present with variable symptomatology.
- Most palliative procedures are intended to augment pulmonary blood flow by placement of systemic-to-pulmonary artery shunts. These shunts may distort the pulmonary vasculature or may cause stenosis and result in hypoxia.
- 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.
Physical
- Physical findings vary according to the source and volume of pulmonary blood flow.
- Obvious profound cyanosis may be noted in the neonatal period. This becomes severe as the ductus narrows. Patients with significant aortopulmonary collaterals may be mildly cyanotic initially but become increasingly cyanotic if they outgrow their source of pulmonary blood flow.
- 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 present at the left lower sternal border. The typical right ventricular outflow tract murmur of classic TOF is not heard. A soft continuous murmur from the DA may occur at the left base. A continuous murmur from the aortopulmonary collaterals may be heard in the back.
- Growth and development often are delayed.
Causes
- Many patients with TOF-PA have associated syndromes and extracardiac malformations.
- 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 TOF-PA have a higher incidence of this syndrome than patients with classic TOF. The prevalence of deletion 22q11 is 16% in TOF-PA with confluent pulmonary arteries and 41% in patients with TOF-PA and multiple aortopulmonary collateral arteries.
- 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 CNS anomalies, genital hypoplasia, and ear anomalies and/or deafness), Alagille syndrome, cat's-eye syndrome, de Lange syndrome, Klippel-Feil syndromes, and trisomy 21.
- Maternal diabetes mellitus; maternal phenylketonuria; and maternal ingestion of retinoic acid, trimethadione, or sex hormones increase the risk of conotruncal abnormalities. Infants of mothers with diabetes mellitus have a 20-fold higher risk than infants of mothers without diabetes mellitus.
- The recurrence risk of siblings with TOF is 3-4%. The recurrence risk increases further if syndromic variants are present.
- Variable patterns of inheritance may be observed.
Heterotaxy, Asplenia
Heterotaxy, Polysplenia
Pulmonary Atresia With Intact Ventricular Septum
Pulmonary Stenosis, Valvar
Total Anomalous Pulmonary Venous Connection
Transposition of the Great Arteries
Tricuspid Atresia
Other Problems to be Considered
Double outlet right ventricle with severe pulmonary stenosis or atresia
Single ventricle with severe pulmonary stenosis or atresia
Lab Studies
- Obtain a complete blood cell count to determine hemoglobin and hematocrit.
- In infants who are sick, an arterial blood gas can assess pO2, acid-base status.
Imaging Studies
- The chest radiograph depicts a normal-sized boot-shaped heart with decreased pulmonary vascular markings. A concavity in the region of the main pulmonary artery is observed. 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.
- Two-dimensional echocardiography with color flow and 2-dimensional Doppler is the most important tool in the diagnosis.
- The parasternal long axis view reveals a large aortic valve that overrides a large malalignment VSD. Two-dimensional and color flow imaging demonstrates lack of patency of the right ventricular outflow tract.
- The suprasternal and high parasternal views provide information regarding the pulmonary trunk, right and left pulmonary artery size, and their confluence. The pulmonary arteries usually appear hypoplastic and may not be visualized at all.
- Color-flow imaging identifies sources of pulmonary artery blood flow including the DA and aortopulmonary collaterals. Significant hypoplasia of the central pulmonary arteries or presence of a small patent ductus arteriosus (PDA) is highly predictive of the presence of aortopulmonary collaterals. If collaterals are suspected, echocardiography alone is inadequate for complete delineation of pulmonary blood flow, and further imaging by MRI or angiography is recommended.
- Determination of the side of the aortic arch is important, particularly if an initial aorta-pulmonary artery shunt is planned.
- In centers with expertise, MRI may be used as a noninvasive method of visualizing the pulmonary arteries and their collateral supply.
Other Tests
- ECG findings are similar to those of other patients with tetralogy of Fallot (TOF). Right ventricular hypertrophy with right axis deviation is usually present. Biventricular hypertrophy may occur in infants with cardiac failure from excessive pulmonary blood flow. TOF-PA can be differentiated from PA with an intact septum because patients with the latter diagnosis have diminutive anterior QRS forces and left ventricular hypertrophy.
- Fluorescent in situ hybridization (FISH) analysis may be performed to detect a chromosome arm 22q deletion.
Procedures
- Indications: 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 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 VSD into the left ventricle and aorta.
- To visualize the VSD, a ventriculogram should be obtained with injection in the left ventricle. Coronary artery anatomy is delineated by an aortic root injection.
- Angiographic depiction of the pulmonary arteries may necessitate a 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 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 by hand causes contrast to flow retrograde through the pulmonary veins reaching the central pulmonary arteries.
- Results: Venous catheterization usually reveals normal right atrial pressures. Right and left ventricular pressures are equal because of the presence of a large VSD. 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 DA. Pulmonary pressures are low with normal pulmonary vascular resistance but may be elevated in the presence of a large systemic-to-pulmonary shunt.
- Unless an atrial septal defect is present, oxygen saturation in the right atrium is low. Systemic arterial saturation depends on the amount of pulmonary blood flow.
- Ventriculography reveals the position of the VSD. The pulmonary arteries may be depicted as confluent or nonconfluent. Areas of stenoses or hypoplasia in the pulmonary arteries may be observed. Details of the systemic to pulmonary collateral supply are delineated, and special attention may be brought to dual supply of a lung segment. Intercommunications between the different collateral vessels and the peripheral pulmonary artery segments may be observed.
- Postcatheterization precautions: General postcatheterization precautions include hemorrhage, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm. Give 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 to 5-6 mL/kg.
- These patients are hypoxemic 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.
- Complications: Taking appropriate precautions often avoids the potential complications of cardiac catheterization, including blood vessel injury, perforation, tachyarrhythmias, bradyarrhythmias, and vascular occlusion.
Medical Care
- Newborn infants with cyanosis due to congenital heart disease almost always benefit from administration of PGE1 to maintain ductal patency while a definitive diagnosis is made. Once the diagnosis of tetralogy of Fallot with pulmonary atresia (TOF-PA) is made, maintain PGE1 infusion through initial surgery.
- Older infants with increased pulmonary blood flow may require treatment for heart failure.
Surgical Care
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 while awaiting complete repair at a later date. The ultimate surgical goals are to incorporate as many pulmonary artery segments as possible into a pulmonary artery confluence, to place a conduit from the right ventricle to the pulmonary artery confluence, and to close the VSD.
- When the pulmonary arteries are hypoplastic, nonconfluent, and supplied by aortopulmonary collaterals, a multistaged repair is often required. 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 modified Blalock-Taussig or central shunts, and they may be unilateral or bilateral. If the pulmonary arteries have grown after placement of the palliative shunts, unifocalization of the pulmonary arteries can be performed; this is done by incorporating the aortopulmonary collaterals and connecting them to the conduit from the right ventricle.
- For complete repair to be performed in a child who has undergone palliation, the central pulmonary arterial area must be greater than 50% of normal; predominantly left-to-right intracardiac shunting must be present; the equivalent of an entire lung must be supplied by the central pulmonary artery confluence; and stenotic lesions in the pulmonary artery outflow must be addressed.
- Some centers have shifted toward performing a single-stage repair, wherein all the multiple aortopulmonary collaterals (MAPCAs) are ligated at the aorta. 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 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. Most patients, however, require repeat catheterizations for balloon dilation or stent placements in stenotic pulmonary artery segments to alleviate elevated right ventricular pressures.
Consultations
- Pediatric cardiology consultation is advised.
- Consult a geneticist to evaluate the presence of syndromic associations and gene deletions, especially in the presence of associated anomalies or dysmorphic features.
- Once the anatomy of a child with TOF-PA is determined by echocardiography and angiography findings, consultation with a cardiovascular surgeon is required. The caregivers need to be aware of the possibility of a multistage repair and repeated surgeries and catheterizations.
- If anomalies involving other systems are present, consultations and follow-up with the appropriate specialists are required.
Diet
- 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.
- 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.
Activity
Exercise tolerance and need for restrictions on physical activity depend on the type of repair and hemodynamic state of the patient.
- Patients with cyanosis will have significantly limited exercise capacity.
- Children and adults who have had complete repair of TOF-PA may have limited exercise tolerance due to ventricular dysfunction, chronotropic impairment, right ventricular outflow tract obstruction/conduit stenosis, or distal pulmonary artery stenoses.
Newborns with tetralogy of Fallot with pulmonary atresia may require the DA as the source of pulmonary blood flow. A PGE1 (Alprostadil) infusion maintains patency of the ductus.
Infants with multiple systemic pulmonary collaterals may develop symptomatic heart failure requiring medical therapy.
Drug Category: Prostaglandins
PGE1 (Alprostadil) promotes dilatation of the DA in infants with ductal-dependent cardiac abnormalities. It is also a vasodilator.
| Drug Name | Alprostadil (Prostin VR Pediatric Injection) |
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| Description | First-line palliative therapy to temporarily maintain patency of DA before surgery. 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. Produces vasodilation and increases cardiac output. Each 1-mL ampule contains 500 mcg/mL. |
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| Adult Dose | Not indicated |
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| Pediatric Dose | Initial dose: 0.05-0.1 mcg/kg/min IV
Maintenance dose: 0.01-0.4 mcg/kg/min IV
Infuse IV into large vein or umbilical cord |
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| Contraindications | Documented hypersensitivity; hyaline membrane disease; respiratory distress syndrome |
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| Interactions | Limited data exist; use caution with concurrent use of antiplatelet drugs or anticoagulants |
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| Pregnancy | X - Contraindicated in pregnancy
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| Precautions | Adverse effects and toxicity include apnea, seizures, fever, hypotension, leukocytosis, fever, and pulmonary overcirculation; neonates are usually intubated prophylactically because of potential risk of apnea (10-12%); prolonged use is occasionally necessary (in hypoplastic left heart syndrome transplant candidates) and may be associated with third spacing of fluid; monitor blood oxygenation and arterial pressure |
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Drug Category: Diuretic agents
These agents promote excretion of water and electrolytes by the kidneys. They 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 CHF symptoms often require multiple diuretics for effective control.
| Drug Name | Furosemide (Lasix) |
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| Description | Increases excretion of water by interfering with chloride-binding cotransport system, which in turn inhibits sodium and chloride reabsorption in ascending loop of Henle and distal renal tubule. Individualize dose to patient. Depending on response, administer adult doses at increments of 20-40 mg, no sooner than 6-8 h after previous dose, until desired diuresis occurs. When treating infants, titrate with 1-mg/kg/dose increments until satisfactory effect achieved. |
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| Adult Dose | 20-80 mg/d PO/IV/IM; titrate up to 600 mg/d for severe edematous states |
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| Pediatric Dose | 1-2 mg/kg/dose PO; not to exceed 6 mg/kg/dose; do not administer more frequently than q6h
1 mg/kg/dose IV/IM slowly under close supervision; not to exceed 6 mg/kg/d |
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| Contraindications | Documented hypersensitivity; hepatic coma; anuria; severe electrolyte depletion |
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| Interactions | Metformin decreases concentrations; interferes with hypoglycemic effect of antidiabetic agents and antagonizes muscle-relaxing effect of tubocurarine; auditory toxicity appears to be increased with coadministration with aminoglycosides; hearing loss of varying degrees may occur; anticoagulant activity of warfarin may be enhanced when taken concurrently with this medication; increased plasma lithium levels and toxicity are possible when taken concurrently with this medication |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Perform frequent serum electrolyte, CO2, glucose, creatinine, uric acid, calcium, and BUN determinations during first few months of therapy and periodically thereafter |
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| Drug Name | Spironolactone (Aldactone) |
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| Description | For management of edema resulting from excessive aldosterone excretion. Competes with aldosterone for receptor sites in distal renal tubules, increasing water excretion while retaining potassium and hydrogen ions. |
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| Adult Dose | 25-200 mg/d PO qd or divided bid |
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| Pediatric Dose | 1.5-3.5 mg/kg/d PO qd or divided q6-12h |
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| Contraindications | Documented hypersensitivity; anuria; renal failure; hyperkalemia |
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| Interactions | May decrease effect of anticoagulants; potassium and potassium-sparing diuretics may increase toxicity of spironolactone |
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| Pregnancy | D - Unsafe in pregnancy
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| Precautions | Caution in renal and hepatic impairment |
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| Drug Name | Hydrochlorothiazide (HydroDIURIL, Esidrix, Microzide) |
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| Description | Inhibits reabsorption of sodium in distal tubules, causing increased excretion of sodium and water as well as potassium and hydrogen ions. |
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| Adult Dose | 25-100 mg PO qd; not to exceed 200 mg/d |
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| Pediatric Dose | <6 months: 2-3 mg/kg/d PO divided bid
>6 months: 2 mg/kg/d PO divided bid |
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| Contraindications | Documented hypersensitivity; anuria; renal decompensation |
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| Interactions | May decrease effects of anticoagulants, antigout agents, and sulfonylureas; thiazides may increase toxicity of allopurinol, anesthetics, antineoplastics, calcium salts, loop diuretics, lithium, diazoxide, digitalis, amphotericin B, and nondepolarizing muscle relaxants |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Caution in renal disease, hepatic disease, gout, diabetes mellitus, and erythematosus |
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Drug Category: Inotropic agents
Positive inotropic agents increase the force of contraction of the myocardium and are used to treat acute and chronic CHF. Poor ventricular function may necessitate the use of inotropic medications.
| Drug Name | Digoxin (Lanoxin) |
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| Description | Cardiac glycoside with direct inotropic effects and indirect effects on the cardiovascular system. 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. |
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| Adult Dose | 0.125-0.375 mg PO qd |
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| Pediatric Dose | 5-10 years: 20-35 mcg/kg PO
>10 years: 10-15 mcg/kg PO
Maintenance dose: Use 25-35% of PO loading dose |
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| Contraindications | Documented hypersensitivity; beriberi heart disease; idiopathic hypertrophic subaortic stenosis; constrictive pericarditis; carotid sinus syndrome |
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| Interactions | IV calcium may produce arrhythmias in digitalized patients
Medications that may increase levels include alprazolam, benzodiazepines, bepridil, captopril, cyclosporine, propafenone, propantheline, quinidine, diltiazem, aminoglycosides, PO amiodarone, anticholinergics, diphenoxylate, erythromycin, felodipine, flecainide, hydroxychloroquine, itraconazole, nifedipine, omeprazole, quinine, ibuprofen, indomethacin, esmolol, tetracycline, tolbutamide, and verapamil
Medications that may decrease levels include aminoglutethimide, antihistamines, cholestyramine, neomycin, penicillamine, aminoglycosides, PO colestipol, hydantoins, hypoglycemic agents, antineoplastic treatment combinations (eg, carmustine, bleomycin, methotrexate, cytarabine, doxorubicin, cyclophosphamide, vincristine, procarbazine), aluminum or magnesium antacids, rifampin, sucralfate, sulfasalazine, barbiturates, kaolin/pectin, and aminosalicylic acid |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Hypokalemia may reduce positive inotropic effect of digitalis; hypercalcemia predisposes patient to digitalis toxicity, and hypocalcemia can make digoxin ineffective until serum calcium levels are within the reference range; magnesium replacement therapy must be instituted in patients with hypomagnesemia to prevent digitalis toxicity; incomplete AV block may progress to complete block when treated with digoxin; exercise caution in hypothyroidism, hypoxia, and acute myocarditis; adjust dose in renal impairment; highly toxic (overdoses can be fatal) |
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Further Inpatient Care
- Admit for testing and surgical intervention.
- 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. Transcatheter placement of a pulmonic valve currently is under development.
Further Outpatient Care
- 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 and Doppler evaluation of hemodynamic adequacy should be performed. After complete repair, the patient needs to be evaluated for the development of right ventricle–to–pulmonary artery conduit stenosis as well as pulmonic regurgitation.
- A few patients may never reach the stage of complete repair because of very hypoplastic pulmonary arteries. These patients often are hypoxemic and polycythemic and may require oxygen supplementation.
Transfer
- Transfer to a tertiary care center is indicated for complete diagnostic evaluation and surgical intervention.
Complications
- Residual right ventricular dysfunction from hypoplastic pulmonary arteries or conduit stenosis
- Cyanosis, hypoxemia, and polycythemia
- Atrioventricular conduction abnormalities, right bundle branch block, ventricular arrhythmias in the postoperative patients
- Significant pulmonic valve regurgitation
Prognosis
- The prognosis depends on the specific anatomy and type of intervention.
- 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 will require one or more conduit replacements, secondary to progressive conduit stenosis or insufficiency.
Patient Education
- Educate patients and their families about anatomic details and long-term prognosis, the potential need for multiple surgeries and catheterizations, and postoperative complications.
- At all patient care visits, emphasize the need for bacterial endocarditis prophylaxis.
- For excellent patient education resources, visit eMedicine's Heart Center. Also, see eMedicine's patient education article Tetralogy of Fallot.
Medical/Legal Pitfalls
- Failure to consider the diagnosis, especially in a newborn with cyanosis
Special Concerns
- Genetic counseling is strongly recommended in patients of childbearing age; the chance that patients with tetralogy of Fallot (TOF) could have an offspring with CHD is as high as 15%.
- Patients with residual right ventricular dysfunction or pulmonary hypertension are advised to avoid pregnancy because it carries significant mortality risk.
- All patients with TOF-PA are required to take appropriate antibiotic bacterial endocarditis prophylaxis.
- Exercise recommendations must be tailored to individual patients by considering the presence of cyanosis, right ventricle hypertension, right ventricle dysfunction, or dysrhythmias.
| Media file 1:
Parasternal long axis two-dimensional echocardiographic image demonstrating a large malalignment ventricular septal defect with overriding of the aorta over the ventricular septum. |
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Subcostal sagittal plane two-dimensional echocardiographic image showing pulmonary valve atresia, with confluent and well-developed pulmonary artery branches. |
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| Media file 3:
Suprasternal long axis color flow echocardiographic image showing a large patent ductus arteriosus supply confluent pulmonary arteries. |
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| Media file 4:
Aortopulmonary view angiogram, with injection in the descending thoracic aorta demonstrating multiple aortopulmonary collaterals supplying pulmonary blood flow. |
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| Media file 5:
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. |
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| Media file 6:
Parasternal long axis color compare echocardiographic image showing the pulmonary artery conduit arising from the right ventricle. |
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Tetralogy of Fallot With Pulmonary Atresia excerpt Article Last Updated: Jul 17, 2006
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